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Long-term toxicity to fish

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Description of key information

An OECD 210 was performed to assess the possible lethal and sub-lethal effects of [1,3(and/or 1,4)-Phenylenebis(1-methylethylidene)]bis[tertbutyl] peroxide during the embryonic and early larval development of the fathead minnow. After several preliminary tests, this study was performed using completely closed test vessels, very limited headspace, and light conditions reduced to the lower end of the optimal range, in order to limit the loss of the substance by volatilization, adsorption or photodegradation. The results led to the conclusions that [1,3(and/or 1,4)-Phenylenebis(1-methylethylidene)]bis[tertbutyl] peroxide did not affect the hatching success (embryonic survival), survival of larvae and the growth of the exposed larvae up to the highest achievable concentration which is nominally 40 µg/l (water solubility limit) corresponding to average measured concentrations of 31 µg/L. 

Key value for chemical safety assessment

Additional information

Before launching the OECD 211 and OECD 210 studies, a large amount of preliminary work was necessary to ensure the good design of the studies in order to avoid the biases already observed in the existing OECD 211 and the new OECD 309 and OECD 305 studies. These investigations were necessary to better understand the behavior of bisperoxide in water compartment.


Several OECD 211 studies were already performed and failure to recover the substance adequately in the old test solutions of all existing studies has led to doubts regarding sufficient exposure to the test substance. It was neccessary to investigate the possibilities for improving quantification of the test material before launching new chronic toxicity study.


In a first step, the bisperoxide exposure was investigated in more details in two preliminary non GLP OECD 201 and 202 studies.
In a second step, it was investigated a preliminary non GLP OECD 211 study under a semi-static conditions in closed system with a comparison of filtration and centrifugation method which could give interesting results about the exposure on the aqueous phase and maybe a better design for the chronic studies.
A new OECD 210 study performed with one of the isomer of the substance (2212-81-9) was also added to the dossier and discussed with the Authorities. After these discussions, it was decided to launch a new OECD 210 study under the same test conditions that the OECD 211. 


The final reports generated for these studies are available in section ‘Overall remarks, attachments’.


These results of this preliminary works indicate that volatility, previously considered as less relevant, is a key factor of test material loss from the system as well as the critical influence of the sampling method. This contradicts the conclusion on the OECD211 study in which the geomean data is considered unreliable due to adsorption and reflects the findings of the OECD309 in which the test material is lost rapidly from a static system despite organic material presence.


 


Two OECD 210 studies are now available in this dossier. 


The first one is performed on the isomer [1,3-Phenylenebis(1-methylethylidene)]bis[tertbutyl] peroxide. As the test item had a low water solubility and high log Kow, the quoted water solubility for the test item was 0.04 mg/L, therefore the test solutions were prepared using a slow-stir saturated solution method of preparation. The test was performed at nominal saturation 32% v/v saturated solution, made from a 100% v/v saturated solution which correspond to the geometric mean measured concentration equal to 0.0015 and 0.0062 mg/L. Under these test conditions, no effects were observed at the saturated concentration.


After several preliminary tests, a new OECD 210 study was performed with the substance [1,3(and/or 1,4)-Phenylenebis(1-methylethylidene)]bis[tertbutyl] peroxide, using completely closed test vessels, very limited headspace, and light conditions reduced to the lower end of the optimal range, in order to limit the loss of the substance by volatilization, adsorption or photodegradation. The results of this study led to the conclusions that [1,3(and/or 1,4)-Phenylenebis(1-methylethylidene)]bis[tertbutyl] peroxide did not affect the hatching success (embryonic survival), survival of larvae and the growth of the exposed larvae up to the highest achievable concentration which is nominally 40 µg/l (water solubility limit) corresponding to average measured concentrations of 31 µg/L.