Monday, July 30, 2007

From Our Town Dump to.....The fate of high tech waste, the journey begins

Crossposted from Earth Forum:

Sidney's post on Waste Management, prompted me to add this post. When I read his title, my own thoughts jumped to management of e-waste (and wondered if this would be covered at that meeting.)

From my impression, this one of those waste issues where growing awareness is making a difference. In my own town, for example, you can rid yourself of computers, televisions and any electronic waste for something like five dollars. But the question is - then what? Turns out it "used" to go into a box car and then apparently on to China. I emphasize "used to" because that's only what I am told. The change, presumably, occurred because of environmental and health concerns. But at the moment no one can tell me if they've really changed their practices (it's something I'm looking into for a future article on the stuff.)

Two articles recently published in Environmental Science and Technology reveal the high risk to residents and workers caused by the dismantling of e-waste in regions where environmental laws are lax or nonexistent. The first article, by Huiru Li and others, is entitled " Severe PCDD/F and PBDD/F Pollution in Air around an Electronic Waste Dismantling Area in China " and the other by Xinhui Bi and others "Exposure of Electronics Dismantling Workers to Polybrominated Diphenyl Ethers, Polychlorinated Biphenyls and Organochlorine Pesticides in South China," describe the exceedingly high concentrations of these toxic chemicals to which not only workers but local residents are exposed during the dismantling processes.

For those interested in further reading on the subject, check out "High Tech Trash," written by Elizabeth Grossman, published by Island Press. An informative and sobering book, through which I'm slowing making my way.

Wednesday, July 25, 2007

Doh! There's more to bioaccumulation than we thought!

Here’s one for the “why didn’t we figure this out sooner” file, or maybe the “gee – those of us air-breathers really are different from our gilled cousins!” You see, for years one of the primary methods of determining the ability of a chemical to accumulate in living creatures was to study the accumulation (or bioaccumulation) of the chemical in fish. The model is based on the idea that fat-loving chemicals, which includes most bioaccumulative chemicals, are essentially absorbed from the surrounding water by fish, or, more or less technically, by “swimming bags of lipid.” Those that are not rapidly metabolized are retained in the fat, allowing not only for accumulation in our little fish, but also for the proverbial big fish that eats the little fish all the way up the food chain to polar bears, bald eagles and homo sapiens. Some infamous lipid-loving chemicals that we all know and fear include certain PCBs, dioxins, and DDTs.

Most governments, including the U.S., have thankfully learned (after…umm decades) to consider carefully a chemical’s potential for persistence, or ability to hang around the environment, and bioaccumulation when evaluating and regulate commercial chemicals.

Great! No more bioaccumlative chemicals climbing up the food chain. Problem solved. Or is it? A recent report by Barry Kelly, Frank Gobas and others, published in Science (Volume 317, pages 236-239) suggests that our current method for evaluating bioaccumulation may miss – and in a big way. According the study, some chemicals that don’t accumulate in fish, or chemicals that might pass the “swimming lipid bag” test with flying colors, can accumulate land mammals and marine mammals.

What’s the difference? After all fat is fat – be it a swimming or walking bag of lipid (which I must admit sometimes I’ve felt myself as I struggle to squeeze into my favorite jeans at the end of the summer.) Turns out, as with anything, there’s more to bioaccumulation than hanging out in fat. Living organisms are dynamic creatures, and most things that enter the body have the potential to be metabolized and/or excreted. Even chemicals that hide out in fat can be eliminated given enough time. But what’s different between fish and polar bears or fish and humans (among other things) is that according to Kelly and others, “…air-breathing organisms in this analysis exhibit higher [biomagnification factors] than those in water-respiring organisms because of their greater ability to absorb and digest their diet, which is related to differences in digestive tract physiology and body temperature.” Additionally, note the author, air-breathers may be less efficient when it comes to eliminating certain chemicals from their bodies than water-respirers.

Go figure. This is where, as a toxicologist who bought into the “bag of lipid” model years ago without question, now wonders – what was I thinking? Chemicals that might pass (and have passed) the fish bioaccumulation test, wouldn't pass a mammalian test, according to the authors who note that these chemicals, “representing a third of organic chemicals in commercial use, constitute an unidentified class of potentially bioaccumulative substances that require regulatory assessment to prevent possible ecosystem and human-health consequences.”

Time once again, to reconsider how we evaluate and regulate, and release chemicals into our environment.

Thursday, July 05, 2007

Our bodies, the ultimate transformers: PFOA and other perfluorinated chemicals in our bodies

Our bodies are constantly working, transforming chemicals from one form to another like that bagel and cream cheese I had for breakfast into something hopefully more useful or, the chemicals from that greaseproof food-packaging paper into something more toxic. Whoa. What?

A few posts back I wrote about perfluorinated chemicals – known as PFOA and PFOS - used for waterproofing and nonstick pans. Then I added a post about PFOA and popcorn bags. Now it’s even more insidious and complicated than being exposed to just PFOA. Considering recently reported concentrations of these chemicals in human blood, Jessica D’Eon and Scott Mabury, in a study just published in Environmental Science and Technology suggest that concentrations in humans are likely the result of “exposure to current-use fluorinated materials and not the historical load present in the environment,” (Certain perfluorinated chemicals have been phased out of use by major producers once recognized as human and environmental contaminants.)

These current-use chemicals, particularly those used to manufacture waterproof or greaseproof paper (think microwave popcorn,) known as polyfluoroalkyl phosphate surfactants or PAPs, can be transformed once transferred from say, that greasy microwave popcorn bag to our fingers or popcorn and then to our guts, not only into PFOA (which a recent draft assessment by EPA suggests is a carcinogen) but also chemical compounds which might be more immediately toxic.

Referring to the byproducts of metabolism D’Eon and Mabury write,“Due to their inherent reactivity, exposure to these transient metabolites is likely of greater toxicological concern than exposure to PFCAs [which includes PFOA] alone.”

Huh. Ain’t that funky now.

Of course further work is necessary before the potential impacts of these kinds of exposures can be fully understood, including a better understanding of how (and how much of) these chemicals migrate into food, what kinds of food are most important for this kind of exposure, and how much of these foods we consume. Microwave popcorn anyone?

You can find the full article, in issue 41, of Environmental Science & Technology, pages 47-99-4805.

Monday, July 02, 2007

New Report on EPA and Nanotech - just what I've been waiting for!

For those of us concerned with health and environmental impacts of new and old chemicals, the production and use of nanomaterials presents a fascinating opportunity to consider and then reconsider the mechanisms by which chemicals are tested and controlled in the United States. While I've been trying to keep up with the toxicology of nanomaterials, I've wondered about the adequacy of our current regulatory framework to evaluate and manage these materials. Fortunately for me and anyone else wondering the same thing, a recent report by Dr. Terry Davies entitled EPA and Nanotechnology: Oversight for the 21st Century opens the door for us, by reviewing the principle laws and regulations developed to manage and control chemicals and considers the effectiveness of their application down in Whoville, where all things are nano.

As Davies notes, “In a few decades, almost every aspect of our existence….is likely to be changed for the better by nano. However, if the potential for good is to be realized, society must also faces nano’s potential for harm.”

One of the primary issues for toxicologists investigating nanomaterials, is my favorite, “It’s hard to find what you don’t know you’re looking for,” or it’s pretty difficult anyway…unless one is trained to expect the unexpected. And it seems that nanomaterials have the potential to behave quite differently not only from their non-nano counterparts, but also from different formulations of the same material. In some cases, as Davies notes, contrary to current underlying toxicological concept that smaller doses tend to be less toxic (in general – there’s a whole ‘nother discussion to be had about hormesis – the differential behavior of some chemicals at very low concentrations) in some cases nanomaterials may behave differently and potentially more toxic when present in lower concentrations than their non-nano counterparts. Just that issue alone has the potential to turn our current toxicity testing, assessment and regulatory practices upside down when it comes to nanomaterials!

But really the focus of Davies report is the “so what” question. Given where we are now – in terms of understanding the potential health and environmental impacts of these materials – what can be done in terms of regulation and management? As Davies points out, while some of EPA’s programs, as they are now, may provide adequate oversight of nanomaterials (he cites FIFRA – which has jurisdiction over all pesticides – as a program that has “strong legal adequacy” when it comes to nanomaterials) TSCA, the Toxic Substances Control Act, which has the greatest potential to cover the most nanomaterials, is “particularly deficient” for a number of chemical oversight functions. According to Davies “the Act desperately needs to be amended, both to deal with nano and to adequately address all types of chemicals.”

This is an informative and readable report, and if you’re at all interested in nanomaterials, you might want to take a look.

The full report is available free and online through the Project on Emerging Nanotechnologies, an initiative of the Woodrow Wilson International Center for Scholars and the Pew Charitable Trusts,