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April 15, 2019

Jason E. Johnston, M.S. Co-Authors “Benchmarking the Current Codex Alimentarius International Estimated Short-Term Intake Equations and the Proposed New Equations” in the Journal of Agriculture and Food Chemistry

The ACTA Group

Bergeson & Campbell, P.C. (B&C®) and The Acta Group (Acta®) are pleased to announce the publication of “Benchmarking the Current Codex Alimentarius International Estimated Short-Term Intake Equations and the Proposed New Equations,” co-authored by Jason E. Johnston, M.S., Senior Scientist with B&C and Acta. The article was published by the Journal of Agriculture and Food Chemistry and can be accessed at  The five co-authors of the study were assembled by Cheryl Cleveland through CropLife America to react to a recent proposal to revise the International Estimated Short-Term Intake (IESTI) equations used in establishing Codex Maximum Residue Limits for pesticide residues on agricultural commodities.  The authors conducted a series of dietary exposure assessments to benchmark exposures estimated using the existing and proposed IESTI equations against distributions of actual exposures.  The authors of this study compared dietary exposures for pesticide residues in strawberries, tomatoes, and apples at five levels of refinement to place results from the IESTI equations into context relative to real-world exposures.  The benchmarking exercise showed that the current IESTI equations are conservative predictors of dietary exposures, which suggests that there is no need to introduce further conservatism that would result from adoption of the proposed IESTI equations.

Mr. Johnston has 30 years of experience in the areas of exposure and risk assessment with experience conducting multiple exposure assessments in residential, occupational, hazardous waste, and consumer product settings in the U.S., Canada, the European Union (EU), and South America. He holds two Master of Science (M.S.) degrees from the Massachusetts Institute of Technology (MIT), one in Chemical Engineering Practice and one in Technology and Policy, which benefit the development of strategies for exposure mitigation using engineering controls, protective equipment, and improvement of label language pertaining to user safety.  Furthering his expertise in this field, Mr. Johnston has worked with industry task forces in developing pesticide occupational exposure data, developing a model to estimate aggregate and cumulative residential exposures to pesticides, developing a regulatory screening model to estimate exposures to antimicrobial agents used in the home, and in coordinating data development by task forces in response to regulatory requirements.

B&C and Acta encourage our clients and friends involved in pesticide and dietary exposure issues at the international level to review this open access article for more information on the protections in the current IESTI approach and the potential impacts from the additional conservatism in the proposed approach.

The full citation of the article is:  Cheryl B. Cleveland, Carrie R. Fleming, Jason E. Johnston, Angela S. Klemens, and Bruce M. Young, “Benchmarking the Current Codex Alimentarius International Estimated Short-Term Intake Equations and the Proposed New Equations,” Journal of Agricultural and Food Chemistry, 2019, 67 (12): 3432-3447.