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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Read across justification for Distilled Tall Oil, Magnesium Salts

Distilled tall oil, magnesium salts is produced by reacting magnesium hydroxide and distilled tall oil. The resulting substance is a UVCB, with the following generic structure:


The R groups are derived from the distilled tall oil starting material, which is a UVCB substance derived from natural sources, with varying composition. Therefore there are a number of different possible combinations for the resulting carboxylic acid groups present in the complex mixture of divalent magnesium salts.

Based on supplier analysis, the distilled tall oil comprises a mixture of unsaturated fatty acids – primarily C18 (~70%) and mixed rosin acids (~30%); typical analysis of a sample of distilled tall oil is presented in Table 1. The variable composition of distilled tall oil means that Distilled tall oil, magnesium salts will comprise a complex mixture of the divalent magnesium salts of both fatty acid and rosin components, in proportion to the ratio of fatty acids:rosin acids found in the starting distilled tall oil. In the absence of data on Distilled tall oil, magnesium salts, the environmental fate, ecotoxicity and toxicology properties are predicted based on read across to related fatty acid and rosin acid salts. Analytical data (Mass Spec., FTIR and NMR) confirm the presence of divalent magnesium carboxylic acid salts and NMR shows the presence of a proportion of cyclic carboxylic acid structures.

No data were identified for magnesium salts of C18 unsaturated fatty acids, which comprises approximately 70% of the registered substance. Data were available however for a similar lithium salt – fatty acids, C18-(unsaturated) lithium salts. Read across to this compound is justified based on the fact that it is also a divalent salt of fatty acids derived from distilled tall oil, which has similar physic-chemical properties. The lithium and magnesium ions present in these salts are not likely to contribute to the toxicity and therefore any effects observed are likely to be due to the fatty acid component.

For the rosin acid salt component (~30%) of Distilled tall oil, magnesium salts, data are read across from a category of substances with similar composition, containing rosin, hydrogenated rosin and rosin acid salts. This category of rosin substances have been registered under REACH using a category approach, and members of this category are considered to be representative of the rosin acid salts found in Distilled tall oil, magnesium salts. The category of rosin substances includes both monovalent and divalent salts of rosin acids, including a magnesium salt. Therefore the rosin acid component of Distilled tall oil, magnesium salts would fit within this category and read across is considered to be appropriate.

Further details are given in the attachment in Section 13.

Aquatic Toxicity Summary

Distilled tall oil, magnesium salt is a UVCB with varying components, but comprising fatty acid salts with predominantly C18 carbon chain lengths and rosin acid salts. Experimental ecotoxicity data is not available for Distilled tall oil, magnesium salt. However, its ecotoxicological properties can be read across from data on its components. Data have been read across from rosin salts and a C18 fatty acid salt.

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

Three fish studies are available for rosin (Akzo Nobel 1998, Akzo Nobel 1999, Inveresk 2001), two studies for tall oil rosin (Akzo Nobel 1998, Akzo Nobel 1999) one reliable study is available for Resin acids and rosin acids, sodium salts (Aventis 2004), one study for hydrogenated rosin potassium salts (Eastman 2005), and one study is available for Fatty acids C18 - (unsaturated) lithium salts (Harlan 2010), all of which can be read across to Distilled tall oil, magnesium salt. LC50 results from these studies are in the range 1.7 to >1000 mg/L.


Reliable invertebrate studies are available for resin acids and rosin acids, calcium zinc salts, resin acids and rosin acids, magnesium salts (Harlan 2010), rosin (Inveresk 2003, Akzo Nobel 1998), tall oil rosin (Akzo Nobel 1998), resin acids and rosin acids, hydrogenated, potassium salts (Eastman 2005), zinc resinate (Water Quality Institute 1993) and Fatty acids C18-(unsaturated) lithium salts (Harlan, 2010). EC/L50 results are in the range 1.6 to >2000 mg/L.


Algal studies are available for rosin (Inveresk 2001), Tall oil rosin (Akzo Nobel 1998), Resin acids and Rosin acids, hydrogenated, potassium salt (Eastman 2005) and Fatty acids C18-(unsaturated) lithium salts (Harlan, 2010). Based on growth, EC/L50 values range from 13 to >1000 mg/L.


The lowest EC50 value is 1.6 mg/L, for Daphnia. This EC50 has been used to determine the appropriate classification and to derive the aquatic PNECs.