Chemical disinfectants are widely used in aquatic parks and rehabilitation facilities to maintain water quality and minimize transmission of pathogens between marine animals and personnel. Yet, litter information is available on the formation of carcinogenic disinfection byproducts (DBPs) from disinfecting water of marine mammal aquaria. Using the commonly observed trihalomethanes (THMs) as a DBP indicator, we monitored concentrations for seven months at The Marine Mammal Center in Sausalito, California, one of the largest pinniped rehabilitation facilities in the world. Concentrations of THMs ranged 1.1-144.2 �g/L in pool waters and generally increased with number of animals housed and the concentration of dissolved organic carbon (DOC) (P<0.05). To identify the sources of THM precursors in marine mammal aquaria, we intensively monitored the mass flows of potential THM precursors (i.e. food and wastes) in an isolated system with nine individual California sea lions to evaluate the sources and reactivity of DOC for 2-5 weeks. The common frozen foods used in feeding pinnipeds, including herring, sardine, and squid, produced an average of 22�34 mg-DOC/g-food in water and 836�1066 �g-THM/g-food after chlorination, whereas the fecal materials, including fresh scat, decomposed scat, and urine, produced 2�16 mg-DOC/g-waste and 116�768 �g-THM/g-waste. Food not eaten by animals could cause a sharp increase of DOC and DBP production and therefore should be removed rapidly from pools. Our model revealed that if even only 5% of uneaten food remains in the pool, the food-derived DOC was estimated to contribute 46% to the THM budget, followed by feces (34%) and urine (20%). The health risk assessment shows marine mammal husbandry staff and trainers are at risk (5.16x10-4 to 1.30x10-3) through exposure of THMs, exceeding the negligible risk level (10-6) defined by the US Environmental Protection Agency.

Monitoring trihalomethane levels in marine mammal aquaria

248th National Meeting (2014)

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