A review of the effects of bromate on aquatic organisms and toxicity of bromate to oyster (Crassostrea gigas) embryos

A critical literature review has been undertaken of the effects that bromate (BrO3-) has on aquatic organisms, Chronic (multigeneration) studies using four marine phytoplankton species indicate a stimulation of cell division at concentrations up to 13.6 mg BrO3- liter(-1), such that the EC50 is >13.6 mg BrO3- liter(-1) (exposure period unspecified), No published data were available for any freshwater algal or phytoplankton species, For freshwater invertebrates, the available data are limited to acute studies using two species: the water flea, Daphnia magna, with a 48-h LC50 of 179 mg BrO3- liter(-1); and the planarian ("flatworm"), Polycelis nigra, with a 48-h LC50 of 2258 mg BrO3- liter(-1). For saltwater invertebrates, there is a greater variety in the spread of species sensitivity to bromate, For crustaceans, the lowest reported acute value is a 24-h LC50 of 176 mg BrO3- liter(-1) for mysid shrimp, For molluscs, the published data are somewhat contradictory, with different workers reporting EC50 values to oyster embryo-larvae of either 0.05-0.1 or 30 mg BrO3- liter(-1). Following repeated attempts to resolve these differences using the Pacific oyster (Crassostrea gigas) embryo development assay, a 24-h EC50 of 170 mg BrO3- liter(-1) was observed, Reported 96-h LC50 values for juvenile saltwater fish range from 427 to 512 mg BrO3- liter(-1), while a 10-day LC50 of 279 mg BrO3- liter(-1) is also reported. For fish early lifestages, newly hatched larvae are more sensitive than embryo hatching, with a larval 96-h LC50 of 31 mg BrO3- liter(-1) being observed, Less severe effects have been reported for older larvae (pro-larvae), for which a 96-h LC50 of 404 mg BrO3- liter(-1) is reported, In conclusion, a number of studies provide evidence for the acute toxicity of bromate to invertebrates and fish in the lowest region of 30 mg BrO3- liter(-1). Applying the factor of 10 used to extrapolate from acute to potential chronic toxicity, the available data suggest that to protect aquatic organisms from longterm adverse effects, concentrations should not exceed approximately 3.0 mg BrO3- liter(-1) (C) 1997 Academic Press.