"Pesticides Are Polluting Our Waters — And We Often Don’t Know It"

"Pesticides bring major benefits to modern agriculture, keeping dangerous bugs and fungi and pathogens at bay while boosting yields and making farming more efficient. But what about risks? Like any chemicals — manmade or not — pesticides can be bad for human health and ecosystems if they’re toxic enough and the amount that ends up in the environment is high enough. It’s often tough, however, to get a clear picture of the full array of problems a pesticide may cause.

A new 'meta-analysis' — a review of existing scientific studies — provides some answers, but raises even more questions in the process. In water bodies near agricultural sites across the world where scientists have detected certain bug-killing pesticides, these substances exceed regulators’ allowed levels more than half the time, the analysis found. But even more concerning, the researchers report Monday in Proceedings of the National Academy of Sciences, is that most of the time we lack any data at all on insecticide levels in waters near these agricultural fields.

Sebastian Stehle and Ralf Schulz of the University Koblenz-Landau in Germany focused their study on 28 common agricultural insecticides. These range from organophosphates, older substances that generally target insects’ nervous systems, to pyrethroids, a relatively new class of pesticides that in many cases have replaced organophosphates and other old pesticides. Many of these pesticides, while toxic to the bugs they’re meant kill, may also be capable of causing harm to “non-target” organisms such as humans."

Puneet Kollipara reports for the Washington Post April 13, 2015.