Drugs Down the Drain

Many years ago a study out of England reported the discovery of mixed-sex fish (primarily male fish with eggs). Although nothing new now, this was one of the first reports of feminized fish. What I remember most about that study, was how we laughed (I was working with some fish physiologists) at some of their possible explanations, which included hormones from the pill or just every-day urine that had been flushed down the toilet.

Years later, the USGS routinely measures drugs, or the remnants of drugs flushed after passing through our bodies, or intentionally flushed by folks wanting to discard old or unused drugs. Scientists are increasingly concerned about the impacts of pharmaceuticals not only on aquatic creatures (imagine swimming in a sea of heart medication, pain killers and birth control pills) but in some cases on drinking water.

Now the American Pharmaceuticals Association (APhA) has teamed up with the U.S. Fish and Wildlife service to educate the public about proper drug disposal through a campaign called SMARxT DISPOSAL.

I don’t have the numbers on how much is estimated to come from intentional disposal and how much is excreted, (although either way – giving drugs a proper burial as described in the disposal guidelines has got to be better than ditching them down the tube – and some, they actually suggest you do flush), but it will be interesting to monitor the impact of this program.

New Journal, Nanotoxicology

For those interested in nanotoxicology, there is a new journal called Nanotoxicology, published by Informa Healthcare. It’s a quarterly and you can review the first issue (just published March 2007) for free, which allows you to access to the first issue. The first article, Toxicology of nanoparticles: A Historical Perspective, by Gunter Oberdorster, Vicki Stone and Ken Donaldson, provides an excellent review. They include some early studies of particles such as viruses and combustion particles that were around well before the age of intentionally manufactured nanomaterials but which fit the nano description, and provided scientists with insights into the movement and fate of very small particles in living systems.

I’d expect an explosive growth in our understanding of how nanoparticles interact with the environment and with living bodies, but it seems there is a long ways to got and an urgency to get there quickly. Notes Oberdorster and others, “There have been many conferences, meetings, and workshops….with as many calls for developing testing strategies, with only few proposals, followed through by far less action.”

This first sample issue is worth a read and the few moments it takes to register for your month-long free access. Other articles include: “Assessing exposure to airborne nanomaterials: Current abilities and future requirements” by Andrew D. Maynard; Robert J. Aitken; Characterization of the size, shape, and state of dispersion of nanoparticles for toxicological studies by Kevin W. Powers; Maria Palazuelos; Brij M. Moudgil; Stephen M. Roberts; and Cellular responses to nanoparticles: Target structures and mechanisms by Klaus Unfried; Catrin Albrecht; Lars-Oliver Klotz; Anna Von Mikecz; Susanne Grether-Beck; Roel P. F. Schins.

Stumbling Through Nanoparticle Definitions

I am still trying to understand the nano-world. It’s a big world and there are many different kinds of very small particles. But I’ve had some trouble finding good definitions of the inhabitants of this new world. What, for example, are quatum dots? And what makes metallic
nanoparticles different from other kinds of nanoparticles?

As discussed earlier down in Whoville, we know that not all nanoparticles (particles smaller than 100 nanometers) are created equally, and, even better -- or worse, depending on your viewpoint and the material -- many nanoparticles aren’t even equal to their larger counter parts. And that really, is just the point, or one of the points at least, of all this technology.

Fortunately for me, the EPA, in their recent Nanotechnology White Paper, organizes nanoparticles into four categories, and though there may be other ways to categorize nanomaterials I found these groupings helpful in understanding the different kinds of nanoparticles that might one day enter our world – if they haven’t already.

Below are EPA's catagorizes for nanomaterials along with some brief examples.

Carbon Based:

Carbon-based nanomaterials include things like fullerenes (cage-like carbon structures) which make up the single walled carbon nanotubes (those are the SWNTs I’ve referred to before) and buckyballs. All are made carbon. Just carbon. When there are 60 carbons involved, a sphere is formed, its a Buckyball. When there are more, the structure is tube – or cage-like, and is made of a single layer of carbons, almost like a tube of chicken wire, it’s a SWNT.

Metal Based:

Metal-base nanomaterials include quantum dots, metal oxides and pure metal nanoparticles. Quantum dots are structures so small that their properties are susceptible to the removal of a single electron. Every living creature depends on a kind of quantum dot for energy production, as electrons are moved around by proteins so the cell can store or use energy.

Manufactured quantum dots can contain a small number of atoms, for example, from tens of atoms to a few hundred. Some manufactured quantum dots are nanosized crystals of various elements (silicon and germanium or cadmium and selenium are a couple of examples), and emit light when excited. What most interesting is that the color of the light, which is based on wavelength, will vary with the size of the crystal or the type of crystal, with smaller particles of a particular crystal emitting light of shorter wavelengths (towards the blue end of the visible light spectrum) and larger particles emitting light of longer wavelengths (towards the red end.)

Titanium dioxide, which you can find in your sunblock lotion, is an example of a metal oxide that is now manufactured as a nano-metal oxide. As explained in an earlier article, it's the nano formulation of this material that allows us to smear the sunblock but avoid looking like a clown.

Metals can also exist as single ions, or larger bulkier structures think gold, or silver. But, as with many nanomaterials, it seems that when metals occur as nanoparticles they may exhibit different properties than their larger counterparts. Nanoized silver (or silver ions), for example, is a potent antimicrobial, but apparently aggregates of silver particles tend to loose their antimicrobial ability.

Dendrimers:

Dendrimers are branched polymers (a polymer is made up of repeating units or monomers. Monomers are molecules that can combine – or polymerize - with similar or identical molecules.) These can be manufactured so that they can carry other molecules within them, such as certain drugs.

Composites:

Composites refer to combinations of nanomaterials with other materials, for example DNA molecules may be combined with various nanomaterials to make a nanosized biocomposite.

These examples just scratch the surface of the world of nanomaterials. But this revolutionary technology is sure to present those charged with protecting human health and the environment a future filled with both opportunity, (providing new materials to clean up and reduce distribution and use of hazardous materials, and new drug formulations) and challenges as health and environmental scientists race to understand the impact of materials that play by new rules.

Length Matters: Nanotoxicity

Obviously size matters for nanoparticles, or the world wouldn’t be making such a big deal of them. Size also matters when it comes to toxicity of nanoparticles. A recent study published in Advanced Materials (Length-Dependent Uptake of DNA-Wrapped Single-Walled Carbon Nanotubes) by Matthew Becker and others, emphasizes that size (such as length and diameter of particles) matters particularly when deciphering toxicity studies. One source of size variation suggests the authors is dispersion of single-walled carbon nanotubes (SWNT) used in toxicity testing.

According to the article:

“Given a constant dosage, differences in dispersion ranging from macroscopic aggregates to micrometer-scale clusters bundles of multiple nanotubes or individually dispersed nanotubes will dramatically affect the absolute size and amount of nanotube surface area to which the cells will be exposed.”

Surfactants are materials used to increase water solubility and in some cases dispersion of a material, and are commonly used in studies of nanoparticle toxcity. Becker’s group used DNA as a surfactant, because they noted,

“These dispersions, in the case of DNA, are even stable enough to allow for the separation of the dispersed material into well-defined subpopulations of the SWNTs.”

Using this method to test the toxicity of SWNTs of varying length to muscle cells, the authors concluded that, “The assays determined an approximate uptake threshold of approximately (189+17) nm. Indicating that nanotubes shorter than this are consumed and likely induce more toxicity.”

Though they note that identifying an upper threshold for toxicity of nanoparticles is nothing earth-shattering or new, they do suggest that such behavior is likely to be a “general phenomenon,” though the actual size threshold is likely to vary depending on the type of cell.

For more information check out: Length-Dependent Uptake of DNA-Wrapped Single-Walled Carbon Nanotubes, by Becker et al, Vol 19:939-945.

Waterproofing the Ocean: the consequence of keeping dry

“Must keep water out” was my mantra. The old red backpack, my faithful traveling companion for over twenty years, cross country, up mountains, at sea, and across the ocean had sprung a leak. Wet through completely when a drenching rain followed my husband and I down the Madison Gulf trail. Socks, underwear, warm clothes – sopping. But rather than purchase a new frame pack, I reached for the Scotchgard™, and methodically sprayed each crack, crevice and seam, confident in that by “renewing” my old pack, I was doing the right thing.

What I didn’t know then, shames me now. What I didn’t know then, apparently the 3M Company and the Dupont Corpration had known for years. That the use of, and manufacturing process for products like Scotchgard™, my Gore-Tex Coat, and the surface on my favorite fry-pan, leave behind more than just consumer goods. What we know now, according to a review recently published by Magali Houde and others from the Unversity of Guelph in the journal Environmental Science and Technology (ES&T), is that the perfluorinated polymers, the most notorious being PFOA and PFOS, used to resist, protect, and repel, have infiltrated almost every living system on earth, from Great Lakes algae to polar bears in Svalbard, from the green-lipped mussel to Kemp’s ridley sea turtle, the bald eagle and the common loon. And, unless you consider yourself separate from life on earth, these chemicals have infiltrated you, me and your next-door neighbor.

By now, this is old news. Many of us are familiar with the stories. Parrots dropping dead, 3M voluntarily “outing” PFOS, reports of PFOA and PFOS in our blood. It is old news that these chemicals persist in the environment and are found from the North Pole to the South Pole and everywhere in-between.

But how did this happen? These chemicals have been around for over fifty years. Where was the US EPA? Where were our environmental protections? Turns out, that these chemicals slipped through, legally, at least one process that would have identified their current role as the environmental contaminants de jour. That is, the Premanufacture Notification process.

Ever since Congress passed the Toxic Substances Control Act back in 1976, the EPA has had the authority to review and regulate each new chemical based on its potential threat to us, and the environment prior its use in commerce. But there’s a catch. According to the EPA, “chemicals in commerce prior to the effective date of the Toxic Substances Control Act were placed on the inventory without going through the premanufacture notice.” And, some classes of chemicals were specifically granted exemptions. These included some of the perfluorinated chemicals involved in the production of PFOA and PFOS. The idea being, according to the agency, that “certain chemical health and safety information [would] be submitted to the Agency…when companies learn of it.”

But in 2004, the US EPA charged that Dupont had violated that bit about providing “certain health and safety” information. Apparently they forgot to report that not only was PFOA persistent, but that it might be toxic to humans and the environment. Oops.

Dupont settled for over $10 million, EPA initiated a voluntary phase-out of the chemical by 2015 (a program in which Dupont along with several other manufacturers, is a participant) and back in 2000, the 3M Company voluntarily phased their use of PFOA, PFOS and related chemicals.

Phew. Glad that’s over.

Or is it?

What about those polar bears, eagles, and loons? What about the starfish, green-lipped mussels, tuna, sea-turtles and otters? Konstantinos Prevedouros and others from Stockholm UniversityE. I. duPont de Nemours, in a study published in ES&T, estimated that over the years, thousands of tons of PFOA or PFOA precursors were released to the environment, with much of it discharged into our waters. and In one case, 61% of the chemical used was released to the environment, most going right into the water, without violating a single law. Well, excepting those companies that knew, but didn’t tell. And this is only part of the legacy bequeathed upon us not just by industry but by our own desire for eggs to slide, fabric to repel, and carpets to gleam. There is no accounting of the tons of PFOS used or released over the years.

“Water is the main vector for exposure in wildlife,” says Frank Gobas, a researcher at Simon Fraser University who studies chemicals that accumulate in wildlife. In the environment, according to Gobas, perfluorinated chemicals exist in a relatively water soluble form. “Marine mammals are likely the most exposed, due to water to fish to mammal transport, which the perfluorinated chemicals tend to favor.”

The big “so what” comes from my son. Each time I begin to write, he knows it’s bad news.

“So what do those kill?” he asks peering over my shoulder.

I explain that aside from killing the occasional parrot - though Dupont and others suggest that birds are sensitive not only to fumes from overheated Teflon but from overheated butter and oils - the effects on wildlife are unknown

And although there may be ample evidence of a chemical’s toxicity in the laboratory (one form of PFOA causes neurotoxicity, liver toxicity, immuno toxicity and developmental toxicity), and ample evidence of the chemicals presence in the tissues of wild animals, one of the more challenging problems in environmental toxicology is linking the presence of that chemical in the environment with harmful effects on wildlife.

For example, Kurunthachalam Kannan, of the New York State Department of Heath, and SUNY Albany, and others, recently reported on the relationship between PFOA and PFOS concentrations in sea otters found dead or dying along the California coast and disease status. The group found more PFOA and PFOS in sea otters determined to be diseased at the time of their death, compared with those classified as non-diseased, However, according to their study, reported in ES&T, they were unable to determine if the higher levels of perfluorinated chemicals were “a cause of the disease, a consequence,or coincidental.”

Kannan’s group also reported a decline in PFOS in the otters over time, following 3M’s phase-out. Was that a surprise? “I expect that it would take much longer for the environment to respond,” says Kannan. “Maybe what we found was circumstantial, but a few other researchers have found a similar decline in seals from the Arctic.”

James Armitage, a PhD candidate at Stockholm University, studies the fate of PFOA in the environment. He agrees that once the release of these chemicals and their precursors is halted, depending on the location, environmental concentrations may decline quite swiftly.

“Given the lifespan of most creatures in the environment,” says Armitage, “I would expect to see a response to declining environmental concentrations fairly rapidly.”

“But,” he adds referring to a modeling study soon to be published, “we observed that concentrations in the North Temperate Zone, the source area, decline almost immediately, while concentrations in the North Polar Zone continue to increase.” The declines he notes are due mainly to redistribution to other ocean areas. In other words, even if phased out, the perfluorinated chemicals aren’t likely to go away soon, they’ll just go somewhere else.

According to those in the industry, there really is no replacement for perfluorinated chemicals. It is the combination of fluoride and carbon that provides the repellent properties that make these chemicals so useful and durable. The 3M Company has already developed a new polyfluorinated chemical to replace PFOA, PFOS and PFOS-related products. Their website, asserts that the reformulated products have been tested for toxicity and bioaccumulation, and have apparently passed with flying colors. But, what the site doesn’t say is that they are persistent in the environment. And though no one expects them to accumulate in the sediments, they are expected to hang around in water.

When asked about the replacement products Enesta Jones of the EPA, says “The new chemical replacements have been subject to considerable scrutiny. The Agency is requiring robust fate and toxicity testing, and will retain regulatory authority over these chemicals until we can be assured they do not present unreasonable risk.”

I hover over my daughter’s leather boots, and ponder my desire to keep her feet dry, a can of Sno-Seal silicon (non-polyfluorinated) water-guard in my hand, and begin to spray.

Monopoly Boards and Polar Fleece, Mysteries of Curbside Recycling Revealed

I shouldn’t admit this, but I get an odd thrill on trash collection day. Maybe it’s because our two trashcans are packed so full that it’s a relief to have the stuff carted away. Or maybe it’s because waking up to empty barrels means I’ve actually remembered to pick up some stickers from the Mini-Mart and put them on the barrels. I don’t mind paying the $2.50 a barrel, in fact, I think it’s more than fair. After all, thanks to the incredible recycling program in town, it’s only once or twice a month we even drag the barrels to the curb.

For years I’ve ignored that nagging question, does recycling really reduce the amount of waste we toss from our homes? Am I justified in bragging to friends and family that we generate only two barrels or so of trash a month? Years ago (in another town) there were rumors that our carefully sorted bottles and paper ended up with the rest of the trash – in the landfill. Some part of me wanted to be content in my ignorance, in my faith that unethical recyclers were a thing of the past or something that only happened in big cities.

But, one afternoon while listening to an National Public Radio story on recycling those new compact fluorescent bulbs, the spiral energy saving bulbs you have to wrestle from all that energy intensive plastic packaging, the commentator noted how few consumers are even aware the new bulbs contain mercury, although each package clearly states that: LAMP CONTAINS MERCURY; Manage in Accord with Disposal Laws; See www.lamprecycle.org.

Listening to the story and aware that I limit her tuna fish consumption to a can a week because of my concern about mercury, my daughter Sophie asked, “What do they do with the mercury, and how do they get it out?”

Good question. In fact, what happens to all the stuff we leave curbside? The yogurt containers, juice cartons, milk jugs, tin cans, and cereal boxes. And why can’t we leave eggs cartons, pizza boxes and plant pots?

According to our local expert, Jan Ameen, Executive Director of the Franklin County Solid Waste Management District, there truly is an afterlife for our milk jugs, soda bottles and computer paper, though disposal is the end of the road for the lowly egg carton.

“Egg cartons use the shortest paper fiber,” Ameen explained. “Basically, they are the end of the paper recycling line. The fiber cannot be used again, so when they go to the paper mill for recycling, they dissolve and end up in the wastewater.

“Pizza boxes can be recycled if they’re not greasy. Most recycling paper mills don’t use chemicals, just warm water to dissolve the paper. There isn’t a good way to get rid of the grease from this process.”

In contrast, all the used and reused printing and computer paper, all the old bills, envelopes, and technical reports on obscure topics I finally cleared from my filing cabinet fared better than the egg cartons and pizza boxes.

“All of the paper from western Massachusetts,” said Ameen, “ends up at a paper recycling mill in Fitchburg, North Shore Fibers. They make Monopoly boards and book covers, mostly, and other paper products.”

It was good news to find my old paper might be hosting games of Monopoly, or protecting someone’s storybook, but I wasn’t really worried about paper recycling. It’s been around for decades, and it seems these days all sorts of paper products are recycled including my Seventh Generation toilet paper, which proudly proclaims the “post-consumer” content (post-consumer meaning made from the stuff we leave curbside) as 80%. Not bad. Neither did I worry about recycling cans. Tin and steel are valuable, so it makes sense we’ve been recycling them for years.

But what about plastics and their array of letters and symbols: PETE, HDPE, LDPE, PP, PS? Why do we no longer sort them, and why can’t we recycle all those plastic plant pots?

It’s a big world, and there’s lots of plastic. The American Chemistry Council reports that in 2005, 922 million pounds of HDPE bottles (those thick plastic bottles like milk jugs and laundry detergent bottles) were recycled, as were over 2 billion pounds of PET and PP bottles (PET are things like coke and juice bottles, and PP are polypropylene – those “next generation” bottles that don’t add a plastic taste to your drinking water.) This represents only about 25 - 30% of all recyclable bottles out there. Sadly, many still end up in the trash. Still, that’s a lot of recycled plastic. And those plastic plant pots? Says Ameen, “Plant pots aren't recyclable because of the dirt and because they are often black (no black plastic is recyclable.)” Though a web search led me to a couple of programs specifically for plant pot recycling, one in New Jersey and one in Missouri, it seems that gardeners nationwide are stymied by the inability to recycle these items locally!

In our town, the first stop for all of our bottles, boxes and papers is the Springfield Materials Recycling Facility, where plastic recyclables are sorted according to type and then sent off for further processing, depending on the item. For plastics, that means recycling them into anything from fiberfill to polyester-like fibers, to those blue recycling bins, to plastic lumber furniture. Ever have a cinder land on your new fleece jacket and watch it melt its way through the fabric? That’s because fleece is plastic! And while some companies still rely on “virgin” polyester to produce fleece, there is now EcoSpun, ECO-Fleece, and EcoPile products made primarily or entirely from our recycled bottles. Even large corporations like Malden Mills, which produces Polartec, are touting their recycled fleece products.

But, I wondered what happens then, when the fleece eventually becomes too ratty to donate to the Salvation Army? Patagonia, the mega-outdoor retail store now recycles old fleece into new products, though they note that their process is currently limited to Polartec, and their own capilene and cotton products from Patagonia. On their website, they say they hope other companies begin taking advantage of old fleece as well.

Ah, but what about those mercury containing fluorescent bulbs? The good news is, according to the EPA, the new bulbs help decrease mercury emissions by reducing the demand for electricity. Primary sources of electricity are coal-fired plants, which still routinely emit mercury into the atmosphere.

The bad news is there is no curbside service for the bulbs, and many distributors don’t have a program in place to recycle the bulbs. Fortunately, this shouldn’t be too much of a problem, since the new bulbs are supposed to last for five years, or 8,000 hours. That’s right - five years, and if they don’t last that long, all you have to do is send in your receipt and UPC (hah!) and get a refund. But when the time does come, and it certainly came sooner than five years for a few of our bulbs (unfortunately, those UPCs were recycled long ago), we can take them to the Montague Transfer Station where they are sent off to Veolia Environmental Services in Stoughton, MA, for recycling. Although at the moment it costs fifty cents a bulb, maybe in five years when we all recycle our bulbs en masse, there will be more recycling options.

Veolia specializes in recycling lighting and electronic wastes. On their website they note that an “estimated 600 million fluorescent lamps are disposed of in U.S. landfills, amounting to 30,000 pounds of mercury waste.” That’s a lot of mercury.

Using an enclosed process Veolia crushes the bulbs, and then extracts mercury and other components. In the end, the company’s website declares that all parts, including glass, metal end-caps, powder, and mercury, can be reused.

So next time you flip on your compact fluorescent, and pull on your favorite fleece for a game of Monopoly, who knows, you could be enjoying the fruits of your recycling efforts!

For more information on recycling in your county check out:

Earth 911: A site that provides you with disposal and recycling information for any zip code in the country.

Ingesting, digesting, and egesting oh my: nanoparticles and water fleas

Years ago when I first met my husband, I am ashamed to say, I may have belittled the importance of his research project. He was studying larval fish, and observing what they ate, how much they pooped and how quickly they grew. Who cared I wondered? I was a toxicologist I’d thought at least my work was somewhat applicable to….to something! That was almost twenty years ago and now he’s out saving wild fish populations, and I’m here typing at my desk! But recently I came across an article entitled “In Vivo Biomodification of Lipid Coated Carbon Nanotubes by Daphnia Magnia” by Aaron Roberts, et al., published in Environmental Science and Technology, which highlights the importance of ingesting and egesting (or eating and pooping) in an environmental context that even a toxicologist can appreciate.

Turns out that what little critters eat, digest and poop may have some important implications for nanomaterials. Roberts et al. reports on the fate (and to some extent toxicity) of single-walled carbon nanotubes or, SWNTs, in aquatic creatures known as Daphnia magnia, or better known as water fleas.

Alone, SWNTs are not water soluble, which apparently limits their utility. In this case, the authors first combined SWNTs with an amphiphilic coating, (that means it goes both way water loving and fat loving,) to render them soluble in water. Rendering SWNTs more water soluble, according to the authors will:

“..not only enable biological studies of cellular responses but also empower the development of next generation single-molucule chemical and biosensors and self-assembled nanodevices,.”

But, they noted, this new and improved water soluble nanomaterial comes with a caveat,

“Because of the large number of applications there may be great potential for discharge of coated, solubilized nanomaterials into the environment.”

Enter, the fleas.

Since solubilized nanomaterials might end up in watery environments, the authors exposed Daphnia to concentrations of coated SWNTs. They reported that up to a point, the Daphnia not only tolerated but (under conditions of starvation) may have even benefited from the coated materials. Daphia ingested the materials, stripped the coatings, and apparently used them as a food source (those in SWNT water survived to a greater extent than those without), and egested (pooped out) uncoated and now insoluble SWNTs. But we all know what happens when we over indulge. When exposed to higher concentrations, the Daphnia didn’t fare so well, and survival was reduced. Additionally the authors noted that coated SWNTs also accumulated on the outer surfaces of Daphnia (also not good.) I would also suggest that all food sources are not created equal. For example what keeps one generation going, might not be sufficient for producing the next, so that further studies of such materials might include life-cycle tests and more intensive investigation into the quality of "food" provided by similarly coated nanomaterials.

In conclusion, the authors note that:

“Our data show that biomodification of lysophospholipid-coated carbon nanotubes in vivo can occur and have dramatic effects on the physical properties of the nanomaterial. These modifications may result in unanticipated effects both on the materials properties as well as the organisms exposed to the nanomaterial. Biomodification is an important phenomenon that should be considered in studies on the biological applications, environmental fate, and toxicity of convalently and noncovalently functionalized nanomaterials.”

You can find the full article, by Aaron P. Roberts, et al., In Vivo Biomodification of Lipid Coated Carbon Nanotubes by Daphnia Magnia in Environmental Science and Technology, ASAP Articles, March 7, 2007.

More on Sunscreens

This morning I finally came across the science article I’d been dreading. With the kids off to school and the dog walked, I settled in to my morning routine, coffee, bagel and Science Magazine. After skimming articles on ancient towers marking the solar calendar in Peru, brain evolution, and African penguins, I came across a News Focus article entitled “A Healthy Tan?” written by Ingrid Wickelgren. Over the past ten years as I’ve coated the kids with sunscreen I’ve been waiting for the inevitable. As a scientist I know that science is always on the move, particularly when it comes to understanding how the body responds to chemical or physical (as in the sun’s ultraviolet rays) insults. As scientists learn more, things change. So I’ve been waiting for the down side of sunscreens. The, “If we only knew then, what we know now.”

Though the news isn’t all that bad, it is worth considering that scientists and those in the health fields are still figuring out the best way to protect those of us who insist on playing in the sun (besides the obvious – just cover up!)

According to Wickelgren:

“Anyone who relies on sunscreen knows it is sticky, inconvenient, and easy to forget. But sunscreen has a lesser known, and more serious, downside: It doesn't adequately protect against the deadliest form of skin cancer.

Although ultraviolet (UV)-blocking sprays and creams protect people against sunburn and the milder forms of skin cancer--squamous cell and basal cell carcinoma--they do not form an effective shield against melanoma, which doctors diagnose in 132,000 people worldwide each year. Ironically, says a growing cadre of skin biologists, what seems to protect best against melanoma is something that sunscreens efficiently thwart: a deep, dark tan.

Dark-skinned people, who also tend to tan well, are up to 500 times less likely to get melanoma and other skin cancers than are fair-skinned individuals. The ability to tan confers protection, researchers say, regardless of the skin's background level of pigmentation. This is due in part to the UV-shielding effect of melanin, the pigment that makes skin cells dark, and perhaps in part to an acceleration of DNA repair that some believe accompanies tanning. But tanning in the sun is a fool's wager, dermatologists say, because it causes dangerous DNA damage, which may lead to cancer before it can be fixed. To provide a sun-independent alternative, scientists are now developing compounds that trigger tanning and DNA repair by acting on molecules that control the melanin production pathway.”

The complete story can be found in Science, March 2, Vol 315 pages 1214-12166.

So, should I order the fish?

Much to my embarrassment, shortly after graduating with my Ph.D. and directing my attention to PCBs and other toxics in fish, whenever we stood by the fish counter at the local seafood restaurant, my father would announce that I was an expert on contaminants in fish. “So, should I get the fish?” he’d ask.

I’d turn red and shrug my shoulders, muttering something like, “I don’t know, depends where it comes from, I guess.” Truth was that I studied the impacts of chemicals on reproduction in fish not humans, so really, I could only answer as an expert for fish concerned about their reproductive health.

But even for those who study the human health impacts of chemicals, the issue of evaluating the risk associated with contaminants in seafood has always been tricky. Risk from contaminant exposure depends on the contaminant, the particular health effects associated with the contaminant, the species of fish (some fattier than others), the age of the fish, where it was caught (if wild), if farmed, what it was fed, how much one eats fish how often, and even on who’s eating the fish!

An recent analysis by Sam Luoma and Ragnar Lofstedt titled "Contaminated Salmon and the Public's Trust" published in Environmental Science and Technology addressed the complexity of that simple question “Should I get the fish?” and “If so, what kind?” They refer to a study published in Science several years back, which reported on concentrations of PCBs and similar chemicals in farmed and wild salmon, and which reported that farmed salmon were, in general, more highly contaminated than wild-caught salmon.

According to Luoma and Ragnar, this set off a “contentious dialogue….mostly because the risk analysis for salmon did not consider a balance of risks,” the end result (at least for a time) was a drop in consumer confidence for farmed salmon resulting in a heavy burden on wild salmon populations.

While the authors don't answer the question "to eat or not to eat", they do provide an interesting discussion about communicating and evaluating risk for complex scientific issues, even ones that seem simple, check out it.

More on Nanotech

Nanotechnology is an interesting field for a toxicologist because of the very public discussion about toxicity, regulation and the future of nanotechnology. Unlike other major technological advances in the past with the potential for health and environmental impacts, nanotechnology is developing under the virtual microscope of the internet – where citizens, researchers, regulators are able to access a great deal of information and can organize via the internet.

Below are a few new articles on the toxicology of nanomaterials and a link to a podcast "The Implications for Health, Safety and the Environment of the Nanotech Revolution."

This interesting and informative podcast sponsored by Nanotechnology Victoria (Austrailia), considers the ethics, toxicology, risk assessment, worker heath and safety. While those interviewed agree that there are data gaps in the toxicology and potential for environmental impacts of nanotechnology, they also note the potential benefits of future nanotechnology products. Views range from a moratorium on nanotechnology development, to greater government and industry resources to improve worker standards to avoid another potential “asbestos-like” disaster for workers in the field, to a call for all involved to recognize the broad range of materials to which the term nanotechnology refers.

For those interested in more technical articles on nanomaterials, below are three articles recently published in Environmental Health Perspectives describing recent toxicological research on nanoparticles.

Cardiovascular Effects of Pulmonary Exposure to Single-Wall Carbon Nanotubes by Zheng Li,¹ Tracy Hulderman,¹ Rebecca Salmen,¹ Rebecca Chapman,¹ Stephen S. Leonard,² Shih-Houng Young,² Anna Shvedova,² Michael I. Luster,¹ and Petia P. Simeonova concludes:

“Taken together, the findings are of sufficient significance to warrant further studies to evaluate the systemic effects of SWCNTs [Single-Wall Carbon Nanotubes] under inhalation exposure paradigms more likely to occur in the workplace or environment, such as low-level chronic inhalation exposure.”

Inhalation Exposure Study of Titanium Dioxide Nanoparticles with a Primary Particle Size of 2 to 5 nm by Vicki H. Grassian,^1,2,3, Patrick T. O'Shaughnessy,³ Andrea Adamcakova-Dodd,³ John M. Pettibone,² and Peter S. Thorne concludes:

“Mice subacutely exposed to 2–5 nm TiO₂ nanoparticles showed a significant but moderate inflammatory response among animals at week 0, 1, or 2 after exposure that resolved by week 3 postexposure.”

Finally, an interesting article entitled Effects of Aqueous C₆₀ Nano-Aggregates to Tetrahydrofuran Decomposition Products in Larval Zebrafish by Assessment of Gene Expression by Theodore B. Henry, Fu-Min Menn, James T. Fleming, John Wilgus, Robert N. Compton and Gary S. Sayler suggests that toxicity in this case was caused by chemicals used in the preparation of the nanomaterials, rather than the nanomaterials themselves.

Could you reheat that please, but hold the plasticizers

Yesterday my mother asked about using plastic wrap in the microwave. She uses it when reheating or warming food, and her reheated food is moist and her oven clean. I don’t, and my oven is encrusted with splatter and my food dry. I don’t know how important covering food is for reheating (other than the splatter) but I just don’t like to use more plastic in my daily life than is needed. I muttered something about probably not a problem, since reheated plastic wrapped microwave food items are not part of her main diet, but then thought maybe I ought to give it a bit more thought.

I know this is one of those questions that has been around for years, and there were lots of websites with titles like “Truth or Fiction” and “Big hoaxes”, and “Plastic Myths” that popped up when I asked Google about it. But the most informative site was one form the Louisiana State University Agricultural Center (see excerpt below.) Basically, the FDA acknowledges that substances like diethylhexyl adipate (DEHA), a chemical used to make plastics more flexible, can and do transfer from plastic to foods during reheating. The controversy (if there is one) is over how much and how toxic.

But most seem to agree that it if one wants to avoid or minimize their ingestion of contaminants from plastic, they heed the following advice:

According to the LSU article on “What’s Safe for Microwaving”:

"• Use only cookware that is specially manufactured for use in the microwave oven. Glass, ceramic containers and all plastics should be labeled for microwave oven use.

• Don’t use margarine tubs, take-out containers, whipped topping bowls and other one-time use containers in microwave ovens. These containers can warp or melt, possibly causing harmful chemicals to migrate into the food.

• Use safe items like plastic wraps, wax paper, cooking bags, parchment paper and white microwave-safe paper towels. Do not, however, let plastic wrap touch foods during microwaving.

• Never use thin plastic storage bags, brown paper or plastic grocery bags, newspapers or aluminum foil in the microwave oven.

In addition, the American Plastics Council recommends that carryout containers from restaurants should not be used in the microwave. These containers may melt or warp, which can increase the likelihood of spills and burns."

Yesterday NPR had an interesting story on mercury in those compact fluorescent lightbulbs (you know those odd shaped spiral bulbs that promise to reduce energy use.)

Who knew, unless they read the not-so-fine-print that says : LAMP CONTAINS MERCURY; Manage in Accord with Disposal Laws; See www.lamprecycle.org. But really, who has time to read when they're struggling just to open the plastic packaging without breaking the bulb?!

Anyway, there's lots of good information on the NPR site on amounts of mercury (small - according to the Energy Star site, which says that if a bulb breaks getting cut by a shard of glass poses a greater risk than the potential for exposure to mercury), and what to do to dispose of the bulbs (check out earth911.org), which shouldn't be an immediate problem since they're supposed to last for five years or 8,000 hours. That's right - five years, and if they don't, all you have to do is send in your receipt and UPC (UP-what? And, where are those receipts?!)

But the bottom line, as noted by the EPA is that in the end, using these bulbs (in addition to other measures reducing electricity use) could help reduce overall emissions of mercury, since coal, one of the most common fuels for electricity production, is one of the major sources of mercury released into the environment.

So What’s in Your Hometown: The Toxic Release Inventory and Citizen’s Right-to-know

A news article published today in Environmental Science and Technology reports on the recent changes to EPA's Toxic Release Inventory. Below is an article I wrote a while back (and just updated), when the EPA was considering changes to the TRI.

What's In Your Hometown?

“So why doesn’t everybody know about these web sites?” demanded Belle, my student. She had just completed the “hometown” assignment for class. The assignment required that they use several websites including the Environmental Protection Agency’s Toxic Release Inventory and Envirofacts websites and the Environmental Defense Fund’s Scorecard website to research their home town. The results, as always are eye-opening, and sometimes distressing.

Together, the three sites listed above, provide location specific information on toxic waste releasers and handlers, Superfund sites, currently operating landfills, the potential health impacts of chemicals in one’s neighborhood. Best of all, their primary purpose is to serve the public, so they are fairly user friendly. In fact, the Toxics Release Inventory is an outcome of the Emergency Planning and Community Right to Know Act, passed in 1986 after the Bhopal, India catastrophe. The Right to Know act requires that the EPA collect information on the handling and release of toxic chemicals from companies around the country, and that they make it open and accessible to all.

While the site is informative, it can be difficult at times to make sense of some of the chemical release information. Fortunately the Environmental Defense Fund’s Scorecard does this for us. Scorecard draws from over 400 databases including the Toxic Release Inventory, and combines these data with other useful information such as health effects data for individual chemicals, and geography, presenting a huge amount of information into “what this means for you.”

And finally, the EPA’s Envirofacts website provides a wealth of information on chemical releases to air, water, and land, and will overlay these data on a map of your town (the other sites map facilities also, but this site includes other information like the location of schools, roads and rivers.)

Using these sites, Belle, who grew up in suburban Pennsylvania, found that in 2002 the SPS Corporation, a supplier of fasteners and metal products to the aerospace and automotive industries, released 1,400 pounds of trichloroethylene into the air, along with smaller amounts of various other pollutants. The plant is just down the street from her home.

Belle also found that her county, Montgomery, PA, ranked number one in the state for superfund sites (there were 16). Fortunately, she also discovered that over the past decade, SPS has reduced their toxic releases by approximately 98%.

But Belle’s revelation paled in comparison to Jaime’s, who reported who reported on the 50 million pounds of toxic chemicals released into the air and waters of her home community of Harris County, TX, which is home to 22 superfund sites. Granted it’s not a fair comparison, one large industrial area verses suburban, PA, but when it’s your own hometown you might want to know about that nearby factory or superfund site, or that well groomed industrial campus down the block. As my students have found, these sites provide a powerful tool for investigating chemical releases in your own community, or in a community you might be considering relocating to.

So why doesn’t the public know about them, my students wanted know. “Someone should write about this,” they said. Hmmmm, had I only been quick enough to turn around and give them an impromptu writing assignment. The next day as I skimmed through New York Time headlines online, an article in the business section caught my eye, “Location, Location, Location, Research, Research, Research,” aha, I thought, here it is, now I won’t have to write about it.

Wishful thinking, though the article listed several sites that might help a future property owner research their location, none of the sites discussed above were included in their list. After some more searching, I managed to find one article on Scorecard, but that was in Realtor Magazine Online, not one that’d I would have just found skimming through the news, and I’m not sure many others would either.

So, I decided, I should write about them. But before I could, I had to fully explore the sites myself (yes, yes, I admit it, after giving this “Hometown” assignment to students for the past five years, I had yet to investigate my own hometown.) Although I didn’t expect our community to turn out anything like Belle’s or Jaime’s, you never know.

Researching my own hometown and surrounding towns, I found dramatic reductions in chemical wastes released, which they attributed to either changing processes or through increased recycling. These reductions or changes in chemical processes are reflected graphically using the “Release Trends Graphs,” a useful feature of the Toxics Release Inventory, and are in part the result of Massachusetts’ Toxic Use Reduction Act, which encouraged facilities to reduce the amount of toxic chemicals they use by increasing efficiency and/or using less toxic alternatives.

There is one small limitation of the Release Inventory that I need to mention. Reporting limits. A facility must report only those chemicals that require reporting (currently EPA a total of 666 chemical and chemical categories) and must only report quantities of those chemicals that are treated, recycled or released, which up ‘til now, were quantities in excess of 500 pounds, or the “annual reportable amount.” So if a facility releaseed 500 pounds or less of a particular chemical release inventory chemical they are not required to report specific amounts. (Although chemicals categorized as “persistent and/or bioaccumulative” have lower reportable amounts.)

Depending on the chemical, 500 pounds may not be much if we’re talking just one or two industries in a community, but here’s the problem, recently, the EPA increased the “annual reportable amounts,” from 500 pounds to over 2,000 pounds. Effectively reducing what we have a right to know about. While a 4-fold change in the amount of chemical reported might not make a huge difference in Jaime's hometown, it would in ours or other small communities who depend upon the Release Inventory to keep tabs on local businesses, or in those communities which may have several smaller releasers.

Toxicology Down in Whoville: Who's testing nanoparticle toxicity?

My daughter is rehearsing to be a Who down in Whoville, a creature invisible and nonexistent to all but Dr. Suess’s Horton who first hear the Whos. This would make her and her fellow Whos, inhabitants of a world the size of a dust mote, nanoparticles I suppose, which according to at least one definition are particles smaller than 100 nanometers (or one billionth of a meter). Around the time Dr. Suess was envisioning the importance and potential of the nanosized Whos, Dr. Richard Feynman, the Nobel Prize winning physicist was also envisioning the technological potential of the very small, well before the term nano-anything even existed. Towards the end of a 1959 lecture, Feynman offered a $1000 reward to anyone who could figure out how produce a nearly Who-sized version of the Encyclopedia Britannica, shrinking the entire series so could fit on the head of a pin.

Though Feynman expected rapid progress, the technological breakthrough (and a legitimate claim for the reward) didn’t come for another thirty years. But since then, the production of nanoparticles, and the field of nanotechnology has blossomed. One institute, Foresite Nanotechnology offers a Feynman Grand Prize of $250,000 for “the first persons to design and build ...a nano-scale robotic arm and a computing device….” By some estimates, nanotechnology is now a billion dollar field, involving both government and industry dollars and it’s growing. The promise of nanotechnology includes both environmental and health applications including more effective drug delivery, potential applications for solar derived power, reduced use of industrial chemicals, and improved environmental cleanup methods.

Until researching this article I had thought the emerging field of nanotechnology would be a great opportunity to witness the fruits of over thirty years of experience with environmental standards, guidelines, laws and regulations. I had thought that development of nanoparticles and nanomaterials (made of nanoparticles) would go hand in hand with human health and environmental toxicity testing. That we would avoid yesterday’s and today’s problems like PCBs, lead paint, and climate change, so that today’s little Cindy-loo Whos won’t need to ask, “How did you let this happen, and how do we fix it?”

Unfortunately, it seems that the Whoville cats have already left the bag. According to Dr. John Balbus of Environmental Defense, the production of nanomaterials has already outpaced knowledge of human health and environmental impacts.

“The Wilson Center [Woodrow Wilson International Center for Scholars] notes 356 nanoparticle products on the shelves around the world,” says Balbus, “and most of them have virtually no in-depth toxicity testing done on the basic material in them…..There are huge knowledge gaps about how these materials will move about and persist, whether they will bioaccumulate, let alone their toxicity to humans or other animals.”

Whoops. What about those thirty years of regulations and guidelines and experience? What about all those toxicity testing techniques designed to protect human health and the environment? After decades of data on thousands of chemicals, one cannot argue that we’re not better off today than we were thirty years ago, but there are also plenty of chemicals that we still just don’t know enough about. And nanoparticles are like the new kid on the block who doesn’t play by the rules, and that’s what makes them so intriguing for industry. In many cases nanomaterials are just different from their counterparts (including both their basic atomic building blocks, and their larger composites – both of which may or may not have already been through all the toxicity testing hoops).

“Ordinary new chemicals go through a series of [initial] screens using computer-based structure-activity-relationships,” explains Balbus, meaning that to some extent researchers and regulators can predict the activity of a chemical based on its structure, comparing the similarity of that structure to chemicals of known toxicity, allowing regulators to determine the need for further more detailed toxicity testing.

“With nanomaterials, we don’t have the experience to be able to predict, so they can’t go through the same screening tests…the tools to use for regular chemicals don’t apply to nanomaterials.”

Titanium dioxide is an example of a chemical with a long history -- dating back to the early 1900’s -- of mass production (now millions of tons per year) in non-nano form, and a more recent history of mass production as a nanomaterial. Traditionally one of the most important white pigments in commerce, one new use for nano-sized titanium dioxide is as a next generation sunscreen, ironically labeled “non-chemical.” Ever wonder how those new sunscreens with titanium and zinc oxide protect you from the sun’s ultraviolet rays without making you look like a clown? Turns out that the typical white smear associated with titanium or zinc oxides result from the excellent light scattering properties of these chemicals. But nanosized particles of titanium dioxide allow visible light to pass through them and so appear clear, while still scattering the sun’s shorter and harmful ultraviolet rays. And, while many in the field agree that a sufficient number of studies on dermal or skin toxicity of nanosized titanium dioxide have been conducted, the same cannot be said of ecotoxicity studies evaluating the potential impacts on the environment.

Although the pending large scale production and potential release of nanoparticles like nanosized titanium dioxide is a recent development, nanoparticles or ultrafine particles have existed in our atmosphere ever since there were fires, volcanos and sea spray to produce them. More recently, manmade sources including traffic and industry have added to the suite of nano-sized particles in the atmosphere, and higher amounts of particulates in the air are consistently linked with adverse health impacts such as increased death rates and respiratory distress. The most recent studies suggest that ultrafine particles cause the greatest harm to the lungs.

In the lungs, says Dr. Vicki Stone, of Napier University, Edinburgh, Scotland, “Smaller particles almost always induce greater cellular response than larger particles of the same chemical composition. Such responses include cell death, and responses that cause activation of inflammation (immune response) and pathways that drive disease.”

In general as particle size gets smaller the toxicity increases, in part because of increased surface or reactive area, and in part because the behavior of the chemical in the environment or in living systems might change.

For example, nano-sized forms of chemicals that normally would not be able to cross into the brain (blocked by what is know as the blood-brain-barrier,) might be able to penetrate and gain access more easily. Similarly nano-sized particles may act differently in the environment. Perhaps becoming more easily dispersed than their counterparts, or perhaps just the opposite, sinking into sediments or settling on soils, making them more likely to be ingested by critters that make a living by stripping chemicals from sediment and soil particles.

However, cautions Stone, “Only a relatively small number of particles of different chemical composition have been tested…so many experiments are needed to verify whether this is a general phenomenon.”

In many cases, whether a product is tested for toxicity and how it is tested depends on the product, the potential for exposure, the amount in production, the proposed end use. For example, a product may be classified as a pharmaceutical, a food additive, a pesticide or a “device” such as a washing machine that sanitizes clothes as it washes, by releasing silver ions and perhaps some nanoparticles as well, (yes there is such a thing, and EPA is currently struggling with how to classify it.) The regulations, standards and guidelines that govern the use and release of a particular chemical may consider all of the above, and this is where a chemical, or an altered form of an existing chemical, may slip through the regulatory cracks.

Fortunately, the US EPA along with several other government agencies, acknowledging the different nature of nanoparticles and nanomaterials, have over the past five years, committed millions of dollars towards health and environmental effects research on nanomaterials; and they’re not the only ones.

“Large companies are certainly concerned about releasing toxic products and having liability risks,” observes Balbus, “so they have done some of the toxicity studies on nanoparticles…..but much of the development and commercialization is being done by small startups that don’t have the resources to do much toxicity testing or exposure testing.”

Stone agrees, “There appears to be huge variation in the way in which different companies are approaching the questions about testing nanoparticle hazard and risk – some have funded extensive research, others are waiting to see whether legislation will require testing, while others are avoiding using nanomaterials until they have a clear understanding of how they will be regulated.”

So, the question is, will the threat of regulation prompt responsible and meaningful health and environmental testing of nanomaterials by industry, heading off further involuntary regulation, or increased creativity in classification of nanoparticles? Let’s hope for all those Whos down in Whoville that it’s the former.

Popcorn, hold the PFOA

Cruising through the latest news in the journal Environmental Science and Technology, I came across an article on PFOA (you know, those fluoropolymers that just a couple of years ago resulted in people tossing out their old non-stick pans, and returning to the heavy iron frying pans that could really knock someone out,) in both non-stick pans and, even more interestingly in the coating of microwave popcorn bags. The chemicals are known to accumulate in the environment (I've got a longer article on this in Green Living if you want to read more.)

The work, led by Kurnthachalam Kannan, published just this month in ES&T, reveals that yes, PFOA and related chemicals (for example chemicals called fluorotelomer alcohols or FTOHs) are released into the air from pans heated to normal cooking temperatures, and even into water boiled in these pans. The good news, was that the amounts released, in most cases, was reduced with repeated use.

But here's what's interesting, Kannan's group also reported that PFOA and FTOHs were released into the air from the packaging used for certain (unnamed brands) of microwave popcorn, and in some cases the amount of FTOHs released from popcorn bags was greater than amounts released from cookware.

SO, the next time you cook popcorn, you might want to do it the old fashioned way, in your new iron pot!

Controlling Toxics?

While researching regulation and toxicology of nanomaterials for a post on this page, I was directed towards the following report produced by Environmental Defense: “Toxic Ignorance: The continuing absence of basic health testing for top-selling chemicals in the United States.”

Interesting reading which discusses the gaps in the U.S. EPA’s Toxic Substances Control Act (TSCA). According to the EPA, TSCA was “enacted by Congress to give EPA the ability to track the 75,000 industrial chemicals currently produced or imported into the United States. EPA repeatedly screens these chemicals and can require reporting or testing of those that may pose an environmental or human-health hazard. EPA can ban the manufacture and import of those chemicals that pose an unreasonable risk.”

Environmental Defense’s 1997 report suggests that sufficient human health and environmental toxicity data exists for only a relatively small percentage of chemicals, (even those produced in high volume). More recently Environmental Defense points to recent progress by EPA and industry towards addressing data gaps.

Nanoparticles

This week there was an interesting article by Barnaby J. Feder in the New York Times reporting on the regulation or non-regulation of nanoparticles. The article raises questions about regulating the release and use of chemicals produced as tiny particles (on the scale of nanometers - or one billionth of a meter.)

As a relatively new technology, it will be interesting to see if regulators and industry learn from past experiences with chemical releases and contamination. One lesson is precaution. I know that’s thrown around a lot lately. But, in terms of industry - take the perfluorinated chemical (PFOA/PFOS) example - where tons were realeased and they were exempted from regulation. Once it was noted as an environmental issue, industry has been able to cut back environmental release by large amounts. If only they had done that from the beginning.

Also these days we do have the capability to evaluate impacts of contaminants both on environment and on health (if you can make a distinction) on a finer scale than we could or did before. What we do with that information, could be based on what we’ve learned in the past - be cautious with chemicals that are persistant or that are constantly released into a system either by either consumer products or by industry – when we don’t know enough about the impacts on living things. I don’t know enough about nanoparticles just yet to know if they fall or would fall into either catagory but I’m not sure if anyone does at this point. I hope to learn more and write up a more detailed article on nanoparticles in the next week or so.

It will be interesting to observe the progress of nanotechnology and regulation of nanotech. Unlike previous technology or industrial chemicals/products, where many, even in the environmental health world, were unaware of a chemical’s widespread release or environmental dispersion many groups are watching this one closely. One group is the Project on Emerging Technologies.

Radon: The Silent Intruder

Many of us here in Western Massachusetts worry about Vermont Yankee (our local, and famously old nuclear power plant). We ask the dentist, “Do the kids really need another x-ray?” and we balance the benefits of mammograms with the risks of radiation. Yet we ignore the radiation than in many homes seeps through basements, through the floorboards and the heating ducts, and into the rooms where our children sleep. We ignore the silent intruder: radon.

We ignore it – yet radon is estimated to provide many of us with over one half of our annual average radiation dose. It is an undisputed human carcinogen. It is an undisputed cause of lung cancer, considered by many health agencies second only to cigarettes. It is also one of the easier contaminants (unlike lead in old paint, formaldehyde in building materials or even mold) to rid from our homes.

At the urging of our lawyer, my husband Ben and I tested our future home just before signing the purchase and sale agreement. Friends and family were skeptical. “Oh radon,” said a family member, “it’s just another one of those scams, someone must be making money off it.” A friend suggested radon is one of those “don’t know, can’t tell,” issues when homes exchange hands. “Why bother to find out? Then you’ll be responsible,” they said.

Sure enough, when we tested our soon-to-be home, it was just a bit above the Environmental Protection Agency action level. This, when the current owners had “inadvertently” opened the window near our radon test can. We requested they allow us to run another – though I can just imagine those doors and windows accidentally flapping open now and again during that test period. In the end, the radon was high enough to ask the sellers to chip in for remediation -- yet low enough for me to rationalize my inattention to it several years later.

As a toxicologist, I know that there is a lot of science - toxicology studies, epidemiological studies, and risk analysis - that go into each and every EPA guideline, standard and action level. Very often politics and economics are mixed in as well.

I know when information on human exposure is unavailable for a chemical, as it often is, that animal models are used to help scientists develop standards, and when this happens, the EPA employs what are called “safety factors,” basically reducing the estimated “safe” dose often by up to as much as 100 times or more. Sometimes that is enough, and sometimes not.

But this is not the case with radon. There are unfortunately plenty of data on human exposure. Five hundred years ago early toxicologists and physicians described a disease of the lungs in mine workers who wasted away and died young. That disease is now known as lung cancer, and the primary suspect is radon. A recent study by the National Cancer Institute found that the rate of lung cancer deaths in underground miners is five times that of the general population.

Radon occurs naturally. It is produced when uranium present in most rocks (but more prevalent in some like granites and shales) breaks down. As a radioactive compound, uranium disintegrates or decays releasing progeny (or daughter) products such as radium, along with energy in the form of radiation. Very often the progeny are also radioactive. In this case, radium decays into radon gas. And so it goes, with radon decaying into polonium and other radioactive products, each releasing radiation as they decay or disintegrate.

Upon disintegration, in the case of radon and its progeny, the radiation released is primarily in the form of an alpha particle - or two protons and two neutrons - that has the potential to cause lung cancer. If a speck of dust containing a speck of disintegrating polonium landed on your hand, it is unlikely it would do you much harm. Unlike x-rays or gamma rays, alpha particles cannot penetrate your skin. However, should you inhale that speck of polonium-containing dust, or air containing radon gas, or any of the radon decay products, and they further decay in your lungs, then that alpha particle can penetrate the delicate membranes surrounding your lung cells and damage genetic material.

Radon for indoor air is measured in pico-Curies (pCi). In the ambient or outdoor air of the United States, the EPA estimates that concentrations of radon generally range from 0.2 to 0.7 pCi/Liter of air, with some locations in places like Iowa reaching 1.4 pCi/Liter year round. However, it is virtually impossible to predict concentrations in the home based on ambient concentrations, or the type of rocks and soil beneath a home. Some homes have very low levels of radon, near ambient concentrations, while others have whoppingly high concentrations, reflecting a combination of the subsurface geology, and specific characteristics of a home, including foundation type, and number of floors.

In the United States there was little public awareness of radon until the day in 1984 when Stanley Watras set off radiation alarms at the Pennsylvania nuclear plant where he worked. Turns out, his exposure was not from the plant but from his home, which measured upwards of 2,700 pCi/Liters in the basement.

In response, the EPA quickly initiated a public awareness program and set 4 pCi/L as a “non-enforceable” or voluntary action level, at which EPA advises mitigation. The level was based in part on guidelines developed a decade earlier to protect Colorado citizens’ homes that had been built on uranium mine tailings. But, according to Dr. R. William Field, an associate professor of Occupational and Environmental Health and Epidemiology at the University of Iowa, College of Public Health, who led one of the largest studies on residential exposure to radon gas and lung cancer in the United States, the “Iowa Radon Lung Cancer Study,” the EPA level of 4 pCi/L is “...not a health based guideline. The Iowa Study and both the North American and European Pooled Radon Studies noted an increased lung cancer risk for prolonged exposures at and below the US EPA’s action level.”

In other words, though the EPA would prefer we reduce concentrations in our home to ambient levels, at the time the action levels were set, 4 pCi/L was considered an achievable goal. But, according to William Bell, coordinator of the Massachusetts State Radon Control Program, “EPA believes that most homes in the US can be fixed to below 4 pCi/L cost effectively. The action guide, the point where you take action and the mitigation goal, the point at which you deem the repairs successful, are in our view, not the same.”

In our case the fix was relatively simple and standard. A thick layer of plastic sealed over our dirt-floor crawl space, a few PVC pipes tucked into the concrete basement floor and an outside fan. Though the most likely time for radon exposure was winter --when the warm air rises up and out of our homes, causing more air and any co-occurring radon to be literally sucked out of the ground and into our home -- much to the dismay of my husband Ben, we were instructed to run the fan year round. “It sucks up electricity,” he grumbled. “I hate hearing the hum of that fan.” I’ve since been informed by Dr. Field that a fan should draw no more than a 60-watt bulb and that only poorly installed fans make much noise.

Still, after five years of sucking our radon away, one construction project which required dismantling of the external pipe and removal of the fan, and a peace-making decision to turn the thing off each spring when we opened our doors and windows for good, the fan rebelled, refusing to budge when we flipped it on for the fall season. From the surly technicians, to put it kindly, who represented the company that installed it, I learned that replacing the fan would cost a few hundred dollars. Not wanting to spend the money and not wanting to deal with that particular company – at the time one of the few choices locally - the rationalizations began. I rationalized the radon away, blissfully unaware that the action level was technology, rather than health based. I practiced my own kind of “don’t know can’t hurt” toxicology, instead of reading the bountiful literature on the contaminant in my home, I concentrated on industrial contaminants in other people’s homes. Though I did occasionally crack open the windows in winter, whenever my thoughts returned to radon.

Until now. This past summer after using a roll of duct tape and my vacuum cleaner to unsuccessfully battle an army of sex-starved winged creatures who had invaded my son’s room, we were informed that the large beam upon which our living room rested for over a hundred years also served as a feeding ground for generations of termites. While replacing the beam, we discovered the “fresh air return” was not so fresh, coming primarily from the dreaded basement, rather than the first floor vents. Thoughts of basement air blowing throughout the house awakened my concern about the air quality in my own home.

This article is the result of that new respect for that invisible intruder. Radon is one of the few chemicals where there is little disagreement among scientists as to its danger. It is one of the few chemicals to which we are exposed that is not in some way associated with industry. And it is a chemical we can, if not rid from our homes, at least reduce without too much expense and effort.

After five years our radon fan is up and running and I have just received two radon test kits to retest the concentrations. This winter the windows in my office will remain closed, and I won’t worry so much about what’s blowing through that heat duct in my children’s room.

Radon Information in Massachusetts:

According to William Bell, in Massachusetts, a radon test kit costs about $20, and makes a great gift. K its can be purchased through the EPA website at http://www.epa.gov/radon/rnxlines.html or http://www.nsc.org/issues/radon/radonkitcoupons.pdf or at local hardware stores. There is only one certified site in the state of MA, which is AccuStarLabs, http://www.accustarlabs.com/shop_homeowner.php. Should your home need remediation, according to Bell, quality remediation should run between $1500-2000. For further information about testing and mitigation contact the MA DPH Radon Hot Line; 1-800-723-6695.

How About Tuna (with a dash of mercury?)

I search the pantry and the fridge for a quick nutritious dinner.

“How about tuna,” suggests Sophie, my youngest. Tuna is her favorite protein, besides cheese, cheese, peanut butter, and cheese.

“I haven’t had it since last weekend,” she adds, turning on the charm.

My concern is mercury. And these days, most of us are aware that there is plenty of it in both fresh water and ocean dwelling fish. For parents with young children who find tuna one of the few foods with protein that their youngsters will eat, the situation is particularly worrisome. As a mother of two and a toxicologist, environmental contaminants are of particular interest constantly intruding upon our lives, while at the same time presenting unfortunate but interesting examples of human impact upon the natural environment.

Mercury, like all metals, occurs in nature and is present in the earth’s crust. While natural sources of mercury include volcanoes and geologic deposits, as most folks know, mercury is also released into the air by other processes such as incineration of medical waste (for example, burning thermometers) and, more importantly, burning coal.

Although the role of mercury as a potent neurotoxicant (a chemical which impacts the brain) has been known for centuries, the exact mechanism by which it causes toxicity remains frustratingly elusive. The term “mad as a hatter,” for example, is thought to originate from early observations of mercury’s neurotoxicity on those in the business. In the 1800s and early 1900s mercury was used in the felting process of hat manufacturing, likely resulting in large exposures and crazy hatters. In modern days, mercury was responsible for the neurotoxic and teratogenic effects (impacts the developing fetus) observed in villagers of Minamata, Japan, in the 1950’s and now known as Minamata disease. The disease was first noticed in the village cats, consumers of discarded or dead fish. The cats apparently danced and stumbled around the village prior to dropping dead on the street. Eventually, the disease manifested in humans, and was traced to mercury which for decades had been released into the water by local industry and accumulated in the fish and shellfish of Minamata Bay.

But mad hatters and Minimata were caused by exposures to much greater concentrations of the metal than are present in the workplace and the environment today. Present concerns for public exposure to mercury involve tiny amounts - in the parts-per-million range – in fish tissues. But even at these very low concentrations (a part-per-million is approximately the concentration of ink when four drops of ink are released into a 55 gallon drum) there is increasing evidence of potential health impacts, particularly on the developing brain. And although release of mercury into the environment is more tightly controlled, it is still released by industrial incinerators and coal-burning power plants (in 2005, the EPA issued its first ever rule to permanently reduce and cap mercury emissions.)

Once released into the atmosphere mercury may travel across state and country lines before it eventually settles and is transformed from metallic mercury into other forms including highly toxic methylmercury. It is this form of mercury, methylmercury that becomes incorporated into the diet of aquatic creatures and those that eat them.

Here is where the tuna comes in. We all know the story, big fish eat little fish, and bigger fish eat those fish. Big fish include tuna, swordfish and other large ocean species, as well as some freshwater species including lake trout and largemouth bass. Methylmercury concentrates as it moves up the food chain. Generally the larger older predators tend to have the greatest concentration of mercury in the flesh. This is why the EPA and FDA suggest that pregnant or nursing mothers and young children stay away from large predatory fish. According to the EPA, ingestion of chunk light tuna should be limited to 12 ounces a week, while albacore tuna should be limited to 6 ounces. Albacore tuna is a different fish than the tuna used for chunk light, which can be skipjack tuna and in some cases yellowfin tuna. Differences in the size, age and life histories explain the difference in accumulated mercury.

I pull a 6 ounce can of chunk light from the shelf, and hand it to Sophie. It is sad that we need to consider “how much,” of a contaminant we’re willing to ingest, or expose our youngsters to, but until mercury emissions into the environment are fully controlled if fish is part of your diet, then it’s a necessary consideration.

If you want to learn more, there are many good sites that provide greater detail on mercury in fish, mercury toxicity and mercury controls that you may want to explore:

EPA sites: http://www.epa.gov/waterscience/fishadvice/advice.html http://www.epa.gov/air/mercuryrule/basic.htm; Physicians for Social Responsibility: http://www.mercuryaction.org/uploads/PSR_Hg3_FishC.pdf; MA Department of Environmental Protection: http://www.mass.gov/dep/bwp/hgres.htm. Specific fish advisories for freshwater fish in the state may be found by searching: http://db.state.ma.us/dph/fishadvisory/.

Antimicrobials: Too Much of a Good Thing?

What do my husband’s armpits, my son’s sandals, my mother’s steak knives and my daughter’s hairbrush all have in common? Antibacterials. They are all impregnated with antibacterial chemicals – well maybe not the armpits, but the underarm deodorant. These days, just about anywhere that is suitable for bacteria is apparently also suitable for antibacterial treatment by manufacturers wishing to attract health-conscious shoppers.

But here’s the rub – antibacterial chemicals are now showing up in the environment – in places they were never meant to be. In water flowing into rivers downstream from sewage treatment plants, in fish, and in treated sewage sludge that is applied to agricultural crops.

Additionally, while it’s clear that the use of antibacterials are beneficial in clinical settings, according to a Food and Drug Administration panel on Nonprescription Drugs there is little or no indication that such additives protect the consumer any better than washing with plain soap and water.

As a one-time teacher of microbiology, I’d always prided myself on having the foresight to stay away from purchasing soap products with antimicrobials. Although to my surprise, there they were in other household I’d purchased including the Teva sandals and the Old Spice Classic with triclosan that I’d bought for my husband.

“[The antibacterials] triclocarban (and triclosan) were introduced in the hay-days of chlorine chemistry, when chemicals like DDT and PCBs were considered safe. Relative to the latter, the antimicrobials are less problematic, but now that PCBs and DDT are banned, the focus has shifted to other chlorinated chemicals like triclocarban and triclosan,” says Dr. Rolf Halden, of Johns Hopkins University.

Recently, Dr. Halden’s group reported in the journal Environmental Science and Technology that the majority of triclocarban that is washed down the drain and into sewage treatment plants ends up in sewage sludge, which in turn may end up on agricultural fields.

His research reveals not only the persistent nature of the chemical (not unlike those other chlorinated chemicals now banned.) It also highlights the high volumes of these chemicals that are used by consumers and released into the environment. Halden’s group estimated that in their study area alone, more than one ton of triclocarban ends up in the environment (and on agricultural land – where it can be taken up by crops) each year!

While Halden is concerned about the release of the chemicals into the environment, Dr. Stuart Levy, the director of the Center for Adaptation Genetics and Drug Resistance at Tufts University, is concerned about the potential for antimicrobials to encourage development of antibiotic or drug resistant microbes.

Development of antibiotic resistance is an important survival mechanism for microbes, and soil microbes in particular. Soil is packed with microbes. They are part of what makes healthy soil healthy. Soil is also a fertile hunting ground for new antibiotics. In fact the first mass-produced antibiotic, penicillin was produced by a soil-dwelling microbe. What better way to stake one’s microscopic claim then to poison one’s neighbors? So soil microbes are constantly battling antibiotics produced by neighboring soil microbes. And in order to “keep up with the Jones’” or at the very least survive the Jones’ constant assaults, bacteria have become adept at developing antibiotic resistance.

The same can be said for the millions of bacteria that live on and in our bodies. When they are constantly exposed to antibiotics, it is possible that some will overcome, and develop antibiotic resistance. This is where the antimicrobials come in.

“We produced the original evidence that triclosan [a chemical simlar in structure to triclocarban] can lead to antibiotic resistance,” said Dr. Levy, “but while resistance to antibacterials has been found among bacteria outside the laboratory, they have not been linked to the use of triclosan.”

“Triclocarban is another antibacterial found in soaps. No one has looked at its mechanisms of action. There is clearly concern about the exposure to both of these antibacterials [causing antibiotic resistance], but in particular triclosan. The other antibacterials of concern are those under the heading of quaternary ammonium compounds like benzalkonium chloride. More and more data are linking resistance to this product with antibiotic resistance.”

So, antibacterials which have the potential to cause antibiotic resistance are released into the environment in huge quantities as a result of consumer use, and an FDA panel has concluded that antimicrobial products appear to be no more protective to consumers than soap and water. Who’s in charge of regulating this stuff?

Antimicrobials are regulated by both the FDA and the Environmental Protection Agency, depending upon their use, and claims made by manufacturers. EPA regulates antimicrobials when they are used as pesticides, for example to reduce odors in my son’s stinky Tevas, but FDA regulates them as drugs when used in something like the bottle of soft-soap that graces the bathroom sink at my daughter’s school. In either case – since triclosan and triclocarban were developed and registered at least thirty years ago, back when persistent chemicals weren’t known to be a problem, and antibiotic resistance hadn’t reared its ugly head – one wonders how today’s research has enlightened the regulators.

“Advances in a number of fields have changed the way we examine and interpret the potential risk of synthetic chemicals,” says Halden. “Many studies conducted in the 1970’s would not pass muster today.”

But there’s hope, according to Stuart Levy, who noted that while “there is no evidence of a change in regulation, there certainly seems to be a greater insight and concern by regulatory agencies like the FDA and EPA. They are both looking more closely at this issue, thanks to the advocacy of scientists and others.”

It’s also worth noting that perhaps not all products present the same risks. “It is presumably more likely that triclosan in a water-solubilizable form [soft-soaps for example] would be more risky than that which has been incorporated into something like a mattress or sneakers,” suggests Levy, who notes that even with these products, the fate of antibacterials is unknown.

So where does that leave us? According to Dr. Bernadette Albanese, a public health expert, “If people spent as much time washing their hands, as they do reading the labels of this stuff, we’d all be better off. Putting antibacterial in soap, towelettes, band-aids is mostly useless. The message should be proper and frequent hand washing, use plain (liquid) soap and paper towels. That is the message the public needs to hear.”

Although I’m not sure I’m ready to give up the microban treated Tevas (have you smelled a well-worn pair of Tevas?) I’ll definitely be reading my consumer products labels more carefully.