Registration Dossier

Administrative data

Description of key information

Highly refined base oils are of low acute toxicity in animal studies conducted by oral (similar to OECD 401), dermal (similar to OECD 402), and inhalation (similar to OECD 403) exposure.  

• The oral LD50 was > 5000 mg/kg bw in male and female rats for highly refined base oils.

• The inhalation LC50 was > 5 mg/L (5000 mg/m3) aerosol in male and female rats for highly refined base oils.

• The dermal LD50 was > 2000 mg/kg/bw in male and female rabbits for highly refined base oils.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LD50
5 000 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LC50
5 000 mg/m³

Acute toxicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LD50
2 000 mg/kg bw

Additional information

Acute Oral

In a key acute oral toxicity study, Sprague-Dawley rats (5/sex) were administered a single oral gavage dose of 5000 mg/kg of highly refined base oil (Klimisch score = 2, ARCO, 1987b).  After 14 days no mortality was observed. One of ten animals exhibited loose stools on the day of dosing. No gross lesions were present at necropsy. All animals exhibited an overall net weight gain over the study period. The acute oral LD50 of white mineral oil is greater than 5000 mg/kg body weight and not classified according to EU guidelines.

 

In a supporting study conducted on highly refined base oil (Klimisch score = 2; ARCO, 1987a), rats were administered a single oral gavage dose of 5000 mg/kg bw. No mortality or other systemic effects were noted at this dose level.

 

Acute Inhalation

For acute inhalation the key study analyzed the effects of white mineral oil on male and female Crl:CD(SD)BR rats exposed (whole body) to 5 mg/L of aerosolized highly refined base oil for 4 hours (Klimisch score = 1, ARCO 1988a).  After 14 days no mortality was observed. Clinical signs included laboured breathing, rates, partial closing of the eyes, nasal discharge, recumbency, and incoordination.  All animals appeared normal at day 5 after exposure and throughout the remainder of the study period. Four of five females had transient weight loss during the first week of observation. The LC50 of highly refined base oil aerosol administered to rats is greater than 5 mg/L (5000 mg/m3). This dose level is not classified according to EU guidelines.

 

In a supporting study, rats were exposed via inhalation to highly refined base oil. The LC50 as measured based on mortality and systemic effects was > 4.5 mg/L aerosol (Klimisch score = 1, ARCO 1988b). In an additional supporting study, rats were exposed to 5.2 mg/L aerosol of highly refined base oil (Klimisch score = 1, MB Research Laboratories, Inc., 1997). Based on mortality and systemic effects, the LC50 was > 5.2 mg/L. These results do not lead to classification of highly refined base oils as acute inhalation toxicants. 

 

Acute Dermal

A key study analyzed the acute dermal toxic effects of highly refined base oil at a dose of 2000 mg/kg under semi-occlusive conditions for 24 hours (Klimisch score = 2, ARCO, 1987c). After 14 days of exposure no mortality or treatment-related lesions were observed. Three animals lost weight on week two and one animal lost weight during the 14-day observation period. No gross lesions were observed upon necropsy. The acute dermal toxicity LD50 of highly refined base oil to male and female New Zealand White Rabbits is greater than 2000 mg/kg and, therefore, is not classified under EU guidelines.

 

In a supporting study, rabbits were dermally exposed to 2000 mg/kg white mineral oil (Klimisch score = 2, ARCO, 1986). No mortality was noted at this dose level.

 

Justification for selection of acute toxicity – oral endpoint

One of two acute oral studies

Justification for selection of acute toxicity – inhalation endpoint

One of three acute inhalation toxicity studies

Justification for selection of acute toxicity – dermal endpoint

One of two acute dermal studies

Justification for classification or non-classification

Based on evaluation of all the acute toxicity data discussed above, HRBOs do not meet the criteria for classification as acute oral, inhalation or dermal toxicants under EU CLP Regulation (EC No. 1272/2008).