Paraffin oils (petroleum), catalytic dewaxed heavy

Endpoint summary

Description of key information

Two key dermal irritation studies were identified.  In one study (API, 1982a) sufficiently refined other lubricant base oils (IP 346 < 3%) were not observed to be skin irritants when applied dermally to the skin of rabbits for 24-hours (mean erythema and oedema scores were 0.17 and 0, respectively at 72 hours). In the second study (API, 1986a) insufficiently refined other lubricant base oils (IP 346  ≥ 3%) were not found to be irritating to rabbits over a 24 to 72 hour period (mean erythema and oedema scores were 2.67) with a 24-hour exposure period.

Two key studies were identified for eye irritation.  Hydrotreated light naphthenic oil (IP 346 ≥ 3%) and solvent dewaxed light paraffinic oil (IP 346 < 3%) were classified as not irritating.

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)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin Irritation

Multiple studies were available to assess the skin irritation potential of other lubricant base oils.

Sufficiently Refined Other Lubricant Base Oils (IP 346 < 3%)

A key primary dermal irritation study (API, 1982a) was identified to evaluate the skin irritation potential of sufficiently refined other lubricant base oils (IP 346 < 3%). In this primary dermal irritation study, 6 New Zealand White rabbits (3 male/3 female) were dermally administered 0.5 mL solvent dewaxed light paraffinic oil (CAS No. 64742-56-9) under occlusive wrap for 24-hours. After the exposure period, the bandages were removed and test sites were wiped with gauze sponges. The animals were observed thereafter and dermal irritation was scored using the method of Draize at 24 hours, 72 hours and on Day 7 post-exposure.

Oedema was not apparent in male or female rabbits at any observation point. Very slight erythema (1) was evident in all male and female rabbits at the 24 hour observation point. Very slight erythema (1) was observed in only 1 male rabbit by the 72 hour observation point and no irritation was visible in any test animal by the end of the 7-day observation period. No differences in irritation were observed between intact and abraded skin sites. Solvent dewaxed light paraffinic oil was not considered to be irritating to the skin of rabbits.

Supporting data from studies conducted in rabbits (API, 1982b; 1982c; 1982d; 1982e; 1982f; 1982g; 1986b; UBTL, 1984h; 1984i; 1984j; 1984k; 1984l; 1984m; 1984n; 1984o; and Trimmer et al. 1989) and humans (Exxon Biomedical Sciences, Inc., 1988d). demonstrate that sufficiently refined other lubricant base oils (IP 346 < 3%) are either only weakly irritating or not irritating to the skin of rabbits and humans.

Insufficiently Refined Other Lubricant Base Oils (IP 346 ≥ 3%)

A key primary dermal irritation study (API, 1986a) was identified to evaluate the skin irritation potential of insufficiently refined other lubricant base oils (IP 346 ≥ 3%). In this primary dermal irritation study, 6 male New Zealand White rabbits were dosed with 0.5 mL of hydrotreated light naphthenic oil (CAS No. 64742-53-6) on two areas of exposed skin, one shaved and one abraded, for 24 hours and covered with an occlusive dressing. The degree of erythema and oedema was recorded according to the Draize scale at 24, 72, 96 hours, and 7 and 14 days. Signs of erythema and oedema were seen across all observation periods at both the intact and abraded sites, but signs disappeared by day 14. The mean erythema and oedema scores for the 24 to 72 hour period were 2.67 and 2.67 for intact skin. For abraded skin, the mean erythema and oedema scores for the 24 to 72 hour period were 2.67 and 2.82, respectively, for abraded skin. This study was performed during 24 hours rather than 4 hours recommended by the current OECD guidelines. Consequently, the result from a shorter exposure time will likely not cause classification of the category.

Based on the evidence available, other lubricant base oils (Insufficiently refined, IP 346 ≥ 3%) are not considered to be skin irritants

Eye Irritation

Multiple studies were available to assess the eye irritation potential of other lubricant base oils. 

Sufficiently Refined Other Lubricant Base Oils (IP 346 < 3%)

In a primary eye irritation study (API, 1982a), 0.1 millilitres of solvent dewaxed light paraffinic oil (CAS 64742-56-9, IP 346 < 3%) was instilled in the eyes of New Zealand White rabbits with and without a 30-second rinse.  A single male rabbit in the no-rinse group showed conjunctival chemosis at 48 hours which resolved by 72 hours. No rabbits in the washed group exhibited irritation; therefore, dewaxed light paraffinic oil is not considered an eye irritant.

Supporting data from studies conducted in rabbits (API, 1982b; 1982c; 1982d; 1982e; 1982f; 1982g; 1986b; UBTL, 1984p; 1984q; 1984r; 1984s; 1984t; 1984u; and 1984v) demonstrate that sufficiently refined other lubricant base oils (IP 346 < 3%) are not ocular irritants.

Insufficiently Refined Other Lubricant Base Oils (IP 346 ≥ 3%)

In a primary eye irritation study (API, 1986a), 0.1 millilitres of hydrotreated light naphthenic oil (CAS 64742-53-6, IP 346 ≥ 3%) was instilled into the eyes of 9 New Zealand White rabbits followed by a one-minute rinse.  No corneal or iridial irritation was observed, and any irritation resolved by 48 hours; therefore, the test substance is classified as not irritating.  

Other lubricant base oils (sufficiently refined and insufficiently refined) are not considered to be eye irritants under the EU classification criteria.

Justification for selection of skin irritation / corrosion endpoint:

One of Twenty Two skin irritation studies.

Justification for selection of eye irritation endpoint:

One of Sixteen eye irritation studies.

Justification for classification or non-classification

Data for skin irritation were derived from studies that were performed during 24 hours rather than 4 hours recommended by the current OECD guidelines. Consequently, the result from a shorter exposure time will likely not cause classification of the category. Based on the data available, other lubricant base oils (insufficiently refined, IP 346 ≥ 3% and sufficiently refined, IP 346 <3%) do not meet the skin irritation criteria under the current EU classification.

Other lubricant base oils (sufficiently refined and insufficiently refined) do not meet the criteria for classification as an eye irritant under Annex VI of EU CLP Regulation (EC No. 1272/2008) because studies conducted in rabbits indicate that the other lubricant base oils tested were non-irritating to the eyes.