While browsing through Facebook status updates earlier today, I noticed that two friends independently posted a link to this op-ed on the New York Times website, written by blogger Nicholas D. Kristof.  Mr. Kristof posted his thoughts on something that has been nagging at us, the consumers, for a while now: chemicals in our plastics that act as so-called endocrine-disrupting chemicals (EDCs).  Simply put, EDCs are imposter molecules that mimic hormones naturally present in our body and therefore interfere with normal biological processes regulated by these hormones.  These affect both men and women but in different ways, as there are notable differences in body chemistry between the sexes.  Perhaps the most infamous EDC is dichlorodiphenyltrichloroethane, more commonly known as the pesticide DDT, which has been banned in the U.S. since the 1970s for possible carcinogenicity and reproductive toxicity, among other big no-nos.  You may have also heard of bisphenol A (BPA), which many companies recently stopped incorporating into their products due to its potential toxic effects.  In females, EDCs have been linked to early puberty, breast cancer, uterine fibroids, disrupted lactation among a variety of possible effects.  EDCs are such a hot issue that the Endocrine Society released an extensive report this year summarizing what is known about their effects.  For me, it was provocative to read that the rise in obesity appears to correlate with the rise in industrial chemical use.

There is a scarily extensive list of known EDCs and many of these are, of course, still in use today.  They are everywhere – from the plastic in your water bottle to canned fruit tins to flame retardants to shampoo.  But what does it all mean?  Is my Brita pitcher leeching poison into my water as we speak?  Do I stop washing my hair?  Even as a scientist-in-training, I find it very difficult to organize the bubbling vat of information published by laboratories around the world on a daily (hourly?) basis.  However, one of the biggest lessons I’ve learned in graduate school is to approach scientific results with a healthy dose of skepticism and to ask a lot of questions. Published research on EDCs is a prime target for this skepticism.  My impression is that many labs continue to duel over what exactly a chemical and how much of it will endanger our bodies.  There are lot of "links," "associations" and "correlations," but as a scientific claim is made it is just as quickly shut down by a competing report.  Sometimes researchers will use a much higher dose of a particular chemical than the average person would normally be exposed, exaggerating the risks.  Studies might be done on cells growing in a plate that don’t behave like a normal cell, or on animals whose physiology does not behave or react like a human’s.  This is particularly true for early studies on a new chemical.  As Candace pointed out in her “What is Women’s Health?” entry, there is also the dangerous tendency to universalize a study that was conducted only on a single gender group, age group, ethnicity, or nationality, and so on and so forth.

All the grains of salt aside, I do appreciate the awareness that the media raises regarding the products we purchase, what they might contain, and how they might be harmful.  I think it is also our personal responsibility to be educated about what we choose to believe and question how something came to be stated as fact.  There is certainly no shortage of information out there.  Here are a few links I found useful regarding EDCs:

  • The Environmental Protection Agency’s Endocrine Disruptor Screening Program, which seeks to identify potential EDCs and determine their specific effects at defined doses
  • The Endocrine Society’s full report on EDCs (opens a PDF)
  • Informative fact sheet about BPA from the National Toxicology Program (opens a PDF)

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DDt has negative effects on pregnant women.Even though its use has been prohibited in most countries for ecologic considerations.It is still used in some developing countries for essential public health purposes.Due to its stability and its capacity to accumulate inadipose tissue it is found in human tissues, and there is now not a single living organism on the planet that does not contain DDT.The possible contribution of DDT to increasing the risks for cancers at various sites and its possible role as an endocrine disruptor deserve further investigation.