Evaluation of Biomarkers of Exposure to 2-Chlorosyringaldehyde and Simulated ECF Bleached Eucalypt Pulp Effluent
Substitution of chlorine dioxide for molecular chlorine as a bleaching agent in hardwood pulp mills has lowered the organochlorine content of effluents, but produces several chlorinated phenolics with unknown effects on the environment. This study examines the effects of 2-chlorosyringaldehyde (2-CS A), quantitatively the major chlorinated phenol found in elemental chlorine free (ECF) bleached kraft eucalypt pulp effluent, on a suite of biomarkers in sand flathead. Fish received an intraperitoneal injection of 2-CSA at doses of 0.15,1.5,15 or 75 mg kg−1. After 4 d, no changes with dose were found in the activities of the detoxification enzymes ethoxycoumarin-o-deethylase (ECOD), ethoxyresorufin-o-deethylase (EROD) or UDP-glucuronosyltransferase (UDPGT). Cytochrome P450 content and serum sorbitol dehydrogenase (SSDH) activity were also unchanged with dose. A subsequent experiment applied the same suite of biomarkers to sand flathead exposed to simulated ECF bleached eucalypt pulp effluent, at concentrations of 0.5, 2 and 8% (v/v). Similarly, there were no significant differences between effluent-exposed and control fish for ECOD, EROD, P450, UDPGT or SSDH. Liver somatic index was also not significantly different between exposed and control fish. Results indicate that liver detoxification enzyme activities, which are widely used biomarkers of pulp mill effluent exposure, may not be useful biomarkers for effluents from mills using ECF bleaching.