Friday, February 19, 2010

Do Chemicals in the Body Pose a Risk?

Biomonitoring studies routinely demonstrate that the human body has become a receptable for a variety of chemicals. Whether these are large scientifically robust analyses such as those conducted by the Center for Disease Control or less robust studies in which a handful of mothers or environmental ministers are checked for a laundry list of chemicals, the fact is that there are many chemicals that are virtually always found in our bodies. But does it really mean anything?

Ah, that's the $64,000 question (or perhaps with inflation, the $64 billion question).

An article published in the February 15, 2010 edition of the New York Times discusses this issue as it relates to the ongoing debate about reform of the Toxic Substances Control Act.

The one thing that is clear is that "presence of a chemical in the body does not necessarily mean it will have an effect." This is repeated by the chemical industry whenever an environmental or health advocacy group publishes a report based on the analysis of a handful of people. And it is absolutely true. Both Henry Falk (of the CDC) and Linda Birnbaum (of the National Institute of Environmental Health Sciences) concur that our ability to measure tiny amounts of chemicals in our bodies has far outpaced our ability to understand what the presence of these chemicals means relative to effects...or the lack of effects.

But others argue that the very presence of so many chemicals in the body is enough to take action.

Aye, and there is the rub. What action is appropriate?

Clearly we are in a situation in which we must make decisions even with uncertainties in our knowledge. So it seems that the focus of TSCA reform should be on collecting the information necessary to reduce that uncertainty and provide greater confidence in decision-making. The results of biomonitoring studies can inform the prioritization process under the new TSCA (or Kid Safe Act) by identifying chemicals that can be given a closer look. But biomonitoring can't be the only prioritization mechanism since we can't adequately measure all chemicals in the Inventory (roughly 85,000 of them). And new chemicals are put on the market every day. So there will be testing of new chemicals, and at the very least, of existing chemicals that have been identified as priorities for further work by their presence in the body, their widespread use, their high production volumes, or their persistent, bioaccumulative and toxic (PBT) properties.

Do we need the new law to require biomonitoring of every new chemical? No. Do we need some sort of biomonitoring, such as the CDC program? Yes. Do we need a way to identify new chemicals to look for in biomonitoring studies? Yes. Will we have to make decisions based on uncertainty? Yes.

The bottom line is that biomonitoring will play a role in prioritizing chemicals for closer review, but we can't get lost focusing on biomonitoring as an end in itself. The key is to reduce risk, not merely document exposure.

No comments: