Opinion ID: 1433888
Heading Depth: 2
Heading Rank: 1

Heading: Toxicity of Cr(VI) Compounds in Electric Power Plants

Text: EEI challenges OSHA's reliance on the Gibb and Luippold cohorts, studies drawn from the chromate production industry, to establish the toxicity of the Cr(VI) compounds found in electric power plants. EEI points to portions of a statement by Dr. Herman Gibb, of the Gibb study, suggesting that the relative toxicity of different forms of Cr(VI) compounds encountered in different industries may vary. ( See Ex. 47-8, Post-Hearing Comments From Herman Gibb on the Proposed Hexavalent Chromium Rule, Mar. 21, 2005 (Gibb Comments)). EEI also points to two cases, Texas Independent Ginners Ass'n v. Marshall, 630 F.2d 398, 403 (5th Cir.1980), and Color Pigments Manufacturer's Ass'n, Inc. v. OSHA, 16 F.3d 1157 (11th Cir.1994), to support its assertion that evidence of health risks in one industry may not be relied on to establish health risks in a second industry. EEI identifies no evidence, in the record or otherwise, suggesting that Cr(VI) compounds encountered in electric power plants are any less carcinogenic than Cr(VI) compounds encountered in chromate production. In reaching a conclusion as to the existence of significant risk, OSHA need not calculate risk with mathematical precision, nor does the substantial evidence standard require the Agency to support its risk determination with anything approaching scientific certainty. Benzene, 448 U.S. at 655-56, 100 S.Ct. 2844. Under the best available evidence standard, so long as they are supported by a body of reputable scientific thought, the Agency is free to use conservative assumptions in interpreting the data with respect to carcinogens, risking error on the side of overprotection rather than underprotection. Id. at 656, 100 S.Ct. 2844. During rulemaking, OSHA considered arguments that risk estimates derived from Cr(VI) compounds found in the chromate production industry were not applicable to other industries. 71 Fed.Reg. 10,334. However, OSHA ultimately determined that all Cr(VI) compounds are carcinogenic, and that the risk estimates derived from the Gibb and Luippold cohorts were reasonably representative of the risks expected from equivalent exposures to different Cr(VI) compounds in other industries. Id. During rulemaking, the Agency specifically asked for Dr. Gibb's opinion on this precise matter through a post-hearing question. Dr. Gibb's response, taken in its entirety, provides no support for EEI's position: Should the exposure response observed in the chromium chemical production worker studies be restricted to setting a PEL only for the chemical production industry? Answer: It is conceivable that differences in exposure (e.g. practical size, nature of the aerosol, etc) between some industries (e.g. steel, aerospace, lead chromate pigment production) and the chromium chemical production industry could lead to differences in cancer risk, but the available data are inadequate to evaluate whether such differences exist .... It is unlikely that adequate studies of all industries affected by this proposed rule will ever be conducted. In the absence of more definitive information regarding specific industries, it is prudent to regard exposure to any hexavalent chromium compound as presenting an excess lung cancer risk and that the exposure response observed in the chromium chemicals production industry should apply to other industries with occupational exposure to hexavalent chromium. (Gibb Comments at 5 (emphasis added).) In explaining its final risk determinations regarding Cr(VI), OSHA stated that the Gibb cohort and the Luippold cohort, were found to be the strongest data sets for quantitative assessment because, in part, the two had the most extensive and best documented Cr(VI) exposures spanning three or four decades. 71 Fed.Reg. 10,176. Dr. Gibb's comments bolster OSHA's conclusion that the Agency based its health risk determination on the best quantitative estimates of excess lifetime lung cancer risks available. Id. at 10,220. To the extent that OSHA's reliance on these estimates might conceivably have been conservative, Benzene permits the Agency to risk error on the side of overprotection. Since Dr. Gibb expressly recommended that OSHA rely on the chromate production studies to establish the toxicity of Cr(VI) compounds generally, his testimony is of no help to EEI. EEI's reliance on Color Pigments and Texas Independent is also misplaced. EEI points to portions of both cases in which the relevant issue was not the inherent toxicity of certain compounds, but the amounts of known toxins encountered in different industries. There is no dispute here that different operations naturally generate different concentrations of Cr(VI). The Cr(VI) standard accounts for these differences by requiring all employers to comply with a uniform exposure limit. In Texas Independent, the cotton dust standard at issue did not establish an exposure limit or require employers to limit cotton dust emissions. See Texas Independent, 630 F.2d at 403. OSHA did not measure exposure levels in the cotton gin industry, but sought to impose medical surveillance requirements on that industry on the basis of negative health effects observed in cotton textile manufacturing processes. Id. at 409. The court determined that OSHA's risk assessment lacked substantial evidence because the concentration of cotton dust in cotton gin operations was substantially lower than the concentrations encountered in cotton manufacturing. Id. at 409. Thus, the disputed issue was the amount of occupational exposure to a particular substance in disparate industries, not the toxicity of the substance itself. Color Pigments is similarly inapplicable. OSHA's technological feasibility analysis for the cadmium standard at issue was based upon the extent to which employers could reduce toxin concentrations below an initial exposure level. 16 F.3d at 1162-63. Proper calculation of the initial exposure level in a given industry was therefore vital. Id. at 1163. OSHA established the initial exposure level in the chemical mixer industry by using data captured from the dry color formulator industry. Id. at 1162. The court ruled that this methodology was inadequate because OSHA failed to account for variables between the industries that would affect the amount of cadmium to which employees were exposed. Id. Thus, the disputed issue was again the level of exposure to a toxic substance in disparate industries, not the toxicity of the substance itself. EEI identifies no case in which a court faulted OSHA for using medical data derived from one industry to establish the toxicity of a substance generally. In fact, in another portion of the Color Pigments decision, the Eleventh Circuit rejected an argument that mirrors the one made here by EEI. The cadmium pigment industry argued that OSHA should have excluded it from the cadmium standard because exposure to cadmium pigment was allegedly less toxic and carcinogenic[] than other forms of cadmium. Id. at 1161. The court disagreed: Given the absence of definiteness on the issue, the volume of evidence that points at least implicitly to the dangers of cadmium pigments, and the serious potential health risks present if cadmium exposure is as great in pigment form as in other compounds, we believe that OSHA was justified in choosing to include cadmium pigments in the PEL, despite the existence of an equally rational alternative. Id. EEI's argument is no more availing. OSHA's conclusion that health risk data derived from the chromate production industry was sufficient to establish the toxicity of Cr(VI) compounds generally is supported by the best available evidence and by substantial evidence. We will therefore not disturb the Agency's decision.