Request to OSHA to Reduce Exposure Levels for Chromium Based on a New Study
July 11, 2000
Charles N. Jeffress
Assistant Secretary of Labor for
Occupational Safety and Health
U.S. Department of Labor
Occupational Safety & Health Administration
Office of Public Affairs - Room N3647
200 Constitution Avenue, NW
Washington, D.C. 20210
Dear Mr. Jeffress:
Using the Freedom of Information Act, we have obtained a copy of an article to be published in the August issue(1) of the American Journal of Industrial Medicine which confirms more clearly than ever before that hexavalent chromium is a potent lung carcinogen.(2) These newly published findings make it clear that your failure to adequately regulate this industrial chemical in a manner consistent with our 1993 petition and 1997 lawsuit to drastically lower workplace exposure levels is in effect a death sentence for thousands of the hundreds of thousands of hexavalent chromium-exposed workers. They also underscore the public health irresponsibility of the Johns Hopkins University researchers and the Environmental Protection Agency (EPA) officials who concluded a Cooperative Agreement to do the study. They then allowed the study to languish unpublished for five years after preliminary data were first presented, knowing all the while the strong relationship between hexavalent chromium and lung cancer demonstrated by the data.
The newly published study is the largest, most comprehensive study of the toxicity of hexavalent chromium ever conducted. Compared to its most prominent predecessor, the so-called Mancuso study,(3),(4) it has more subjects, longer follow-up and better exposure data, and was able to adjust for smoking. The study demonstrates that lung cancer death rates were almost double what would otherwise have been expected for this group and may even be elevated at air chromium levels below those we have recommended as a new standard (see below). With these data finally in hand, there can be no further justification for failing to immediately promulgate regulations to reduce worker exposures to this hazardous chemical.
Background on chromium
Chromium is a metal that is used in the production of metal alloys, such as stainless steel, chrome plating and pigments. It is also used as a catalyst in various chemical processes and is a component of the cement used to manufacture refractory bricks. In the early 1980s, it was estimated that 200,000(5) to 390,000(6) workers were exposed to hexavalent chromium in their workplaces.
The first case of chromium-induced lung cancer was reported in 1890.(7) Since then the evidence of hexavalent chromium carcinogenicity has continued to accumulate. Although there are studies demonstrating increased risks of lung cancer in chromate pigment industry and plating industry workers, the primary evidence of the carcinogenicity of hexavalent chromium came from two studies conducted among chromium production plant workers. In the so-called Mancuso study, 332 workers hired between 1931 and 1937 were followed. Markedly elevated risks of lung cancer were demonstrated.2,3 The other major study, by Hayes, et al., demonstrated that lung cancer death rates were twice as high in the production plant workers as in other city residents.(8) Chromium has been declared a carcinogen by the EPA,(9) the National Toxicology Program(10) and the International Agency for Research on Cancer.(11) While there is little doubt about the carcinogenicity of hexavalent (soluble) chromium, the carcinogenicity of trivalent (insoluble) chromium remains contested.
The National Institute for Occupational Safety and Health recommended in 1975 that the Permissible Exposure Limit (PEL) for total chromium be lowered from the current 100 ug/m3 to approximately 2 ug/m3 as an eight-hour time-weighted average.(12) On July 19, 1993, Public Citizen's Health Research Group (HRG) and the Oil, Chemical and Atomic Workers Union (OCAW, now the Paper, Allied-Industrial, Chemical and Energy Workers International Union, PACE) filed a petition with OSHA requesting that the agency issue an Emergency Temporary Standard (ETS) to lower the PEL for total chromium to 0.5 ug/m3. In our petition, we included a risk assessment that estimated that 22% of workers exposed for a working lifetime to chromium levels at the current PEL would develop lung cancer. OSHA contracted for its own risk assessment, conducted by K.S. Crump Division of ICF Kaiser.(13) That risk assessment, based on lifetime exposures of 50 ug/m3 (as opposed to 100 ug/m3 in our petition), estimated that 9%-34% of workers would contract lung cancer as a result of hexavalent chromium exposure.
On March 8, 1994, OSHA denied the petition for the ETS, but admitted in its response that "there is clear evidence that exposure ... at the current PEL ... can result in an excess risk of lung cancer"(14) and other related illnesses. The agency also undertook to publish a Notice of Proposed Rulemaking (NPRM) in the Federal Register "not later than March 1995." Over five years later, this has still not taken place.
After the promised NPRM failed to transpire, HRG wrote to OSHA which then promised an NPRM in July 1996 and a Final Rule by April 1998. On September 30, 1997, OCAW and HRG sued OSHA in the United States Court of Appeals for the Third Circuit in Philadelphia. On March 13, 1998, the court ruled against OCAW and HRG, in effect leaving the pace of rulemaking at OSHA's discretion. In its submissions to the court, OSHA indicated that an NPRM would be published by September 1999. On April 24, 2000, OSHA published its Semi-annual Agenda and now anticipates an NPRM in June 2001,(15) six years later than its original promise.
History of the EPA/Johns Hopkins study
To investigate the relationship between workplace hexavalent chromium exposure and health, the EPA entered into a Cooperative Agreement with Dr. Peter Lees at Johns Hopkins University School of Hygiene and Public Health. The study was to assess the relationship between chromium exposure and various health outcomes, including lung cancer (see details below). OSHA referred to this study in its response to our 1993 petition. In November 1994, John Martonik, Acting Director of OSHA's Directorate of Health Standards, wrote to the EPA stating that the study was "important to our rulemaking process" and inquiring when the study might be completed. "Due to the important public health policy issues that depend, in part, upon the completion of your update, I must seriously question the adequacy of the [Johns Hopkins University] staff commitment to completion of this project," he said.(16) Herman Gibb of the EPA's Office of Research and Development and the first author of the new article, responded that "We expect a final report should be available by June 1995."(17) By 1995, the study was sufficiently complete to permit a presentation at the 11th International Symposium on Epidemiology in Occupational Health.(18) Similar results were presented at a conference in 1996,(19) followed by another in 1997(20) and two in 1999.(21),(22) No additional raw data were added to the database after 1995, and the 1995 and 1999 presentations present identical mortality ratios. These are only slightly changed in the article to be published.
Thus, although the study was essentially completed in 1995, and although the researchers and the sponsoring agency were fully aware that these data were critical in a federal rulemaking procedure that would affect hundreds of thousands of workers, the study results remained unpublished until now. The industry capitalized upon this combination of incompetence and indifference by writing a series of letters to OSHA requesting that any rulemaking be delayed until the results were published.(23),(24),(25)
We remain unsure precisely why this indefensible delay occurred. As early as 1993, OSHA requested a data tape with the study results from the EPA.(26) The EPA responded that the tape was not yet complete.(27) On the other hand, it is claimed that the EPA offered the data tape to OSHA in 1998, but OSHA failed to respond to the offer.(28) Regardless, this kind of interagency squabbling is an embarrassment to both agencies and may well have resulted in delaying the promulgation of a potentially life-saving occupational health standard.
The EPA/Johns Hopkins study findings to be published in the August American Journal of Industrial Medicine
The study1 included 2357 men who worked at the chromate production plant in Baltimore, MD originally described by Hayes, et al.7 The workers began employment between 1945 and 1974 and their vital status was determined as of December 31, 1992 using the National Death Index, and before that using a variety of other sources, such as voter registration lists, Department of Motor Vehicles data and Social Security Administration records. Chromium levels were measured randomly during much of the study period and chromium exposure was calculated cumulatively, adjusted for the employment duration and work location of each particular worker. The researchers also estimated hexavalent and trivalent chromium exposure separately. Mortality levels in the workers were compared to those of otherwise similar persons in the state of Maryland. The study adjusted for age, race and smoking status at the time of initial employment.
These methods are a substantial improvement over those available to Mancuso.2,3 The present study has seven times as many workers, five times as many person-years of follow-up and twice as many lung cancer deaths. It measured hexavalent chromium directly and concurrently (not indirectly and after-the-fact as in Mancuso), had smoking data and used multivariate analysis, a statistical technique for measuring the independent contribution of different variables. The present study was also able to assess the hazards of chromium exposure at much lower levels than in the Mancuso study.
Overall, lung cancer deaths occurred at 1.8 times the rate that would have been expected for otherwise similar Maryland residents. There was a strong dose-response relationship between cumulative hexavalent chromium exposure and the risk of death from lung cancer. Those in the lowest quartile of exposure had a risk of death from lung cancer that was no greater than otherwise similar Maryland residents. Those in the second exposure quartile had risks 1.4 times what would have been expected, although this did not quite reach statistical significance. Those in the third exposure quartile had a risk of death from lung cancer 1.6 times higher than would have been expected. The mean exposure in this quartile was 0.66 ug/m3,(29) approximately equal to the PEL for which OCAW and HRG petitioned in 1993. Workers in the fourth quartile were 2.2 times more likely to die from lung cancer than would have been expected; this quartile included the current Occupational Safety and Health Administration (OSHA) PEL. If anything, these data demonstrate that the OCAW and HRG were too conservative in our 1993 petition. Taking the lower end of the third exposure quartile as the basis for a PEL, not a very stringent standard, the new PEL would be 0.2 ug/m3, not the 0.5 ug/m3 for which we originally petitioned.
The researchers also used multivariate analysis to control for smoking, decade of employment and race. Compared to the first exposure quartile, the increased hazards of lung cancer were 1.8, 2.5 and 3.3 for the second, third and fourth exposure quartiles respectively. This indicates that although smoking was a risk factor for lung cancer in this study (only four of the lung cancer deaths were in workers who did not smoke at the time of initial employment), cumulative hexavalent chromium exposure emerged as a strong and independent predictor of death from lung cancer. Trivalent chromium was not associated with lung cancer mortality. The authors conclude: "The current study confirms the elevated lung cancer risk from hexavalent chromium exposure observed in other studies and presents the best opportunity to date of evaluating the lung cancer exposure-response relationship from exposure to hexavalent chromium."
In another study based on the same cohort, also to be published in the August issue of the American Journal of Industrial Medicine, and also obtained through the Freedom of Information Act, the same authors evaluated the relationship between hexavalent chromium exposure and skin and nasal irritation.(30) Nasal irritation and nasal ulceration were each diagnosed in more than 60% of the cohort. Nasal ulceration, skin irritation and perforated eardrums were all more common with increasing exposure to hexavalent chromium. The median hexavalent chromium exposure at the time of these and other clinical findings was generally 20 ug/m3, one-fifth of the current OSHA standard. These findings make still more urgent the need to drastically lower the PEL.
Five years since the findings of the lung cancer study were first presented, the data are now fully public. The findings are strong, the methods rigorous and the conclusion inescapable: OSHA is guilty of a massive dereliction of duty that has led to the preventable deaths of thousands of workers. Unfortunately, the chromium case is emblematic of the overall pro-industry orientation of OSHA under the Clinton administration. Clinton's OSHA has failed to propose a single new regulation of a hazardous chemical in the 7½ years it has been in power. (The two regulations it has finalized, methylene chloride and 1,3-butadiene, were first proposed during previous administrations.) If you do not want your administration to go down in history as a massive failure, immediately proposing a rule to regulate chromium is as good a place to start as any.
Peter Lurie, M.D., M.P.H.
Sidney M. Wolfe, M.D.
Public Citizen's Health Research Group
1. While the study will appear in the August issue, the journal has informed us that it will be in the hands of subscribers on the 13th or 14th of July.
2. Gibb HJ, Lees PSJ, Pinsky PF, Rooney BC. Lung cancer among workers in chromium chemical production. American Journal of Industrial Medicine 2000;38:115-26.
3. Mancuso TF. Chromium as an industrial carcinogen: part I. American Journal of Industrial Medicine 1997;31:129-39.
4. Mancuso TF, Hueper WC. Occupational cancer and other health hazards in a chromate plant: a medical appraisal. I. Lung cancers in chromate workers. Industrial Medicine and Surgery 1951;20:358-63.
5. National Institute for Occupational Safety and Health. National Occupational Exposure Survey (1980-83). Department of Health and Human Services, Cincinnati, Ohio, 1984.
6. Centaur Associates, Inc. Technological and economic analysis of regulating occupational exposure to chromium. Unpublished report prepared for the Occupational Safety and Health Administration, 1981.
7. Langard S. One hundred years of chromium and cancer: a review of epidemiological evidence and selected case reports. American Journal of Industrial Medicine 1990;17:189-215.
8. Hayes RB, Lilienfeld AM, Snell LM. Mortality in chromium chemical production workers: a prospective study. International Journal of Epidemiology 1979;8:365-73.
9. US Environmental Protection Agency. Health assessment document for chromium. Environmental Criteria and Assessment Office, Research Triangle Park, NC, 1984 (US EPA-600/8-83-014).
10. US Department of Health and Human Services. 9th Report on Carcinogens, National Institute for Environmental Health Sciences, Research Triangle Park, NC, 2000.
11. International Agency for Research on Cancer. IARC monographs on the evaluation of carcinogenic risks to humans, chromium, nickel and welding. 1990;49:49-256. Lyons, France, World Health Organization.
12. National Institute for Occupational Safety and Health. Criteria for a recommended standard ... Occupational Exposure to Chromium (VI). Cincinnati, Ohio, HEW Pub. No. (NIOSH) 76-129, 1975.
13. K.S. Crump Division. Evaluation of epidemiological data and risk assessment for hexavalent chromium. ICF Kaiser, Ruston, LA, May 1995.
14. Dear JA, Assistant Secretary of Labor for Occupational Safety and Health. Letter to Sidney M. Wolfe, Director, Public Citizen's Health Research Group, March 8, 1994.
15. 65 Fed Reg 23013-23081, April 24, 2000.
16. John F. Martonik, Acting Director, Directorate of Health Standards Programs, Occupational Safety and Health Administration. Memorandum to Herman J. Gibb, Office of Research and Development, Environmental Protection Agency, November 18, 1994.
17. Gibb HJ, Office of Research and Development, Environmental Protection Agency. Letter to John F. Martonik, Acting Director, Directorate of Health Standards Programs, Occupational Safety and Health Administration, December 21, 1994.
18. Lees PSJ, Gibb HJ, Rooney BC. Derivation of exposure-response relationship for chromium from historic exposure data. Presented at 11th International Symposium on Epidemiology in Occupational Health, 1995.
19. Gibb HJ, Chen CW, Lees PSJ, Pinsky P, Rooney BC. Carcinogenic risk assessment of chromium. Presented at Industrial Health Foundation Chromium Symposium, Crystal City, VA, April 23-24, 1996.
20. Gibb HJ. Chromium -- hazard identification and dose response assessment. Presented to CSI Metal Finishing Subcommittee, Washington, DC, June 2, 1997.
21. Gibb HJ, Lees PSJ, Pinsky P, Rooney B. Lung cancer exposure response among workers in chromium chemical production. Presented at AESF/EPA Conference for Environmental Excellence, Orlando, FL, January 1999.
22. Gibb HJ. Considerations for designs of epidemiologic studies for carcinogenic risk assessment of metals. Presented at Jackson State University, Jackson, MS, Spring 1999.
23. Boggs RF, Vice President, Organization Resources Counselors, Inc. Letter to Joseph Dear, Assistant Secretary of Labor for Occupational Safety and Health, September 30, 1994.
24. Sonntag WA, Director of Government Relations, National Association of Metal Finishers, American Electroplaters and Surface Finishers Society. Letter to Joseph Dear, Assistant Secretary of Labor for Occupational Safety and Health, October 3, 1994.
25. Spurlock LA, Vice President, CHEMSTAR, Chemical Manufacturers Association. Letter to Joseph Dear, Assistant Secretary of Labor for Occupational Safety and Health, November 11, 1994.
26. Adkins CE, Director, Health Standards, Occupational Safety and Health Administration. Letter to William Farland, Director, Office of Health and Environmental Assessment, Environmental Protection Agency, September 21, 1993.
27. Farland W, Director, Office of Health and Environmental Assessment, Environmental Protection Agency. Letter to Charles Adkins, Director, Health Standards, Occupational Safety and Health Administration, October 19, 1993.
28. Anon. OSHA never responded to 1998 offer to share hex chrome data. Inside OSHA, November 1, 1999, pp. 1, 6.
29. The cumulative exposures listed in Table VI of the article were converted into instantaneous exposures by multiplying by 1000 to convert mg to ug and dividing by 45 to convert cumulative lifetime exposures into time-weighted averages, the unit used for PELs.
30. Gibb HJ, Lees PSJ, Pinsky PF, Rooney BC. Clinical findings of irritation among chromium chemical production workers. American Journal of Industrial Medicine 2000;38:127-31.