Yet amid the global cloud of concern, the US Environmental Protection Agency (EPA) continues to greenlight paraquat use on millions of acres, and has downplayed scientific findings linking paraquat to Parkinson’s, an incurable brain disease. The agency said in June it would hold a round table over the summer to re-examine the “safety challenges” associated with paraquat. But no such event has yet been held or scheduled.

Now, clues to how and why the US remains one of the world’s last large markets for widespread paraquat use are coming to light through troves of internal Syngenta records recently revealed through litigation.

The records show that as paraquat markets around the world started crumbling over concerns for public health, Syngenta, a Swiss-headquartered multinational, fought to keep a tight hold on the US market, where use of paraquat nearly tripled between 2000 and 2018, a time period when dozens of other countries were banning paraquat.