PBS interview from 1997:

DH: The general impression out there, by most people, is that there is quite a bit of testing that goes on before any product gets out on the market.

TC: There have been safety nets. But unfortunately the safety net that we used as our model was this 70 kilogram adult male. And we did not look at what happens during embryonic development in the womb or in the egg. And from the minute the sperm enters the egg, and this individual begins to develop, this whole process is driven by chemicals called hormones: first hormones that came with the egg from the mother and then gradually, as the cells split and split and divide and begin to form an organism, they begin producing some of their own hormones, but not much.

These chemicals are working at a concentration of 1/10th of a trillionth of a gram. That is all it takes of a hormone to make a change in how an individual develops in the womb.

Now, we are talking about chemicals that are getting in the human body at parts per million, parts per billion, parts per trillion. That is a lot higher than what the system operates within. And we didn't understand this. So testing chemicals on a fully grown individual who has developed and isn't developing any more, it would take a much larger dose of something to change the way that individual functions. Now we have to go back and think about what happens with humans those first 266 days from conception to birth.

http://www.pbs.org/wgbh/pages/frontline/shows/nature/interviews/colborn.html
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Arty turns 10 this summer.