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California Taking Comments on Updated Chlorpyrifos Risk Assessment

The California Department of Pesticide Regulation and the Office of Environmental Health Hazard Assessment are pursuing health protections on chlorpyrifos, which is one of the most widely used agricultural pesticides in the United States, according to California EPA. The Department of Pesticide Regulation (DPR) recently released an updated draft risk assessment for a 45-day public comment period, and on Sept. 15 it will host a public workshop on the risk assessment at the Pesticide Registration and Evaluation Committee meeting in Sacramento.

The release of the risk assessment starts a public and scientific review of the document, which could lead to increased restrictions on chlorpyrifos statewide. DPR announced it is currently developing interim restrictions on use of the pesticide and plans to submit recommendations to county agricultural commissioners in September 2017, including:

  • Increasing distances between sites where the chemical is applied and sensitive locations, such as homes and schools. These would be specific to each type of application method.
  • New restrictions on methods used to apply chlorpyrifos.

In addition, the Office of Environmental Health Hazard Assessment is referring chlorpyrifos for potential listing as a developmental toxicant under Proposition 65 and has posted an announcement that the state's Developmental and Reproductive Toxicant Identification Committee will consider the listing of chlorpyrifos at its next public meeting. "While chlorpyrifos has been protecting crops for more than 50 years, new information in the scientific community leads us to believe the level of risk it poses is greater than previously known," said CalEPA Secretary Matthew Rodriquez. "We need to better understand the science to ensure our actions protect public health. The actions we are taking today reflect our commitment to the health and safety of all Californians, and the environment."

DPR scientists believe chlorpyrifos may pose a public health risk as a toxic air contaminant based on its assessment of the latest studies in the scientific community. That finding as indicated in the updated draft risk assessment has not been peer reviewed, however, and it must go through a public comment period and be independently evaluated by other scientists. After the 45-day written public comment period, the draft assessment will go before an independent panel of nine scientists known as the Scientific Review Panel. Its review may conclude in December 2018.

The Developmental and Reproductive Toxicant Identification Committee, an independent panel of 10 scientific experts that determines whether chemicals are added to the Proposition 65 list for causing birth defects and other reproductive harm, also will consider public comments presented at its Nov. 29 meeting. If the committee adds chlorpyrifos to the Proposition 65 list as a developmental toxicant, businesses that knowingly cause exposures above minimum levels must provide a Proposition 65 warning.

DPR's updated draft risk assessment and other documents about chlorpyrifos are available at

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