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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

TCP exhibits acute toxicity to fish.

Key value for chemical safety assessment

LC50 for freshwater fish:
41.6 mg/L

Additional information

The available studies on acute toxicity to fish indicate significant species to species variability. Japanese medaka was fewest susceptible as evidenced by a 48-h LC50of 109 mg/L (MITI 1992). The study is valid and conclusive but the exposure time shorter than the standard. Geiger et al (1990) found a 96-h LC50 of 66.5 mg/L to fathead minnow (Pimephales promelas). The study is considered valid and conclusive and however it was not performed under GLP.

In further toxicity studies conducted with several fish species, the lowest LC50 value (7-day incubation, which does not mean exposure, see below) was established for guppies (Poecilia reticulata) to be 41.6 mg/L (Könemann 1981). For the rainbow trout (Oncorhynchus mykiss) and bluegill sunfish (Lepomis macrochirus) the 96-h LC50s were 42 and 75 mg/L respectively while the estimated NOEC value was <10 mg/L (Bowman 1986).

However these studies have methodological deficiencies with regard to the analytical dose verification they trigger the hazard assessment because the found the lowest effect levels. Loss due to evaporation of TCP from the aqueous phase was demonstrated in a study simulating a 48-h daphnid open vessel test (Solvay 2001, Internal Memorandum). Due to the non-verification of the actual exposure level only an underestimation the toxic effects is possible. In conclusion the LC50 of TCP is assessed to be 41.6 mg/L as the actual exposure to the evaporating test item may be not more than 96 h. This is considered an acceptable approximation of the short term toxicity to fish for assessment since fish are obviously not the most sensitive taxonomic group.

Because good long term observations form fish are available further testing on fish acute effects is beside the point.