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There are no data available for the aquatic toxicity of hexadecyl palmitate (CAS 540-10-3). Therefore, the aquatic hazard of the target substance was assessed by a read-across approach to four structurally and chemically closely related substances in order to fulfill the standard information requirements laid down in Annex XI, 1.5, of the REACh Regulation (EC) No 1907/2006.

According to Article 13 (1) of this regulation, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met.” For aquatic toxicity in particular, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across). In regard to the general rules for grouping of substances and the read-across approach, the regulation specifies (Annex XI, Item 1.5) that substances may be predicted as similar provided that their physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity.

 

The target substance hexadecyl palmitate (CAS 540-10-3) is an ester of a C16 fatty acid (palmitic acid) and a C16 fatty alcohol (cetyl alcohol). The four selected source substances have similar fatty acid and fatty alcohol chain lengths. The source substance docosyl docosanoate (CAS 17671-27-1) is an ester of a C22 fatty acid and C22 fatty alcohol. The source substance tetradecyl myristate (CAS 3234-85-3) is an ester of a C14 fatty acid and C14 fatty alcohol. The source substance dodecyl oleate (CAS 36078-10-1) is an ester of a C18 fatty acid and a C12 fatty alcohol. The source substance (Z)-octadec-9-enyl oleate (CAS 3687-45-4) is an ester of a C18 fatty acid and a C18 fatty alcohol.

Based on the high degree of similarity between the structural and physico-chemical properties, the selected source substances are considered suitable representatives for the assessment of the aquatic toxicity of the target substance. On this basis, it is assumed that the target substance will exhibit a similar ecotoxicological profile as the source substances. A detailed read-across justification is provided in in the analogue justification in IUCLID section 13.

By means of the read-across approach, GLP guideline studies for acute and chronic toxicity of hexadecyl palmitate (CAS 540-10-3) are available for three and two trophic levels, respectively. The compiled data for acute toxicity (fish, daphnia and microalgae) and chronic toxicity (daphnia and algae) indicate no short-term or long-term toxicity on aquatic freshwater organisms of all trophic levels up to the limit of water solubility of the source substances. Furthermore, no toxic effects towards microorganisms of activated sludge were recorded.

Due to the low water solubility (< 0.846 µg/L, OECD 105), long-term testing on aquatic invertebrates was necessary to fully assess the potential aquatic toxicity. The available read-across studies for aquatic invertebrates were performed with the source substances (Z)-octadec-9-enyl oleate (CAS 3687-45-4) and dodecyl oleate (CAS 36078-10-1). After 21 d of exposure, no effects on the reproduction of D. magna were observed in either study and both resulted in a NOELR (21 d) of ≥ 100 mg/L (nominal, WAF, OECD 211), indicating no effects on reproduction up to the limit of water solubility. Both studies reported analytically measured test item concentrations below the analytical detection limits (< 0.0423 mg/L and 0.005 mg/l, respectively), reflecting the very low water solubility of the test items.

Therefore, it can be concluded that hexadecyl palmitate (CAS 540-10-3) presumably does not exhibit short-term or long-term effects to aquatic organisms up to the limit of water solubility (< 0.846 µg/L, OECD 105) and does not affect the degradation process in commercial sewage treatment plants.

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