Identification and treatment of a waste stream at a bleached-kraft pulp mill that depresses a sex steroid in the mummichog (Fundulus heteroclitus)

Changes to indicators of reproductive performance have been documented in f ish exposed to some bleached kraft pulp mill effluents (BKPMEs). However, r esponses are not consistent across mill types or processes. It is not clear where the sources of the effects are within mills, what the causative comp ounds are, or what process changes are effective to remove these sources. O ur previous studies suggested that condensates were a source of compounds t hat reduced plasma testosterone in the mummichog (Fundulus heteroclitus). R esults also suggested that reverse osmosis (RO) treatment of condensates re moved this source. The objective of this study was to use a toxicity identi fication evaluation approach and expose mummichog to various waste streams in the laboratory to identify the effluent source that depressed plasma tes tosterone in the mummichog and the effects of RO treatment. In 7- and 21-d exposures, mummichog were exposed to dilutions of RO feed condensate, RO pe rmeate, combined mill effluent (CME), and final effluent. Results confirmed that condensates depressed plasma testosterone in mummichog. Chemical char acterization of the condensate indicated that plant phytosterols were likel y not the responsible compounds. Results also confirmed that RO treatment r emoved the potential of the condensates to depress plasma testosterone in m ummichog at environmentally relevant concentrations of final mill effluent (1%).