Americans aren't the only ones getting fatter—our animals are also growing overweight, reports Pro Publica. And it isn't just pets and lab animals piling on the pounds (though they are; the likelihood of chimps living with or near humans being obese increased tenfold between 1985 and 2005): one study found feral rats in Baltimore are also getting plumper. This is more than just an interesting piece of trivia, Pro Publica reports: It raises the question of whether the usual culprits of "too much food" and "not enough exercise" are really the only things causing the obesity crisis. Now scientists are considering whether the chemicals we put into our air, soil, and water have a role to play as well.
"I found evidence of chemicals that affect every aspect of our metabolism," says a Stirling University scientist, who studies the effects of chemicals on animals. For instance, she says, there's evidence some of the ingredients in insecticides make mice less physically active, while chemicals in plastics may alter human metabolisms. Another chemical, BVO, which is banned in Europe but common in US soda drinks, may also interfere with the human hormone system. Of course, the sugar in those drinks isn't doing us any favors, either, but, says one obesity researcher, "Obesity really is more complex than couch potatoes and gluttons." (A pair of recent studies linked teen diabetes and obesity with ... food packaging.)