4-tert-butylphenol

Long-term toxicity to fish

Description of key information

The long-term toxicity study conducted with ptBP was mainly designed to determine if exposure of fathead minnows to ptBP during their early development would result in changes typically associated with exposure of fish to estrogenic chemicals.  In this study the most sensitive endpoints were growth, secondary sex characteristics, and the onset of hatching. Clearly defined estrogenic effects were only apparent in the 300 µg/L treatment group as evidenced by feminization of gonadal ducts of male fish and elevated levels of vitellogenin in females. 

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

100 µg/L

Additional information

In an early-life stage toxicity test conducted in accordance with the OECD Guidelines for the Testing of Chemicals No. 210 and in compliance with GLP, the effect of ptBP on sexual differentiation and gonadal development of fathead minnow (Pimephales promelas) was evaluated (Krueger et al., 2008). Fathead minnows were exposed to ptBP at concentrations of 10, 30, 100 and 300 µg/L for up to 128 days. The exposure period included a five-day hatching period followed by up to 123 days of post-hatch development of larvae and juvenile fish. Specifically, the study was designed to detect changes in the endocrine-mediated endpoints including sex ratio, elevated levels of vitellogenin (VTG), feminization of testes, changes in growth and changes in the expression of secondary sex characteristics. Traditional endpoints of fish early life-stage studies including effects of the test substance on time to hatch, hatching success, stage specific survival and growth were also monitored. Taking all available information into account, the most sensitive endpoints were growth, secondary sex characteristics, and the onset of hatching. These endpoints showed effects that appeared to be related to small delays in development. Overall statistical LOEC and NOEC values were 30 µg/L and 10 µg/L, respectively. Clearly defined estrogenic effects were apparent only in the 300 µg/L treatment group, as evidenced by feminization of gonadal ducts of male fish and elevated levels of VTG in females. Since the effects at 10 and 30 µg/L appear not to be of biological relevance the NOEC under the conditions of this study is 100 µg/L.