□ @KI criteria for a recommended standard occupational exposure to TUNGSTEN and CEMENTED TUNGSTEN CARBIDE U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE Public Health Service Center for Disease Control National Institute for Occupational Safety and Health criteria for a recommended standard OCCUPATIONAL EXPOSURE TO TUNGSTEN and CEMENTED TUNGSTEN CARBIDE U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE Public Health Service Center for Disease Control National Institute for Occupational Safety and Health September 1977 For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 DHEW (NIOSH) Publication No. 77-127 PREFACE The Occupational Safety and Health Act of 1970 emphasizes the need for standards to protect the health and safety of workers exposed to an ever-increasing number of potential hazards at their workplace. The National Institute for Occupational Safety and Health has projected a formal system of research, with priorities determined on the basis of specified indices, to provide relevant data from which valid criteria for effective standards can be derived. Recommended standards for occupational exposure, which are the result of this work, are based on the health effects of exposure. The Secretary of Labor will weigh these recommendations along with other considerations such as feasibility and means of implementation in developing regulatory standards. It is intended to present successive reports as research and epidemiologic studies are completed and as sampling and analytical methods are developed. Criteria and standards will be reviewed periodically to ensure continuing protection of the worker. I am pleased to acknowledge the contributions to this report on tungsten and cemented tungsten carbide by members of the NIOSH staff and the valuable constructive comments by the Review Consultants on tungsten and cemented tungsten carbide, by the ad hoc committees of the American Academy of Industrial Hygiene and the American Medical Association, and by Robert B. O ’Connor, M.D., NIOSH consultant in occupational medicine. The NIOSH recommendations for standards are not necessarily a consensus of all the consultants and professional societies that reviewed this criteria document on tungsten and cemented tungsten carbide. A list of Review Consultants appears on page vi. sJohn F. Finklea, M.D. Director, National Institute for Occupational Safety and Health The Division of Criteria Documentation and Standards Development, National Institute for Occupational Safety and Health (NIOSH), had primary responsibility for development of the criteria and recommended standard for tungsten and cemented tungsten carbide. Sonia Berg of this Division served as criteria manager. Stanford Research Institute (SRI) developed the basic information for consideration by NIOSH staff and consultants under contract CDC-99-74-31. The Division review of this document was provided by Richard A. Rhoden, Ph.D. (Chairman), J. Henry Wills, Ph.D., and Howard L. McMartin, M.D., with Gregory Ness (Division of Surveillance, Hazard Evaluations, and Field Studies), and Charles C. Hassett, Ph.D. John J. McFeters and Mary E. Cassinelli (Division of Physical Sciences and Engineering) submitted written comments. The views expressed and conclusions reached in this document, together with the recommendations for a standard, are those of NIOSH. These views and conclusions are not necessarily those of the consultants, other federal agencies or professional societies that reviewed the document, or of the contractor. v REVIEW CONSULTANTS ON TUNGSTEN AND CEMENTED TUNGSTEN CARBIDE Mary 0. Amdur, Ph.D. Associate Professor of Toxicology Harvard University School of Public Health Boston, Massachusettes 02115 Edward L. Farley President Oil, Chemical, and Atomic Workers International Union Local 2-24410 Salida, Colorado 81201 Michael E. Lichtenstein Industrial Hygiene Engineer Boeing Aerospace Company Seattle, Washington 98124 Morton Lippmann, Ph.D. Associate Professor Institute of Environmental Medicine New York University New York, New York 10016 Frederick T. McDermott District Engineer State of Michigan Department of Health Pontiac, Michigan 48055 Howard J. Sawyer, M.D. President and Medical Director Detroit Health and Safety Associations, Incorporated Farmington Hills, Michigan 48024 James Cohn US Department of Labor Liason Office of Standards Development Occupational Safety and Health Administration vi CRITERIA DOCUMENT: RECOMMENDATIONS FOR AN OCCUPATIONAL EXPOSURE STANDARD FOR TUNGSTEN AND CEMENTED TUNGSTEN CARBIDE Table of Contents Pa8e PREFACE iii REVIEW CONSULTANTS vi I. RECOMMENDATIONS FOR A STANDARD FOR TUNGSTEN AND CEMENTED TUNGSTEN CARBIDE 1 Section 1 - Environmental (Workplace Air) 4 Section 2 - Medical 5 Section 3 - Labeling and Posting 7 Section 4 - Personal Protective Clothing and Equipment 8 Section 5 - Informing Employees of Hazards from Tungsten 12 Section 6 - Work Practices 13 Section 7 - Sanitation 15 Section 8 - Environmental Monitoring and Recordkeeping 15 II. INTRODUCTION 19 III. BIOLOGIC EFFECTS OF EXPOSURE 21 Extent of Exposure 21 Historical Reports 23 Effects on Humans 24 Carcinogenicity Reports 38 Epidemiologic Studies 41 Animal Toxicity 52 Correlation of Exposure and Effect 85 Carcinogenicity, Mutagenicity, Teratogenicity, and Effects on Reproduction 92 IV. ENVIRONMENTAL DATA AND ENGINEERING CONTROLS 100 Environmental Concentrations 100 Engineering Controls 104 Sampling and Analysis 108 V. WORK PRACTICES 117 Table of Contents (Continued) Page VI. DEVELOPMENT OF STANDARD 122 Basis for Previous Standards 122 Basis for the Recommended Standard 124 VII. RESEARCH NEEDS 134 VIII. REFERENCES 137 IX. APPENDIX I - Method for Sampling Tungsten and its Products in Air 146 X. APPENDIX II - Analytical Method for Tungsten 150 XI. APPENDIX III - Material Safety Data Sheet 156 XII. TABLES AND FIGURES 166 I. RECOMMENDATIONS FOR A STANDARD FOR TUNGSTEN AND CEMENTED TUNGSTEN CARBIDE The National Institute for Occupational Safety and Health recommends that employee exposure to elemental tungsten and its compounds and to cemented tungsten carbide dusts in the workplace be controlled by adherence to the following sections. The standard is designed to protect the health and provide for the safety of employees for up to a 10-hour work shift, 40- hour workweek, over a working lifetime. Compliance with all sections of the standard should prevent adverse effects (except sensitization) of these materials on the health and provide for the safety of employees. The recommended environmental limits for the standard are measurable by techniques that are reproducible and available to industry and government agencies. Sufficient technology exists to permit compliance with the recommended standard. Although NIOSH considers the workplace environmental limits to be safe levels based on current information, employers should regard them as the upper boundaries of exposure and make every effort to maintain exposures as low as is technically feasible. The criteria and standard will be subject to review and revision as necessary. Approximately 70% of US tungsten production is eventually used in the manufacture of cemented tungsten carbide, where tungsten carbide is mixed with cobalt and/or other metals, including nickel, and their oxides or carbides to form a material valued for its hardness and wear resistance. The term "insoluble tungsten," used throughout this document, refers to elemental tungsten and all insoluble tungsten compounds (Table XII-1). The 1 term "soluble tungsten" refers to those compounds of tungsten which are soluble in water and therefore readily translocated from the lungs, skin, or gastrointestinal tract to internal organs of experimental animals (Table XII-1). For the purpose of compliance with the recommended standards, insoluble tungsten compounds include all those for which water solubility is listed as "insoluble" or less than 0.01 g/100 cc. Soluble tungsten compounds are those listed as "very soluble," "soluble," "slightly soluble," equal to or greater than 0.01/100 cc or "decomposes." Those compounds for which no solubility information is listed should be considered soluble unless it can be demonstrated that they are insoluble in water. As a rough guide for control of airborne concentrations of tungsten compounds, the standard for insoluble tungsten should apply whenever processes within a building or independent structure involve only those stages which produce insoluble tungsten compounds from other insoluble tungsten compounds, eg, starting with ammonium-p-tungstate through tungsten carbide (Figure XII-1). Whenever soluble tungsten compounds are starting, intermediate, or final products, the standard for soluble compounds should apply throughout that building, unless it can be demonstrated through differential sampling and analysis that both limits are being met as appropriate. The term "cemented tungsten carbide" or "hard metal" refers to a mixture of tungsten carbide (WC), cobalt, and sometimes other metals and metal oxides or carbides. The tungsten carbide content of hard metal is generally 80% or more, and the cobalt content is generally less than 10%, but it may be as high as 25%. When the cobalt content exceeds 2%, its contribution to the potential health hazard is judged to exceed that of 2 tungsten carbide and all other components, and the recommended standard for such mixtures is based on the current US federal standard for occupational exposure to cobalt, 0.1 mg/cu m. If a future NIOSH recommendation