Rosin, maleated

Endpoint summary

Additional information

The Rosin adducts and rosin adduct salts category is a UVCB category and includes rosin or rosin salts that have been chemically reacted with either fumaric acid or maleic anhydride. Rosin acids are the predominant components of rosin (>85%). Rosin acids are composed of three skeletal classes of tricyclic carboxylic acids which share similar structures, but vary in the position of the double bonds and methyl groups. As each member of this category is a UVCB, the organic components will vary in type and proportion. The presence of a metal cation will not alter the structure of the organic component of the molecule. The organic component can therefore be viewed as similar across the category.

 

The available ecotoxicity results indicate that there may be differences in environmental toxicity between substances reacted with fumaric acid and substances reacted with maleic anhydride, although the reasons for this are not clear. Therefore, although maleated and fumarated substances are structurally similar and it is appropriate for these substances to be considered within a single category, for ecotoxicity endpoints read across is not conducted between fumarated and maleated substances.

 

Fumarated substances

One fumarated rosin substance is being registered within the Rosin adducts category (rosin, fumarated) and another substance falls within the category definition and has data available, but is no longer being registered under REACH (rosin, fumarated, reaction products with formaldehyde). Both substances are structurally similar and a comparison of the available acute ecotoxicity data (acute Daphnia and fish) also shows that these substances demonstrate similar toxicity.

 

Maleated substances

The ecotoxicity of maleated substances is affected by the solubility of the test item, with more soluble substances rosin, maleated and resin acids and rosin acids, maleated sodium salts showing higher aquatic toxicity compared to the poorly soluble substance resin acids and rosin acids, maleated calcium salts.

 

Rosin, mealeated and resin acids and rosin acids, maleated, sodium salts are both partially soluble and for these substances EC50 values of 9.3 and 4.8 mg/L, respectively, were determined for the most sensitive species.

 

Resin acids and rosin acids, maleated, calcium salts is poorly soluble and for this substance the EL50 values determined in aquatic toxicity studies were all above the highest loading rate tested. This difference in solubility between monovalent salts of rosin substances, such as the maleated sodium salt and divalent salts such as the maleated calcium salt, is also observed for rosin salts. Due to its low solubility, no effects at the limit of solubility were observed for resin acids and rosin acids, maleated calcium salts in acute ecotoxicity studies with test solutions prepared as Water Accommodated Fractions.

 

As a full base set of acute ecotoxicity data is available for resin acids and rosin acids, maleated, calcium salts and the EL50 values in all studies were determined to be greater than the limit of solubility, it is most appropriate to use the data for the substance itself in order to complete REACH ecotoxicity endpoints and to classify the substance. For PNEC derivation purposes, however, a single set of PNECs is derived to cover all maleated rosin substances, based on the most sensitive result for any maleated rosin substance. The PNECs are therefore derived based on the acute fish LC50 for the soluble maleated rosin substance resin acids and rosin acids, sodium salts. This is considered to be a worst-case approach for PNEC derivation.