Overbased reaction products of distilled tall oil and magnesium hydroxide’

Short-term toxicity to fish

Description of key information

No ecotoxicity studies are available for Distilled tall oil, magnesium salt. However, a number of studies are available that can be read across to provide information on the rosin and fatty acid components of the substance.
There are a wide range of ecotoxicity results reported that can be read across from the rosin component of Fatty acids, tall oil, magnesium salts. The most conservative LC50 value is 1.7 mg/L. An LL50 of 24 mg/L is read across from the fatty acid component of the substance. For classification purposes the worst case value of 1.7 mg/L is used. 

Additional information

A number of reliable studies are available that can be read across from the rosin and the fatty acid components of Distilled tall oil, magnesium salt.

A number of studies are available for rosin, hydrogenated rosin and rosin salts. These are read across to the rosin component of Distilled tall oil, magnesium salt. Four reliable studies are available for rosin. A GLP-compliant, guideline study with Brachydanio rerio is available (Akzo Nobel 1998). The study used WAF techniques, but there was no analytical verification of the test concentrations. It is therefore considered to be reliable with restrictions. The study determined an LL50 of >1 <10 mg/L. A second study (Akzo Nobel 1999) was conducted in a similar manner, but with the addition of humic acid in the test media to determine if this has any mediating effect on toxicity. This study determined an LL50 of <10 mg/L. Another study is also available for rosin (Inveresk 2001). This study used Pimephales promelas as the test species and used WAF techniques, with no analytical verification of test concentrations conducted. The study determined an LL50 of >1000 mg/L. Another study is available which determined an LC50 0f 60.3 mg/L. However, ultrasonication was used in order to get the substance into solution. The EC50 is therefore above the solubility for the test item and these results should be used with caution.

Two studies are available for tall oil rosin, which is considered to be equivalent to rosin, one without humic acid in the test media and one with (Akzo Nobel 1998, Akzo Nobel 1999). Both studies utilized WAF techniques with no analytical verification of test concentrations. The study without humic acid determined an LL50 of >1 <10 mg/L and the study with humic acid also determined an LL50 of <10 mg/L.

One reliable study is available for Resin acids and rosin acids, sodium salts using the test species Danio rerio and this is considered a key study (Aventis 2004). The study is GLP-compliant and follows a standard guideline. Some analytical verification of test concentrations was conducted. There were some limitations in the study design and the results should be assessed with caution as particulate matter may have been detected in some of the test concentrations that could affect results. The LC50 determined from this study was 5.4 mg/L.

One study is available for hydrogenated rosin potassium salts (Eastman 2005). The study followed a standard guideline but there was no analytical verification of test concentrations. The study determined a nominal LC50 of 1.7 mg/L.

A reliable GLP guideline study is available for Fatty acids C18 - (unsaturated) lithium salts, acute toxicity to rainbow trout (Oncorhynchus mykiss) (Harlan, 2010). This result is read across to the fatty acid component of Distilled tall oil, magnesium salt. Following a preliminary range-finding test, fish were exposed to nominal loading rates of 10, 18, 32, 56 and 100 mg/l WAF for 96 hours at 14ºC under semi-static test conditions. Analytical verification of test concentrations was conducted. The number of mortalities and any sub-lethal effects of exposure in each test and control vessel were determined 3 and 6 hours after the start of exposure and then daily throughout the test until termination after 96 hours. Given that the toxicity cannot be attributed to a single component or a mixture of components but to the test item as a whole the results were based on nominal loading rates only. The 96-Hour LL50 based on nominal loading rates was 24 mg/l WAF.