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

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

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 long-term toxicity to aquatic invertebrates was considered not scientifically justified. REACH Regulation No. 1907/2006, Annex IX, Sect. 9.1., Col. 2, states as follows: “9.1.: Long-term toxicity testing shall be proposed by the registrant if the chemical safety assessment according to Annex I indicates the need to investigate further the effects on aquatic organisms.”

The chemical safety assessment does not indicate the need to further investigate the effects on aquatic organisms for the following reasons:

Exposure and stability considerations:
The test item is not stable in the aquatic environment. Due to the unstable nature of organic peroxides, it can be assumed that upon contact with water and organic matter, the test item undergoes rapid degradation resulting in the formation of respective alcohols and acids. Therefore, an abiotic degradation of the test item in the environment is expected.

In addition, the test item is considered readily biodegradable based on a Closed Bottle Test according to OECD 301 D (please refer to IUCLID section 5.2.1).

Based on the points outline above, long-term toxicity testing is considered scientifically not justified since the test item is not stable in the aquatic environment.
Further, Environmental Risk Assessment revealed safe use of the substance throughout its whole life cycle due to very low exposure of the water compartment which is especially based on the following facts:

Organic peroxides, when released into the sewage of a plant production or a downstream user’s plant, are treated with other substances in dedicated sewage treatment plants. The activated sludge stemmed from these sewage treatment plants are then extracted and treated as chemical waste. From the production plant, the release of organic peroxide into the sewage is very limited, not to say completely negligible. The waste water from production plant can be treated on site (at least a physical/chemical treatment, which will neutralize potential residual organic peroxide), which is usually followed by a biological treatment. Regarding the rest of the lifecycle, 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 and with this aquatic organisms are not considered to be significantly exposed by the test item.

Moreover, 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). Due to these results the test substance was considered to have no bioaccumulation potential and to have low potential to cross biological membranes. In addition, the CSA does not show a need for an additional long-term aquatic test. For more details on exposure assessment see risk assessment report in section 13.

Therefore, long-term toxicity testing with daphnia is considered to not improve the chemical safety assessment.
In summary, long-term toxicity testing in an aquatic invertebrate species is considered not scientifically justified according to REACH Regulation No. 1907/2006, Annex IX, Sect. 9.1., Col. 2.

Description of key information

The study need not to be conducted following provisions of REACH Regulation No. 1907/2006, Annex IX, Sect. 9.1., Col. 2. For more details please refer to "Justification for type of information".