A GUIDE TO THE WORK-RELATEDNESS OF DISEASE Revised Edition Stanley Kusnetz, M.S. Marilyn K. Hutchison, M.D. Editors U.S. DEPARTMENT of HEALTH, EDUCATION,and WELFARE Public Health Service Center for Dteeeee Control National Institute for Occupati.onal Safety and Health Jan."" 1979 DISCLAIMER Mention of company name or product does not constitute endorsement by the National Institute for Occupational Safety and Health. This guide is based upon the reports submitted in accordance with NIOSH Contract No. 21Q-75-oo75 (J. E. Osterritter, M.D., Principal Investigator) and NIOSH Contract No. 210-77-0089 (Barbara M. O'Conner and George Christakis, M.D., authors). NIOSH Project Officers: Contract No. 21Q-75'()()75 Marilyn Hutchison, M.D. Stanley Kusnetz, M.S. NIOSH Project Officer: Contract No. 210-77.()()89 Stanley Kusnetz, M.S. DHEW (NIOSH) Publication No. 79-116 ii PREFACE The mission ofthe National Institutefor OccupationalSafety and Health (NIOSH) is to protect the health and safety of working men and women. Within the contextofits program are NIOSH efforts that are directed toward the identification of those disease conditions that are closely related to or caused by the work environment as a necessary prerequisite to their pre­ vention. This guide, originally published in part in 1976, has been revised and expanded to reflect new knowledge as well as suggestions submitted by users of the guide. The guide is designed primarily as an aid to state agencies and others con­ cerned with occupational disease compensation. It presents one method for assembling and evaluating evidence that may be relevant in determining the work-relatedness of a disease in an individual. Information on fourteen disease-producing agents is presented to illustrate the decision-making process. It should be noted thatsuchinformationmaynotbe complete and does not necessarily reflect the most recent data regarding health standards and epidemiologic studies. NIOSH will welcome suggestions from users of the guide for its improvement. III ABSTRACT This guide discusses various factors associated with es­ tablishing the relationship between disease and occupation. Prepared as an aid to state agencies, physicians, and others concerned with workers' compensation for occupational disease, the publication describes a method for collecting, organizing, and appraising medical, occupational, and other evidence with the aim of determining the probable work­ relatedness of a given disease. Illustrativematerial on fourteen disease-producing agents is included. The guide also contains a list of occupations with potential exposure to selected agents, and other information that may be useful to those with decision-making responsibility in cases of occupa­ tional disease. iv CONTENTS Preface __ iii Abstract _ _iv Acknowledgments _.. _.. _. _.. _ _. _. _ vi Introduction _.. _. __ _. __ 1 Chapter I-An Approach to Decision-Making 3 Chapter II-Evidence of Disease _. .. 5 Chapter III-Epidemiology ._ __ . 9 Chapter IV-Evidence of Exposure 11 Chapter V-Aggravation of Preexisting Conditions 15 Chapter VI-Validity of Testimony _.. _ _........... 21 Chapter VII-Conclusions __ . __ _ __ 25 Chapter VIII-Examples ofthe Method 27 Antimony. _ _ __ 28 Inorganic Arsenic _.............. .. 40 Asbes tos 54 Benzene _._.............................. .. 63 Carbon Monoxide _ _................. .. 73 Coke Oven Emissions _ _.......... .. 80 Cotton Dust _ __ . __ . _. .. 88 Inorganic Lead _ _. .. 99 Inorganic Mercury _ _. .. 117 Nitrogen Dioxide , _. .. .. 134 Noise _.. _. _. _ _ _. _.. 146 Crystalline Silica __ 155 Sulfur Dioxide _ __ 168 Toluene Diisocyanate _.. _ _.. _ _. 177 Appendix A-I-Epidemiologic References 185 Appendix A-2-Bibliography 191 Appendix B-Case Histories _ 201 Appendix C-Respiratory Questionnaire __ . 213 Appendix D-Occupations and Selected Potential Exposures _ _ _ _ 219 Appendix E-Glossary __ _ _ 241 Appendix F-Sample OSHA Regulations for Mandatory Physical Examinations and Medical and Biological Monitoring _.. 269 v ACKNOWLEDGMENTS We wish to express appreciation to the following members of the advisory committee for their contributions during this program: Gabriel R Blumenthal Workmen's Compensation Attorney Florida Elmer O. Friday, Jr. Chairman Florida Industrial Relations Commission Florida James E. Harlow Senior Safety Engineer The Bendix Corporation Florida Marge Lehner Claims Adjuster Underwriting Adjusting Company Florida Bart F. O'Brien Assistant Vice President Johnson & Higgins Michigan Nonna J. Wagner Workmen's Compensation Judge Florida Austin F. Henschel, Ph.D.; Larice Ede; and Jim Carpenter of the Division of Technical Services, NIOSH, contributed substantially to reviewing, editing, and preparing the manuscript for publication. vi INTRODUCTION Background Until this century, suing the employer was the only way for disabled workers or their families to obtain compensation for on-the-job injuries. Under common law, workers had to prove the employer's negligence in order to be compensated for work injuries. The injured worker, because ofthis narrow interpreta­ tion of law, found that compensation through the courts was seldom satisfactory. By 1920, all but six states had passed workers' compensation statutes that sought to remedy past deficiencies and to avoid costly litigation by making employers responsible for the economic loss to workers due to injuries sustained at work. Although the new laws established a more equitablecompensa­ tion system, the system has not kept pace with the substantial changes that have taken place in the last half century in the labor force, in medical knowledge and techniques, and in industrial toxicology. In 1970, Congress established a National Commission on State Workmen's Compensation Laws to reexamine the adequacy of the compensation system inlightof these changes. The Commission's published report to the Congress in 1972 lists the objectives of a modern workers' compensation program. Included is a statement that all work­ related injuries or diseases should be covered by the compensa­ tion system. The report also states that coverage restricted to a list ofspecified occupational diseases is incompatible with complete protection. 1 Decision-Making In order for the compensation system to treat both injury and disease in a uniform manner, disease must be related to the workplace as effectively as injury. For the decision-maker, however, establishing the causality ofa disease is often a diffi­ cult task, especially when it becomes necessary to decide if an employee's disease resulted from, or was aggravated by, employment-related factors. In contrast to a traumatic injury, which is readily apparent to the affected employee and to those around him, a cause-effect relationship between disease and an agent or conditions in the workplace may not be clear. Occupational disease may be slow to develop. Symptoms ofdisease may be confused with changes that are due to the aging process, or with the effectsofsmoking or alcohol abuse. Additionally, information on'past work expo­ sures is often unavailable, inadequate, or incomplete. Not all individuals react in the same way to similar exposures to disease-producing agents. Off-the-job exposures may contri­ bute or be a primary cause ofillnesses and accidents. Theseare but some of the factors which must be considered in the decision-making process. The decision of the person responsible for determining the work-relatedness ofa disease must be based on anevaluationof the available information. When appropriate evidence is presented in a logical and orderly sequence, when major issues are identified, and the basis for any presumption is defined, then the decision-making process is facilitated andanequitable decision is likely to result. The following text outlines and describes a method for the collection, presentation, and evaluation of medical, occupa­ tional, and other evidence of occupational disease; presents selected information on fourteen disease-producing agents to illustrate the methodology; and discusses some problem areas associated with decision-making. 2 CHAPTER I-AN APPROACH TO DECISION-MAKING Rationale In the current workers' compensation system, the end result of the adjudicatory process is a decision that the claimant (employee) has or has not established that he has an occupa­ tional disease, that is, a disease condition resulting from, or aggravated by, his employment. In general, a disease is occupa­ tional if: 1. The medical findings ofdisease are compatible with the effects of a disease-producing agent or agents to which the worker has been exposed; 2. there exists in the worker's occupational environment (past or present) exposure to an agent or agents sufficient to have caused the disease; and 3. the weight of evidence supports that the disease is of occupational rather than non-occupational origin. It would be convenient if a method could be devised which invariably led to a correctand unequivocal descision regarding the presence ofan occupational disease. However, itis doubtful that such a system could be developed. A case in which the relationship of an illness to a documented agent exposure is clearly evident is not apt to be contested or to require the mechanism of a formal claims inquiry. The element of judgment is minimal and decision-making is relatively simple. On the other hand, decision-making may be extremely difficult in many contested claims. Honest differences of opinion are common, "facts" may be subject to different interpretations, 3 and considerablejudgmentis necessary when data arelacking or incomplete. This guide is an effort to define a step-by-step method for assembling and appraising evidence for the purpose of aiding the decision-making process. It is intended to be ofparticular assistance in cases where the suspected agent is not generally known to produce disease, and in those in which nonoccupa­ tional exposures must be considered. The Method This guide presents a suggested approach to decision-making that consists of six basic steps: 1. Consideration of evidence of disease, 2. consideration of epidemiologic data, 3. consideration of evidence of exposure, 4. consideration of validity of testimony, 5. consideration of other relevant factors, and 6.