Tuesday, May 20, 2008

Great Future in Plastics

First published in the Montague Reporter, May 2008

It was a simple enough design. Pink and white tampon applicators separated by blue milk bottle caps and strung into a necklace. Those treasures washed by the sea onto our beach, and collected by my father over the course of a few hours one Sunday morning, provided the perfect accessory to the orange fishnet cape adorned with fading coke bottles, pieces of old lobster trap and other assorted beach waste items. Twenty years later, the image of my father, in his faded blue oxford shirt, dungarees and size 12 Jack Purcells sterilizing a pot of tampon applicators in my mother’s kitchen and in my mother’s soup pot, reminds me of a rare moment of father-daughter complicity.

That year as I attended the annual Society of Toxicology and Chemistry Halloween Dance dressed as “Beach waste,” I was na├»ve about the dangers of plastics. At the time those tampon applicators and milk bottle caps simply signaled failures of waste handling and sewage treatment – an issue George Bush the first used disingenuously to his advantage while campaigning against Massachusetts’ Michael Dukakis.

What I didn’t know back then was that the plastic army of tampon applicators, bottle tops, fishing nets, coffee cups and Barbie dolls (an occasional head, arm or leg had been know to wash ashore) wasn’t just gathering on the shores of my beloved Nantasket beach. These insidious soldiers of the chemical revolution were infiltrating oceans world-wide – and worse, over the years bits of plastic have literally become a part of life. In their relatively short time on earth (in 2007, synthetic plastics celebrated centennial birthday) plastic now contaminants marine mammals, seabirds and most of us – kids and pets included.

I’m sure John Wesley Hyatt hadn’t intended to promote such a legacy when in an effort replace the ivory used for billiard balls he invented one of the first known plastic back in 1863. Although, it’s not clear that his intention was to save the thousands of elephants slaughtered for their tusks, but rather to collect a $10,000 award offered for suitable ivory replacements. Nor should he have been concerned, since his process used natural substances including cellulose, a compound more prone to biological degradation than its synthetic followers, (and 140 years later, a compound that is back in style.)

Probably Leo Baekeland, hadn’t envisioned the reach of his invention either, when, in 1909 he developed Bakelite the world’s first synthetic plastic and wonder material. As a thermoset plastic, a magical resin that could assume any shape as a liquid resin, and then once hardened remain resistant to heat and solvents – Bakelite quickly found its way into the American dream – from telephones to electrical devices, automobiles and jewelry.

But it’s not Bakelite that scientists are finding in North Pacific albatrosses, or in us. It’s the next generation of polymer plastics which have invaded our lives for better or worse. In 2007, the American Chemistry Council reported upwards of 13 billions pounds of plastic resin produced by U.S. industries a year. This is 13 billion pounds of substances resistant to degradation and substances which we are now just beginning to understand can impact the development and function of reproductive systems in subtle yet potentially very important ways.

By now, unless you live radio-free and newsprint free you’ve likely heard about bisphenol-A which leaches from those colorful polycarbonate Nalgene bottles we all bought to avoid buying bottled water, and hard plastic baby bottles and some food-can linings. If not, you must have heard about phthalates – the plastic additive used to soften poly-vinyl chloride (or PVC) and which leaches from items like IV bags, those cute yellow rubber duckies my kids used to mouth during bath-time, teethers and soft plastic books. (Phthalates are also ubiquitous in personal care products including shampoos and lotions –another route of exposure for infants.)

Bisphenol A, and some forms of phthalates act like the potent sex hormone estrogen. For decades scientists have known that exposure to unnatural levels of sex hormones (either too much or too little), particularly during key periods of sexual development can result in tragic outcomes for both sexes. Estrogen is a naturally occurring hormone, which acts by binding with an estrogen receptor. Any other chemical that binds with this receptor and turns it on is an estrogen mimic. Some chemicals may bind with the estrogen receptor but instead of acting like estrogen, block the receptor from any further action – these substances are referred to as antiestrogens. The same is true of other hormones like the male sex hormone testosterone – there are mimics and inhibitors. Collectively these substances are called endocrine disruptors.

The impacts of synthetic estrogen exposure are best illustrated by diethylstilbesterol or DES. For those who don’t recall, DES was a synthetic estrogen prescribed to women from the 1950s through the 1970s to stem complications during pregnancy. Although eventually found ineffective, it continued to be prescribed until the consequence of extraneous estrogen exposure reared its ugly head in the form of clear cell adenocarcinoma in daughters exposed in utero. Later, structural differences in the reproductive tract and infertility were identified in both DES sons and daughters.

That bisphenol A acts as an estrogen is no surprise. Back in the 1930’s the chemical was almost developed as a synthetic estrogen, until DES stole the show. So seventy years later how does this stuff – a known estrogen - end up in plastic drinking bottles and plastic can liners?

Plastics are polymers – that is, they’re made up of many repeating units, strung together like a paper chain. The broad range of plastics we’re familiar with today results from the diversity of repeating units and chain formations discovered and developed at a feverish pace over the past century: vinyl, polyurethane, polystyrene, Teflon, Nylon, neoprene, polyethylene, polypropylene, and in 1953, researchers resurrected bisphenol A in the form of polycarbonate. That’s right. A key link in the polycarbonate chain is bisphenol A. Only back then, we can only hope, no one figured their grandchildren would be sucking down mom’s milk, lovingly pumped so that she could continue to work, from polycarbonate plastic bottles, or that food cans would be lined with the stuff. Or maybe no one figured that individual units of plastic could actually break loose.

But the fact is they do. And the more scientists look, the more they seem to find – whether it’s bisphenol A leaching from polycarbonate bottles, or phthalates leaching from IV bags. And as with many toxicants like mercury and lead, it’s our precious next generation that bears the brunt of our collective ignorance.

“So what would you do?” asked my neighbor, mother of two young boys. “Do you still drink out of plastic?”

Her mother had just given her the “You’re intelligent, how can you feed your children that stuff,” lecture – but she hadn’t yet tossed the sippy cups, rubber duckies and baby bottles.

I nodded sheepishly. I do love those colorful polycarbonate drinking glasses I purchased at Stop&Shop several years ago. And yes, last hiking trip we all sipped from the bright red Chaco Canyon polycarbonate liter bottle.

“I figure the water’s not sitting there all day,” I said, explaining that the greatest leaching of bisphenol A was reported after liquids were heated, or in very “well-used” or distressed polycarbonate. We didn’t even get into the phthalate issue, which extends beyond the use and leaching of phthalates from plastics, to personal care products

“But,” I conceded, “I did just buy some new water bottles, made from polyethylene, for the kids.” Unlike polycarbonate, polyethylene doesn’t leach any thing toxic, at least not that we know.

As I said this, I am sure that the little enviro-region of my brain, the one that lights up every time I do something hypocritical, began flashing away. Did I say I replaced one plastic with another? And did I say that while wearing my favorite purple polyester fleece and polyvinylchloride-bottomed Dansko clogs? Did I say that after dumping a box of broken plastic toys – nonrecyclables – into our 40 gallon plastic barrel?

Even more concerning than the plastic and related compounds in our food and beverage containers – substances which can eventually be manufactured out of these products, or avoided by the careful consumer, are the reports that millions of tons of plastic, from fishing nets to bits of what might once have been tampon applicators and polyester clothing, now circulating in the regions of the Central North Pacific Ocean (gyres). By some estimates, these trash or plastic gyres cover an area equivalent to the size of Texas. And although plastics may not degrade they can break into bits – some as small as 20 microns, creating a plastic soup served up to unsuspecting wildlife.

Writes Charles Moore founder of Algalita, a marine research foundation focused on the protection of marine environments, “I now believe plastic debris to be the most common surface feature of the world's oceans. Because 40 percent of the oceans are classified as subtropical gyres, a fourth of the planet's surface area has become an accumulator of floating plastic debris.”

Further, scientists suspect that some of that plastic may be circulating around for hundreds of years to come. For better or worse – plastics are part of our lives. But they don’t have to be part of us and they don’t have to be part of all creatures on earth. Improved production practices, and products that are easily recycled back into the same products, rather than dead ends like lawn furniture and plastic lumber, and improved public awareness might not rid the North Pacific of its trash right now – but maybe generations from now.

In the ‘60’s movie The Graduate, when Mr. McGuire, a family friend of young Benjamin Braddock advised “Plastics…..There’s a great future in plastics,” he had no idea.


Wednesday, May 14, 2008

Motherhood the Elephant in the Laboratory: time to speak up

This is, and isn't, a little off topic but as editor of Motherhood the Elephant in the Laboratory: women scientists speak out, I'm happy to announce that this book of 34 personal essays is now in print thanks to Cornell University Press, and many bold women who wrote about how motherhood influenced their science careers and vice-verse.

Writing and teaching about toxicology (to undergrads and sometimes to highschoolers) is one of the indirect impacts becoming a mother has had on my own career. Because I made the choice to work part-time, which is not an easy thing to do in the sciences, I've kept my own scientist alive through all sorts of interesting people and projects over the years. All of this fueled my desire to reach a broader audience through writing, beginning with articles in our local paper, the esteemed but very small Montague Reporter (hence the Neighborhood Toxicologist) and now through this blog.

As I write on the blog created for the book, Sciencemoms, those who take alternative routes through science ought not be considered failures, or second-class scientists - but apprecaited for their role as communicators, educators, and synthesizers. For more on this see the sciencemoms blog about the two recent editorials in the journal Science. The editorials, written by Bruce Alberts, highlight and support development of programs encouraging scientists to seek alternatives to academia.

Any thoughts on this topic are welcome either here, or at sciencemoms (and you don't have to be a mom - or a women to speak up!)

Tuesday, May 13, 2008

Tetrodotoxin 101

A good way to hook students into the wonderful world of toxicology is tetrodotoxin. Sound familiar? It’s what makes fugu, or puffer fish, what it is - a potentially deadly Japanese delicacy. Or does it? Would the delicacy be so appealing if the consumer didn't risk death or paralysis?

For those unfamiliar with fugu or tetrodotoxin, note that a mere “taste” of the stuff can and does kill. Although not the most potent toxin in the toolbox (recall that we’re talking toxin - or naturally produced poison) that honor most likely goes to either C. botulinum toxin (the toxin whose presence may be indicated by those puffed up cans – like the tuna can I once pulled from a grocery shelf,) or ricin – most recently of Las Vegas fame – and produced by the lowly castor bean.

Although non-toxic preparation of fugu has been raised to an art by highly skilled Japanese chefs, and although not all wild puffer fish contain enough toxin to kill, one article estimates that upwards of 50 mortalities may occur each year in Japan following puffer fish ingestion.

But now there’s good news for those who just must nibble – yet who’d prefer to avoid death or illness (tetrodotoxin inhibits muscle contraction causing paralysis). A recent article in the New York Times by Norimitsu Onishi reveals not only some interesting fugu history, but also describes the current trend towards raising tetrodotoxin free fugu.

For years, scientists seeking out the source of fugu (and many other marine species) tetrodotoxin had been baffled – where did it come from? Was it produced by the fish themselves or was it in the food they ate? And why didn’t it kill puffer fish and other tetrodotoxin laden marine animals?

Recent studies now suggest that, like many other potent toxins, tetrodotoxin is produced by the smallest of small, bacteria. By providing a home for bacteria, the boxy puffer is offered protection (and fortunately for the puffer fish, they’re at an advantage thanks to a genetic mutation, which makes them immune to its toxicity.)

As you might guess, here’s where the non-toxic fugu come in. By knowing the source, fish farmers can now feed fugu tetrodotoxin-free food (say that ten times fast) producing a risk free meal.

Although, for some the thrill of fugu may be in the risk – for others writes Onishi,, fugu liver is just plain tasty – like foie gras but without the guilt.