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Toxicity to soil macroorganisms except arthropods

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Reference
Endpoint:
toxicity to soil macroorganisms except arthropods: short-term
Data waiving:
exposure considerations
Justification for data waiving:
the study does not need to be conducted because direct and indirect exposure of the soil compartment is unlikely
Justification for type of information:
The performance of a test for toxicity to soil macroorganisms is scientifically not justified.
REACh Regulation No. 1907/2006, Annex IX, Sect. 9.4, Col. 2 states as follows: “9.4.1: These studies need not to be conducted if direct and indirect exposure of the soil compartment is unlikely.”
Direct and indirect exposure of the test item to soil is highly unlikely for the following reasons:

1) The bioaccumulation factors (BCF) were calculated to be 3.348 L/kg or log BCF 0.525 (Monomer), 274.3 L/kg or log BCF 2.438 (dimer) and 3.399 L/kg or log BCF 0.531 (MIBK). Furthermore the substance is readily biodegradable. 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) 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.

2) The determination of the biodegradability of the test item was performed according to OECD guideline 301D. The test item is evaluated as readily biodegradable in the closed bottle test.

3) The adsorption/desorption properties were calculated in QSAR estimations. KOC values were calculated to be 4413 L/kg (dimer, log Koc=3.6448), 70.03 L/kg (MIBK, log Koc=1.8453) and 13.42 L/kg (Monomer, log Koc=1.1279).

Taken together, these data show that the substance is rapidly degraded in the environment by biotic and abiotic mechanisms. In addition, bioaccumulation can be excluded based on the physical/chemical properties of the substance.

Based on the use profile of the substance exposure to the soil compartment is expected to be low. If expose will happen to a small extent, the substance will be of no toxicological relevance due to the fast degradation. Thus, further testing for the soil compartment is scientifically not justified.

Chemicals can reach the soil via several routes: 1. Application of sewage sludge in agriculture. 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. So it is expected that organic peroxides are not present in sludge. 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 soil is not exposed to organic peroxides via use of sludge. As a consequence, soil is not exposed to organic peroxides via the application of sewage sludge in agriculture. 2. Direct application of chemicals. Based on the uses inventoried for organic peroxides there is no direct application of these substances on the soil compartment. Indeed, all uses are within industrial settings. 3. Deposition from the atmosphere. Deposition from the atmospheric compartment involves volatilization, vaporization or direct release of a considered substance into the atmosphere. Due to their dangerous intrinsic physico-chemical properties, organic peroxides are carefully handled in (semi-)closed systems and their transport, production and use are ruled by several regulations. This is also in line with the release factor to atmosphere for curing agents from ESD n°3. Based on organic peroxides uses, deposition on soil from the atmosphere is also not expected. Based on these arguments no test is proposed for the soil compartment.

Description of key information

The performance of a test for toxicity to soil macroorganisms is scientifically not justified, according to REACh Regulation No. 1907/2006, Annex IX, Sect. 9.4, Col. 2 and Annex XI, 3) exposure considerations.

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