Earlier this year, the Department of Pesticide Regulation received a question concerning the applicability of the medical supervision provisions in Title 3, California Code of Regulations (3CCR) section 6728 to ethephon (Ethrel, Proxy, CottonQuick, etc.). At the time, the U.S. Environmental Protection Agency (U.S. EPA) had classified ethephon as an organophosphate. Since it was in Toxicity Category I, the Worker Health and Safety (WHS) and Enforcement Branches distributed a joint County Agricultural Commissioner letter (WHS 06-01/ENF 06-06) informing commissioners that medical supervision applied to the use of ethephon.

The regulations require medical supervision whenever an employee regularly handles a pesticide with the signal word "DANGER" or "WARNING" that contains an organophosphate or carbamate for the commercial or research production of an agricultural plant commodity. Both organophosphate and carbamate are defined in 3CCR, section 6000.

More recently, the U.S. EPA corrected its classification of ethephon, determining it to be an organophos phonate. Organophosphonates do not fall within the definition of organophosphate in 3CCR section 6000 and therefore are not currently covered by the medical supervision requirements.

Based on a review of the toxicity, ethephon does inhibit cholinesterase. It is not a potent inhibitor, but does consistently inhibit cholinesterase in animal studies. U.S. EPA states "humans may be more susceptible to the clinical toxicity of ethephon than experimental animals." The Department will evaluate the need to change the regulation so that active ingredients like ethephon fall under the medical supervision requirements.

If you have any questions, please contact the Enforcement Branch Liaison assigned to your county.