Does a common herbicide cause cancer? Over the past several years, that question has stirred up no shortage of controversy, with international health agencies offering conflicting information. The weedkiller, a chemical called glyphosate, is commonly sold by the agribiz giant Monsanto under the brand name RoundUp. Introduced in the mid-1970s, it’s now the world’s most widely used pesticide, with some 250 million pounds sprayed on US crops annually.
RoundUp has long been considered a benign alternative to harsher weedkillers. After extensive reviews, most regulatory agencies—the US Environmental Protection Agency, the European Food Safety Authority, and those of many other nations—have come to the conclusion that it does not cause cancer. So when the International Agency for Research on Cancer (IARC), a division of the UN’s World Health Organization, declared RoundUp a probable carcinogen in 2015, there was an international outcry. Shortly after, 184 plaintiffs in California filed a legal case against Monsanto, saying that the company failed to warn them about the risks of its product. Since then, in a separate suit, hundreds more plaintiffs have claimed that RoundUp caused their cancers, citing the IARC’s findings as evidence.
About that evidence: According to a new Reuters investigation, Aaron Blair, the scientist who led the IARC’s review panel on glyphosate, had access to data from a large study that strongly suggested that Roundup did not cause cancer after all—but he withheld that data from the RoundUp review panel. Weirder still: Blair himself was a senior researcher on that study. From the Reuters report: