Invited Perspective: The Far Reach of PFAS—Inert Ingredients and Adjuvants in Pesticide Formulations

Abstract

Environmental contamination of per- and polyfluoroalkyl substances (PFAS) has been a growing concern over the last few decades because of their potential adverse human health effects and their biological persistence. 1,2 Many “hot spots” of exposure have been identified, such as the Ohio Valley area of West Virginia 3,4 and the Cape Fear Region of North Carolina. 5 Studies on background exposures not related to hot spots of environmental contamination have burgeoned over the last few years. 1 These studies have evaluated exposures over the life course and potential health outcomes ranging from intrauterine growth and birth outcomes to immunologic effects and cancers. 1 More recent studies have focused on identifying important pathways of environmental exposures. 6 To date, the primary pathway of human exposure is believed to be dietary ingestion of contaminated food and water, with smaller contributions from sources such as household dust (likely resulting from the use of PFAS in stain-resistant textiles and industrial applications) and the use of PFAS-contaminated consumer products. 6 In a commentary in this issue of Environmental Health Perspectives, Donley et al. 7 discuss another potentially significant pathway of exposure to PFAS: the use of pesticides in both agriculture and residential applications. They discuss how fluorination techniques are used to enhance the desirable properties of active ingredients in pesticide formulations. In addition, through their review of pesticide information obtained from the US Environmental Protection Agency (EPA), the Canadian Pest Management Regulatory Agency, the US Geological Survey, and publicly available databases, they have uncovered the use of PFAS as inert ingredients and as adjuvants used to control dispersion properties. Despite the likely presence of PFAS in pesticide formulations and their potential adverse impacts, they have not been considered in pesticide regulatory efforts or in toxicologic evaluations of pesticides. The US EPA regulations of pesticide active ingredients and formulations have always been complex. The 1996 Food Quality and Protection Act 8 mandates that the US EPA consider chronic, acute, aggregate, and cumulative exposures, as well as potential exposures in vulnerable populations, in their pesticide risk assessments. Most of these data are initially provided by the manufacturers of the pesticides, but data published later may be used in reassessments. Currently, manufacturers are not required to list inert or adjuvant ingredients on the labels of their pesticide formulations, which can also include phthalates and volatile organic chemicals. 9,10 However, without a full understanding of all of the components that may be used in pesticides and formulations, especially those that contain PFAS, the true risk associated with their exposures cannot be fully addressed. Donley et al. 7 provide recommendations that would enable a more accurate picture of potential PFAS exposures from pesticide use. They call for a discontinuation of certain manufacturing activities, mandatory disclosure of inert and adjuvant ingredients, comprehensive studies of the full environmental fate and transport of all pesticide components and degradates, and more human biomonitoring studies. Many of these activities should be completed by manufacturers before obtaining registrations for a specific pesticide or formulation use. Although these recommendations would yield important information in understanding holistic exposures related to pesticide use, they would not address the cumulative risk associated with exposure to the pesticide formulation cocktails. The US EPA should also strongly reconsider their risk assessment of pesticides to include human health hazards associated with mixtures of chemicals, which include inert ingredients and adjuvants added to pesticide formulations. The regulations surrounding pesticides are currently outdated and ineffective, 11,12 so this discovery of PFAS presence in pesticide formulations represents a new opportunity for the US EPA to improve the scientific validity of pesticide risk assessment to better capture real-world exposure scenarios.