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Categories

Category name:
Fatty acids esters with glycols

Justifications and discussions

Category definition:
1.1.1 Category Hypothesis
The Glycol Ester category covers glycol mono- and diesters of an aliphatic diol (ethylene
glycol (EG), propylene glycol (PG) or 1,3-butyleneglycol (1,3-BG)) and fatty acids. The fatty
acid chains comprise carbon chain lengths ranging from C6 to C18, saturated or
mono unsaturated C16 and C18, branched C18 and epoxidized C18.
Fatty acid esters are generally produced by chemical reaction of an alcohol (e.g. ethylene
glycol) with an organic acid (e.g. stearic acid) in the presence of an acid catalyst. The esterification reaction is started by a transfer of a proton from the acid
catalyst to the acid to form an alkyloxonium ion. The acid is protonated on its carbonyl
oxygen followed by a nucleophilic addition of a molecule of the alcohol to a carbonyl carbon
of acid. An intermediate product is formed. This intermediate product loses a water molecule
and a proton to give an ester. Di- and/or monoesters are the final products of esterification of an aliphatic diol and
fatty acids.
The available information on ecotoxicological properties of the Glycol Esters category
members show that no effects up to the limit of water solubility occurred in either acute and
chronic studies representing the category members. Moreover, all category members show a similar pattern in environmental distribution and behaviour
characterised by low water solubility, high log Kow and log Koc.
Glycol esters have a common metabolic fate that involves a stepwise hydrolysis of the ester
bonds by gastrointestinal enzymes by which the breakdown of glycol esters results in structurally similar chemicals, the fatty acid component and the respective alcohol. Following hydrolysis of the ester
bond, the breakdown product will be absorbed and metabolised. The toxicological properties show that all category members have similar toxicokinetic behaviour explained bythe common metabolic fate of glycol esters independently of the fatty acid chain length and
degree of glycol substitution.
Category rationale:
In accordance with Article 13 (1) of Regulation (EC) No. 1907/2006, "information on intrinsic
properties of substances may be generated by means other than tests, provided that the
conditions set out in Annex XI are met. In particular for human toxicity, environmental fate
and ecotoxicity, information shall be generated whenever possible by means other than
vertebrate animal tests, which includes the use of information from structurally related
substances (grouping or read-across).
Therefore, the available experimental data were collected and evaluated according to Annex
XI in regard to:
- tests which cover an exposure duration comparable to or longer than the
corresponding test method referred to in Article 13(3) if exposure duration is a
relevant parameter),
- have adequate and reliable coverage of the key parameters addressed in the
corresponding test method referred to in Article 13(3),
- the adequacy of the results for the purpose of classification and labelling and/or risk
assessment, and
- the documentation of the test procedures shall be adequate and reliable.
Only data that were judged to cover the requirements specified above were used as
adequate data suitable for the category and its members.
In this particular case the similarity of the 14 category members is justified, in accordance
with the specifications listed in Regulation (EC) No. 1907/2006 Annex XI, 1.5 Grouping of
substances and read across, on basis of scope of variability and overlapping of composition,
representative molecular structure, physico-chemical properties, toxicological,
ecotoxicological profiles and supported by various QSAR methods. There is no convincing
evidence that any one of these chemicals might lie out of the overall profile of this category,
respectively. The key points that the members share are:
common functional groups,
common precursors and the likelihood of common breakdown products via biological
processes, which result in structurally similar chemicals, and
constant pattern in the changing of the potency of the properties across the category.

Further details in the report.