Resin acids and Rosin acids, polymd., esters with pentaerythritol

Endpoint summary

Additional information

The category of Rosin Esters consists of rosin which has been esterified with alcohols, typically methanol, ethylene glycol, diethylene glycol, triethylene glycol, glycerol and pentaerythritol. Resin acids are the predominant components of rosin (>85%). Resin acids are composed of three skeletal classes of tricyclic carboxylic acids which share similar structure, but vary in the position of the double bonds and methyl groups. Hydrogenated rosin is implicitly included in the definition of rosin as disproportionated rosin which is a combination of hydrogenated and dehydrogenated rosin naturally produced when rosin is heated. The category therefore also includes the hydrogenated rosin forms of these substances. Due to the reactivity of resin acids, dimers can be formed. These rosin dimers are also known as oligomers or by the trivial name of polymerised rosin.

As each member of this category is a UVCB, the resin acid components will vary in type and proportion.

The number of ester bonds that can be formed is driven by the alcohol. Methanol can form mono-esters, ethylene glycol, diethylene glycol and triethylene glycol can form mono- and di- esters, glycerol can form mono-, di- and tri-esters and pentaerythritol can form mono-, di-, tri- and tetra-esters. In each case, the esterification reaction results in a UVCB containing esters with varying numbers of ester bonds formed by the reaction of the various resin acids with the alcohol.

Several reliable studies are available for category members, following OECD Testing Guideline 301B ready biodegradation screening study. None of the studies showed a level of biodegradation greater than 60% within 28 days of treatment under the conditions of the study. Ready biodegradation is not observed for any category member. However, biodegradation studies conducted with UVCB substances are not always relevant, as individual constituents within a UVCB will have different biodegradation potential.

 

For the purposes of persistence assessment, a screening assessment has been conducted assessing the biodegradation potential of constituents within the UVCB. Based on the results of this screening assessment, direct ready biodegradation testing is underway to assess the degradation potential of the mono-ester fraction of rosin ester substances.

Information on accumulation in aquatic organisms is vital for understanding the environmental behaviour of a substance. Accumulation is a general term for the net result of absorption (uptake), distribution, metabolism and excretion (ADME) of a substance in an organism.

Rosin ester substances are UVCB substances containing rosin ester and non-esterified resin acid constituents. The bioaccumulation potential of the substances is therefore assessed based on a QSAR screening assessment of rosin ester constituents and measured data for resin acids.