EPA’s FIFRA Science Advisory Panel has published its Minutes for the SAP’s April 19-21 Meeting to Consider and Review Scientific Issues Associated with Chlorpyrifos:  Analysis of Biomonitoring Data. The SAP Minutes criticize EPA’s proposed change of  the Point of Departures (PoDs) for chlorpyrifos from doses eliciting 10% red blood cell AChE inhibition to adverse effects changes in neurodevelopment as measured by epidemiology studies conducted by Columbia Center for Children’s Environmental Health.  For example, the SAP Minutes conclude at page 22 that:

“The Panel agrees with the Agency that there are complex unknown variables that are recognized as uncertainties. Because many uncertainties cannot be clarified, the majority of the Panel does not have confidence that the CCCEH cord blood data on chlorpyrifos levels can accurately be used in quantitative risk assessment to determine a Point of Departure (PoD). The cord blood data were obtained from a single measurement at the time of delivery and the quantitative risk assessment made multiple assumptions based on this value. Some members of the Panel do not have confidence that a single value obtained at birth can be used to accurately estimate the magnitude or pattern of exposure that occurred during the preceding ten months of pregnancy. Some members of the Panel were also concerned about the lack of knowledge of the sensitive window(s) of exposure during pregnancy that would lead to neurodevelopmental outcomes. Without accurate knowledge that exposure occurred during a sensitive window, it is impossible to derive causation. A major source of uncertainty for the Panel was the lack of verification and replication of the analytical chemistry results that reported very low levels of chlorpyrifos (pg/g). Imputing quantitative values when the concentration of analyte falls below the level of detection (LOD) was a particular concern, especially given that a large fraction of cord blood samples included in the analyses presented with levels below LOD. While this may be appropriate in some epidemiological studies, some members of the Panel caution the Agency when attempting to use analytical data derived without Good Laboratory Practices (GLP) or chain of custody protocols in place for regulatory decision-making, while at least one Panel member found no issue with sample tracking and shipment reported in the CCCEH study.”

The SAP Minutes are available here.