Another Nitrosamine Issue: Apples listed on EWG’s “Dirty Dozen.” How to Deal with the Mounting Concerns about this Family of Chemicals

January 10, 2021

Paustenbach and Asssociates

Each year, the Environmental Working Group (EWG) establishes a “Shopper’s Guide to Pesticides in Produce”, which evaluates pesticide residues in 46 popular fruits and vegetables and ranks them based on level of pesticide contamination. The 12 fruits and vegetables at the top EWG’s ranking are infamously referred to as the “Dirty Dozen,” and apples are currently listed as number 5 (EWG 2021a). 

Most non-organic apples in the United States are sprayed with the pesticide diphenylamine (DPA) after they are harvested, which prevents the apple skins from developing black or brown patches during cold storage (EWG 2019). In their most recent evaluation (2016), the United States Department of Agriculture (USDA) reported that 80% of the tested U.S. apples contained DPA, with the average concentration reported to be 0.28 ppm (EWG, 2019; USDA, 2016). In a 2018 safety assessment, the U.S. Environmental Protection Agency (EPA) concluded that the maximum allowable concentration for DPA on apples was 10 ppm (EWG, 2019). 

In contrast to the United States, in June 2012, the European Food Safety Authority (EFSA) reduced the allowable level of DPA on imports to 0.1 ppm, largely due to the “possible formation of nitrosamines during storage of the active substance and during processing of treated apples” (EFSA, 2012; EWG, 2014). Nitrosamines can form when nitrogen-containing compounds combine with amines. The EFSA indicated that nitrosamines may form if DPA (an amine) combines with nitrogen (which is ubiquitous in the environment) during storage or processing of the apples (EWG, 2019; EFSA, 2008). 

Nitrosamines are a class of chemicals and have generally been shown to be carcinogenic in laboratory animals (NTP, 2016) at certain doses.  Epidemiology studies, however, are inadequate or lacking, depending on the nitrosamine compound (NTP, 2016). Humans are regularly exposed to nitrosamines or their precursors through consumption of a wide variety of foods (in addition to apples) and consumer products, although the major source of human exposure to nitrosamines is via endogenous production in the human digestive tract (NTP, 2016). To date, there have been no epidemiological studies that have linked human exposure to nitrosamines via food consumption, or by endogenous production in the digestive tract to cancer even though the stomach can form up to 1,000-fold greater doses than those are eaten via food or drugs. The EWG reported that “even low levels of nitrosamines on raw apples, or in apple juice and applesauce could potentially pose a risk to human health” (EWG, 2014), without acknowledging the quantity formed in the digestive tract due to nitrite intake from various foods.

Paustenbach and Associates understands that personal injury litigation around nitrosamine impurities in foods, pharmaceuticals, and consumer products has been escalating for the past 3-4 years. We recommend that those who have detected nitrosamine impurities in their foods, consumer products, or pharmaceuticals conduct a thorough health risk assessment in order to fully characterize the possible health risks. Then, when completed, it is often wise to share the results in the published literature and with consumers (perhaps through social media). In our experience, getting ahead of these kinds of matters is the best way to avoid litigation, and to help inform various forms of the media. Over the past two years, we have assisted several clients who have detected nitrosamines at certain concentrations in their products and have completed relevant risk assessments, as well as put those risks into context.  Our scientists have 40+ years of experience characterizing these types of hazards and have offered a range of ways to respond to these kinds of challenges. 

Please contact us for more information regarding Paustenbach and Associates’ capabilities: 


EFSA (2008). “Conclusion Regarding the Peer Review of the Pesticide Risk Assessment of the Active Substance Diphenylamine”. EFSA Scientific Report, 2008, 188. 

EFSA (2012). “Conclusion on the Peer Review of the Pesticide Risk Assessment of the Active Substance Diphenylamine.” EFSA Journal, 2012, 10(1):2486-2527.

EWG (2021a). “Full List: EWG’s 2021 Shopper’s Guide to Pesticides in Produce”. Retrieved December 2021. Available at  

EWG (2019). “Apples Doused with Chemical After Harvest.” Retrieved December 2021. Available at  

EWG (2014). “Most U.S. Apples Coated with Chemical Banned in Europe.” Retrieved December 2021. Available at  

NTP (2016). “N-nitrosamines. Report on Carcinogens.” Fourteenth Edition. Retrieved December 2021. Available at  

USDA (2016). “Pesticide Data Program: PDP Database Search.” Retrieved December 2021. Available at