NICKEL CARBONYL

OSHA comments from the January 19, 1989 Final Rule on Air Contaminants Project extracted from 54FR2332 et. seq. This rule was remanded by the U.S. Circuit Court of Appeals and the limits are not currently in force.

CAS: 13463-39-3; Chemical Formula: Ni(CO)₄

The current OSHA PEL and the NIOSH recommended limit for nickel carbonyl is 0.001 ppm TWA, as Ni. Nickel carbonyl is a gaseous compound at ordinary pressure or a colorless, highly volatile liquid, with a musty odor. In 1976, the ACGIH increased its TLV for nickel carbonyl from 0.001 to 0.05 ppm. The ACGIH’s former 0.001-ppm TLV was based primarily on the high incidence of nasal and lung cancer among workers exposed to nickel carbonyl during work in nickel refinery operations. In addition, the ACGIH cited evidence (Sunderman, West, and Kincaid 1959/Ex. 1-384) that rats exposed to nickel carbonyl developed lung tumors that metastasized to the kidneys. At the time, the ACGIH (1966/Ex. 1-13) noted that these tumors were not of a type generally associated with exposure to environmental agents.

In its 1976 documentation for the 0.05-ppm TLV for nickel carbonyl, the ACGIH cited the work of Doll, Morgan, and Speizer (1970/Ex. 1-821), who evaluated the exposures of nickel refinery workers in whom cancers had been found. Doll and associates (1970/Ex. 1-821) found that there had been no exposures to nickel carbonyl in the facility, and this finding led the ACGIH to conclude that nickel carbonyl was not the causative agent of the cancers reported among the refinery workers in the earlier studies it had relied on to set the 0.001-ppm TLV. A report that no excess nasal or lung tumors had occurred among workers exposed over a 50-year period in a nickel refinery in Wales (Renzoni, personal communication, 1975, as cited in Documentation of the Threshold Limit Values for Substances in Workroom Air, 3rd ed., ACGIH 1976) appeared to the ACGIH to corroborate Doll et al.’s (1970/Ex. 1-821) results. The ACGIH concluded that the TLV for nickel carbonyl should be raised based on the acute, systemic effects of this substance, and that carcinogenicity was not an appropriate basis for limit-setting (ACGIH 1976). In the 1986 Documentation for the 0.05-ppm TLV for nickel carbonyl, the ACGIH (Ex. 1-3) concluded that, “although the evidence that nickel carbonyl is carcinogenic to humans is inconclusive, this recommended TLV (i.e., one set at 0.05 ppm) is also adequate to minimize any potential carcinogenic effects” (ACGIH 1986/Ex. 1-3, p. 424).

OSHA received comments on nickel carbonyl from NIOSH (Ex. 8-47, Table N6A) and from Inco United States, Inc. and Inco Limited (Exs. 3-915 and 167). Inco urged OSHA to adjust the PEL for nickel carbonyl to 0.05 ppm and also stated that the limit for this substance should not be enforced until an adequate sampling and analytical method has been developed. On this issue of the health basis for an increase in the PEL, OSHA notes that Inco, like the ACGIH (1986/Ex. 1-3), believes that it is appropriate to increase this limit on the sole basis of results of negative epidemiological studies and a personal communication attesting to the absence of a “significant positive association with risk” in a Welsh refinery. However, as described in the introduction to this section, OSHA must meet a more stringent test before raising a limit. In addition, the interpretation of negative studies in humans is complicated by a host of factors (see Section VI.A of this preamble).

As to Inco’s second point, OSHA notes that it has an in-house sampling and analytical method for nickel carbonyl that is available from the Agency on request. In addition, the limit for nickel carbonyl at issue is the limit that was assigned to this substance in 1971, at the time the Agency was established. OSHA is not required to perform feasibility analyses on its existing limits, and the Agency is unaware of any unusual compliance difficulties with this substance.

NIOSH (Ex. 8-47, Table N6A) concurs that retention of OSHA’s limit is appropriate because NIOSH regards nickel carbonyl as a potential occupational carcinogen. Thus, OSHA finds the evidence discussed by the ACGIH insufficient to warrant an increase in the limit; some of this evidence is in the form of a personal communication. The Agency concludes that increasing the limit for this substance would increase the significant risk for exposed workers. In the final rule, OSHA is therefore retaining the existing PEL for nickel carbonyl of 0.001 ppm as an 8-hour TWA.