Calcium didocosanoate

Endpoint summary

Additional information

Acute aquatic toxicity

None of the substances in the calcium salts of monocarboxylic acids C14-C22 category are considered to be acutely toxic to fish, invertebrates or inhibitory to algal growth as all of the substances have acute LL or EL50s of >100 mg/L.

Testing strategy

Due to the lack of experimental ecotoxicity data for members of calcium salts of monocarboxylic acids C14-C22 category novel testing was undertaken. Where testing has been conducted to generate data in order to complete ecotoxicity endpoints, testing of calcium myristate (C14), at the lower end of the category, and calcium 12-hydroxystearate (C18), as a hydroxylated member of the category was considered the most efficient approach. The data for the shortest carbon chain length were generated to provide a worst case scenario, as this is expected to be the most bioavailable. The testing of substances at strategic points in the category is designed to ensure that the most conservative results are identified and, where appropriate, provide a classification which covers all of the substances in the category. Proprietary data are available for the toxicity of calcium 12 -hydroxystearate to Daphnia and algae growth. Therefore, acute toxicity to fish testing was undertaken in order to create a complete dataset for this substance. As all of the substances in the calcium salts of monocarboxylic acid C14-C22 category are considered to have comparable lack of toxic effects in the aquatic environment, the additional testing of calcium behenate, the longest carbon chain length substance, was not considered to be scientifically justified.

Due to the low aqueous solubility, calcium myristate and calcium 12-hydroxystearate were tested as Water Accommodated Fractions. Amounts of test item were added to the surface of the dilutent at the appropriate loading rates. After the addition of the test item, the media was stirred by magnetic stirrer using a stirring rate such that a vortex was formed to give a dimple at the water surface. The stirring was stopped after 23 hours and the mixtures allowed to stand for 1 hour. A wide bore glass tube, covered at one end with Nescofilm was submerged into the vessel, sealed end down, to a depth of approximately 5 cm from the bottom of the vessel. A length of Tygon tubing was inserted into the glass tube and pushed through the Nescofilm seal and the WAFs removed by mid-depth siphoning to give the WAFs with the first approximate 75-100 mL discarded and using a glass wool plug if dispersed test item was seen in the aqueous phase. 

While ensuring that media were compatible with the water chemistry requirements of the test species, the tests on the three taxa were conducted using water from the same source with similar characteristics. As the water solubility of the substances in the category are likely to be influenced by the hardness of the water, the ecotoxicity tests were all conducted in media with the same hardness, approximately 150 mg/L CaCO₃. The changes from the standard test media were employed to reduce effects observed from variations in the formation of soap scum between the tests for different species. As far as possible, tests were also conducted concurrently in order reduce the variation in the solubility and stability of the substance between the different tests. As the substances could not be analysed directly, the calcium, free fatty acid and total organic carbon were measured in the exposure media.

Fish

The acute toxicities of calcium myristate and calcium 12-hydroxystearate to fish showed no effects at a water accommodated fraction loading rates of 100 mg/L, giving 96 hour LL50 of > 100 mg/L WAF. The acute toxicities to fish were determined in GLP-compliant, limit tests following OECD guideline 203 (Harlan 2013).

The 96 hour NOEC for calcium stearate to fish showed no toxicity at 2.2 mg/L, the highest concentration tested, as determined in an unpublished proprietary study (TUV Bayern 1992) following OECD guideline 203. Only a summary is available and there are significant limitations in reporting. Insufficient data are available to determine the methods used to disperse the test substances in water and the hardness of the water used in the test media preparation. As such, this study is not considered reliable enough for use as a key study. The toxicity to fish of an undiluted grease containing calcium 12-hydroxystearate thickener which was applied to a glass sheet and placed at the bottom of a test vessel gave an LD50 of > 12.5 g/L following a non-standard guideline EPS 1/RM/13 (Hydroqual 2003a, b).

The results of the proprietary studies on calcium myristate and calcium12-hydroxystearate have been read across to the remaining substances in the category. None of the substances in the calcium salts of monocarboxylic acids C14-C22 category are considered to be acutely toxic to fish as the substances have an acute LL50 of >100 mg/L WAF.

Invertebrates

The acute toxicity of calcium myristate to Daphnia showed no effects at a water accommodated fraction loading rates of 100 mg/L, giving a 48 hour EL50 of >100 mg/L. The acute toxicity to Daphnia was determined in GLP-compliant, limit test following OECD guideline 202 (Harlan 2013).

There was no immobilisation of Daphnia magna by calcium stearate in a proprietary 48 hour acute test following EEC 92/69 C2 method (Osterreichisches Forschungszentrum Seibersdorf 2000). The study was conducted as a limit test, with a single nominal loading rate of 2.4 mg/L and no immobilisation of the Daphnia was observed. The 48 NOEC was therefore determined to be ≥ 2.4 mg/L nominal.

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.

The results of the proprietary studies on calcium myristate have been read across to the remaining substances in the category. None of the substances in the calcium salts of monocarboxylic acids C14-C22 category are considered to be acutely toxic to invertebrates as the substances have an acute EL50 of >100 mg/L WAF.

Algae

The toxicity of calcium myristate to algal growth at a water accommodated fraction loading rates of 100 mg/L gave a 72 hour EL50 of > 100 mg/L WAF for calcium myristate. The toxicity to algal growth was determined in GLP-compliant, limit test following OECD guideline 201 (Harlan 2013).

The toxicity of calcium 12-hydroxystearate to the freshwater algae has a 72 hour Water Accommodated Fraction NOELR of 1000 mg/L. The results are taken from a proprietary study following OECD 201 (Laboratoire d'Analyses de Fluides 2007) but only a summary is available. The toxicity of grease containing calcium 12-hydrosytearate thickener to algae has a 72 hour ErL50 of >1000 mg/L, with a NOELR of 1000 mg/L. The acute toxicities of grease containing calcium 12 -hydroxystearate to algae have been taken from a regulatory review document (API 2008) citing proprietary acute toxicity tests (Shell Research Limited 1995a) following MAFF/U. K. OCNS/PARCOM.

The results of the proprietary studies on calcium myristate have been read across to the remaining substances in the category. None of the substances in the calcium salts of monocarboxylic acids C14-C22 category are considered to be toxic to algal growth as the substances have an acute EL50 of >100 mg/L and a NOELR of 100 mg/L.

Summary

The acute toxicities of calcium myristate to fish, Daphnia and algal growth and calcium 12-hydroxystearate to fish showed no effects at a water accommodated fraction loading rates of 100 mg/L. Therefore, for fish the 96 hour LL50 is > 100 mg/L WAF, for Daphnia the 48 hour EL50 is >100 mg/L WAF and for algal growth inhibition the 72 hour EL50 is >100 mg/L WAF and NOELR is 100 mg/L WAF. The acute toxicities to fish, Daphnia and toxicity to algal growth were determined in GLP-compliant, limit tests following OECD guidelines 203, 202 and 201, respectively (Harlan 2013).

The acute ecotoxicity datasets for calcium myristate, the shortest carbon chain length substance in the category, and calcium 12-hydroxystearate, with intermediate carbon chain length, have been read across to the remaining substances in the category. This is supported by additional data for calcium stearate and calcium 12 -hydroxystearate.

Chronic aquatic toxicity

Algal studies report both acute and chronic endpoints and therefore the data collected from the algal growth inhibition study will be used to provide chronic data for this trophic level. The toxicity of calcium myristate to algal growth at a water accommodated fraction loading rates of 100 mg/L gave a 72 hour NOELR of 100 mg/L WAF for calcium myristate. The toxicity to algal growth was determined in GLP-compliant, limit test following OECD guideline 201 (Harlan 2013). The toxicity of calcium 12-hydroxystearate to the freshwater algae has a 72 hour Water Accommodated Fraction NOELR of 1000 mg/L. The results are taken from a proprietary study following OECD 201 (Laboratoire d'Analyses de Fluides 2007) but only a summary is available.

REACH Chapter R5 (ECHA 2011) states that chronic aquatic ecotoxicity testing may be triggered if the CSA indicates that there is a need to investigate further the effects on the environment. Testing may be triggered if additional testing could alter the conclusions on classification, PBT assessment or the level of concern. Calcium salts of monocarboxylic acids C14-C22 are readily biodegradable, have low potential for bioaccumulation and show no acute toxicity at up to 100 mg/L WAF. No chronic effects were observed in the algal toxicity tests at up to 1000 mg/L WAF. Additional chronic toxicity tests would therefore not lead to changes in the classification or the conclusion that these substances are neither PBT nor vPvB. As the members of this category are not classified or considered to be PBT/vPvB, an exposure assessment is not required and so additional chronic testing is not required to refine this assessment (ECHA R7b 2012). Further chronic testing of invertebrates and fish is therefore not triggered and these data requirements are waived.

Sediment toxicity

No data are available for the toxicity to sediment organisms. Sediment toxicity data is not a data requirement at the registered tonnage band.

References

ECHA (2011) Guidance on information requirements and chemical safety assessment – Chapter R.5: Adaptation of information requirements. European Chemicals Agency, ECHA-2011-G-15-EN

ECHA (2012) Guidance on information requirements and chemical safety assessment – Chapter R.7b: Endpoint Specific Guidance. European Chemicals Agency