Extracts (petroleum), solvent-refined heavy paraffinic distillate solvent

Carcinogenicity

Description of key information

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

Key value for chemical safety assessment

Carcinogenicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no study available

Carcinogenicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Carcinogenicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Study duration:

chronic

Species:

mouse

Justification for classification or non-classification

Dermal exposure to the untreated 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 untreated distillate aromatic extracts (UDAEs) 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 UDAEs 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 (API, 1989),

repeated dermal application of 50 uL aliquots, twice/week of distillate aromatic extract (Light paraffinic distillate solvent extract, CAS No. 64742-05-8) to the clipped skin of mice for two years resulted in an increased incidence of dermal tumours. The material was a dermal carcinogen following repeated application to the clipped skin of mice.

 

Additional data support that UDAEs are carcinogens (Gradiski, 1983; Doak et al., 1985). 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).

Justification for selection of carcinogenicity via dermal route endpoint:

One of seven dermal carcinogenicity studies available.

Carcinogenicity: via dermal route (target organ): other: skin