For more than a half-century, North American farmers have been spraying atrazine, an herbicide, on their crops — most notably corn — in the millions of pounds per year. This widespread use of the weed killer has also created no small amount of runoff, ensuring that atrazine winds up in lakes, streams and, on occasion, even drinking water, according to a recent report by Global News. “Atrazine is the number one contaminant found in drinking water in the U.S. and probably globally[,] probably in the world,” University of California-Berkeley scientist Tyrone Hayes told the news organization. The prevalence of atrazine has, over time, gotten the attention of a number of groups — and some government organizations — regarding its use and, some say, overuse. One such organization is Health Canada, which confirmed recently that atrazine could indeed make its way into local drinking water. The agency says that, “because atrazine has been classified in Group III (possibly carcinogenic to humans),” it has set an acceptable amount of 5 parts per billion in drinking water; in the U.S., that level is 3 parts per billion.

But the problem is that atrazine levels in drinking water can vary from place to place, with agricultural regions obviously being more at risk (though not exclusively, as atrazine contained in runoff can travel for hundreds of miles). “In areas where atrazine is used extensively, it (or its dealkylated metabolites) is one of the most frequently detected pesticides in surface and well water. Atrazine contamination has been reported in British Columbia, Nova Scotia, Prince Edward Island, Quebec, Ontario and Saskatchewan,” said Health Canada. The compound is manufactured by Syngenta, the world’s foremost agribusiness giant; the European Union banned atrazine in 2004. Nevertheless, research on the compound and its effects has continued, and not just on humans: The effects of atrazine on amphibian and other wildlife are also being studied. “Atrazine is probably the most well studied pesticide on the planet, perhaps only rivaled by DDT,” University of South Florida Prof. Jason Rohr, told Global News. More