I think you mean sex? (sorry, pet peeve of mine!) I've never heard this claim, do you have a citation (about female contribution)? When I taught WS103 we discussed many factors that went into sex differentiation, including proximity to ovulation and hormone levels of the mother. I have read many studies in which environmental factors affect sex and intersexuality.

I also don't think they are claiming that these women were exposed at work. PCBs get into the water, the environment, the air, etc.