Now it’s getting interesting.

A new court filing made on behalf of dozens of people claiming Monsanto Co.’s Roundup herbicide gave them cancer includes information about alleged efforts within the Environmental Protection Agency to protect Monsanto’s interests and unfairly aid the agrichemical industry.

The filing, made late Friday by plaintiff’s attorneys, includes what the attorneys represent to be correspondence from a 30-year career EPA scientist accusing top-ranking EPA official Jess Rowland of playing “your political conniving games with the science” to favor pesticide manufacturers such as Monsanto. Rowland oversaw the EPA’s cancer assessment for glyphosate, the key ingredient in Monsanto’s weed-killing products, and was a key author of a report finding glyphosate was not likely to be carcinogenic. But in the correspondence, longtime EPA toxicologist Marion Copley cites evidence from animal studies and writes: “It is essentially certain that glyphosate causes cancer.”

Attorneys for the plaintiffs declined to say how they obtained the correspondence, which is dated March 4, 2013. The date of the letter comes after Copley left the EPA in 2012 and shortly before she died from breast cancer at the age of 66 in January 2014. She accuses Rowland of having “intimidated staff” to change reports to favor industry, and writes that research on glyphosate, the key ingredient in Monsanto’s Roundup, shows the pesticide should be categorized as a “probable human carcinogen.” The International Agency for Research on Cancer, an arm of the World Health Organization, declared as much – that glyphosate was a probable human carcinogen – in March 2015 after reviewing multiple scientific studies. Monsanto has rejected that classification and has mounted a campaign to discredit IARC scientists.

The communication, if authentic, could be an explosive development in the snowballing multi-district litigation that now comprises more than 60 plaintiffs from around the United States accusing Monsanto of covering up evidence that Roundup herbicide could cause cancer. The plaintiffs, all of whom are suffering from non-Hodgkin lymphoma (NHL) or lost a loved one to NHL, have asserted in recent court filings that Monsanto wielded significant influence within the EPA’s Office of Pesticide Programs (OPP), and had close ties specifically to Rowland, who until last year was deputy division director within the health effects division of the OPP. Rowland managed the work of scientists who assessed human health effects of exposures to pesticides like glyphosate and he chaired the EPA’s Cancer Assessment Review Committee (CARC) that determined glyphosate was “not likely to be carcinogenic to humans.” Rowland left the EPA in 2016 shortly after a copy of the CARC report was leaked and cited by Monsanto as evidence that the IARC classification was flawed.