Slack wax (petroleum), hydrotreated

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Slack waxes are waxes with entrained oils. Since paraffin and hydrocarbon waxes are non-hazardous the category hazard profile is determined by the entrained oils. Since the entrained oils are a minor portion of the slack waxes, this is considered to be a worst-case approach.

Slack Waxes (Carcinogenic or Unknown Feed-stock)

Read across justification

No dermal sensitization studies have been reported for slack waxes (carcinogenic or unknown feed-stock), but a study has been reported for unrefined / acid treated lubricant base oils and paraffin waxes, similar to the oil entrained in slack waxes (carcinogenic or unknown feed-stock).

One key read-across study (API, 1986a) was identified to evaluate the skin sensitising potential of slack wax (carcinogenic or unknown feed-stock). In this study API 84-01, an unrefined light paraffinic oil (CAS No. 64741-50-0) was administered to Hartley albino guinea pigs. None of the animals in this study became sensitized following treatment with the test material. In contrast, all the positive control animals were sensitized by their treatment with 2,4-dinitrochlorobenzene.

Slack Waxes (Non-carcinogenic Feed-stock)

Read across justification

No dermal sensitization studies have been reported for slack waxes (non-carcinogenic feed-stock), but studies have been reported for refined lubricant base oils, materials similar to the oil entrained in slack waxes (non-carcinogenic feed-stock).

Three key read-across studies (API, 1982e; Shell, 1997; and Exxon Biomedical Sciences, Inc., 1988a) were identified to evaluate the skin sensitising potential of slack wax (non-carcinogenic feed-stock).

In a guinea pig skin sensitization test (API, 1982e), 10 male Hartley guinea pigs were induced and subsequently challenged by topical administration of solvent dewaxed light paraffinic oil. Initially 3 guinea pigs were tested with 0.1, 0.5, 1.0, and 2.0 mL of solvent dewaxed light paraffinic oil in a range-finding study. Based on the results of the range-finding study, the 1.0 mL dose was selected for the subsequent induction and challenge phases of the experiment. 24 hours prior to exposure, the guinea pigs were shaved with a clipper blade on either side of the thorax from the shoulders down till the hips. 1.0 mL of the test material was applied to 1 square inch gauze sponges backed by an occlusive plastic wrap that was then kept in contact with the skin for 6 hours with elastic tape. 24 hours after patch removal, the animals were scored for irritation based on the method of Draize. The test material was subsequently applied (following the same procedure) three times per week for three consecutive weeks following which the animals were held for a period of two weeks and then challenged with 1.0 mL of solvent dewaxed light paraffinic oil. The procedure followed for the challenge phase was the same as that employed during induction. A positive control group of 10 male guinea pigs was dosed with 0.5 mL of 0.05% w/v solution of chlorodintrobenzene in ethanol and data generated was analyzed using the student's t test. A significant difference was observed in the mean erythema scores between the induction (sensitizing) and challenge phases. However, the challenge mean scores were zero for both parameters observed (erythema and oedema) indicating that solvent dewaxed light paraffinic oil is not a sensitizer. In the positive control group, challenge erythema scores were significantly higher than those observed in the induction phase indicating that chlorodintrobenzene is a dermal sensitizer. Under the conditions of this study, solvent dewaxed light paraffinic oil was not considered to be a dermal sensitiser.

In another key read-across dermal sensitisation study using paraffin wax (Shell, 1997), Dunkin Hartley albino guinea pigs (10/sex) were tested using the Magnusson & Kligman Guinea Pig Maximisation Test along with appropriate positive and negative controls. At the topical challenge phase, no skin reactions were observed at 24 or 48 hours in both the controls and groups treated with 10% or 50% paraffin wax in propylene glycol. There was a 0% sensitisation rate. Therefore, under conditions of this study, paraffin wax is not a dermal sensitiser.

In a human skin sensitisation study (Exxon Biomedical Sciences, Inc., 1988a), 112 adult volunteers were dermally exposed to 0.2 mL of lubricant base oil (MRD-88-289). The participants were treated once a day, four days a week, for 13 exposures. A challenge phase was conducted where the participants were treated with 0.2 mL once a day, four days a week, for one week. Participants were asked to report any change in dermal effects for two weeks after the end of the challenge week. Irritation was scored following The International Contact Research Group System (3) and the Product Investigations, Inc scoring method. Based on the small number of slight or mild irritation responses recorded, the lubricant base oil (MRD-88-289) was not considered to be a dermal sensitiser in humans.

Supporting data from studies conducted in human volunteers (EMBSI, 1988b, 1988c, 1988d) indicate that lubricant base oils are not dermal sensitizers.

Migrated from Short description of key information:

One key read-across study (API, 1986a) was identified to evaluate the skin sensitising potential of slack wax (carcinogenic or unknown feed-stock). API 84-01, an unrefined light paraffinic oil (CAS No. 64741-50-0) was administered to Hartley albino guinea pigs. None of the animals in this study became sensitized following treatment with the test material.

Three key read-across studies (API, 1982e; Shell, 1997; and Exxon Biomedical Sciences Inc., 1988a) were identified to evaluate the skin sensitising potential of slack wax (non-carcinogenic feed-stock). In a guinea pig skin sensitisation test (API, 1982e), 10 male Hartley guinea pigs were induced and subsequently challenged by topical administration of solvent dewaxed light paraffinic oil. A significant difference was observed in the mean erythema scores between the induction (sensitizing) and challenge phases. However, the challenge mean scores were zero for both parameters observed (erythema and oedema) indicating that solvent dewaxed light paraffinic oil is not a sensitizer. A 0% sensitisation rate was observed when Hartley albino guinea pigs were dermally exposed to paraffin wax (Shell, 1997). The test material was not considered to be a dermal sensitiser.  In a human skin sensitisation study (Exxon, 1988a), 112 adult volunteers were dermally exposed to 0.2 mL of lubricant base oil (MRD-88 -289). Based on the small number of slight or mild irritation responses recorded, the lubricant base oil (MRD-88-289) was not considered to be a dermal sensitiser in humans.

Justification for selection of skin sensitisation endpoint:

One of 4 available studies.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

Migrated from Short description of key information:

This endpoint is not a REACH requirement and no data are available for this endpoint but these substances are not expected to cause respiratory sensitisation.

Justification for classification or non-classification

Based on available data on similar materials, slack waxes (carcinogenic or unknown feed-stock and non-carcinogenic feed-stock) are not expected to be skin sensitizers and do not meet the EU CLP Regulation (EC No. 1272/2008) criteria for skin sensitisation.