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Public Radio's Environmental News Magazine (follow us on Google News)

Chemical's "Dirty Dozen"

Air Date: Week of

Host Steve Curwood talks to University of Wisconsin Professor Anders Andren about a call for a ban on the use of 11 "persistent toxic substances," including several chlorinated compounds, along with lead and methyl mercury. An advisory committee to the US-Canada International Joint Commission says the chemicals are unsafe in every known concentration.


CURWOOD: Some chlorinated compounds are among what the International Joint Commission calls the "dirty dozen" of "persistent toxic chemicals" that linger in the environment. The IJC has called for the "virtual elimination" of these chemicals from the Great Lakes basin. Dr. Anders Andren is a water chemist at the University of Wisconsin and the co-chair of the IJC's virtual elimination task force. He's with us now on the line from Madison, Wisconsin. Hello, Dr. Andren.

ANDREN: Hello there.

CURWOOD: I'd like to ask you, first of all, what is a "persistent toxin" and how is this different from your garden variety toxic?

ANDREN: Well, we recognize that there are 60,000 to 70,000 commercial chemicals in use right now. Some of them are toxic, and again another fraction of them are persistent. And so we define persistence as a substance that has a half-life in water, air, sediment, soil, or [?] of greater than eight weeks and a substance that bioaccumulates in tissue of living organisms.

CURWOOD: What are some of the ones that you're most concerned about?

ANDREN: Those substances of particular concern right now are those substances like PCBs, polychlorinated dibenzodioxins, furans, toxifene, lead, mercury, especially the methyl-mercury form in some of the pesticides.

CURWOOD: How does chlorine fit into this group of chemicals?

ANDREN: There are approximately 15-20,000 chlorinated organic compounds, many of which have been shown in the laboratory to be quite toxic and to bioaccumulate. Because they comprise such a large fraction of toxic substances, they have received particular attention.

CURWOOD: Why virtual elimination? Is it your view that there is no safe level of these substances in the environment?

ANDREN: The view of the task force is that there might be for some of them, but we do not have the capability at this time to know where the safe level is. Secondly, in the past we used death as an endpoint. We find that's not the way to do it now. We are using neurotoxicological symptoms, we used immune deficiency type of defects, and more and more of these have been unravelled every day. We will not know for a long time what the safe level is; therefore, we prescribe a cautionary principle for those substances that in the laboratory have been shown to be exceedingly toxic.

CURWOOD: In sum and in brief - the twelve compounds that you've named here - basically what is their threat to us and the environment?

ANDREN: It is very clear to most people that the wildlife in the Great Lakes basin have been harmed by these substances. We see immune deficiency problems, we see crossed bills, we see poor hatching success, and so forth, and I think the weight of evidence clearly indicates that it's a combination of these substances that cause these problems.

CURWOOD: And the threat to us as humans?

ANDREN: That is much more controversial and there are studies right now underway. In particular, there is a fairly energetic research program underway to see how these substances attack the human immuno-deficiency systems.

CURWOOD: What implications beyond the Great Lakes do you think your work has?

ANDREN: We believe that these principles will be adopted not only nationally by the US and Canada, but globally. We believe that we are now recognizing, as our DDT example tells us, that setting standards and limits in just one country is not enough. There is a very often-quoted sentence that says something to the effect that air pollution observes no national boundaries. We are, in our report, also saying that you have to look at this in a global sense.

CURWOOD: Thank you. Dr. Anders Andren is the co-chair of the virtual elimination task force of the U-S-Canada International Joint Commission.



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