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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Reference
Endpoint:
bioaccumulation in aquatic species: fish
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
the study does not need to be conducted because direct and indirect exposure of the aquatic compartment to the substance is unlikely
Justification for type of information:
The performance of a study on bioaccumulation in fish was considered scientifically not justified.

REACH Regulation No. 1907/2006, Annex IX, Sect. 9.3.2, Col. 2, states as follows: “9.3.2: The study need not to 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 compartment is unlikely. ”
Direct and indirect exposure of the test item to surface water is highly unlikely. Due to the unstable nature of organic peroxides, it can be assumed that upon contact with water and organic matter, the test item undergoes 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 was found to be readily biodegradable in a closed bottle test.

The test item is also highly insoluble in water with a logPow > 6.5 (13.0, calculated), indicating that it highly unlikely passes biological membranes.
Very low exposure of the water compartment is further 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 is not considered to be significantly exposed by the test item.
In addition, bioaccumulation potential was estimated by QSAR calculation for the parent compound. The substance was within the applicability domain of the model and thus fulfilling validity criteria of the QSAR calculation. A calculated BCF value of 15.1 L/kg was obtained, being way smaller than the threshold value of 2000 L/kg for the B criterion. This further indicates no concern in regards to bioaccumulating potential of the test item.

In conclusion, according to REACH Annex IX, Sect. 9.3.2, Col. 2 the study does not need to be conducted as exposure to the aquatic environment is unlikely, as outlined above. Further, the substance is readily biodegradable and thus not considered to be P or vP. Therefore, testing on bioaccumulation properties in regards to PBT or vPvB assessment is also not applicable. In addition, QSAR calculation indicates no concerns in regards to bioaccumulation potential.

Based on these points testing for bioaccumulation is considered neither scientifically justified nor reasonable. And for animal welfare reasons no test is proposed for bioaccumulation in fish.

Description of key 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. ” 

The test substance is readily biodegradable and has logPow of > 6.5 and a log Koc of > 5.63. Furthermore, the water solubility of the test item is very low (< 1ng/L). Thus, the test substance has a low potential to cross biological membranes. In addition, BCF value was calculated to be 15.1 L/kg wet-wt. Therefore, the test substance was considered to have no bioaccumulation potential.

Key value for chemical safety assessment

BCF (aquatic species):
15.1 L/kg ww

Additional information