Today, field-scale crop location data are available at higher spatial resolution and classification accuracy than ever before. These data represent “best available scientific data” and can improve the confidence of human health and ecological risk assessments by providing more realistic, site-specific exposure estimates. For example, state-wide agricultural-focused land cover on an annual basis with 56 crop classes and a spatial resolution of ~2 meters is now available in California. Given that California ranks first in total crop receipts in the US and bounds nearly 20% of all federally listed species, increased spatial land use data resolution has the potential for measurable impact in risk assessment. Other novel opportunities exist for incorporating better data by cooperating with specialty crop grower groups who often have field surveys locating their member’s farms (<i>e.g., </i>Florida green beans).  High-confidence data can be used to improve Percent Crop Area (PCA) adjustment factors required for estimating drinking water concentrations in human health risk assessments. From a FIFRA/ESA perspective, it is proving difficult to make determinations for many crop-species combinations with any degree of confidence using the spatial information presently available. Although inconvenient, there is arguably a need to incorporate better data as it becomes available.<br/>To demonstrate the impact of the newly-available California land use data, a case study was conducted to contrast the effects of refined crop cover data on spatial proximity to non-target terrestrial species’ habitat. From an aquatic perspective, watershed scale (HUC-12) PCAs calculated using the EPA crop use sites, the 2014 CWS PCA guidance document approach, and the CA DWR land cover will be covered. These results can be used to gauge the impact that higher spatial resolution and classification accuracy can have on pesticide risk assessments relying on crop location information.

Refined land cover for improving the confidence of pesticide risk assessments

256th National Meeting (2018)

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