Hydrocarbons, C9-C11, n-alkanes, isoalkanes,

Endpoint summary

Description of key information

Hydrocarbons, C9-C11, n-alkanes, isoalkanes, <2% aromatics is not considered to be a skin sensitizer based on read across data available from Human Repeated Insult Patch Tests (HRIPT).

Additional information

Hydrocarbons, C9-C11, n-alkanes, isoalkanes, <2% aromatics is not considered to be a skin sensitizer based on weight of evidence from read across data available from Human Repeated Insult Patch Tests (HRIPT).

The irritating and sensitizing potential of the hydrocarbons, C7-C9, isoalkanes, <2% aromatics on human skin was evaluated in an intensified version of the Shelanski and Shelanski Repeated Insult Patch Test (ExxonMobil 1988a). Occlusive contact was carried out on only 25 subjects by applying 2 x 2 cm webril pads containing 0.2 ml of the neat test substance to the skin of each subject under impermeable adhesive-face plastic covers. Contact was interrupted after a few hours because of the intense responses. Skin reactions were assessed after 24, 48 and 72 hours, subjects were not patched for the rest of that week. Under the test conditions, there was no evidence that the test material, hydrocarbons, C7 -C9, isoalkanes possesses a skin sensitizing potential.

 

In another study, the phototoxic and photocontact allergenic potentials of the test material (hydrocarbons, C7-C9, isoalkanes, <2% aromatics) were determined in human volunteers, either with or without irradiation with both UV-A and UV-B light after treatment (ExxonMobil, 1988b). The primary irritant and the contact allergenic potentials of the test material were also established, as required for control purposes. Under the test conditions, the test material, hydrocarbons, C7 -C9, isoalkanes was not a photosensitizer.

 

In a third study, the test substance (hydrocarbons, C7-C9, isoalkanes, <2% aromatics ) was evaluated for skin irritating properties in humans following a simulated use patch technique. Each test subject was patch tested before and after a 3-week simulated use period (ExxonMobil, 1962d). Under the test conditions, there was no evidence that the test material, hydrocarbons, C7 -C9, isoalkanes possesses a skin sensitizing potential.

 

A study (ExxonMobil, 1991) ws conducted to determine the potential of the test material (C9-C11, n-alkanes, isoalkanes, cyclics, <2%aromatics) to cause dermal irritation and sensitization in humans. 118 humans were exposed to the test material. Induction applications (0.1 ml test material, neat) were made to the arm for 24 hours under a semi-occlusive patch. Sixty-one subjects exhibited strong cutaneous reactions consisting of strong erythema/edema, papules, and vesicular responses to test substance at the first induction evaluation. The evaluation of this sample was discontinued on July 26, 1991 by the Test Operations Supervisor and the Investigator due to this strong reaction. The overall response patterns (induction, challenge, and rechallenge) suggest that the test material is consistent with a severe clinical irritant.

A key human skin patch test (ExxonMobil Corp, 1988c) was conducted to determine the potential of Hydrocarbons, C10-C12, isoalkanes, <2% aromatics to cause dermal irritation and sensitization in humans with or without UV irradiation. Twenty-eight humans were exposed to the test material. Dermal examinations occurred after exposures (day 1 and day 2) and then at 24h, 48h, and 72h post exposure. Dermal irritation and damage was assessed and scored according to a modified Draize scale. The most severe reaction noted in all experimental paradigms was noted as a "1" or slight erythema. The test material did not elicit any effects which could be construed as a characteristic of a phototoxic propensity or of a primary irritant. MRD-88-296 showed no evidence of being a photo contact allergen and no evidence of being either a primary irritant or a contact allergen. Based on these data and results, Hydrocarbons, C10-C12, isoalkanes, <2% aromatics would not be classified as a dermal irritant or as a dermal sensitizer.

 

Another key human skin patch test (ExxonMobil Corp, 1988d) was conducted to determine the potential of Hydrocarbons, C10-C12, isoalkanes, <2% aromatics to cause dermal irritation and sensitization in humans. The induction applications were made to a site on the back (0.2 ml test material, neat) using an occlusive patch.  The patch held the material in place for 24 hours at which time, the subjects returned for an evaluation of the application site and for new test material to be applied.  Due to 35 subjects developing an erythema score between 3 and 5, it was decided that a 50/50 w/w test sample (in USP petrolatum) would be applied to an alternate test site using a semi-occlusive patch for the duration of the experiment after subjects were treatment-free for one week.  Applications were held in place via a semi-occlusive patch for 24 hours and subjects were examined daily for dermal effects before receiving a fresh application of 50/50 w/w test material for a total of 9 additional applications.  A 3-5 day rest period followed the last induction application.   A challenge application was applied to a naïve site on the back that consisted of a 50% (w/w) of test material preparation held in place by a semi-occlusive patch for a total of 4- 24 hour applications. 

There was no indication that the test material possesses a skin-sensitizing propensity as there was no recordable skin irritation noted in any of the patients.  When the test material, neat was applied under occluded conditions, the severe irritation that occurred indicates that it would be considered a dermal irritant.  However, the occlusion of the test material prevents evaporation and changes the permeability of the dermis.  In order to determine the irritancy of the test material in a relevant paradigm, a 50% (w/w) solution of the test material was applied under a semi-occluded patch.  No significant dermal irritation was noted and thus, Hydrocarbons, C10-C12, isoalkanes, <2% aromatics would not be considered a dermal irritant.

In a third key study (ExxonMobil Corp., 1962e), Hydrocarbons, C10–C12, isoalkanes, < 2% aromatics and Hydrocarbons, C11–C12, isoalkanes, < 2% aromatics were evaluated for skin irritating properties in humans following a simulated use patch technique. A total of 101 subjects, including males and females, participated in the program. Each subject was patch tested before and after a three-week simulated use period. Under conditions and procedures used in the investigation the test materials will not be considered primary skin irritants under semi-occluded conditions. None of the test materials produced skin fatigue on repeated daily application during a three-week simulated use period. None of the test materials were skin sensitizers.