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HUMAN HEALTH IMPACTS OF EXPOSURE TO POPS
Citation:
BIRNBAUM, L. S. HUMAN HEALTH IMPACTS OF EXPOSURE TO POPS. Presented at 2nd Network Conference on Persistent Organic Pollutants, Birmingham, UK, April 15 - 19, 2007.
Description:
The Stockholm Convention on persistent organic pollutants (POPs) was adopted in 2001 to protect human health and the environment from chemicals that are highly toxic, persistent, bioaccumulative and undergo long range transport. These POPs include 9 pesticides, polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs). However, these are not the only persistent contaminants of concern. The US EPA has also developed national action plans for other persistent, bioaccumulative toxicants (PBTs) such as alkyl-lead, benzo(a)pyrene, mercury compounds, and octachlorostyrene. However, there are emerging chemicals which clearly meet the definitions used for POS/PBTs. One major class involves the highly fluorinated alkly acids (PFAAs) such as PFOS and PFOA which are extensively used as surfactants, but have recently been detected in people, as well as environmental samples and wildlife. New studies demonstrate the potential for various toxicities for these compounds including developmental and reproductive effects, immunosuppression, and cancer. The other major class involves certain brominated flame retardants (BFRs), including tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), and polybrominated diphenyl ethers (PBDEs). All have been detected in environmental samples and biota, and HBCD and PBDEs have been found in the Arctic. The stereoisomeric composition of the commercial HBCD mixture is distinct from what is found in biota. Likewise, the congener composition of the commercial PBDE mixtures is very different from that found in various environmental matrices, wildlife, or people. To date, TBBPA and HBCD are essentially unregulated, although the release of TBBPA is captured under EPA's high volume chemical's program. In contrast, the commercial Penta and Octa PBDE mixtures have been formally banned in the EU and several US states. The sole manufacturer voluntarily ceased production over two years ago. Action on these two products was driven by the potential health concerns. Although studies demonstrating toxicity of the Deca PBDE product are more limited than for the lower brominated species, there is growing concern not only for its inherent toxicity, but for its ability to break down into the lower brominated congeners. Health effects reported in invertebrates, fish, and mammals include hepatotoxicity, dermal effects, reproductive toxicity, immunotoxicity, endocrine disruption, developmental reproductive and neurotoxicity, and cancer. Although the presence of these chemicals in people has been verified, few studies have looked to see if there is any evidence of adverse effects in the human population from exposure to PBDEs. A major concern is the potential for greater than additive effects from the mixture of POPs present in the environment, wildlife, and people. (This abstract does not reflect Agency policy.)