I've seen a number of posts recently linking to articles regarding a supposed link between the larvicide pyriproxyfen and the increased rates of birth defects in South America. Many of these have been followed by the question, "Why aren't major news outlets reporting this?" Here's why:
The sole source of any information about this "link" is from a group called Associação Brasileira de Saúde Coletiva, or ABRASCO, which has been translated into English as Physicians In Crop-Sprayed Towns. They released a study earlier this month claiming that the rise in microcephaly came after some South American countries began including pyriproxyfen in their drinking water, and that the larvicide was causing the birth defects.
By all means, doctors can take political positions against chemicals they believe pose public health concerns (and this one is a full-on lobbying group -- according to their website, they've held events that more than 7,500 legislators attended). But when they release the results of their "research," these studies should be regarded with the same skepticism as any other information provided by any other lobbying group or group with a specific political agenda. There is a strong taint of bias in such information. That's why, say, Natural News and GM Watch are reporting on it but the AP and New York Times aren't.
All that said, the local government in Rio Grande do Sul, a state in the south of Brazil, suspended the use of pyriproxyfen over the weekend. The irony is that countries began including this larvicide in water supplies to reduce the proliferation of mosquitoes -- which are known to carry the Zika virus, which is, at this point, the strongest contender for the culprit behind the increase in microcephaly.