Aquatic biomonitoring of reclaimed water for potable use: the San Diego Health Effects Study.

Highly treated reclaimed wastewater was evaluated as a possible supplement to raw water sources required to meet San Diego's growing need for potable water. Biomonitoring experiments employing fathead minnows (Pimephales promelas) were used to compare reclaimed water with the city's current raw water supply. Juvenile fish were exposed in flow-through aquaria in field laboratories located at the reclamation plant (AQUA II) and at a municipal potable water treatment facility (Miramar). Biomonitoring measurements were survival and growth, swimming performance, and trace amounts of 68 base/neutral/acid extractable organics, 27 pesticides, and 27 inorganic chemicals found in fish tissues after exposure. Biomonitoring revealed differences in survival, growth, and swimming performance only after 90- and 180-d exposure. Reclaimed water and raw water were not readily distinguishable in 28-d chemical bioaccumulation tests in terms of organic chemical contaminants in fish tissue except for pesticide levels, which tended to be higher in raw water. Similar inorganic species were found in samples from both waters, although there was greater evidence of bioaccumulation of certain contaminants from raw water. Based on biomonitoring parameters included in these experiments, the use of reclaimed water to supplement raw water supplies would appear to pose no major public health threats. The results of these studies will be combined with additional health effects information before final conclusions are reached about the suitability of reclaimed water for human consumption.