Retrospective Monitoring of Triclosan and Methyl-triclosan in Fish: Results from the German Environmental Specimen Bank

ORGANOHALOGEN COMPOUNDS – Volume 66 (2004) 1489 Introduction During the last years there were several reports on the appearance of the biocides triclosan (TCS; 5chloro-2-(2,4-dichlorophenoxy)phenol; CAS No. 3380-34-5) and chlorophene (CP; 4-Chloro-2(phenylmethyl)phenol; CAS No. 120-32-1) in the environment. TCS is used in numerous personal care products like toothpaste and soaps, but also in textiles and shoes. The current annual consumption in Germany is estimated to be 40 t (0.5 g per capita and year). During use large amounts of TCS and CP are disposed into waste water. Modern waste water treatment plants (WWTP) eliminate approximately 95 % of TCS, mainly by biodegradation and adsorption to sludge. It was observed that during waste water treatment methyl-triclosan (MTCS; 5-chloro-2-(2,4-dichlorophenoxy)anisole; CAS No. 4640-01-1) is formed, probably due to microbial methylation. In a WWTP effluent up to 1 % MTCS in relation to TCS was detected. The environmental half-life of TCS is assumed to be low, mainly because it is susceptible to photodegradation at environmental pH levels while MTCS is stable under these conditions. The logPow values of 4.7 for TCS and 5.2 for MTCS (estimated with KowWin Vers. 1,67, respectively) indicate potential for bioaccumulation. In aquatic biota, the presence of MTCS was first reported for fish from the Tokyo Bay in Japan in 1984 where up to 38 ng/g MTCS were detected (whole body basis). In Swiss lakes influenced by wastewater effluents the occurrence of MTCS was observed and levels of up to 35 ng/g MTCS (wet weight basis) were detected in fish from these lakes. Another study revealed the presence of TCS and MTCS in plasma of fish from a North American river at levels of up to 10.4 ng/g and 0.0132 ng/g, respectively. Based on these findings it is assumed that MTCS is more persistent than TCS. In order to investigate the exposure of aquatic organisms towards CP, TCS and MTCS in Germany a retrospective monitoring of breams (Abramis brama) from representative rivers was initiated. Samples from the period 1994 to 2003 were taken from the archive of the German Environmental Specimen Bank (ESB) to evaluate temporal changes and regional differences of the occurrence of the target compounds.