OSHA formerly had a limit of 5 mg/m3 as an 8-hour TWA for oil mist. The Agency proposed to retain 5 mg/m3 as an 8-hour TWA PEL and to add 10 mg/m3 as a 15-minute STEL; however, the final rule retains the former 8-hour TWA but does not add a STEL. The ACGIH has a 5-mg/m3 TLV-TWA limit and a 10-mg/m3 TLV-STEL for oil mist (mineral), which refers to the airborne mist of petroleum-based cutting oils or of white petroleum oil; the odor of this substance is described as similar to that of burned lubrication oil.
Studies in animals have shown that repeated six-hour daily exposures to 5 mg/m3 caused no adverse effects (Wagner, Wright, and Stokinger 1964, as cited in ACGIH 1986/Ex. 1-3, p. 449). At 100 mg/m3,slight changes, including lung effects, were observed in exposed animals (Lushbaugh, Green, and Redemann 1950/Ex. 1-792). It has been suggested that heat-decomposed oil fumes are irritating to the lungs (Wagner, Dobrogorski, and Stokinger 1961/Ex. 1-773).
OSHA received a number of comments on the proposed STEL for oil mist (Exs. 3-829, 3-830, 3-856, 3-1115, 188, and 194; Tr. pp. 7-47 to7-53). For example, William Fladung, Manager of Environmental Control forthe Timken Company, believes that the limits for oil mist presented inthe proposed rule are not justified by the evidence discussed in the preamble to the proposal (Ex. 3-856). According to this commenter, "the only health effect observed in animals is `lung irritation.' No health effect has been observed in humans" (Ex. 3-856). This view was shared by representatives of the Independent Lubricant Manufacturers Association (Ex. 3-830), the Specialty Steel Industry of the United States (Ex.3-829), and the Anti-Friction Bearing Manufacturers Association(Ex. 3-1115).
In response to these comments, OSHA has reviewed the toxicological evidence for oil mist. Proctor, Hughes, and Fischman (Chemical Hazards of the Workplace, 2nd ed., 1988) report a single case of lipoid pneumonitis in a worker repeatedly exposed to high concentrations of oil mist, and these authors also note that some mineral oils (i.e.,those containing additives and impurities) have been linked to cancers of the skin and scrotum. NIOSH submitted comments to the record notingthat certain types of oils and/or their additives may present a carcinogenic hazard (Ex. 150, Comments on Oil Mist). The United Auto Workers and the AFL-CIO (Tr. pp. 7-47 to 7-53) urged OSHA to adopt a lower PEL on the basis of oil mist's carcinogenic effects. According to the UAW, oil mist "has been known for many years...[to] cause skin cancer, particularly scrotal cancer among exposed workers" (Tr. p. 7-50). The UAW also believes that oil mist exposure increases the risk of primary malignancies of the respiratory and upper digestive systems (Tr. p.7-50). However, OSHA believes that these carcinogenic effects maybe attributable to contaminants in the oil, such as polycyclic aromatic hydrocarbons and certain additives. OSHA also notes that modern refining techniques have generally eliminated these hazardous substances from mineral oils.
After a review of the record evidence, OSHA finds that the toxicological data on this substance do not support the addition ofa STEL at this time. Accordingly, the final rule retains the 8-hour TWA PEL of 5 mg/m3 but does not add a 15-minute STEL of 10 mg/m3 for mineral oil mist. The Agency concludes that the existing 8-hour TWA limit will protect exposed employees against the significant risks of eye and respiratory tract irritation potentially associated with exposures to mineral oil mist. OSHA finds that these eye and lung effects constitute material impairments of health.