Alkenes C20+

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

There were no skin sensitisation studies identified for alkenes, C24 -28; therefore read-across was made from alkenes, C20-24.

For the first study, concentrations for the main study were determined by “sighting tests” in which groups of guinea pigs were treated with various concentrations of test material (Driscoll, 1998).

 

Based on the outcome of the “sighting tests”, a group of 30 female guinea pigs were used in the main study with 20 serving as test animals and 10 as controls. In the induction phase, immediately before treatment, on day 0, the animals were clipped free of hair on the shoulder region and a row of three injections comprised of 0.1 mL Freund's Complete Adjuvant plus distilled water in the ratio 1:1, a 25% w/v formulation of test material in arachis oil, and a 25% w/v formulation of test material in a 1:1 preparation of Freund's Complete Adjuvant plus distilled water were made on each side of the mid-line. The degree of erythema was evaluated at 2 and 48 hours using the Draize scale (Draize, J. H.; 1977). A week later (day 7), the same area on the shoulder was clipped free of hair again and treated with a topical application of the undiluted test material that was secured with occlusive wrap. This occlusive dressing was kept in place for 48 hours. The degree of erythema and oedema was determined 24 hours later after the patches were removed using the Draize scale (1977). Any other toxicologically relevant reactions were also recorded. Control animals were induced in a manner similar to the test animals.

 

The challenge phase was initiated on day 21 following the induction phase. Shortly before treatment an approximate area of 50 X 70 mm on both flanks of the each animal was clipped free of hair and the test material was applied to saturation to the shorn right flank of each animal on a filter paper which was held in place with an occlusive wrap. To ensure that maximum non-irritant concentration was used in the challenge phase, the test material at a concentration of 50% v/v in arachis oil was also similarly applied to a separate skin site on the left shorn flank of the animals. These patches were also occluded to keep the test material in contact with the skin. After a 24 hour contact period, the dressing was carefully removed and the challenge sites were cleaned with cotton wool soaked in diethyl ether to remove any residual test material. Approximately 24, and 48 hours after removal of the challenge dressing, the degree of erythema and oedema was quantified using the Draize scale (1977). Any other toxicologically relevant reactions were also noted.

 

In the main study, very slight to moderate to severe erythema was noted at the intradermal induction sites of all test group animals at the 24 hour observation period. These effects had lessened to very slight to well-defined erythema at the 48 hour observation. Very slight erythema was noted at the intradermal induction sites of all control animals at the 24 and 48 hour observation period.

 

In the topical induction test, very slight erythema was noted at the induction sites of 14 test animals at the 1 hour observation period. Bleeding from injection sites of six test group animals was noted at the 1 hour observation period. No skin reactions were noted at the induction site of any of the test animals at the 24 hour observation period. Bleeding from the injection sites was noted in two control group animals at the 1-hour observation. No signs of erythema or oedema were noted at the treatment sites of control group animals at the 1 and 24-hour observations.

 

Following topical challenge, no skin reactions were noted at the challenge sites of the test or control animals at the 24 and 48 hour observation period. There were no changes in animal body weights during course of the study. Based on these results, the study authors concluded that test material produced a 0% (0/20) sensitisation rate in the female albino guinea pigs.

 

In a guinea pig maximization skin test by Richeux (2008), concentrations for the main study were determined by “sighting tests” in which groups of guinea pigs were treated with various concentrations of test material.

 

Based on the outcome of the “sighting tests”, a group of 15 female guinea pigs were used in the main study with 10 serving as test animals and 5 as controls. In the induction phase, immediately before treatment, on day 0, the animals were clipped free of hair on the shoulder region and a row of three injections comprised of 0.1 mL Freund's Complete Adjuvant plus isotonic sodium chloride in the ratio 1:1, 100% of the test material, and a 50% formulation of the test material 1:1 preparation of Freund's Complete Adjuvant plus olive oil, on each side of the spine.A week later (day 7), the scapular region of all test and control animals was shaved and was brushed with a solution of sodium lauryl sulfate at 10% in thick vaseline, in order to create a local irritation. On Day 8 the same area on the shoulder region was previously for intradermal injetions was clipped again and treated with a topical application of the test material formulation. The topical application of the test material was 100% under occlusive dressing, which was kept in place for 48 hours. The degree of erythema and oedema was determined 24 hours later after the patches were removed using the Draize scale (1977).The induction of the control animals was performed identical to that used for the test animals except that the test material was omitted from the intradermal injections.

 

The challenge phase applied the test material formulation at 12.5% in liquid paraffin to the flanks of the each animal. The flanks were clipped free of hair. The test material was applied to one side of the shorn flank of each animal under occlusive dressing. To ensure that maximum non-irritant concentration was used in the challenge phase, the test material at a concentration of 6.25% (v/v) in liquid paraffin was also similarly applied to a separate skin site on the opposite shorn flank of the animals. These patches were also occluded to keep the test material in contact with the skin. After a 24 hour contact period, the dressing was carefully removed and the challenge sites were cleaned if required. Approximately 24, and 48 hours after removal of the challenge dressing, the degree of erythema and oedema was quantified using the Draize scale (1977). Any other toxicologically relevant reactions were also noted.

 

In the preliminary sighting tests no skin reactions were noted at the intradermal induction sites following treatment with the test material at concentrations of 100%, 50%, 25%, 12.5%, 6.25% and 3.125%. The concentration chosen for use in the Intradermal Induction phase of the main test was 100%. Well defined erythema was noted at the topical induction sites of the preliminary sighting test after treatment with 100% test material concentration. Slight erythema was noted at the test site for the 50% test material concentration as well as at 25% test material concentration. No skin reactions were noted at the topical induction sites for the 12.5% test concentration sites. No skin reactions were noted at the topical challenge sites of the preliminary sighting test animals following treatment with the test material at concentrations of 12.5%, 6.25%, 3.125% and 1.56%.

 

No skin reactions were noted at the topical challenge site of the 6.25% or 12.5% in liquid paraffin test or control group animals at the 24 and 48 -hour observations.

 

Following topical challenge, no skin reactions were noted at the challenge sites of the test or control animals at the 24 and 48 hour observation period. Animal body weight increases were comparable to those noted in the control group over the course of the study. Based on these results, the study authors concluded that test material produced a 0% (0/10) sensitisation rate in the female albino guinea pigs.

 

Migrated from Short description of key information:
Two read-across skin sensitisation studies (OECD 406) was identified for alkenes, C24-28, in which alkenes, C20-24 were found not to be sensitising to guinea pigs. Alkenes, C24-28 are not dermal sensitisers and contain no chemical alerts for respiratory sensitization.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Alkenes, C24 -28 are not expected to cause respiratory sensitisation based on results of skin sensitisation testing and an absence of reactive chemical alerts.

Migrated from Short description of key information:
Alkenes, 24-28 are not expected to cause respiratory sensitisation based on results of skin sensitisation testing and an absence of reactive chemical alerts.

Justification for classification or non-classification

Negative results from skin sensitisation studies with alkenes, C20-24 (structural analogues) were read-across to alkenes, C24-28. It was therefore inferred that alkenes, C24-28 would also not be a skin sensitizer. Therefore, alkenes, C24-28 do not meet the criteria for classification as a dermal sensitizer under EU Dangerous Substances Directive 67/548/EEC or CLP EU Regulation 1272/2008. 

Alkenes, C24-28 arenot expected to be respiratory sensitisersbased on results of skin sensitisation testing and an absence of reactive chemical alerts.