Paraffin waxes and Hydrocarbon waxes, microcryst., hydrotreated

Endpoint summary

Description of key information

The acute toxicity of paraffin and hydrocarbon waxes is low with no observed mortalities from oral (OECD 401/420) or dermal (OECD 402) applications.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

5 000 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Value:

mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Additional information

Paraffin and hydrocarbon waxes have low acute toxicity with an oral LD₅₀greater than 5000 mg/kg (in rat) and a dermal LD₅₀of greater than 2000 mg/kg (in rabbit). Inhalation toxicity studies were not reported for paraffin and hydrocarbon waxes, as inhalation is not an expected route of exposure due to the very low vapour pressure and high boiling point of these substances.

In an acute oral toxicity study (International Bio-Research, 1976a, b, Klimisch score = 1), paraffin wax in Arachis oil diluent and microcrystalline wax in Arachis oil diluent, were tested in rats (5/sex/dose) at dose levels ranging from 1000 to 5000 mg/kg. The rats were observed for clinical signs of toxicity for the following 7 days and then weighed, killed and autopsied. There were no mortalities or clinical signs of toxicity during the observation period. Growth rates were normal, and no microscopic changes were observed at autopsy. The LD₅₀was concluded to be greater than 5000 mg/kg. The study was conducted prior to promulgation of GLP guidelines but was considered a well-conducted study.

In an acute oral toxicity study (SafePharm Laboratories Limited, 2007a, Klimisch score = 1), 5 female Sprague-Dawley rats were given a single oral dose of paraffin wax (undiluted via gavage) at 5000 mg/kg bw and observed for 14 days. There were no treatment related clinical signs, necropsy findings or changes in body weight. The oral LD₅₀was determined to be >5000 mg/kg body weight in female rats. 

In several supporting studies (Elder 1984, Klimisch score=2), acute oral toxicity tests on various formulations of paraffins ranging from 5% to 16% did not produce any mortality and the LD₅₀s were greater than 60 ml/kg, 5000 mg/kg, and 10000 mg/kg in rats and an LD₅₀of greater than 25 ml/kg in beagle dogs. Acute oral tests on 4.35% and 20% microcrystalline waxes produced LD₅₀s in rat greater than 25000 mg/kg and 10000 mg/kg, respectively. Additional acute oral toxicity studies in rats (BIBRA Toxicology International, 1993a; BIBRA Toxicology International, 1993b) also reported LD₅₀s >5000 mg/kg body weight.

In an acute dermal toxicity study (Shell International Petroleum Mij.B.V, 1993), groups of five male and five female young adult Sprague-Dawley rats were dermally exposed to Paraffin wax (SX30) for 24 hours to approximately 10% of body surface at a dose of 2000 mg/kg body weight. Animals then were observed for 14 days. The test article caused slight skin irritation reactions in a majority of treated animals which persisted throughout the study. However, a previous study performed at BIBRA (Report No.1091(3) /1/93) demonstrated that SX30 is only a mild irritant and has no corrosive (irreversible) properties when applied to intact rabbit skin for 24 hours. Based on this the dermal LD50 was calculated to be >2000 mg/kg body weight. Supporting dermal toxicity data in rabbits (CTFA, 1972 and Elder, 1984) indicate that paraffin and hydrocarbon waxes have LD50s >3600 mg/kg.

In an additional supporting study (CTFA, 1972a; Elder, 1984), rabbits were exposed to paraffin wax in a closed-patch test for 24 hours, which resulted in an LD₅₀of > 3600 mg/kg bw.

Justification for selection of acute toxicity – oral endpoint

One of 11 acute oral toxicity studies showing similar results

Justification for selection of acute toxicity – dermal endpoint

one of 2 acute dermal studies showing similar results

Justification for classification or non-classification

Paraffin and hydrocarbon waxes do not meet the EU criteria for acute oral or dermal toxicity and are therefore not classified.