A California Court of Appeals has rejected various arguments made by Monsanto Company, challenging the listing of glyphosate based on the Proposition 65 Labor Code listing mechanism, where carcinogens listed by the International Agency for Research on Cancer are automatically listed under Proposition 65.

The court did not agree that the Labor Code listing of IARC carcinogens amounted to an unconstitutional delegation of “a quasi-legislative authority to an outside agency without providing for adequate standards or appropriate safeguards.”  The court noted that Californians voted to pass Proposition 65 in part because they felt that state agencies had failed to adequately protect individuals from chemical exposures and decided that—at a minimum—some substances would be listed based on the Labor Code listing mechanism as a matter of course.

This decision adds to the case law concerning glyphosate under Proposition 65.  It remains to be seen where the dust will settle with regard to Proposition 65 warnings for glyphosate, which is now the subject of a 1,100 microgram safe harbor level, given the outcome of a recent decision in which a California federal court agreed that such warnings would be misleading commercial speech under the First Amendment of the Constitution.