Uptake of water disinfection by-products into food
Humans are exposed to water disinfection by-products (DBPs) through direct ingestion of tap water and via inhalation and dermal absorption. Additional exposure from cooking foods in tap water containing DBPs has not been explored. We conducted controlled laboratory experiments to determine potential excess exposures to DBPs—haloacetonitriles and haloacetic acids (HAAs). Some HAAs and haloacetonitriles decomposed within 10 minutes in boiling water; other analytes remained. During cooking in or contact with water, foods—frozen carrots, frozen green beans, dried pinto beans, chicken, pasta (spaghetti), and lettuce—absorbed up to 60 percent of HAA DBPs. In general, chlorodibromoacetic and tribromoacetic acids were not detected in the food after cooking. Pasta rinsed in HAA-containing spiked reagent water was shown to absorb additional HAAs and elevate the excess dietary exposure above that from cooking alone. HAA-containing tap water used to boil foods during preparation can increase the potential for human exposure, the magnitude of which depends on the types of foods cooked, the cooking duration, the volume of water used to cook the food, and the quantity of the food consumed. Regulators should consider excess dietary exposures when defining the acceptable quantities of DBPs, at least for HAAs, in tap water.