No chemical used by farmers, it seems, gets more attention than glyphosate, also known by its trade name, Roundup. That's mainly because it is a cornerstone of the shift to genetically modified crops, many of which have been modified to tolerate glyphosate. This, in turn, persuaded farmers to rely on this chemical for easy control of their weeds. (Easy, at least, until weeds evolved to become immune to glyphosate, but that's a different story.)
Glyphosate had been considered among the safest of herbicides. So it was a shock to many, last year, when the International Agency for Research on Cancer announced that this chemical is probably carcinogenic.
Since that announcement, however, others have looked at the same collection of data and come to contrary conclusions. The European Food Safety Agency convened a group of experts who concluded that glyphosate probably does not cause cancer. So did the UN's Food and Agriculture Organization.
Now the Environmental Protection Agency has issued its own report, and it also concludes that glyphosate is not likely to cause cancer in humans. Outside scientists will review the report in October.
The report is part of a lengthy process by which EPA is reviewing many agricultural chemicals, and deciding whether farmers will be allowed to use them.
European regulators, meanwhile, are locked in a political battle over whether glyphosate use will continue to be permitted on that continent. The European Commission has authorized continued sales of the chemical, but only temporarily.