Extracts (petroleum), heavy paraffinic distillates, solvent-deasphalted

Carcinogenicity

Description of key information

For carcinogenicity, TDAEs (IP 346 ≥ 3%) were evaluated using read-across information from distillate aromatic extracts.  TDAEs (IP 346 < 3%) were evaluated using read-across data from other lubricating base oils (IP 346 < 3%).  Distillate aromatic extract was found to have carcinogenic potential when administered dermally on mice in a read-across, non-guideline study.  Other lubricant base oils with IP 346 < 3% are not carcinogenic in read-across dermal application studies (similar to OECD 451).

Justification for classification or non-classification

Dermal exposure to the distillate aromatic extract, in addition to causing skin irritation, resulted in skin cancer in the mouse. Based on this, treated distillate aromatic extracts (IP 346≥ 3 wt%) are classified as Carcinogenic, Category 1B (H350) according to the EU CLP Regulation (EC No. 1272/2008).

Based on the lack of a carcinogenic effect after dermal exposure to other lubricant base oils (IP 346 < 3wt%), treated distillate aromatic extracts (IP 346 < 3 wt%) are not classified according to the EU CLP Regulation (EC No. 1272/2008).

Additional information

Treated distillate aromatic extracts (TDAEs) are a further processing of distillate aromatic extracts (DAEs) in an attempt to reduce the amount of 3-7 ring PAC that is present. Since the treatment is mostly a selective reduction of PACs, the data from DAEs can serve as read across where treatment was insufficient and a significant amount of PACs still remain (≥ 3 wt% DMSO extractables as measured by IP-346). Where treatment was sufficient to reduce the 3-7 ring PACs (<3 wt% DMSO extractables as measured by IP-346), the material is most similar to a lubricating base oil and it is this data that should be used for read across. 

TDAEs (IP 346 ≥ 3 wt%)

One key read-across carcinogenicity study was identified for treated distillate aromatic extracts (IP 346≥ 3 wt%). In this study, DAE (no CAS number provided) was tested dermally on female albino EOPS mice for a total of 12 months (Gradiski et al., 1983). A treatment dose of 0.05 millilitres of undiluted test material was applied three times weekly for the first month and twice weekly for the next 11 months to the shorn dorsal lumbar skin of a group of 30 mice. A group of 60 female mice shaved once weekly served as untreated controls. At study termination, depilation and cutaneous atrophy was noted and attributed to skin irritation or repeated scratching. 83% of animals treated with distillate aromatic extract developed one or more skin tumours; 33% benign, 17% malignant and 33% benign and malignant. Observed malignant tumours included squamous cell carcinomas and sarcomas. By comparison, no skin tumours or cutaneous lesions were observed in any of the white oil or untreated control animals.

 

The authors concluded that dermal exposure to the tested untreated distillate aromatic extract, in addition to causing skin irritation, resulted in skin cancer in the mouse. It was observed that general mortality decreases as the refinement of the oil increases. Untreated distillate aromatic extract, which contains polycyclic aromatic hydrocarbon substances, produced a biological response and was found to be carcinogenic.

 

Additional data support that DAEs are carcinogens (API, 1989; CONCAWE, 1994; Doak, 1985; Horton and Denman, 1955; Institute of Petroleum, 1991; Kane et al., 1984; McKee and Przygoda, 1987). This information is presented in the dossier.

 

TDAEs (IP 346 < 3 wt%)

A read-across study on carcinogenicity was identified for TDAEs (IP 346 < 3wt%). Doak et al. (1983) reported on an 18-month dermal carcinogenesis carcinogenicity study of twelve mineral oils originating from naphthenic and paraffinic feed stocks and refined by a number of processes. All of these oils are considered “sufficiently” refined. The oils were evaluated for their potential to induce cutaneous neoplasia in female CF1 mice. The oils were applied to the shorn dorsal skin for up to 78 weeks using the following treatment regimes:

a(i) - undiluted oil applied twice weekly or 78 weeks

a(ii) - undiluted oil applied twice weekly for 22 weeks with no further treatment

b(i) - undiluted oil applied once weekly for 78 weeks

b(ii) - undiluted oil applied once weekly for 22 weeks and then once fortnightly

c - diluted oil (1:1 v/v with medicinal grade liquid paraffin) applied twice weekly for 22 weeks and then once weekly

d - diluted oil (1:1 v/v with medicinal grade liquid paraffin) applied once weekly for 78 weeks 

This study lends further support to the concept that the degree of refining influences the carcinogenic potential of the oils. Whereas mild acid / earth refining processes are inadequate to substantially reduce the carcinogenic potential of lubricant base oils, hydrotreatment and / or solvent extraction methods can yield oils with no carcinogenic potential. Based on the results of the skin painting studies, all of the solvent extracted oils are non-carcinogenic. 

There are additional supporting studies on other lubricant base oils (IP 346 < 3 wt%) that support the lack of carcinogenic potential for TDAEs (IP 346 < 3 wt%) (API, 1983; Horton, et al., 1955; Kane, et al., 1984; Halder, et al., 1984; McKee, et al., 1989; UBTL, 1991a; UBTL, 1991b; UBTL, 1991c; UBTL, 1991d).