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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

May be accumulated in organisms; triclosan is not B or vB (BCF < 2000 L/kg)

Key value for chemical safety assessment

Additional information

 

Bioaccumulation of Triclosan was investigated in a flow-through system set up according to OECD guideline 305 C. Zebra fish were exposed for five weeks to a concentration of 3 and 30 µg/l respectively followed by depuration period of two weeks. A BCF of 4157 at a concentrations of 3 µg/l was detected whereas at a concentration of 30 µg/l the BCF was 2532. After the depuration period a loss of 98 - 99 % was demonstrated (Ciba-Geigy Ltd. 1991). Comparable results were obtained by a study testing the dependence of bioaccumulation of Triclosan at different concentrations on pH (Schettgen et al., 1999). After an uptake period of 25 days the BCF ranged from 7900 at pH 6 and an initial substance concentration of 35.9 µg/l to 3740 at a pH of 9 and an initial concentration of 46.7 µg/l.

Triclosan bioaccumulates in organisms in a short time period. However the observed loss during depuration was comparably fast and high.

 

Additional information on the uptake and excretion of triclosan in goldfish is available (Unilever, 1975). According to this non-guideline ADME study, Triclosan is taken up by the fish with a high rate. Accumulation took place predominantly in the gall bladder. Triclosan is excreted fast by the fish as well, which is enhanced by food uptake. Over a 10 -d depuration phase, an average of 96% of the initial radioactivity was excreted.

 

The study by Ciba-Geigy (1991) was selected as key study. Taking into account all available information summarised in the comparison of both studies (BASF SE, 2012), it can be concluded that there is a much higher level of uncertainty in the BCF results from the Schettgen et al. (1999) study than in the results from the Ciba-Geigy (1991) study. Especially the uncertainty on test media preparation, the high variation in the recovery of Triclosan in the fish tissue along with the exceeding concentration of methanol in the test raises serious doubts on the validity of the Schettgen et al.(1999) study.

 

The results from an in vivo model based on biotransformation rates for catfish liver show that the BCF of TCS is < 2000 L/kg (BASF SE, 2016).

 

In addition, a review by BASF SE (2015) discusses the available experimental studies and other available data on the bioaccumulation potential of TCS. The author (J. Arnot) shows that all of the available studies have merits and limitations and a weight-of-evidence approach is suggested. In the it becomes evident that TCS may accumulate in fish; however, it can be shown that the TCS is neither B nor vB (BCF < 2000).