Fatty acids, C16-18, Me esters

Short-term toxicity to fish

Description of key information

No effects up to limit of water solubility  (WS < 1 mg/L)

Additional information

No experimental data evaluating the acute toxicity of Fatty acids, C16-C18, methyl esters (CAS No. 85586-21-6) to fish are available. Therefore, toxicity data from two structurally similar category members, methyl palmitate (CAS No. 112-39-0) and Fatty acids, C16-18 and C18 unsaturated, methyl esters (CAS No. 67762-38-3) are used as read-across in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. All three substances are fatty acids esterified with methanol, containing fatty acid C-chain lengths of C16 (CAS No. 112-39-0) and C16-18 (CAS No. 67762-38-3 and the target substance, CAS No. 85586-21-6) respectively. The log Pow (> 5 for all substances) and water solubility values (0.004 mg/L for CAS No. 112-39-0, < 0.05 mg/L for CAS No. 67762-38-3 and < 1 mg/L for CAS No. 85586-21-6) of these three substances indicate that, besides the structural similarity that will lead to similar toxicity profiles, a comparable behaviour in water can be expected. Based on this information, it is justified to use the toxicity data from the two category members as read-across for Fatty acids, C16-C18, methyl esters (according to Regulation (EC) No. 1907/2006, Annex XI, 1.5.

One study evaluating the acute toxicity of methyl palmitate (CAS No. 112-39-0) to fish species is available (Guhl, 2001). This test was conducted according to ISO Guideline 7346-1. Danio rerio was exposed to the test substance for 96 h within a semi-static water regime, at nominal concentrations ranging from 100 to 3000 mg/L. After the exposure period, 100% mortality was observed at the highest concentrations tested (1000 and 3000 mg/L), whereas no effects were reported in any other group and therefore, the LC50 (96 h) was determined to be 550 mg/L (nominal concentrations). Nevertheless, methyl palmitate is highly insoluble in water (water solubility 0.004 mg/L) and thus, the observed effects are expected to be rather physical than associated to toxicity of the substance. Test solutions were prepared by direct addition of the substance in the vessels, followed by an ultrasonic treatment but no filtration was performed.Undissolved test material in the bottom of the test vessels and an oily film floating in the surface were observed in the test solution, probably causing the observed effects (e.g. by clogging of fish gills).

The study with Fatty acids, C16-18 and C18 unsaturated, methyl esters (CAS No. 67762-38-3) was conducted according to the German Guideline DIN 38412/15 (Richterich and Mühlberg, 2001).Leuciscus iduswas exposed for 48 h to the test substance within a static water regime, at nominal concentrations ranging from 1 to 10,000 mg/L. After the exposure period, no effects on fish survival were reported at any of the concentrations tested except for the highest (10,000 mg/L, nominal), at which 100% mortality occurred (LC50 (48 h) = 5500 mg/L, nominal). Once again, since the water solubility of the test substance is < 0.05 mg/L and the solution was prepared by direct addition and no filtering step, the observed effects are most likely caused by physical interference with undissolved test substance rather than due to toxicity.

Based on the results obtained for structurally similar category members (according to Regulation (EC) No. 1907/2006, Annex XI, 1.5) Fatty acids, C16-C18, methyl esters (CAS No. 85586-21-6) is not expected to show acute toxicity to fish species up to the limit of its water solubility (< 1 mg/L).