Fatty acids, C18-unsatd., trimers

Endpoint summary

Description of key information

Based on read-across from structurally related substances within a category approach, fatty acids, C18-unsaturated, trimers are not irritating to the skin and not irritating to the eyes.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Additional information

Justification for grouping of substances and read-across

In accordance with the specifications listed in Regulation (EC) No. 1907/2006 Annex XI, 1.5 Grouping of substances and read across, the similarity of category members has been shown to be justified based on the scope of variability and overlapping of composition, representative molecular structure, physico-chemical properties, tox-, ecotoxicological profiles and supporting Information by various validated QSAR methods. This information is given in further detail within the category justification for the grouping of chemicals and read-across (see IUCLID Section 13) for the dimerised fatty acids and its derivatives, and once more within the endpoint summary and discussion for Toxicokinetics.

For assessment of human health hazards of the category members, trends and similarities in toxicokinetic behaviour are most relevant. In particular, the molecular weight-dependent decrease in oral and dermal absorption and common metabolic pathways, which are explained by trends in molecular structure and common functional groups (monomers, dimers and trimers of similar long-chain fatty acids). This justifies the assumption that the toxicological profile of all category members is similar and effects or the lack of effects observed in toxicological studies of one ore more substances can also be expected and explained for the other substances in the category.

Therefore, in accordance with Annex XI, Item 1.5, of Regulation (EC) No 1907/2006, in order to avoid the need to test every substance for every endpoint, the category concept is applied for the assessment of human health hazards. Thus where applicable, human health effects are predicted from adequate and reliable data for reference substance(s) within the group by interpolation to other substances in the group (read-across approach).

All the available information from the substances within the category is taken into account for each endpoint to be assessed. Key studies are selected for assessment of the test substance and for read-across as to fulfil the requirements laid down in Annex XI, Item 1.5, of Regulation (EC) No 1907/2006, i.e. in all cases the results are adequate for the purpose of classification and labelling and/or risk assessment; have adequate and reliable coverage of the key parameters addressed in the corresponding test method referred to in Article 13(3); 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; and adequate and reliable documentation of the applied method is provided.

 

Discussion

Skin

The available data on the skin irritating potential of fatty acids, C18-unsaturated, trimers was limited to a non-guideline study conducted to determine the primary irritation index.

The primary irritation of fatty acids, C18-unsaturated, trimers to the skin was determined by an occlusive patch-test technique in albino rabbits. An amount of 0.5 mL of the test substance was brought onto the intact or abraded skin under a surgical patch. Six rabbits were treated on the intact skin, the other six on the abraded skin. After a 24 h exposure, the patches and the material applied were removed and the resulting skin reactions were evaluated at 24 and 72 h post-application. During the course of the exposure period one rabbit died, probably because of a dislocation of the backbone. The dermal effects observed after 24 and 72 hours consisted of very slight erythema with or without very slight edema. The primary irritation index of the test material was calculated to be 1.0. There were no distinct differences between reactions of the intact skin and those of the abraded skin. Based on the primary skin irritation index, it was concluded that the test material was a slight primary skin irritant (van Beek, 1983).

More reliable studies were available for structurally related substances. Thus, read-across was performed following a category approach.

The skin irritating potential of fatty acids, C18-unsaturated, dimers (CAS No. 61788-89-4) was assessed in a study conducted according to OECD Guideline 404 and in compliance with GLP. A volume of 0.5 mL of the test material was applied undiluted to the clipped skin of 3 New Zealand White rabbits for 4 hours under semiocclusive conditions. The skin of all animals showed very slight edema, and slight to well-defined erythema. The mean erythema and edema scores over 24, 48 and 72 h for each individual animal were 2.0/1.7/0.7 and 1.0/0.7/0.0, respectively. The observed effects were fully reversible within the observation period of 14 days (Mulder, 1986).

The skin irritating potential of fatty acids, C18-unsaturated, dimers, hydrogenated (CAS No. 68783-41-5) was assessed in a study conducted according to OECD Guideline 404 and in compliance with GLP. A volume of 0.5 mL of the test material was applied undiluted to the clipped skin of 3 New Zealand White rabbits for 4 hours under semiocclusive conditions. A slight erythema was observed in all animals at 1, 24, 48, 72 hours readings. It remained until day 6 in only one animal. The irritative phenomena were only minor, but they remained until day 6. Very slight changes in skin structure were also observed. No edema was observed. The mean erythema and edema scores over 24, 48 and 72 h for each individual animal were 1.0/1.0/1.0 and 0.0/0.0/0.0, respectively. The observed effects were fully reversible within 7 days (Saboureau, 1989).

In another study conducted in compliance with EU Method B.4, fatty acids, C18-unsaturated, dimers, hydrogenated were slightly skin irritating in rabbits after 4 h semiocclusive exposure. The test material caused well-defined erythema in one animal and very slight erythema in the two other animals, 1 hour after test material removal. The erythema noted in one animal increased temporarily to well-defined by the next day and thereafter very slight erythema persisted to day 7. The well-defined erythema decreased to very slight within 24 hours and persisted thereafter to day 14. A further animal showed very slight erythema during the first week of observation. No edema was observed in any of the animals. The treated skin of all three rabbits showed some scaliness when examined on days 7 and 14. No signs of systemic intoxication were observed in any of the rabbits. The mean erythema and edema scores over 24, 48 and 72 h for each individual animal were 1.0/1.3/1.0 and 0.0/0.0/0.0, respectively. The observed effects were fully reversible within 21 days (Daamen, 1988).

 

Eye

There are no data available on the eye irritating potential of fatty acids, C18-unsaturated, trimers. Therefore, assessment of eye irritating properties was based on read-across from structurally related substances within a category approach.

Fatty acids, C18-unsaturated, dimers (CAS No. 61788-89-4) were assessed for the induction of eye irritation in a study compliant with OECD Guideline 405 and according to GLP. A volume of 0.1 mL of undiluted test material was applied into the conjunctival sac of one eye of each of 3 New Zealand White rabbits, and the animals were observed at intervals for up to 96 h. Slight conjunctival redness was observed in all animals, as well as slight chemosis in two of the rabbits. Adverse effects on the cornea and the iris were not observed in any of the rabbits during the entire observation period. The mean chemosis scores over 24, 48 and 72 h for each individual animal were 0.0/0.0/0.3. The observed effects were fully reversible within 48 h (Mulder 1986).

The eye irritating potential of the fatty acids, C18-unsaturated, dimers, hydrogenated (CAS No. 68783-41-5) was investigated in a study conducted according to EU Method B.5 and in compliance with GLP. The test material (0.1 mL) was instilled into one eye of each of 3 New Zealand White rabbits, and the animals were observed at intervals for up to 14 days. The test material affected the conjunctivae only. Approximately 1 hour after exposure, all three animals showed diffuse redness of the palpebral conjunctivae and slight chemosis. The observed redness had decreased to slight in one animal within 24 hours and within 48 hours in the other two animals. The chemosis of all three rabbits, which was only observed on the palpebral conjunctivae after the first reading, resolved between days 3 and 7. No adverse effects on the cornea and the iris were observed in any of the rabbits during the entire observation period. The mean cornea and chemosis scores over 24, 48 and 72 h for each individual animal were 0.0/0.0/0.0 and 1.0/1.0/1.0, respectively. The observed effects were fully reversible within 7 days (Daamen, 1988).

Fatty acids, C18-unsaturated, dimers, hydrogenated were assessed for the induction of eye irritation also in a GLP-study compliant with OECD Guideline 405. The undiluted test material was applied into the conjunctival sac of one eye of each of 3 New Zealand White rabbits, and the animals were observed at intervals for up to 72 h. A slight enanthema together with lacrymation was observed in all 3 animals at both 1-hour and 24-hour readings. One animal alone showed slight chemosis at the 1-hour reading. Not any lesion of iris or cornea was recorded. The mean cornea, iris and chemosis scores over 24, 48 and 72 h for each individual animal were 0.0/0.0/0.0 in all cases. The observed effects were fully reversible within 24 h (Saboureau, 1989).

Taken together, the available information on structurally related substances included in the chemical category indicates that fatty acids, C18-unsaturated, trimers are not likely to induce irritation in contact with the eyes.

Justification for classification or non-classification

Based on read-across from structurally related substances within a category approach, the available information on the skin and eye irritating potential of fatty acids, C18-unsaturated, trimers is conclusive but not sufficient for classification.