Historical Development and Use of Worker Exposure Data
Occupational handler exposure data for use in preparing risk assessments has been a USEPA guideline requirement since 1986. At that time, the only way registrants could satisfy the requirement was to conduct product-specific exposure studies on workers who mix, load, and apply pesticides.
Based on the premise that handler exposure to pesticides is generic rather than product-specific, the agricultural chemical industry and the regulatory agencies cooperated in establishing the Pesticide Handlers Exposure Database (PHED) in the early 1990s. Companies contributed their exposure data for the common benefit of all registrants, while waiving their rights to data compensation. PHED was then used by the regulatory agencies and all registrants to satisfy the data requirements, regardless of whether or not the registrants contributed to the database.
The PHED was not a comprehensive database, did not include several important scenarios, was becoming increasingly outdated, and, in some cases, data were of questionable quality. Therefore, USEPA, CDPR and PMRA announced in early 2001 that they would take a new approach, ultimately to supplement or replace PHED. The new approach would consist of monographs of handler exposure scenarios, compiled from all available sources. Consequently, the agricultural chemical industry assumed the responsibility of developing these monographs through the formation of AHETF in December of 2001 with the mission of sharing member resources in the design, evaluation, and development of an agricultural mixer/loader and applicator exposure database for use in regulatory risk assessments.
USEPA considers the AHETF data to be the 'most reliable' and is using these data for routine exposure and risk assessments for pesticides whose use is consistent with the AHETF monitored exposure scenarios as verified on their web site. See Occupational Pesticide Handler Exposure Data, https://www.USEPA.gov/pesticide-science-and-assessing-pesticide-risks/occupational-pesticide-handler-exposure-data#data-assess, which provides background on handler exposure and explains that USEPA relies upon AHETF data in their risk assessments as presented in the Occupational Pesticide Handler Unit Exposure Surrogate Reference Table, https://www.epa.gov/sites/production/files/2020-03/documents/opp-hed-pesticide-handler-surrogate-unit-exposure-table-march-2020.pdf.