Di-tert-butyl peroxide

Endpoint summary

Description of key information

Short term toxicity to fish

QSAR and measured results for acute toxicity for di-tert butyl peroxide and its analogue (tert-butylhydroperoxide, CAS 75-91-2) show that algae are the most sensitive organism when compared to fish and daphnia. Toxicity data for fish embryos and Daphnia do not show a significant difference (EC50 values do not differ by a factor >10). Based on these observations and the correction for the expected loss of test substance from the existing fish test, an LC50 value for fish of 171 mg/L (the water solubility limit) is used as a worst case for the short-term toxicity to fish endpoint. In reality the LC50 is expected to exceed the water solubiity limit.

Short term toxicity to fish embryos

Toxicity data from an OECD236 study show that the LC50 for fish embryos is >100 < 1000 mg/L.

Long term toxicity to fish

According to ECHA guidance on information requirements and chemical safety assessment (v1.2, November 2012), Chapter r7b, Section 7.8.5, including Figure 7.8.4, if based on acute aquatic toxicity data neither fish nor invertebrates are shown to be substantially more sensitive, long term studies may be required on both. There are no indications from short term toxicity data that fish are substantially more sensitive than Daphnia. According to the integrated testing strategy, the chronic Daphnia study is to be conducted first. If based on the results of the chronic Daphnia test and the application of a relevant assessment factor no risks are observed (PEC/PNEC<1), no long term fish test may be conducted. A chronic Daphnia test result is available, and the results of the chemical risk assessment indicate no risk to the environment, thus the long term fish test is waived.

Short term toxicity to aquatic invertebrates

A reliable OECD 202 GLP study onDaphnia magnais available. No immobilization was observed in a limit test at 150 mg/L. However, analytical measurements showed concentration of the substance decreased in the medium from 126% at test initiation to 19% at test termination, presumably due to loss to the atmosphere despite the use of closed vessels. The geometric mean was used in place of nominal concentrations. Finally a 48h-EC50 > 73.1 mg/L was calculated. This is considered acceptable as test substance concentrations were still measurable at the end of the study.

Long term toxicity to aquatic invertebrates

One OECD 211 GLP study is available with a 21 d NOEC of 7.2 mg/L

Toxicity to aquatic algae and cyanobacteria

A GLP study on Pseudokirchneriella subcapitata following OCED 201 conducted in sealed vessel with analysis was performed. The geometric mean of measured concentrations was used providing a 72h-ErC50 = 36 mg/L and a 72 h ErC10 of 15 mg/L.

Toxicity to microorganisms

The toxicity of the substance to activated sludge was tested in a reliable GLP study following OECD 209 and guidance on the testing of difficult substances. A 30 minute EC50 >1000 mg/L, which is above the water solubility, was observed. No effect up to the highest concentration tested of 1000 mg/L.