[1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide

Endpoint summary

Description of key information

One key study is available for each of the following endpoints:

Short term Toxicity to Fish: OECD Test Guideline 203 (1984). The LC50(96 h) was calculated to be750 mg/L, with 95% confidence limits of 360 and 1570 mg/L. Based on the results of this study, [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide would be classified as not dangerous to fish in accordance with the Directive 67/548/EC. However, given that during the test a layer of test substance remained visible on the surface of the test media in all test concentrations, the LC50 value should be handled with care. Moreover no analytical monitoring was performed during the test. Based upon the fact that no mortality was observed this test can be considered as valid with restrictions.

This is confirmed by a non-GLP FET according to OECD 236: Test material can be concluded to have an LC50 / EL50 in excess of its water solubility limit for fish embryos / hatchlings.

Short term Toxicity to Aquatic invertebrates: Analogous CAS 25155-25-3 [1,3(or 1,4)-Phenylenebis(1-methylethylidene)]bis[tert-butyl]peroxide was not found to be acutely toxic to Daphnia magna when dispersed in water at a nominal loading rate of 1.0 mg/L equivalent to an initial mean measured concentration of 0.0219 mg/L. Consequently, the 48-hour EC50 value for [1,3(or 1,4)-Phenylenebis(1-methylethylidene)]bis[tert-butyl]peroxide could not be calculated but must be >1.0 mg/L (>0.0219 mg/L). The “no observed effect loading rate” was 1.0 mg/L (0.0219 mg/L as initial mean measured concentration).

Toxicity to freshwater algae: The acute toxicity of analogous CAS 25155-25-3 [1,3(or 1,4)-phenylenebis(1 -methylethylidene)]bis[tert-butyl] peroxide was evaluated with Pseudokirchneriella subcapitata in a study performed in accordance with OECD testing guideline 201 and GLP requirements.

The algae were exposed to nominal test concentrations of 1 mg/L under static conditions during 72 hours. The mean measured concentrations were not maintained between 80 and 120 % of nominal. The test substance was not found to be acutely toxic to Pseudokirchneriella subcapitata at a nominal loading rate of 1.0 mg/L, equivalent to an initial mean measured concentration of 0.0471 mg/L.

A study with the target substance (CAS 2212 -81 -9) is was performed to strengthen the Read Across.

The effect of the test item on the growth of Pseudokirchneriella subcapitata has been investigated and gave EC50 values of greater than 0.0068 mg/L based on the geometric mean measured test concentration.  The No Observed Effect Concentration was 0.0068 mg/L.

This study showed that there were no toxic effects at the limit of water solubility (100% v/v saturated solution).

Both studies show that the test substances did not give an effect at the limit of water solubility.

Long term Toxicity to Aquatic invertebrates: The analogous test substance CAS 25155 -25 -3 at its maximum achievable solubility in test medium (generated from a 10 mg/L water accommodated fraction) did not have any detectable effects on the reproduction or length of Daphnia magna in a 21 day chronic study under semi static conditions with daily refreshment. The NOELR (No observed effect loading rate) can therefore be expressed as 10 mg/L. The NOEC of the test material may also be expressed as 40.6 µg/L based on the mean measured initial concentration.

This is confirmed by a non-GLP study according to OECD guideline 211 with the registered substance (CAS 2212 -81 -9). A NOEC for reproduction and length, for the substance as time weighted average test material was determined as the limit of solubility of the test material (63 µg/L), this is equal to a NOELR of 10 mg/L.

Another non-GLP study according to OECD guideline 211 with the registered substance (CAS 2212 -81 -9) without chemical analyses of the test concentrations confirms this result as well. A NOEC for reproduction and length, for the substance as time weighted average test material was determined as the limit of solubility of the test material, this is equal to a NOELR of 10 mg/L.

The test substance may therefore be concluded as non-toxic to the reproduction of Daphnia Magna up to its solubility limit. Hence no chronic effects to Daphnia would be expected.

Long term Toxicity to Fish: A long term fish study according to OECD guideline 210 was also conducted. Newly fertilized fathead minnow eggs (4 replicates of 20 eggs per group) were exposed to solutions of the test item at nominal concentrations of 32 and 100% v/v saturated solution for a period of 33 days at a temperature of 23 to 27 °C under semi‑static test conditions. The test solutions were renewed daily throughout the test. The test item solutions were prepared by stirring an excess (10 mg/L) of test item in test water, after the stirring period the preparation was allowed to stand for 1 hour before the aqueous was removed avoiding any undissolved test itemto produce the 100% v/v saturated solution of the test item. This saturated solution was then further diluted as necessary, to provide the 32% v/v saturated solution test group.

Exposure of the fathead minnow early-life stages to the test item gave no effects on no. hatched, post-hatch survival, body length and -weight based on the geometric mean measured test concentrations of 0.0015 and 0.0062 mg/L, respectively. Therefore, this study showed there were no toxic effects at saturation or at 10 mg/L loading.

To summarize no effect of[1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide was observed up to its water solubility limit.