Lubricating oils, used

Endpoint summary

Description of key information

Acute Oral Toxicity:

Acute oral toxicity of various paraffinic and naphthenic other lubricant base oils (IP 346 < 3%) in male and female rats was evaluated in API, 1982a by a single oral gavage administration of 5000 mg/kg body weight. The studies adhered to OECD Guideline 401, which is equivalent or similar to OECD Guideline 420. Based on the lack of clinical signs of toxicity or mortality, the acute oral LD50 for other lubricant base oils "sufficiently refined" and "insufficiently refined" is >5000 mg/kg.

Acute Dermal Toxicity:

Acute dermal toxicity of various paraffinic and naphthenic other lubricant base oils (IP 346 < 3%) in male and female rabbits was evaluated in a key Study by API, 1982a. At doses of either 2000 or 5000 mg/kg body weight. Based on the lack of adverse systemic effects or mortality, the acute dermal LD50 for other lubricant base oils "sufficiently refined" is >5000 mg/kg.

Acute Inhalation Toxicity:

Acute inhalation toxicity of various paraffinic and naphthenic other lubricant base oils (IP 346 < 3%) in male and female rats was evaluated in a key study by Exxon Biomedical Sciences, Inc, 1988a. An aerosol concentration of 5mg/L was found to have no effect. Additional supporting studies also evaluated the acute inhalation toxicity of greater and less than 3% OLBOs. The acute inhalation LC50 for other lubricant base oils is >5.0 mg/L.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

5 000 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

5 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Dose descriptor:

LD50

Value:

5 000 mg/kg bw

Additional information

Acute oral toxicity:

Many key and supporting studies were available to assess the acute oral toxicity of other lubricant base oils (OLBO). Two studies were selected as key studies (API, 1982a and API, 1986a) and 14 were selected at supporting studies. The API 1982a study analyzed the acute oral toxic effects of paraffinic oil (CAS 64742-56-9), a sufficiently refined (IP 346 < 3%) OLBO. In this study, rats were administered a single neat oral dose (5 g/kg) via gavage of the respective OLBO. After 14 days of observation, no mortality or adverse clinical signs of toxicity were seen in either male of female rats. At necropsy, one female rat exhibited cystic masses on the spleen; otherwise, necropsy did not reveal any gross abnormalities in either male or female rats. The acute oral LD₅₀for both studies was >5,000 mg/kg (5 g/kg). Based on this data, paraffinic oil and hydrotreated light naphthenic distillate are nontoxic when administered orally.

Supporting data from studies (API 1982b; 1982c; 1982d; 1982e; 1982f; 1982g 1986b; UBTL, 1983a; 1983b; 1983c; 1983d; 1983e; 1983f) conducted in rats demonstrate that other lubricant base oils (IP 346 < 3%) have acute LD₅₀s >5000 mg/kg or >2000 mg/kg (NOTOX, 1994).

Acute Inhalation Toxicity:

Multiple key and supporting studies were available to assess the acute inhalation toxicity of other lubricant base oils. Two studies were selected as key studies (Exxon Biomedical Sciences, Inc., 1988a and API, 1987a) and 12 were selected as supporting studies. The Exxon Biomedical Sciences, Inc., 1988a study analyzed the toxic inhalation effects of a solvent extracted paraffinic oil, a sufficiently refined (IP 346 < 3%) OLBO. In this study, five male and five female young adult Sprague- Dawley rats were exposed by inhalation route to MRD-87-102 (a sufficiently refined lubricant base oil; IP 346 <3%) for four hours (whole body) at a concentration of 5.53 mg/L. Animals then were observed for 14 days. No mortality in either the control or exposed group was reported. There were no statistically significant differences in mean body weight between groups. Based on the results of the study, the four hour LC₅₀for MRD-87-102 in rats by inhalation would appear to be greater than 5.53 mg/L.

Numerous acute inhalation studies have been made on other lubricant base oils having viscosities ranging from 10-30 cSt (Exxon Biomedical Sciences Inc., 1988b; 1988c, Mobil Oil Corporation 1984a; 1984b, Bioresearch Laboratories, Ltd., 1984a; 1984b; 1984c; 1984c; 1984d; 1984e; 1984f; 1984g; 1984h, Whitman et al. 1989). The majority of the studies show no or minimal lethality at high doses (> 5 mg/L). Only one sample

seems to be more toxic, API 83-12 (which results in LC₅₀= 2.18 mg/L). This sample has higher aromatic content and slightly lower viscosity in comparison to the rest of the samples. Most likely the polycyclic aromatic compounds (PACs) content does not contribute to acute toxicity endpoints. The greater acute inhalation toxicity of this substance is more likely caused by the viscosity (10 cSt). Overall, the weight of evidence suggests that LC₅₀values for this category of other lubricant base oils are greater than 5 mg/L.

Acute Dermal Toxicity:

Multiple studies were available to assess the acute dermal toxicity of other lubricant base oils. The API 1982a study analyzed the acute dermal toxic effects of solvent dewaxed light paraffinic oil (CAS 64742-56-9), a sufficiently refined (IP 346 < 3%) OLBO, at a dose of 5000 mg/kg bw/day for 24 hours on male and female rabbits. In this study, dermal administration at 5000 mg/kg did not result in any dermal irritation or signs of clinical toxicity. Gross necroscopy did not reveal any signs of systemic toxicity at the 5000 mg/kg dose level.

The dermal LD₅₀was determined to be >5000 mg/kg bw.

 

Supporting data from studies (API 1982b; 1982c; 1982d; 1982e; 1982f; 1982g; and 1986b) conducted in rabbits have also demonstrated that sufficiently refined other lubricant base oils (IP 346 < 3%) have dermal LD₅₀s of >5000 mg/kg bw.