Benzyl butyl phthalate

Long-term toxicity to fish

Description of key information

A two-generation toxicity test on Pimephales promelas found showed no effects relevant for risk assessment for benzyl butyl phthalate at any of the test concentrations (up to 64.6 — 67.5 µg/L). The NOEC from this study is therefore taken to be 64.6 µg/L.This result is the most sensitive chronic NOEC reported for benzyl butyl phthalate for fish, invertebrates and algae. However, it has not been used for the derivation of the PNEC as the study was designed to investigate endocrine disrupting effects and therefore the exposure concentrations were very low. No effects were observed in the test so the NOEC is unbounded. Instead the NOEC of 75µg/L for Mysidopsis bahia has been used to derive the aquatic PNEC. The PNEC derived is therefore consistent with the PNEC derived in the EU RAR for benzyl butyl phthalate.

Additional information

Rhodes et al. (1995) performed a chronic toxicity test on the freshwater fish Oncorhynchus mykiss. This was a GLP test and was equivalent/similar to the guidelines EPA 797.1600 (U.S. EPA Toxic Substances Control Act 40 CFR, Part 797.1600 [as modified in Testing Consent Agreement 40 CFR, Part 799], and the ASTM Standard Guide for Conducting Early Life-Stage Toxicity Tests with Fishes). The test showed no effects on hatchability, survival, or growth for benzyl butyl phthalate at any of the test concentrations (up to 0.20 mg/L). This study is used as a key study to fulfil this endpoint.

Hicks (2008) performed a two-generation reproduction and early-life stages test upon the freshwater fish Pimephales promelas in accordance with GLP and based upon multiple guidelines. Endpoints that were examined quantitatively included F0/F1 survival, body length of males and females, body weight of males and females, cumulative F0 fecundity, number of spawns, percent fertility, percent hatchability, and plasma vitellogenin in F1 males and females. No statistically significant effects were observed for any endpoint. In addition, gonadal histopathology was examined qualitatively. The qualitative assessment of gonadal tissues suggested the presence of increases in the incidence and severity of spermatogonia in testes of males in both treatment groups, increased incidence of oocyte atresia in females in both treatment groups, and altered gonadal stage scores in both males and females at the high concentration. These diagnoses were characterized by visual impression of relative changes in the numbers of various cell types. No statistics were carried out to identify if the differences observed were significant or not. They are therefore not relevant for REACH.

Gledhill et al. (1980) performed a 14 day flow-through test with the freshwater fish Pimephales promelas. The 14 -day LC50 was 2.25 mg/L. This study is from a review article and limited information on test methods is available, however it can be used as a supporting study to fulfil this endpoint.