The application of chemical disinfectants to control drinking water pathogens was one of the most significant public health achievements of the past century. With an estimated 76 million illnesses attributable to foodborne pathogens per year in the US, food has superceded water as a vehicle for enteric pathogens. Outbreaks linked to contaminated produce have heightened the importance of food disinfection in processing facilities, typically using chlorinated washwaters, but disinfectant exposures requirements have not yet been formalized. Washing facilities use significant volumes of water. There is pressure to reuse washhwater in drought-prone areas, but the significant concerns regarding pathogens may promote the use of even high disinfectant contact times. Disinfectants react with food to produce potentially carcinogenic disinfection byproducts (DBPs). Disinfectant doses for food disinfection must be optimized to balance the acute risk of pathogens against the chronic risk of DBPs, just as they have been optimized for drinking water disinfection. Food may be more important than water for DBP exposure. Drinking water disinfection involves application of ~2-5 mg/L chlorine to water containing ~1-2 mg/L dissolved organic carbon, while food washing can involve application of up to 200 mg/L chlorine to produce containing ~20 g/L organic carbon. Research to date on DBPs during food washing have focused on the same low molecular weight volatile DBPs targeted in drinking water (<i>e.g</i>., trihalomethanes), but these compounds generally do not partition to food, and so represent a concern for washwater disposal. We targeted the prediction of non-volatile DBPs from chlorine reactions with food biomolecules. Using chlorine doses typical for food washing, we demonstrate the formation of chlorotyrosines from tyrosine in lettuce and spinach at concentrations exceeding the combined concentrations of the volatile DBPs of current concern. Halotyrosines remain in the food, and would be bioavailable after their liberation from protein in the stomach. These halotyrosines form at high yield from one biomolecule (tyrosine), while the volatile DBPs represent the low yield byproducts of reactions of chlorine with many biomolecules. A similar approach could be pursued to identify other high-yield, non-volatile DBPs from other biomolecules to better characterize the risks of disinfection byproducts for optimization against pathogen control during food disinfection.

Chlorotyrosines versus volatile byproducts from disinfection during washing of lettuce and spinach

255th National Meeting (2018)

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