I read an interesting study reported by Paul Brown, in the Guardian, which finds that twice as many girls are being born as boys in some Arctic villages. Exposure of pregnant women to man-made chemicals is suspected in this dramatic shift in birth ratios.
The normal birth ratio found around the world is that slightly more boys are born a year than girls. The article even talks about a community where only girls have been born. 
One possible explanation for this drastic change is that pregnant women are being exposed to hormone-disrupting chemicals that can change the sex of a child in the womb during crucial stages of development. DDT, PCBs, and flame-retardants (such as PBDEs) are all examples of hormone-disrupting chemicals. These chemicals, the article explains, can travel to the Arctic, and accumulate in the food chain, and then into the blood streams of primarily meat- and fish-eating Inuit communities.
Arctic communities aren’t the only ones that are experiencing a changing birth ratio. Other communities in Canada, such as Aamjiwnaang, an Aboriginal Reserve located just outside of Sarnia, Ontario, have been experiencing a similar shift in birth ratios. 
I recently visited Aamjiwnaang on a work trip, and took a Toxic Tour of the area. Stay tuned to this blog. In the next week I will be talking about how this community is being affected by its proximity to industry.
Toxic Nation Campaigner