Petrolatum (petroleum), oxidized, calcium salt

Carcinogenicity

Description of key information

The carcinogenic potential of petrolatums is associated with the biologically available/active impurities such as polycyclic aromatic constituents (PAC) found in the entrained oil of these substances. Severely refined petrolatums, produced from feedstocks from which the aromatic constituents have been removed are not carcinogenic. 

Justification for classification or non-classification

Sufficiently Refined Petrolatum

Sufficiently refined petrolatums are not classified for carcinogenicity according to EU guidelines. Refined petrolatum were found to be non carcinogenic in oral carcinogenicity study in rats and dermal exposure studies in mice and do not meet the EU criteria for classification.

 

Additional information

The carcinogenic potential of petrolatums is associated with the biologically available/active impurities such as polycyclic aromatic constituents (PAC) found in the entrained oil of these substances. Severely refined petrolatums, produced from feedstocks from which the aromatic constituents have been removed are not carcinogenic. 

No inhalation carcinogenicity studies have been reported with petrolatums or similar materials.  

 Sufficiently Refined Petrolatum

 

There have been several studies on sufficiently refined petrolatums (oral and dermal).  

 

In a key oral carcinogenicity study (Oser et al., 1965), three pharmaceutical and food-grade petrolatum blends were tested in FDRL rats. To conduct the study, 50 FDRL rats of each sex, individually housed, were given ad libitum access to diets containing 5% (5000 mg/kg/day) of each of the three petrolatum blends for 2 years. A group of 100 rats of each sex served as controls and was fed normal diet that had been supplemented with 1% vitamin mix and 0.2% Aurofac 10. The animals were observed daily for appearance, behaviour and survival. Weekly measurements were made of body weight for the first 12 weeks of the study, and weights were measured biweekly thereafter. Weekly measurements were also made of food intake for the first 12 weeks. Measurements of haematological parameters were made at 12, 26, 52, 72 and 100 weeks. Surviving rats were sacrificed at scheduled termination. These, as well as, rats dying spontaneously were necropsied, and weights of the liver, kidneys, spleen, heart, adrenals, thyroids and pituitary were recorded. Several organs were removed for microscopic examination. Growth rates were unaffected, and there were no differences in survival. There were small, statistically significant differences in food efficiency, but these were judged to have not been toxicologically important. Haematological and clinical parameters were unaffected by treatment. There were no differences at necropsy between petrolatum-exposed and control animals. Furthermore, there were no histological changes that could be attributed to dietary exposure to petrolatum. Finally, none of the petrolatum blends caused an increase in tumour incidence in any tissue or organ examined. Accordingly, petrolatum was judged to be non-carcinogenic following oral administration.

 

In a key dermal carcinogenicity study (Kane et al., 1984), carcinogenicity of severely refined petrolatum (CAS No. 8009-03-8) was evaluated as part of a series of mouse skin painting bioassays with 46 clearly defined samples of refinery streams associated with lubricant base oil processing. Male C3H mice, 6 to 8 weeks old, were allowed to acclimate and were housed individually or in small groups. The animals were shaved biweekly, and the undiluted test material was applied to the shaven interscapular regions. The petrolatum that had been produced by a solvent extraction process was painted on the skin of 50 male C3H mice at 25 milligrams twice weekly for 80 weeks. Positive control groups were treated with solutions of benzo(a) pyrene, and negative control groups included an inactive oil-treated group and a no-treatment group. No tumours developed in any of the mice to which the highly refined petrolatum was applied. The study was repeated in 25 animals using the same application dose of 25 mg/application, twice weekly for 80 weeks, and, again, none of the animals developed tumours.

 

In another key dermal carcinogenicity study (Lijinsky et al., 1966), amber petrolatum (NF grade) was evaluated for carcinogenicity in Swiss mice. The petrolatum was dissolved in isooctane to make a 15% solution and applied twice weekly to the skin of 40 male and 30 female mice throughout the life of each animal. A control group of 50 males and 50 females received skin application of isooctane only. Tumour incidence in the petrolatum-treated group (5 tumours in three animals, 3 tumours regressed) was similar to that from the vehicle control group (2 tumours in two animals).  It was concluded that amber petrolatum was not carcinogenic.