Thank you.
I think that whatever you do is good. I think longer term...but you may want to learn from your initial study and then update your methodology. So I don't know whether you're talking about one long study or multiple. But it's true that the body burdens only tell you what's present in the body. They don't tell you very much about what impact it's having. I'll come back to that.
On the question of blood in urine, there's a lipid content in blood; blood carries fat. And because there's a lipid content in blood.... I don't know the formulae. There's a pretty good formula that you can use--blood sampling as a surrogate for estimating the lipid content from the blood content. So yes, I think, for all practical purposes, blood sampling will give you what's available in the fat. You don't just multiply it by how many litres of blood you have in the body. You have to do a more complicated calculation on that.
Urine sampling will tell you things, but the chemicals that bioaccumulate are of special concern. They tend to be fat-soluble and not water-soluble. Most of the toxic purification processes of the body are water-based. The kidneys are very good at removing water-based toxicants from the body and they're very bad at releasing fat-based toxicants from the body. But there is some metabolism going on and I believe information can be gained from urine sampling, both with regard to the stuff that is water-soluble and also in terms of breakdown products as well from some of the other substances. In terms of the chemicals of the kind we're talking about, blood sampling gives you a better picture of what's going on in the body.
Are we too late? We were probably too late in 1930 when we went down some of these chemical pathways, but you're never too late, because there's always going to be another generation. On the information that I reported about the prostate, this was information I learned in the early nineties at a workshop that the IJC sponsored. What's too late is if the information is not acted upon. The hurdles of taking the information that's out there in the scientific community--getting through the noise, the manufacture of doubt, the delays--means what's too late is the action that's taken by legislators, regulators, and so on. So in a way we can refine our knowledge. It's absolutely true. When PCBs were introduced, they were introduced because they were considered to be very stable and very non-toxic. Now everybody in Canada and the U.S. agrees that PCBs are bad.
When the Stockholm Convention was negotiated, I heard the same story from I don't know how many countries: PCBs can't possibly do any harm, because the electrical people wash the grease off their hands with the PCBs after they're done. They take it home, and in some countries they use it as a surrogate for mustard oil in cooking. We haven't seen any problems. So the anecdotal information of no harm will continue to the day that legislative and regulatory action is taken.