Thursday, December 10, 2020 In December 2020, EPA released its Proposed Interim Decision for the Registration Review of Chlorpyrifos (PID). The PID states that chlorpyrifos degrades into chlorpyrifos oxon, a toxic and potent acetylcholinesterase inhibitor that potentially causes neurodevelopmental effects. Importantly, the PID indicates that the state of the science is still unclear after years of studies despite some studies that have found neurodevelopmental effects to pre-natal, infants, and children from chlorpyrifos exposures. This statement echoes the EPA’s statements in the draft Ecological Risk assessment and Revised Human Health Risk Assessment for chlorpyrifos released in September 2020 that seemingly walked back many of the findings that were in EPA’s 2016 risk assessment. Only time will tell how the data and findings in the recently released PID stand up to review by the scientific community. However, the findings in the PID should not move the needle too much in favor of plaintiffs or defendants in chlorpyrifos litigation.