Paraffin waxes and Hydrocarbon waxes, microcryst., hydrotreated

Carcinogenicity

Description of key information

Oral and dermal carcinogenicity studies have been conducted on petroleum waxes, and were judged to be negative, i.e., the petroleum waxes were not considered to be carcinogenic.  

Key value for chemical safety assessment

Carcinogenicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

5 700 mg/kg bw/day

Study duration:

chronic

Species:

rat

Carcinogenicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Carcinogenicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

128 mg/kg bw/day

Study duration:

chronic

Species:

mouse

Justification for classification or non-classification

Paraffin and hydrocarbon waxes are classified as non-carcinogenic and are not classified according to EU guidelines. The classification is based on 8 studies with 5, unspecified, paraffin waxes in rats, mice and rabbits.

Additional information

Oral and dermal carcinogenicity studies have been conducted on waxes, and were judged to be negative, i. e., the waxes were not considered to be carcinogenic. Based on a report that the application dose in the dermal carcinogenesis studies was approximately 7.5 mg, applied three times per week, and assuming an average body weight for the mice of 25 g, the average daily dose in the dermal studies was approximately 128 mg/kg/day.

In a key carcinogenicity study (Klimisch score = 2), five petroleum waxes (3 of the waxes were microcrystalline and the other two were unidentified) were given to male and female Sprague-Dawley rats at a dietary concentration of 10% for 2 years (Shubik et al., 1962).  Survival rates and growth rates were unaffected by oral exposure to any of the waxes tested.  A number of tumours were found in all groups at necropsy.  The most common tumours were those of the mammary regions (fibrocarcinomas, adenocarcinomas, fibromas, and sarcomas), of the adrenal glands (cortical adenomas with a few carcinomas and pheochromocytomas) and of the pituitary.  The number of tumour-bearing animals and the incidence of tumours of each type were similar across groups.  No other toxic effects were found at histological examination. The authors concluded that the five petroleum waxes were devoid of carcinogenic or other toxic action when fed at a level of 10% in the diet. Based on the body weights, this equates to a daily dose of approximately 5700 mg/kg/day. 

A lifetime skin painting carcinogenicity study of petroleum waxes (Klimisch score = 2) was conducted in mice and rabbits (Shubik et al., 1962). Five petroleum waxes were selected from 36 samples on the basis of their ultraviolet absorptivity, representing the range of aromatic contents. Each of the 5 waxes was dissolved in warm benzene to achieve 15% solutions. Survival rates of the mice were similar for treated and control animals with a better survival among females than males.  No degenerative or necrotic changes were observed. A few epidermal tumours appeared in most groups, including controls. A few sebaceous gland adenomas were also found in some of the wax-painted groups. Two tumours originating from the skin appendages, a squamous cell carcinoma and a benign trichoepithelioma, were observed in the wax-painted groups.  The authors judged that these studies were negative. According to the report, the wax sample was applied three times weekly at a dose of approximately 7.5 milligrams. Assuming the mice weigh approximately 25 grams, this equates to an average daily dose of approximately 128 mg/kg/day. 

No inhalation carcinogenicity data are available on paraffin or microcrystalline waxes.