The world is focused on glyphosate, but another commonly used farm herbicide could be just as poisonous.

The Environmental Protection Agency (EPA) is required to review pesticides and herbicides approved for use in the US every fifteen years. The agency just completed its updated environmental impact assessment of atrazine, the second most widely used herbicide.

Atrazine is a chlorine-based chemical just like DDT—the once-popular insecticide—and PCBs (polychlorinated biphenyl). It can persist in soil for twenty-two years. Lots of evidence shows the extent to which atrazine is contaminating our food supply, which is little surprise given that as much as 70 million pounds of the stuff is used by farmers each year, mostly on corn.

In its 500-page draft report, the EPA found that atrazine, which is produced by biotech giant Syngenta, can be dangerous to animals and fish—and leaves behind a troubling amount of residue. According to the report, atrazine exceeds the agency’s “levels of concern” for chronic risks to animals and fish by 198 times and 62 times, respectively. Despite the length of the report, the EPA found it convenient to omit all discussion of atrazine’s risk to humans, promising to return to that subject in the future.

What the EPA did report, however, vindicates the research of Tyrone Hayes, PhD, who found that atrazine exposure was chemically castrating male frogs. At the time, he was working for Novartis, which is now owned by Syngenta—which of course refused to publish his research. Hayes quit, obtained independent funding, and published the research, but was then the victim of what seemed clearly to be a smear campaign by Syngenta.

Atrazine does not typically kill animals outright, but has been shown to adversely affect their developmental, hormonal, and reproductive systems. In its draft report, the EPA also acknowledges that adverse effects on animals can occur at exposure levels much lower than previously thought.

Heavy atrazine use can cause dire consequences for plant life. The EPA found that atrazine runoff and spray drift reduces land-based plant biodiversity, among other problems.