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EC number: 614-523-2
CAS number: 68475-37-6
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
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.
A number of aquatic toxicity studies have been performed on Rosin Esters
with varying results. Many of the historic studies utilized techniques
that attempted to increase the solubility of the substances for testing,
such as the use of solvents, ultra-sonication, etc., or were conducted
by dilution of Water Accommodated Fraction (WAF) instead of preparing
WAF from several loading rates. These studies are not believed to be
reliable indicators of inherent toxicity, even though they show EC50
values > 166 mg/L. These studies have been given Klimisch 3 scores (not
More recent studies have utilized WAF techniques according to current
guideline recommendations, which are believed to be more reliable.
GLP-compliant, guideline studies are available for fish, Daphnia and
algae (Harlan Laboratories 2010 and 2014, Inveresk 2001a-e).
Based on the available ecotoxicity data, substances in the Rosin esters
category with lower molecular weights are more toxic to aquatic
organisms than those with higher molecular weights. This is likely to be
due to the lower molecular weight substances being more soluble, whereas
higher molecular weight substances are poorly soluble and less
The substances with the lowest molecular weights in the category are
Resin acids and rosin acids, Me esters and Resin acids and rosin acids,
hydrogenated, Me esters. These two substances are considered to be the
low molecular weight members of the category and read across between
these two substances is used to complete REACH ecotoxicity endpoints,
and to determine the classification of these substances. The lowest EC50
available for these substances is 27 mg/L, from a Daphnia study with the
test material Resin acids and rosin acids, hydrogenated, Me esters
(Inveresk 2002). This result is read across to Resin acids and rosin
acids, Me esters. Studies with fish and algae determined EL50 values
above the highest concentration tested.
For higher molecular weight esters (with molecular weights higher than
for the Methyl esters), no effects were seen at the limit of solubility
in the available acute ecotoxicity studies. Acute ecotoxicity studies
are available that ‘bracket’ higher molecular weight category members.
Studies are available for the substance resin acids and rosin acids,
esters with ethylene glycol, which has the lowest molecular weight of
any of the 'high molecular weight' substances, and for resin acids and
rosin acids, esters with pentaerythritol and resin acids and rosin
acids, esters with glycerol, the highest molecular weight members of the
category. All these studies determine EL50 values above the highest
Due to the differences in ecotoxicity observed between low and high
molecular weight esters, one set of PNECs has been derived to cover low
molecular weight substances in this category and one set to cover high
molecular weight substances.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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