Reproductive steroid responses in fish exposed to pulp mill condensates (original) (raw)

Since 1997, a number of approaches (artificial stream exposures, lab bioassays) have been used to identify waste-stream sources of contaminants at the Irving Pulp & Paper Ltd. (IPP) mill, in Saint John, Canada. These studies have shown that chemical recovery condensates have the greatest potential for reducing circulating and gonadal steroids in mummichog (Fundulus heteroclitus), an endemic fish species. A solid phase extraction technique was developed to isolate the hormonally-active substances from the condensates, and a toxicity identification evaluation (TIE) approach was used to gain a better understanding of the chemical characteristics of the active substances. The extract was fractionated by high performance liquid chromatography and the fractions were used in a seven-day bioassay. Mummichog were exposed in static aquaria with daily renewal to either the whole condensate extract, or one of the six fractions at 1 % v/v. Steroid reductions in recent exposures were not as pronounced as had been observed during studies which investigated the overall potency of the extract at the same concentration. As well, differences in responses were observed between the sexes. A dose-response experiment indicated that greater steroid reductions are elicited at 4% v/v in male mummichog. Therefore, the TIE was continued at 4%v/v, however, no steroid reductions were observed in any of the fractions. Some fractions induced increases in plasma testosterone, which had never been observed previously. Ongoing work is focusing on developing an understanding of the extent to which variability in the fish responses are linked to reproductive state and differences in responses between the sexes, while additional work is concentrating on variability in condensate constituents and the fractionation protocol.