Reaction mass of 4-methylpentane-2,2-diyl dihydroperoxide, dioxybis-4-methylpentane-2,2-diyl dihydroperoxide and methylisobutylketon

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Endpoint:

bioaccumulation in aquatic species: fish

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

The performance of a test for bioaccumulation in aquatic species, preferably fish, is scientifically unjustified.
REACh Regulation No. 1907/2006, Annex IX, Sect. 9.3.2, Col. 2, states as follows:
“9.3.2 The study need not be conducted if: - the substance has a low potential for bioaccumulation (for instance a log Kow <= 3) and/or a low potential to cross biological membranes, or - direct and indirect exposure of the aquatic environment is unlikely.”

Direct and indirect exposure of substances of the organic peroxides group to surface water is highly unlikely.

The test item itself was demonstrated to be readily biodegradable.

Very low exposure of the water compartment is further based on the following facts:
Organic peroxides, when released into the sewage of a manufacturing or a downstream user plant, are treated with other substances in dedicated sewage treatment plants. The activated sludge from these sewage treatment plants is then removed and treated as chemical waste. From the production plant, the release of organic peroxide into the sewage is very limited, not to say negligible. The waste water from production plant can be treated on site (at least a physical/chemical treatment, which will decompose organic peroxides by chemical reaction), which is usually followed by a biological treatment. Regarding industrial end uses, organic peroxides are mainly used as cross-linking agent/polymerization initiator for the production of resins/rubbers/polymers. Based upon the fact that organic peroxides are totally consumed during the process (>99%, which is confirmed by the release factor to sewage for curing agents from ESD n°3), the surface water is not exposed to organic peroxides via the waste water system. As a consequence, the surface water is not considered to be significantly exposed by the organic peroxides.

The log Pow values of 2 out of 3 constituents of this multi-constituent substance (monomer=1.3, MIBK=1.31) are well below the threshold of 3 as given in REACH Annex IX. Only the experimental log Pow value of the dimer (4.2) is above the threshold value of 3 but is still below the threshold value of 4.5 defining B-substances described in REACH Regulation No. 1907/2006, Annex XIII and in the guidance document (Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.11: PBT/vPvB). Based on the properties of organic peroxides the substance can be expected to hydrolyse rapidly. Due to these results the test substance was considered to have no bioaccumulation potential and to have low potential to cross biological membranes.

In conclusion, according to REACH Annex IX, Sect. 9.3.2, Col. 2 a bioaccumulation study does not need to be conducted since exposure to the aquatic environment is unlikely, as outlined above. With respect to the PBT or vPvB assessment a bioaccumulation test is also not indicated since the test item is readily biodegradable and thus, not persistent (neither P nor vP).

Furthermore, vertebrate studies shall only be the conducted as a last resort. Thus, a BCF study in fish is also not justified considering animal welfare reasons.

Description of key information

A study does not need to be conducted according to REACH Annex IX Section 9.3.2 Column 2.