A Broad Scan of Bay Contaminants: Cutting-Edge Analysis Identifies Low Levels of Five Unmonitored Compounds in Wildlife of San Francisco Bay

A Bay RMP study employed a cutting-edge analytical technique to detect low levels of five unmonitored compounds in wildlife of San Francisco Bay. San Francisco Bay wildlife were tested for previously unmonitored contaminants using a non-targeted analysis that screens mainly for long-lived, fat-soluble, chlorine- and bromine-rich chemicals. Bay mussel and harbor seal samples contained five contaminants not previously identified in Bay wildlife, and for which toxicity is largely unknown. The detection of these compounds suggests that the original or “parent” contaminants may not always be the most important chemical to monitor in wildlife. 

Most of the Bay chemical contamination was from high priority contaminants that the RMP already monitors, or closely related compounds. This suggests that many of the highest priority persistent chlorinated and brominated chemicals have already been identified, with key contaminants regularly monitored. 

Future non-targeted analysis could include techniques that examine water-soluble compounds. Examples include many cleaning and personal care product ingredients, contaminant break- down products or metabolites, and chemicals that associate with protein-rich tissues like blood rather than fats. Although some of these water-soluble chemicals do not linger long in the environment, they are widely used and may be continuously discharged to the Bay at relatively high levels, potentially leading to prolonged exposure and toxicity to aquatic life.