HHRA Executive Director Publishes Paper on the Dietary Risk Index System for Measuring Pesticide Risk from the Diet

We are all exposed to pesticide residues in the foods we eat, the Dietary Risk Index (DRI) is one way of measuring the potential risk from these exposures.

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In a January 26, 2023 press release, the California Department of Pesticide Regulation (DPR) released a provocative report entitled “Sustainable Pest Management: A Roadmap for California.” The Roadmap report sets “ambitious goals and actions to accelerate California’s systemwide transition to sustainable pest management and eliminate prioritized high-risk pesticides by 2050.” Also by 2050, the Roadmap report envisions that “Sustainable pest management has been adopted as the de facto pest management system in California.” The report captures the ideas and input of a diverse stakeholder group that met over two years to help DPR, Cal-EPA, and the California Department of Food and Agriculture develop a comprehensive plan sufficient to transform agriculture in the State from often heavily-pesticide dependent management systems to systems grounded in pest-prevention, biological control, and reduced-risk biopesticides. The Roadmap identifies and addresses most of the factors shaping pest management systems in the State and calls for dozens of new research, education, training, and regulatory initiatives. In order to guide the implementation process, DPR requested comments from the public that were due March 13, 2023. In crafting HHRA’s comments, Chuck Benbrook and Mark Lipson drew on their decades of experience tracking and advising DPR on pesticide use and regulatory issues.
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HHRA Paper Analyzes Pesticide Dietary Risk in Individual Samples of Foods
One of the main sources of pesticide exposure is through the diet. It is critically important to understand pesticide residues in foods and how dietary risks have changed over time. Over the last 20 years HHRA’s Executive Director Charles Benbrook has developed an analytical database that quantifies the relative risk posed by residues in the diet. Known as the Dietary Risk Index (DRI), this system was created to help researchers compare risk levels across foods and pesticides, track changes in dietary risk over time, and assess the impact of where food is grown on residues and risk levels, as well as how production systems influence residues and risks (conventional versus organic). The DRI combines the results of United States and United Kingdom pesticide residue testing programs with data on food serving sizes and each pesticide’s chronic Reference Dose or Acceptable Daily Intake. Chronic DRI values are a ratio: the amount of residue in a serving of food relative to the maximum amount allowed by regulators. DRI values are a ratio: the amount of residue in a serving of food relative to the maximum amount allowed by regulators. Data generated by the DRI helps guide HHRA’s policy and public health by highlighting which food-pesticide combinations account for the most worrisome risks in the food supply. The DRI system initially reported aggregate values for a given food/pesticide combination. These values are derived from multiple individual samples of a food collected by regulatory agencies. For these DRI values, each individual number represents many servings of a given food. In 2022, HHRA added additional functionality the the DRI to report dietary risk in individual samples of a given food. The paper “Tracking pesticide residues and risk levels in individual samples—insights and applications,” which was published in the peer-reviewed journal Environmental Sciences Europe in July 2022, describes the methodology and data sources used to calculate these individual sample DRI values, and highlights some of the results and what they can tell us about residue levels in the global food supply. This is the first analytical system worldwide to provide this level of insight into residues in food. As the paper reports, “dietary risk levels are highly skewed. A large number of samples pose moderate, low, or very-low risks, and relatively few samples pose high or very-high risks.” Thus, regulators and researchers can use the DRI to pinpoint where pesticide dietary risks needs to be mitigated. Like all of HHRA’s peer-reviewed publications, this paper is open access and available free of charge. Click here to view the full text. Access DRI data here.

Charles Benbrook, HHRA’s Executive Director, and his colleague Donald Davis of the University of Texas-Austin’s Biochemical Institute published a peer-review paper in October, 2020 describing the analytical system they developed to measure the risk from pesticide exposure in the diet.

This peer-reviewed paper describes the methodologies and data sources incorporated in the Dietary Risk Index system, or DRI. This system quantifies the relative risks from exposure to pesticides in foods. The paper serves as a gateway to an analytical system that, for the first time, provides insights into the levels and distributions of pesticide risks in different foods, in foods grown in the U.S. versus imported food, and in conventionally grown versus organic food. See much more on the DRI, and access the system via interactive lookup tools at Dr. Benbrook’s website Hygeia Analytics.

In short, applications of the DRI show clearly where the “hot potatoes” are in the food supply relative to pesticide risk, as well as the significant share of the food supply posing little or no risk. DRI tables drive home the fact that pesticide dietary risk is substantially concentrated in just a few dozen foods, and for these relatively high-risk foods, a small percent of annual production accounts for most of the risk.

These findings support two encouraging conclusions. First, for all crops, many farmers have developed Diversified Pest Management (DPM) systems that routinely avoid significant residues and pesticide risk. By investing in prevention-based research and DPM system innovation, the same success in avoiding high-risk pesticide uses can be replicated on a higher percentage of annual production.

Second, regulators can dramatically reduce overall pesticide dietary risk by focusing on the few pesticide-food combinations accounting for most pesticide risk. They have a number of tools to draw upon in reducing residues including lowering maximum, allowed application rates, extending pre-harvest intervals, and altering how pesticides are applied (i.e. switching from liquid sprays onto growing plants to granular applications incorporated into the soil).