Registration Dossier

Toxicological information

Carcinogenicity

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Description of key information

One key (OECD 453) carcinogenicity study was identified that evaluated multiple unrefined/acid treated oils. Of the 94 oils tested in mice, there were 3 unrefined paraffinic distillates and 3 unrefined naphthenic distillates. All of these unrefined oils were carcinogenic. A number of other supporting studies also gave positive results

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

Additional information

Chasey and McKee (1993) evaluated ninety-four oils in the mouse epidermal cancer bioassay in order to understand the effects of various types of refining processes on carcinogenic potential. These studies were conducted over a 15 year period. In these studies, male C3H mice, about 6-10 weeks of age, were obtained from either Jackson Laboratories (C3H/HeJ) or Charles River Laboratories (C3H / HeNCrlBR). These mice were randomly distributed into test groups of 40 or 50 animals. In early studies, mice were housed five per cage in suspended wire-mesh cages. In later studies, they were housed singly, in the same type of cages. The hair in the interscapular area was clipped once weekly to facilitate test material application. The test materials were applied by automatic pipette in either 37.5 microlitre aliquots twice a week or 25 microlitre aliquots three times a week. In early studies, treatment continued until the animals died spontaneously or were sacrificed in a moribund state. In later studies, surviving mice were sacrificed either after 24 months of treatment or at the time at which grossly diagnosed squamous cell carcinomas developed.  Animals were examined twice weekly for the appearance of dermal tumours.  Each tumour in the treatment area was examined carefully and classified grossly.  All grossly diagnosed tumours were examined microscopically after study termination. Of the 94 oils tested, there were 3 unrefined paraffinic distillates and 3 unrefined naphthenic distillates. All of these unrefined oils were carcinogenic.

Additional data supports that unrefined/acid treated oils should be classified as Carcinogenic, Category 1A, H350 (API, 1989; ARCO, 1985c,d,e; ARCO, 1986a,b,c,d; Horton and Denman, 1955;). This information is presented in the dossier.

Justification for selection of carcinogenicity via dermal route endpoint:

One of a large number of repeat dose skin painting studies in mice with unrefined or poorly refined mineral oils. All samples tested were considered dermal carcinogens

Justification for classification or non-classification

Based on the study results, and the EU harmonised classification, unrefined/acid treated oils are classified as Carcinogenic Category 1A (H350), according to the EU CLP Regulation (EC No.1272/2008).