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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

ptBP was found to be acutely toxic to fish (rainbow trout) with an approximate 96h-LD50 value of 5.1 mg/L.

Key value for chemical safety assessment

Additional information

An acute toxicity study was performed to assess the acute aquatic toxicity of ptBP to rainbow trout (Oncorhynchus mykiss) for a period of 96 hours (SafePharm, 1991). The study followed the OECD Guidelines for Testing of Chemicals No. 203. A preliminary range-finding study was conducted with rainbow trout (2 fish/concentration) at nominal test concentrations of 0.01, 0.1 and 1.0 mg/L. The concentration of 1 mg/L was the highest test concentration prepared due to the limited solubility of the test material in water and auxiliary solvent. In the definitive study, a limit test was conducted at a nominal concentration of 1 mg/L in two replicates (10 fish/replicate). In parallel, a control and a solvent control (10% Tween-80-dimethylformamide) group were also tested. No mortality occurred at any of the tested concentrations. The LC50 at 96 hours exposure was determined to be greater than 1 mg/L.

Aquatic toxicity of ptBP was also determined in a flow-through test with fathead minnow (Pimephales promelas) (Holcombe et al., 1984, cited in the EU Risk Assessment). No test guidelines were followed; however, the test was performed in a US EPA lab, suggesting that US EPA standards may have been followed. There were 5 test concentrations; measured mean concentrations were 1.16, 1.87, 3.1, 5.44, and 9.47 mg/L, giving a mean recovery of 99%. PtBP were tested as one of 24 organic compounds and specific test conditions for the test with ptBP were not included. The 96h-LC50 value was determined to be 5.14 mg/L, based on measured concentrations.


In a semi-static toxicity study with Oryzias latipes, conducted in accordance with the OECD Guidelines for Testing of Chemicals No 203, a 96 h-LC50 value of 5.1 mg/L was determined for ptBP, based on nominal concentrations (EA of Japan, 1996, cited in the EU Risk Assessment). DMSO was used as a solubilizer, to increase the solubility of the test material.


In a similar semi-static study using Oryzias latipes, performed according to the Japanese standard JISK 0102-1986-71, the 48h-LC50 was determined to be 4.0 mg/L for ptBP, based on nominal concentrations (MITI, 1992, cited in the EU Risk Assessment). This study, however, is not considered to be valid as the test period was 48 hours instead of 96 hours exposure.