Pulp and paper mill effluent treatments have differential endocrine-disrupting effects on rainbow trout.

Endocrine disruption (ED) effects due to pulp and paper mill effluents extracts involving different industrial procedures and effluent treatments (nontreated, primary, and secondary treated) were evaluated using immature triploid rainbow trout in a pulse-exposure toxicity experiment. The protocol involved the use of intraperitoneal injection of mill extracts (solid-phase extraction [SPE]) corrected for individual fish weight and included several laboratory standards (steroidal hormones and phytosterols). Biological endpoints at two different levels of biological organization were analyzed (molecular and individual organism). Results indicated that nonsignificant changes were observed in the individual physiological indices represented by condition factor, liver somatic index, and gonad somatic index during the experiment. Significant induction of liver ethoxyresorufin-O-deethylase activity was observed between different effluent treatments and experimental controls. Significant endocrine-disrupting effects at the reproductive level were observed in all effluent treatments involving significant increments in plasma vitellogenin (VTG) levels. Fish exposed to untreated effluent extracts had significantly higher VTG levels compared to fish exposed to primary and secondary treatment effluent extracts, indicating a decrease of the estrogenic effect due to the effluent treatment. The present study has shown that for the Chilean pulp and paper mill SPE extracts evaluated, an endocrine disruption effect was induced in immature triploid rainbow, reaffirming the significant estrogenic effects demonstrated previously in laboratory and field experiments.