Trihalomethanes in marine mammal aquaria: Occurrences, sources, and health risks Jun-Jian Wang a , Alex T. Chow a,b, *, Joelle M. Sweeney b,c,d , Jonna A.K. Mazet b a The Belle W. Baruch Institute of Coastal Ecology & Forest Science, Clemson University, SC, USA b Wildlife Health Center, One Health Institute, School of Veterinary Medicine, University of California, Davis, CA, USA c The Marine Mammal Center, Sausalito, CA, USA d Moss Landing Marine Labs, Moss Landing, CA, USA article info Article history: Received 4 December 2013 Received in revised form 26 February 2014 Accepted 4 April 2014 Available online 16 April 2014 Keywords: Chlorination Bromide California sea lion Disinfection byproducts Food Waste abstract Disinfecting water containing the high levels of dissolved organic carbon (DOC) commonly generated during pinniped husbandry may cause the formation of carcinogenic disinfec- tion byproducts (DBPs). Little information is available on DBP levels, sources, and health risks in 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 1.1e144.2 mg/L in pool waters and generally increased with number of animals housed (P < 0.05). To identify the sources of THM pre- cursors 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 dissolved organic carbon (DOC) for 2e5 weeks. The common frozen foods used in feeding pinnipeds, including herring, sardine, and squid, produced an average of 22e34 mg-DOC/g-food in water and 836e1066 mg-THM/ g-food after chlorination, whereas the fecal materials, including fresh scat, decomposed scat, and urine, produced 2e16 mg-DOC/g-waste and 116e768 mg-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. Marine mammal husbandry staff and trainers are at risk (5.16  10 4 to 1.30  10 3 ) through exposure of THMs, exceeding the negligible risk level (10 6 ) defined by the US Environmental Protection Agency. ª 2014 Elsevier Ltd. All rights reserved. 1. Introduction Around the world, there are at least 240 large marine aquaria/ ocean life centers in w40 countries displaying marine mammals or serving as rehabilitation facilities listed by MarineBio.org (2012). Chemical disinfectants are widely used in such facilities to maintain water quality and minimize transmission of pathogens among animals and to personnel * Corresponding author. The Belle W. Baruch Institute of Coastal Ecology and Forest Science, Clemson University, P.O. Box 596, Geor- getown, SC 29442, USA. Tel.: þ1 843 546 1013x232; fax: þ1 843 546 6296. E-mail addresses: achow@clemson.edu, atchow@ucdavis.edu (A.T. Chow). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/watres water research 59 (2014) 219 e228 http://dx.doi.org/10.1016/j.watres.2014.04.007 0043-1354/ª 2014 Elsevier Ltd. All rights reserved.