Fatty acids, C18-unsatd., mono- and diesters with neopentylglycol and di-and triesters with trimethylolpropane

Long-term toxicity to aquatic invertebrates

Description of key information

An experimental study is planned for a structurally related category member, however based on available read across data no chronic toxic effects to aquatic invertebrates up to the limit of water solubility (<1 mg/L).

Additional information

There is no long-term test on aquatic invertebrates available for fatty acids, C16-18 (even numbered) and C16-18unsatd. (even numbered), mono-, diesters with neopentyl glycol and di-, triesters with trimethylolpropane (CAS 85186-92-1). Since all substances within this polyol esters category are readily biodegradable, it is not foreseen that they will pose a risk to aquatic invertebrates on the long-term. However, due to the poor water solubility of the test substance and as long term toxicity to aquatic organisms is a mandatory endpoint in accordance to Regulation (EC) No 1907/2006, Annex IX 9.1 Aquatic toxicity, tests the long term toxicity on invertebrates are proposed in order to confirm that no chronic toxicity to aquatic organisms occurs for the polyol esters. In total Three TMP esters were selected for testing: CAS 85566-29-6 having mainly chain lengths of C12 and C14 was recognized as a suitable candidate to cover these chain lengths within the polyol esters. Whilst Fatty acids, C8-10 (even), C14-18 (even) and C16-18 (even)-unsatd., triesters with trimethylolpropane (formerly CAS 85186-89-6) was chosen to cover the unsaturated slightly longer chain lengths of C16:1/C18:1, Fatty acids, C16-18 (even numbered) and C18-unsatd., branched and linear, di- and triesters with trimethylolpropane (former CAS 85005-23-8) which was also selected as representative for this chain length, but it was also selected in order to cover saturated and branched C16/C18 chain lengths. Fatty acids, C16-18 (even numbered) and C16-18unsatd. (even numbered), mono-, diesters with neopentyl glycol and di-, triesters with trimethylolpropane (CAS 85186-92-1) has both a PE and NPG (neopentyl glycol) moiety; nevertheless this structural difference is not considered as significant in the OECD toolbox check and in addition data from the NPG polyol esters (CAS 42222-50-4) can be used for read across to reflect that this slight structural difference has no effects up to the water solubility. Hence chemical safety assessment according to Annex I of Regulation (EC) No. 1907/2006 does not indicate the need to investigate further the chronic toxicity to aquatic organisms since reliable tests on the long-term toxicity to aquatic invertebrates are available and provided which indicate that the polyol esters will not exhibit long-term effects to aquatic invertebrates up to the limit of water solubility, and in addition a read across will be made in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 to the structurally closest related category members Fatty acids, C8-10 (even), C14-18 (even) and C16-18 (even)-unsatd., triesters with trimethylolpropane (former CAS 85186-89-6) and Fatty acids, C16-18 (even numbered) and C18-unsatd., branched and linear, di- and triesters with trimethylolpropane (former CAS 85005-23-8) will be made once the data is available.

The read-across substances are representative to evaluate the toxicity on daphnids since they have a similar structure and thus cover the target substance adequately. A detailed justification is given within the endpoint summary 6.1 and within the category justification section 13.

Three chronic toxicity tests to daphnia are available and can be used as read across for this chemical safety assessment. In the first read across study, the chronic toxicity of Fatty acids, C16-18 and C18-unsatd., triesters with trimethylolpropane (CAS 68002-78-8) to aquatic invertebrates was tested in a guideline study following OECD 211 (Grell, 2013). Daphnia magna were exposed to the test substance in a semi-static test system. The water accommodated fraction (WAF) was used for the preparation of the test solutions. During the exposure period of 21 days the mortality and reproduction rate of the test animals was recorded. The substance affected neither the survival rate nor the reproduction rate of D. magna. Based on the loading rate a NOELR ≥ 0.11 g/L was determined. Thus toxic effects C16-18 and C18-unsatd., triesters with trimethylolpropane (CAS 68002-78-8) were not observed within the limit of water solubility (WS<0.05 mg/L).

The second read study on the long-term toxicity of 2,2-dimethyl-1,3-propanediyl dioleate (CAS No. 42222-50-4) to aquatic invertebrates was performed as a limit test according to OECD guideline 211 and GLP (Schlechtriem, 2013). The test organism Daphnia magna was exposed to the test substance in a semi-static system for 21 days, at a nominal concentration of 1 mg/L. No significant effects on reproduction or body length were observed, and the NOEL was determined to be ≥ 1 mg/L.Furthermore, the long term toxicity to aquatic invertebrates was investigated in a test performed with the read-across substance fatty acids, C8-10 (even numbered), di-and triesters with propylidynetrimethanol (CAS 11138-60-6) according to OECD guideline 202 "Daphnia sp. Acute Immobilization Test and Reproduction Test", Part 2 (1993) under semi-static conditions (Low, 1996). This test guideline is similar to OECD 211 which was adopted in 1998. The study period of 15 days does not meet the criteria of today standard methods recommending 21 days study duration. However, according to the Guidance on information requirements and chemical safety assessment, Chapter R7.b (ECHA, 2012) the study can be regarded as valid for a long-term evaluation as corresponding criteria were fulfilled (e.g. 80% survival in the control, surviving females produce three broods in 21 days or less, > 60 brood neonates per female in the control on average). In addition, all requested endpoints could be determined (time to first brood, number of offspring produced per female, growth and survival) and NOELR values for survival or reproductive endpoints could be calculated. In this study Daphnia magna were exposed to nominal concentrations of 0, 24, 97, 242, 1018 and 2570 mg/L (prepared as water accommodated fraction, WAF). No effects were observed up to the highest test concentration resulting in a NOELR of ≥ 2570 mg/L based on reproduction and immobilization.

Based on these results from the structurally related read-across to category members (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) which are characterized by a similar ecotoxicological profile and comparable structure, it can be concluded that fatty acids, C16-18 (even numbered) and C16-18unsatd. (even numbered), mono-, diesters with neopentyl glycol and di-, triesters with trimethylolpropane (CAS 85186-92-1) will not exhibit chronic toxicity effects to aquatic invertebrates up to the limit of water solubility. As it can be seen in the data matrix of the category justification in section 13 and the overall endpoint summary IUCLID 6.1, all reliable data in the category support the hazard assessment of each category member by showing a consistent pattern of results, i.e. no toxic effects to aquatic organisms were observed up to the limit of water solubility for the polyol esters.