It's somewhat hard to know what to make of this since the actual study hasn't been peer reviewed or published yet and the authors make a few crazy statements in the article. But it is certainly quite alarming and even somewhat plausible. A few thoughts:
- There are probably some subtleties involved with accurately measuring the gender ratio of live births (e.g. confusion with infant mortality), but they would have to have some seriously screwy methodology to find a ratio of 2:1 if something wasn't really going on. No matter what the cause is, a 2:1 sex ratio is a big problem for these communities.
- The statement that the chemicals are "capable of triggering changes in the sex of unborn children in the first three weeks" just seems crazy to me. I'm no biologist, but I would be shocked if the chemicals could actually change the chromosomes of the fetus. If this effect is real, I'm sure it has more to do with decreasing the viability of male embryos so that fewer survive, or something like that. Enviroblog is similarly skeptical.
- (Although it is true that endocrine disruptors have been linked to hormonal imbalances leading to ambiguous genitalia in frogs -- see here -- but it doesn't seem like that is the cause of the skewed ratio in this case. Again, hard to tell without reading the paper.)
- Still, the results seem plausible to me because we know (1) accidental exposure to high-levels of endocrine disruptors in Seveso, Italy in 1976 led to a similar pattern of skewed gender ratios in the decades following exposure, (2) chemicals like PCBs bioaccumulate as you go up the food chain and exposure is likely to be higher in a diet consisting of bear and fish, and (3) Arctic populations have long been shown to have some of the highest blood levels of these chemicals due to weather patterns that concentrate pollution in the polar regions.
- A recent peer-reviewed study found a much smaller, but detectable shift, toward more girls than boys among live births in the U.S. and Japan since 1970, and they also speculated that chemical pollution might be the cause. The small shift in sex ratio amounts to 250,000 'missing' boys.