Court Reinstates Suit Alleging Roundup “Expiration” Due to Carcinogenic Impurity
Allegations that Monsanto’s popular Roundup-brand weedkillers degrade into a carcinogenic impurity will proceed, after the Ninth Circuit reinstated a proposed class action a district court had dismissed for failure to state a claim.
Unlike the many personal injury suits over Roundup, the plaintiffs in this case assert purely economic harms. They allege that consumers would have paid less for concentrated Roundup products had they known that glyphosate—the active ingredient—gradually degrades into harmful levels of N-Nitrosoglyphosate (NNG) over time from exposure to nitrites in “everyday air and water,” effectively causing the products to “expire.”
The District Court for the Northern District of California dismissed the case in December 2023, finding two key allegations implausible: that NNG is substantially certain to form at levels of 1 part per million (ppm), and that 1 ppm NNG is unsafe.
The Ninth Circuit disagreed, emphasizing that plausibility does not require probability. While no regulation sets a specific 1 ppm limit for NNG, the panel found that an expert opinion combined with EPA statements sufficed to support a plausible claim regarding NNG’s hazard.
Similarly, although the complaint failed to allege that any products purchased by the plaintiffs or other consumers contained 1 ppm NNG, the court held that a variety of factual allegations—including that “Monsanto had discovered NNG at levels above 1 ppm in relevant products in its own possession”—were enough to make the plaintiffs’ claim about the occurrence of 1 ppm NNG plausible.
However, the Ninth Circuit affirmed the dismissal of claims against Roundup distributor The Scotts Co., finding that plaintiffs failed to allege that Scotts had “unbridled control” over the challenged conduct or knowledge of the alleged expiration.
The Ninth Circuit also criticized the lower court’s reliance on an incomplete version of a key study submitted by Monsanto, which likely presented findings in a more favorable light. “The parties and the court should be concerned about submission of and reliance upon an incomplete document,” the opinion states.
The case is Koller v. Monsanto Co., No. 24-43, opinion filed March 27, 2025.