Docosyl methacrylate

Endpoint summary

Description of key information

Short-term toxicity to fish

The LC50 of the substance was determined to be > 10000 mg/L.

Long-term toxicity to fish

The study does not need to be conducted because from data for all 3 trophic levels there is no indication that thorough assessment on long-term toxicity to fish is necessary.

Short-term toxicity to aquatic invertebrates

The study does not need to be conducted because the substance is highly insoluble in water, hence indicating that aquatic toxicity is unlikely to occur.

The study does not need to be conducted because a long-term aquatic toxicity study on invertebrates is available.

Long-term toxicity to aquatic invertebrates

The 21-d NOEC of the substance was determined to be ≥ 5.73 µg/L.

Toxicity to aquatic algae and cyanobacteria

The 72-h EC50 and NOEC of the substance is considered to be > 10 µg/L and 10.0 µg/L, respectively.

Toxicity to microorganisms

The EC50 (after 180.0 min) of the substance is > 10000 mg/L (nominal).

Additional information

General comment on validity of ecotoxicity studies with solvent in which the test concentrations exceed the limit of solubility by several orders of magnitude

Several ecotoxicity tests with structural analogues of docosyl methacrylate have been performed at concentrations orders of magnitude above the limit of solubility. In those cases, rapid stirring or solvent or both have been used to disperse the test material. In those studies, no attempt has been made to determine whether the test material was dissolved and only in one study it was acknowledged that the test material was present in the form of an emulsion.

Based on the measured water solubility (< 1 µg/L) of the close structural analogue dodecyl methacrylate (CAS 142-90-5) it can be assumed, that in those cases the test material was present almost entirely as small, undissolved droplets forming an emulsion. As a consequence that the 'concentration' no longer determines the dose in the test organism but the stochastical, individual contact of the test organism with droplets of the test material and the kinetics of the subsequent absorption of the droplet by the test organism. Test results obtained this way are artefacts and not representative. They cannot be used establishing a concentration-effect relationship. Therefore, test results have only been used when the test was performed without solvent and the nominal test concentration was not higher than approximately ten-fold above the solubility of the structural analogue dodecyl methacrylate in water.

Conclusion

Considering the three trophic levels, fish, aquatic invertebrates and algae, the test results available clearly demonstrate the absence of ecotoxicity within the range of water solubility of the structurally analogue long-chain alkyl methacrylate esters. Furthermore, there is no evidence for toxicity to microorganisms. Therefore it is considered as unlikely that docosyl methacrylate possess aquatic toxicity properties.