May 18, 2023

EPA Proposes New Occupational Risk Mitigation Measures for Two Pesticides

EPA recently proposed new mitigation measures intended to protect the health of workers with occupational exposures to the pesticides chlormequat chloride and diazinon, according to press releases published in late April. The mitigation measures for chlormequat chloride were put forward as EPA considers a potential new use for the pesticide in regulating food crop growth. The agency’s mitigation measures for diazinon were proposed in light of an updated occupational risk assessment identifying new risks of concern for people who work with the chemical.

Chlormequat chloride is currently registered as a plant growth regulator used for ornamental plants grown in greenhouses and nurseries. EPA has proposed the use of chlormequat chloride as a tool to increase the yield of small grains such as wheat, barley, oats, and triticale. Specifically, the pesticide’s ability to block hormones stimulating plant growth may reduce the problem of “lodging,” or the bending or breakage of the stems of small grains, an issue that can negatively impact yield, harvestability, and quality. EPA’s human health and environmental risk assessments for chlormequat chloride, conducted ahead of the proposed registration decision, found no risks of concern. Regardless, EPA is proposing mitigation measures to protect workers who may be exposed to the pesticide under its potential new use, as well as birds, reptiles, mammals, amphibians, and invertebrates in the surrounding environment. These measures include requiring workers to wear long-sleeved shirts, long pants, socks, shoes, and waterproof or chemical-resistant gloves while handling chloremequat chloride as well as 24-hour restricted entry intervals to areas under treatment and mandatory and advisory spray drift management statements. The proposal will be available for public comment on until May 26.

Diazinon is an insecticide used on fruit and vegetable crops, orchards, outdoor nurseries, and cattle ear tags. On March 15, 2023, EPA announced its decision to expediate its actions on diazinon due to an updated risk assessment that found potential risks of concern for workers who mix, load, and apply diazinon, as well as to bystanders exposed to spray drift. Adama U.S. and Drexel Chemical Company, the registrants of diazinon, are working with EPA voluntarily to develop mitigation measures several years ahead of the normal review process, typically conducted every 15 years due to evolving risk assessment practices and policies. The registrants have agreed to cancel aerial application, backpack and mechanically pressurized handgun application, and wettable powder formulation for diazinon, as well as to reduce spray drift and implement buffer restrictions to protect bystanders. Stakeholders will have the opportunity to comment on the new mitigation measures when EPA issues its proposed interim decision for diazinon, currently planned for fiscal year 2026. The pesticide’s updated risk assessment may be read on

More information about the proposed measures for both pesticides can be found in EPA’s news releases on chlormequat chloride and diazinon.