Fatty acids, C16-18, zinc salts

Short-term toxicity to fish

Description of key information

Fatty acids, C16-18, zinc salts:

The acute toxicity of fatty acids, C16-18, zinc salts to fish is above the water solubility limit of around 1 mg/L. A similar conclusion was made in the EU RAR Zinc distearate (CAS-No.: 557-05-1 & 91051-01-3 EINECS-No.: 209-151-9 & 293-049-4) Part 1 - Environment (Final report R074_0805_env, May 2008) as follows: "In the three available acute toxicity tests with fish (TÜV, 1992: fish species not reported; Berger, 1995a, b: zebrafish Brachydanio rerio; Dowden & Bennett, 1965: bluegill Lepomis macrochirus), no effects were observed at nominal zinc distearate concentrations up to the water solubility limit or at nominal concentrations that were 3 to 4 orders of magnitude higher than the water solubility limit. From these data, although very limited, it is concluded that the toxicity of zinc distearate to bacteria and the acute toxicity of zinc distearate to Daphnia magna and fish is (far) above the water solubility limit of around 1 mg/L." Thus, fatty acids, C16 -18, zinc salts is not acutely toxic to fish.

Only limited data are available for the toxicity of fatty acids, C16-18, zinc salts to fish. Thus, read-across to the assessment entities soluble zinc substances and C16-18 fatty acids is applied since zinc cations and fatty acid anions (C16-18) determine fate and toxicity in the environment. Since C16 -18 fatty acids have a low potential for ecotoxicity, the hazard assessment of fatty acids, C16-18, zinc salt is based on zinc ions. Please refer to the endpoint summary of the respective assessment entity for further details.

 

Fatty acid anions (C16-18):

Fatty acids as contained in plant and animal tissue are a natural component of soil, represent a significant part of the nutritional demands of living organisms, are rapidly degraded and non-bioaccumulative and therefore of low toxic potential towards microorganisms.

 

Zinc:

The key data (lowest LC50 values) are summarised as follows:

- for Oncorrhynchus mykiss: 0.169 mg Zn/L (single value) at neutral/high pH and low hardness

- for Pimephales promelas (single values) at high hardness: 0.78 mg Zn/l and 0.33 mg Zn/l at low and neutral/high pH, respectively

Additional information

Fatty acids, C16-18, zinc salts:

Aquatic fish toxicity data on Fatty acids, C16-18, zinc salts are available from a study performed according to EU Method C.1 (Acute Toxicity for Fish) in the former version of 1992 (Henkel KGaA, 1995), from a study performed according to OECD Guideline 203 (Fish, Acute Toxicity Test) but reported only in a short study report (TÜV Bayern Sachsen E.V., 1992) and from an old publication (Dowden, BF, Bennett, HJ 1965). None of the studies do fully comply with the requirements of the recent guidelines regarding performance and/or documentation. However, in accordance to the judgement given on the same set of data in the EU risk assessment of zinc distearate carried out within the framework of EU Existing Chemicals Regulation (EEC) No 793/93 (Final report R074_0805_env, May 2008), the total set of data is regarded as sufficient to come to a conclusion on the intrinsic aquatic fish toxicity of the substance. In accordance to Annex XI of Regulation (EC) No 1907/2006, the total set of data is used in a weight of evidence approach to fulfil REACH data requirements on aquatic fish toxicity. In the most reliable study (Henkel KGaA, 1995), the acute toxicity of Fatty acids, C16 -18, zinc salts to fish was investigated according to EU Method C.1 (Acute Toxicity for Fish) in the former version of 1992. Fish (Danio rerio) were exposed for 96 hours to nominal concentrations of 0 (control), 1000, 3000 and 10000 mg/L under semi-static conditions. Up to and including the highest nominal test concentration neither behavioural abnormalities nor mortality occurred. Test was conducted at nominal concentrations far exceeding the water solubility by 3 to 4 orders of magnitude. Measures to disperse the test substance in the test water were used. The actual test concentrations were below the detection limit (1 mg/L) of the analytical method used. Therefore, a numeric value for the actually test concentrations cannot be given. However, due to the very high level of nominal test concentrations and the measures used to disperse the test substance in the test medium, it is very likely that the actual test concentrations included the water solubility limit which is in the range of 1 mg/L (c. f. EU risk assessment zinc distearate carried out within the framework of EU Existing Chemicals Regulation (EEC) No 793/93 (Final report R074_0805_env, May 2008)). No effects were observed at nominal Fatty acids, C16-18, zinc salts concentrations up to the water solubility limit in the two further studies either. In accordance to the evaluation given in the EU Risk assessment, from the results of these tests it is concluded, that the toxicity of the substance Fatty acids, C16-18, zinc salts to fish is above the water solubility limit of around 1 mg/L.