Regulations (Preambles to Final Rules) - Table of Contents Regulations (Preambles to Final Rules) - Table of Contents
• Record Type: Occupational Exposure to Cadmium
• Section: 3
• Title: Section 3 - III. Regulatory History

III. Regulatory History

A. OSHA's Existing PELs

OSHA's existing permissible exposure limits for cadmium were originally developed by the American National Standards Institute. In 1941 the American Standards Association (now American National Standards Institute, or ANSI) set as guidelines an American Defense Emergency Standard of 1000 ug/m(3) for cadmium and its compounds. This was done to reduce discomfort from exposures to cadmium and to reduce the incidence of acute health effects. ANSI revised its standard to current levels (ANSI Z37.5, 1970) which OSHA adopted in 1971 as a national consensus standard under section 6(a) of the Occupational Safety and Health Act of 1970 (29 U.S.C. 655). These PELs, as specified in 29 CFR 1910.1000, Table Z-2 are an 8-hour time-weighted average (TWA PEL) of 100 ug/m(3) for cadmium fume with a ceiling concentration of 300 ug/m(3) and an 8-hour TWA of 200 ug/m(3) for cadmium dust with a ceiling concentration of 600 ug/m(3). OSHA's existing PEL in the construction industry is 100 ug/m(3) for cadmium oxide fumes and 200 ug/m(3) for metal dust and soluble salts (29 CFR 1926.55).

B. Other Agency Findings

In preparing this document, OSHA reviewed the existing regulations for occupational exposures in other countries worldwide. The range of existing PELs runs from the ban of all non-essential uses of cadmium in Sweden to OSHA's existing TWA PEL of 200 ug/m(3) for cadmium dust.

Sweden also established a PEL of 20 ug/m(3) for all existing uses of cadmium along with a PEL of 10 ug/m(3) for all new workplaces. Australia has a PEL of 50 ug/m(3) for both dust and fume but is presently proposing a level of 10 ug/m(3). China and the former USSR follow a PEL of 10 ug/m(3). Finland established a fume PEL of 10 ug/m(3) and dust PEL of 20 ug/m(3), while France allows cadmium oxide dust to be 50 ug/m(3). Japan's PEL is set at 50 ug/m(3). The regulations in the United Kingdom are under review, but the current allowable exposure level is 50 ug/m(3) except for the respirable cadmium sulfide level which is set at 40 ug/m(3) (Ex. L-140-50).

The German government bans the use of cadmium chloride and has also been intent on changing its cadmium exposure levels for all other cadmium compounds based on the MAK carcinogenic classification "A2" which defines cadmium as "unmistakably carcinogenic in experimental animals only" (ACGIH documentation of TLV, 1991).

Agencies and institutions other than OSHA have revised their air quality standards for cadmium. In 1976, the National Institute for Occupational Safety and Health (NIOSH) recommended that exposures to any form of cadmium should not exceed a concentration greater than 40 ug/m(3) as a 10-hour TWA or a concentration greater than 200 ug/m(3) for any 15-minute period. This recommended limit was intended to protect against renal damage and pulmonary disease. In 1984, NIOSH issued a Current Intelligence Bulletin (CIB), which recommended that cadmium and its compounds be regarded as potential occupational carcinogens based on evidence of lung cancer in workers exposed to cadmium in a smelter and that exposures should be reduced to the lowest possible level.

The Environmental Protection Agency (EPA) issued a Health Assessment Document (HAD) for cadmium in 1981 which presented the health effects and potential risk to human health associated with environmental exposure to cadmium. An update of the HAD in 1985 concluded that the epidemiologic evidence is suggestive of a significant risk of lung cancer from exposure to cadmium. According to the EPA's 1984 Proposed Guidelines for Carcinogenic Risk Assessment, cadmium is classified as a Group B1 substance and is thus considered to be a "probable" human carcinogen (Ex. 4-04).

In 1987, the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO) summarized the results from tests for genetic and related effects of a large number of compounds thought to be potentially carcinogenic. The IARC working group of experts evaluated these data as well as epidemiologic and animal studies and concluded that cadmium and cadmium compounds should be classified in Group 2A--"probably carcinogenic to humans" (Ex. 8-681). Since 1946, the American Conference of Governmental Industrial Hygienists (ACGIH) has recommended that exposures to cadmium be controlled. In 1946, ACGIH recommended a Maximum Allowable Concentration (MAC) of 100 ug/m(3) for cadmium. After 1948, the MAC was called the Threshold Limit Value (TLV). In 1956, a TLV of 100 ug/m(3) was assigned to cadmium oxide fume. In 1965, a value of 200 ug/m(3) for cadmium (metal dusts and soluble salts) was proposed; it was adopted as a recommended value in 1967. In 1970, the ACGIH TLV of 200 ug/m(3) for cadmium dust and salts remained unchanged, but the TLV for cadmium fume was changed to a ceiling. In 1973, the ACGIH announced its intent to change the TLV for cadmium fume to 50 ug/m(3) and in 1974 announced its intent to extend this TLV to cadmium dusts and salts. A note was added in 1975 indicating that cadmium oxide production involved carcinogenic or co-carcinogenic potential.

Recently, the ACGIH has recommended further changes in air quality standards for cadmium. They have classified cadmium as a potential human carcinogen and published a Notice of Intent to lower the TLV to 10 ug/m(3) for total dust and 2 ug/m(3) for respirable dust to protect workers from lung cancer and renal dysfunction. ACGIH justified this latest change in part by noting:

In consideration of the strength of the white rat inhalation studies and with some additional support from the retrospective human mortality study by Thun et al., an A(2) designation as an industrial substance of carcinogenic potential for man is given to cadmium and its compounds (Ex. 8-664).

The Mine Safety and Health Administration (MSHA) publishes air quality standards which include cadmium. MSHA frequently incorporates, by reference, the ACGIH TLVs as permissible exposure levels. Currently, MSHA is in the process of updating its PELs to take account of proposed ACGIH changes in the TLVs. MSHA published a Notice of Proposed Rulemaking (NPRM, 8/29/89) proposing alternative TWA PELs of 10 ug/m(3) and 5 ug/m(3) for cadmium. The record for this notice closed on August 30, 1991 and internal review is now underway with an anticipated final standard publication date of February 1993.

Since 1987, the National Center for Health Statistics (NCHS), Department of Health and Human Services, Center for Disease Control, has included cadmium-in-urine measurements in its current third National Health and Nutrition Examination Survey (NHANES III). This survey, originally started in 1974, provides national estimates of diagnosed and undiagnosed medical conditions, as well as information on normal and abnormal conditions in the general population of the U.S. Such information is used by government agencies to obtain a more complete picture of national health and medical needs (Ex. 8-679). OSHA considers the inclusion of cadmium by NCHS to indicate a high level of concern regarding cadmium-related health effects among the general population of the United States. This emphasizes the importance of promulgating a final cadmium standard since general cadmium exposures among the U.S. population are much lower than cadmium exposures among most occupational groups.

C. Unified PEL

In keeping with the recommendations of other agencies like NIOSH, EPA and the ACGIH, this standard does not differentiate between exposure to cadmium fumes or dust. Since the early 1940's, acute inhalation of cadmium fumes from soldering or welding was known to cause severe health effects such as chemical pneumonitis and death (Ex. 8-678). These properties led researchers to readily accept the possibility of adverse health effects associated with exposure to fumes. It is now generally accepted that overexposures to cadmium in any form results in the same final chronic endpoints of cancer and kidney dysfunction (Exs. 4-27, 4-28, 4-68, and 4-19). By 1970, when ANSI republished their original guidelines, it acknowledged that exposures to cadmium fumes or dusts cause irreversible lung damage, proteinuria, and kidney damage. In the mid-1970's the ACGIH announced an intent to change the TLV for all forms of cadmium (fumes, dust, and salts) to 50 ug/m(3), and the differentiation between fumes and dusts was set aside.

D. Chronology of Cadmium rulemaking

OSHA's decision to reduce the PELs for cadmium exposures is, in part, in response to a petition, of June 18, 1986, from the Health Research Group (HRG) of Public Citizen, joined by the International Chemical Workers Union (ICWU), which requested OSHA to issue an Emergency Temporary Standard (ETS) for cadmium providing for a permissible exposure limit (PEL) of 1 ug/m(3) as an 8-hour TWA and 5 ug/m(3) as a ceiling limit. In support of their position the petitioners cited several studies which they believed provided evidence that workers were in grave danger from occupational exposure to cadmium at and below current PELs.

The major human study cited was that by Thun et al. (Ex. 4-68), which found significant increases in lung cancer in cadmium smelter workers. The petitioners also cited several animal studies which demonstrate the carcinogenic potential of cadmium. The most notable of these was an inhalation study cited in which rats exposed to cadmium chloride at levels below OSHA's PEL, developed lung cancer while the unexposed controls developed none (Ex. 4-67). Other human studies cited by the petitioners showed statistically significant increases in prostate cancer among battery factory, smelter, and alloy factory workers exposed to cadmium. Other human studies cited by the petitioners also showed evidence of renal damage and non-malignant respiratory disease among workers exposed to cadmium at levels below the PEL. The exposure limits requested by HRG and ICWU were aimed at ensuring that workers would not be at excess risk of cancer and kidney disease.

On July 1, 1987, OSHA denied the petition for an ETS on the grounds that the record did not support findings that cadmium posed a "grave danger" as defined by the courts. However, OSHA determined that the existing PELs at that time are not sufficiently protective and that the Agency should proceed with permanent rulemaking under section 6(b) of the Act to reduce cadmium exposure. In July of 1989, petitioners, alleging unnecessary delay on OSHA's part, filed a petition for a Writ of Mandamus in the U.S. Court of Appeals for the D.C. Circuit seeking to compel the Agency to issue the proposed and final standards by specified dates. On October 20, 1989, the court ordered the case held in abeyance and ordered OSHA to file a report within three months on the status of the proposed rule and the date by which the Agency expected to issue a final rule. OSHA duly filed its status report, projecting publication of the proposal around the end of January 1990 and publication of the final cadmium rule within 24 months thereafter.

On February 6, 1990 OSHA published its proposed rule to regulate occupational exposure to cadmium (55 FR 4052). The main health effects targeted by the Agency were lung cancer and kidney damage. Based on the Agency's review of major epidemiological studies of lung cancer and renal dysfunction among workers exposed to cadmium, and based on the Agency's quantitative risk assessment, OSHA proposed establishing a PEL of 1 ug/m(3), or in the alternative, a PEL of 5 ug/m(3).

In proposing two alternative PELs, OSHA acknowledged that either PEL would be difficult to achieve in some sectors through engineering controls alone. In these particular industry and occupational sectors reliance upon respirators would be considerable.

Thereafter, on February 12, 1990, the Court of Appeals indicated that it was satisfied with OSHA's compliance to date but noted: (1) that OSHA's projection of 24 months for publishing a final standard exceeded by six months the 18-month period previously projected by the Agency, and (2) that all parties agree that exposure to cadmium poses a serious risk to workers and that OSHA should therefore proceed expeditiously. Consequently, the court ordered that the case continue to be held in abeyance, pending further review, and further ordered OSHA to file with the court, every six months until the final rule is issued, a report indicating the status of the rulemaking and the date by which the Agency expects to issue a final rule.

A public hearing on the proposal was held in Washington, D.C. on June 5-13, 1990, and in Denver on July 17-19, 1990. In response to significant public and expert comment on the proposed medical surveillance provisions, OSHA on July 2, 1990 sent a memo to all hearing participants, requesting further information, testimony, and comments on medical surveillance and smoking in the workplace (Ex. 46). OSHA made this request to hearing participants in order to maximize their participation in the development of the final requirements for medical surveillance and in light of substantial comment in expert and other testimony at the hearings in Washington, D.C., and in pre-hearing written comments.

In the memorandum, OSHA summarized the submissions to the record as follows:

(a) Employer action generally should not be triggered on the basis of a single biological parameter;

(b) Prior to the onset of kidney disease, cadmium levels in urine provide the most practical indication of cadmium body burden;

(c) Concurrently high values in tests for both cadmium in urine and beta-2-microglobulin in urine provide the best early indicator of kidney dysfunction;

(d) A pre-placement (initial) medical examination is necessary for all employees previously, as well as currently exposed to cadmium above the action level to establish their health status;

(e) A termination of employment examination is also necessary to establish the health status of all employees previously exposed above the action level and to facilitate prognosis;

(f) Medical exams may not be necessary annually so long as periodic biological monitoring results are within normal ranges;

(g) Physician's discretion should be an important part of any medical surveillance program;

(h) A physician's decision that an employee must be medically removed from exposure to cadmium above the action level may mean that the employee cannot be returned to work in facilities with cadmium exposure;

(i) Multiple physician review may be an appropriate mechanism to assure the quality of medical determinations; and

(j) OSHA should directly address the issue of smoking among cadmium exposed workers.

In response to these submissions OSHA presented updated medical surveillance provisions and sought further testimony and comment.

In addition, in the memo, OSHA requested information and comments on several issues relating to smoking, including but not limited to: whether smoking is likely to increase the smoker's body burden of cadmium; whether smoking is likely to contribute to cadmium-induced disease; whether OSHA should require the examining physician to inquire about the patient's smoking history and status, and; whether OSHA should require the examining physician to advise the patient that smoking is a source of cadmium exposure that is cumulative with whatever occupational exposure the patient absorbs and that the patient therefore should stop smoking. Comment and information was requested to be provided in testimony at the Denver hearing site and/or in post-hearing comment.

After the Denver hearing of July, 1990, a post-hearing comment period of 90 days was established by the hearing officer, Administrative Law Judge Julius A. Johnson. On September 18, 1990, SCM Chemicals, Inc., a cadmium pigment manufacturer, moved to extend the post-hearing comment period. SCM sought the extension to allow submission to the record of studies that were about to be initiated regarding the possible confounding effect of the photo-decomposition (solubilization) of cadmium sulfide on the results of an important long term inhalation study of rats exposed to cadmium sulfide and other cadmium compounds (Glaser, U., et al., "Carcinogenicity and Toxicity of Four Cadmium Compounds Inhaled by Rats," Toxicological and Environmental Chemistry, Vol. 27, pp. 153-62, 1990). That study by Glaser et al. showed cadmium sulfide to be a lung carcinogen of approximately equal potency with other cadmium compounds. The follow-up studies were to test whether the evidence of equal potency might be attributable, in whole or in part, to the existence of more toxic compounds in the inhaled cadmium sulfide aerosol. Industry representatives asserted that the toxic compounds were produced by the photo-decomposition of cadmium sulfide prior to inhalation by the test animals. The SCM motion was denied by Judge Johnson, but OSHA indicated that if significant new evidence soon became available, the Agency would consider reopening the record. The post hearing comment period ended on October 18, 1990.

On April 22, 1991, the Dry Color Manufacturers' Association (DCMA), representing cadmium pigment manufacturers and users, filed a motion with Judge Johnson to reopen the hearing to allow cross examination of OSHA witnesses regarding the carcinogenicity of cadmium sulfide in light of the results of the follow-up studies which had been completed, or alternatively to remove cadmium pigments from the current rulemaking. In its opposition to the motion, OSHA indicated that, in the interest of fairness and fully developing the record, the Agency would carry out a limited reopening of the record to allow submission of the results of the follow-up studies and written public comment on the studies and underlying issues. DCMA's motion was denied by the judge on May 13, 1991. On May 24, 1991, Judge Johnson certified the record for the public hearing as closed. Thereafter, on June 17, 1991, DCMA moved for reconsideration of its previous motion. On July 5, 1991, OSHA denied the motion to reconsider. In its letter of denial, OSHA reiterated that the Agency would reopen the record for the limited purpose of receiving the final reports of the two recent studies and updated assessments of those reports and to seek public comment on the new evidence and the underlying issues concerning cadmium sulfide. OSHA then contracted with one of its experts at the hearing, Dr. G. Oberdorster, who is a co-author of one of the follow-up studies, and with one of the co-authors of the other study, Dr. U. Heinrich, to assess cadmium sulfide's solubility, bioavailability, toxicity, carcinogenicity and potency relative to other cadmium compounds in light of all the evidence, including their own studies.

The record was reopened for 45 days on September 18, 1991 and closed on November 4, 1991. OSHA submitted the reports of the additional studies of cadmium sulfide and the assessments by Drs. Oberdorster and Heinrich. New data had to be submitted by October 18, 1991, and other comments could be placed in the record until the record closed.

On February 12, 1992 OSHA filed its required status report to the court requesting a six-month extension due to unanticipated difficulties in developing specific portions of the final standard and the complexities of the issues that need to be addressed.

The International Chemical Worker's Union (ICWU) and Public Citizen's Health Research Group (HRG) moved to have the court impose a deadline of August 31, 1992, for OSHA to publish the final standard. Although OSHA expected to have completed the standard by this date, the Agency opposed a court imposed deadline. On March 20, 1992, the court ordered OSHA to issue the final rule by August 31, 1992 (International Chemical Workers Union, et al., v. Strunk and Martin, No. 89-1357, March 20, 1992).

On June 5, 1992, DCMA filed another motion with the Agency to remove cadmium pigments from consideration in the final rule due to evidence adduced subsequent to the public hearings alleging that cadmium pigments are less toxic than other cadmium compounds (Ex. 171; and see Ex. 172). OSHA denied the motion for reasons stated in previous responses to DCMA and in this preamble (Ex. L-173).

In this rulemaking, OSHA has developed two final standards, one for general industry, maritime, and agriculture, and a separate one for the construction industry. In both standards, the Agency has concluded that excess exposure to cadmium in any form does pose a significant threat to the health of workers, whether it is from material impairment of kidney function, lung cancer or other cadmium-related illnesses. OSHA determined that the TWA PEL should not be set above 5 ug/m(3) based on the record of evidence and its own quantitative risk assessment. The Agency found that the animal and human data show strikingly similar evidence of cadmium toxicity. The decision to establish the PEL at 5 ug/m(3) was made on the basis of feasibility as well. OSHA's quantitative risk assessment does not take account of the reductions in risk attributable to the ancillary provisions. Although OSHA's risk assessment indicates that some risk may remain at a TWA PEL of 5 ug/m(3), the Agency has relied upon the ancillary provisions to eliminate significant risk at the new PEL.

[57 FR 42102, Sept. 14, 1992; 58 FR 21778, April 23, 1993]

Regulations (Preambles to Final Rules) - Table of Contents Regulations (Preambles to Final Rules) - Table of Contents