Ever heard of tributyltin? Probably not, but odds are you’ve been exposed to it. The chemical is used as a biocide in industrial water systems, breweries (gulp), and in wood preservatives; and as a pesticide on so-called "high-value" food crops (think fruits and vegetables). Its residues are also found in fish and shellfish.
And … exposure to it may be contributing to growth in obesity and diabetes rates, according to an article in the December 2008 BioScience, the journal of the American Institute of Biological Sciences. From an AIBS press release:
The harmful effects of the chemical on the liver and the nervous and immune systems in mammals are well known, but its powerful effects on the cellular components known as retinoid X receptors (RXRs) in a range of species are a recent discovery. When activated, RXRs can migrate into the nuclei of cells and switch on genes that cause the growth of fat storage cells and regulate whole body metabolism; compounds that affect a related receptor often associated with RXRs are now used to treat diabetes. RXRs are normally activated by signaling molecules found throughout the body.
The researchers also found that "tributyltin causes the growth of excess fatty tissue in newborn mice exposed to it in utero." That’s an attribute it shares with other ubiquitous nasty substances: environmental estrogens such as bisphenol A and nonylphenol, found in plastics.
The researchers argue that it’s "plausible and provocative" to link the obesity epidemic to the rise in use of industrial chemicals over the past decades.
But … doesn’t our EPA protect us from harmful chemicals? Get real. (Here’s Dave Roberts’ emotional reaction to Stephen Johnson’s reign at EPA; and here’s mine.) Over at Natural News, Sherry Baker points to a new new study by the National Research Council revealing severe structural problems that impede the EPA from effectively gauging risk. According to the study:
The U.S. Environmental Protection Agency’s process of generating risk assessments — which estimate the potential adverse effects posed by harmful chemicals found in the environment in order to protect public health — is bogged down by unprecedented challenges, and as a decision-making tool it is often hindered by a disconnect between available scientific data and the information needs of officials.
Here’s my favorite bit:
The committee found that EPA is struggling to keep up with demands for hazard and dose-response information and is challenged by a lack of resources. For example, the risk assessment for trichloroethylene, a chemical that is linked to cancer, has been under development since the 1980s and is not expected until 2010.
What’s the rush?