Fatty acids, C16-18, calcium salts

Short-term toxicity to aquatic invertebrates

Description of key information

The acute toxicities of calcium myristate and calcium 12-hydroxystearate to Daphnia showed no effects at a water accommodated fraction loading rate of 100 mg/L. Therefore, the 48 hour LL50 is determined to be > 100 mg/L WAF for all of the substances in the calcium salts of monocarboxylic acids C14-C22 category.

Additional information

The acute toxicity to Daphnia was determined in a GLP-compliant, limit test (Harlan 2013) following OECD guideline 202. As no effects were observed in the preliminary range finding tests, the definitive toxicity to Daphnia test was conducted as a limit test at 100 mg/L alongside a blank control. Twenty Daphnia divided into four replicates were exposed to water accommodated fractions of calcium myristate for 48 hours in standard ecotoxicity media adjusted to a hardness of approximately 150 mg/L CaCO₃. Observations of immobilisation or abnormalities of behaviour or appearance of the Daphnia were made at 24 and 48 hours and the test solutions analysed for total organic carbon at test initiation and termination. No effects were observed, so the EL50 was >100 mg/L WAF.

The calcium 12 -hydroxystearate 24 hour NOELR to Daphnia is ≥ 1000 mg/L as determined in a static 24 hour study following OECD 202. The results are taken from a proprietary study (Laboratoire d'Analyses de Fluides 2007) but only a summary of the study is available. Ten Daphnia were exposed in the dark to Water Accommodated Fractions of saturated solutions, prepared by stirring for 20 hours with a magnetic bar, followed by 4 hours separation.

 

The acute toxicity of grease containing calcium 12-hydroxystearate thickener and performance additives to marine invertebrates gives a 48 hour EL50 of >1000 mg/L WAF. The acute toxicity of grease containing calcium 12 -hydroxystearate to marine invertebrates is taken from a regulatory review document (API 2008) citing proprietary studies (Shell Research Limited 1995a, b) following a non-standard guideline MAFF/U.K.OCNS/PARCOM. 2 g of grease was stirred for 24 hours in 2 L of artificial seawater before being left to stand for 1 hour. There is no information available on the concentration of calcium 12-hydroxystearate in grease, which also contains performance additives, but thickeners typically constitute up to around 10 % of a finished grease product. Only a summary of the study is available, but the results are taken from a regulatory document. The review document prepared by the American Petroleum Institute (2008) was submitted to the US EPA as part of the High Production Volume program. The EPA website states that the EPA’s OPPT uses methods established in EPA guidance, which are similar to those described in Klimisch et al. (1997), to evaluate data submitted under the HPV Challenge Program for its quality and completeness. A two tier assessment is used to assess overall scientific integrity of the information, with initial screening followed by a more rigorous evaluation. Therefore, although the method used is not known, the values presented here are acceptable as they are from a reliable secondary source.

 

There was no immobilisation of Daphnia magna by calcium stearate in a proprietary 48 hour acute limit test following EEC 92/69 C2 method, giving a 48 NOEC of ≥ 2.4 mg/L nominal (Osterreichisches Forschungszentrum Seibersdorf 2000). Solutions were prepared by adding 2.4 mg test substance to 1 L dilution water and stirring for 24 hours in the dark before filtering. 20 Daphnia were exposed to a 2.4 mg/L in a limit test for 48 hours under static conditions.

 

Calcium myristate, the shortest carbon chain length substance in the category, has a 48 hour EL50s of >100 mg/L WAF to Daphnia. Calcium 12-hydroxysterate, with intermediate carbon chain length, has a 24 hour NOELR to Daphnia of ≥ 1000 mg/L. These results are supported by published studies on grease containing calcium 12-hydroxystearate as a thickener and a proprietary study on calcium stearate. All of these results indicate that calcium salts of monocarboxylic acids C14-C22 are not acutely toxic to invertebrates.

References

Klimisch HJ, Andreae M, Tillmann U (1997) A systematic approach for evaluating the quality of experimental toxicological and ecotoxicological data. Regulatory toxicology and pharmacology, vol. 25, pp. 1-5