Occupational Injuries and Deaths among Loggers, United States
Todd M. Frazier, Sc.M. Robert J. Mullan, M.D.
Surveillance Branch Division of Surveillance, Hazard Evaluations, and Field Studies Patrick J. Coleman, Ph.D.
Safety Surveillance Branch Division of Safety Research National Institute for Occupational Safety and Health Introduction
Logging has long been recognized as one of the most hazardous occupations in the United States (1). To evaluate the incidence of occupational injury and death among loggers and to discern risk factors, the National Institute for Occupational Safety and Health (NIOSH) has examined data on morbidity, disability, and mortality collected in four federal and state systems (2). This report summarizes information on the nature and extent of accidents among loggers and the implications of that knowledge for preventing injuries and promoting safety. Materials and Methods
United States Census Data. The 1970 U.S. Census showed 79,507 persons in the categories lumberman, raftsman, and woodchopper (referred to as loggers in this study). Of these persons, 73,192 were employed specifically in the logging industry (3). For the purposes of this report, this group constitutes the population at risk. Over 51% of the loggers in the United States are less than 40 years of age, 23% are 40-49, 18% are 50-59, and 8% are more than or equal to 60 (4). These data from the 1970 census were used as a denominator to calculate injury incidence ratios (number of injuries divided by the number of loggers enumerated by the 1970 census).
Health Interview Survey. The annual Health Interview Survey (HIS), performed by the National Center for Health Statistics, includes data on limitation of activity, persons injured, hospitalizations, days of disability, dental and medical visits, incidence of acute conditions, and prevalence of selected chronic conditions (5). Approximately 40,000 households, comprising about 110,000 persons, are selected for interview in a probability sample representative of the civilian, noninstitutionalized population of the United States. The annual response rate is more than or equal to 95% for households eligible for the sample.
During interviews conducted for HIS, workers are asked about injuries they incurred within 2 weeks before their interviews. An injury is a condition of the type that is classified according to the nature-of-injury code numbers (800-999) in the International Classification of Diseases (ICD) (6). Statistics for acute injuries include only those injuries that involve at least one full day of restricted activity or require medical attention. Since one person may incur more than one injury in a single accident, the number of persons injured in a specified interval may be lower than the number of injury conditions used to calculate incidence.
For this study, data for the period 1969-1974 were obtained for males employed in the manufacture of lumber and wood products, a classification that includes loggers (7). Persons in the labor force were classified by occupation to code categories in the Classified Index of Occupations and Industries of the U.S. Bureau of the Census, which was used for the 1970 decennial census (8).
Social Security Administration's Continuous Disability History Sample File. Since 1956 the Social Security Administration (SSA) has been paying cash benefits to eligible disabled workers (9). To qualify for benefits, workers disabled after age 30 must have worked in jobs covered by social security for at least 5 of the 10 years immediately preceding the onset of disability; progressively fewer years of coverage are required for younger workers. To be eligible, a worker must be unable to engage in any substantial, gainful activity because of a medically documentable physical or mental impairment that has lasted or can be expected to last for at least 12 months or is expected to culminate in death.
From 1969 to 1972, approximately 96% of the 80 million workers in the United States were insured under the program, and about 1.6 million of these workers received Social Security disability benefits. Recently, more than 400,000 workers have been granted disability benefits each year.
The source of data for this report was the Continuous Disability History Sample (CDHS) file. This file contains long-term data, and new recipients of disability insurance benefits who meet the selection criteria are listed in the file when their claims are processed. The file is updated annually to accumulate new earnings and entitlement data for each applicant. From these data, a statistically selected sample is chosen to ensure representativeness and an overall sampling rate of approximately 20%.
Disabling conditions are coded according to the eighth revision of the ICD (7). "Occupation" indicates the disabled worker's longest full-time occupation in the 10 years preceding the alleged date of the disability; it is coded according to the occupational classification in the Dictionary of Occupational Titles (10).
Washington State and California Mortality Studies. Washington and California (by coincidence in the same lumber region) have conducted occupational mortality investigations that include workers in the logging industry as one of the occupational groups studied (11,12). The primary source of material for the California study was the state death file for the years 1959-1961. Over this 3-year period, about 407,000 deaths among California residents were recorded. This study used the subfile of about 199,000 white male decedents more than or equal to 20 years of age. Information was collected from death certificates on occupation, industry, and cause of death coded according to the seventh edition of the ICD (13). The basic occupational coding scheme used was the Bureau of the Census Classified Index of Occupations and Industries as it was used for the 1960 census of population (14).
For the Washington State study, death-certificate information was obtained for the years 1950-1971. Since the study included an ICD code change, codes from the eighth revision were translated back to codes as shown in the seventh revision. Occupational coding was done according to the 1960 Bureau of the Census Classified Index of Occupations and Industries.
Washington State and California Workers' Compensation Files. Data for 1979 from the workers' compensation files of California and Washington were made available to NIOSH from the Supplementary Data System (SDS) of the Bureau of Labor Statistics, U.S. Department of Labor (15). The SDS obtains data on occupational injury and illness from states, based on employers' first reports of injury submitted to compensation agencies for state workers. The data are a by-product of state-administered workers' compensation programs. The following information is collected for each worker: occupation, industry, sex, nature of injury or illness, part of body affected, source of injury or illness, and type of accident. Specific descriptive characteristics of injuries to loggers in California and Washington have been tabulated, both to provide detail not available through the other data systems and to compare the nature of injury of cases in the workers' compensation files with those in the SSA sample.
For these data bases, the nature of injury is coded according to the American National Standards Institute, Inc. (ANSI) z16.2 classification. While the ANSI z16.2 classifications are not strictly comparable to the ICD codes, comparisons can provide useful information. Results
Findings Based on Data from HIS. Injuries reported by workers--including loggers--who produce lumber and wood products varied from sprains and strains to severe fractures (Table 1). In the period 1969-1974, workers who produced lumber and wood products experienced an injury rate 38% higher than that for all types of workers combined. Furthermore, loggers in the Western Region reported a disproportionately high share of the injuries reported for loggers throughout the country, i.e., 20% of all U.S. loggers live in the Western Region but account for 32% of the logging-related injuries (Figure 1).
Findings Based on Data from SSA. In the period 1969-1973, 1,053 awards for continuous disability were made to loggers as the result of disabling injuries sustained in work-related accidents. In that period, 33% of all disabling injuries reported by this mechanism involved fractures of the lower limbs; injuries to the upper extremities, skull, spine, and trunk accounted for 25%; and dislocation without fracture accounted for 4% of all awards (Table 2). This last finding contrasts with the data from HIS, in which dislocation without fracture caused a high proportion (64%) of continuous disability among loggers.
Analysis of these data by geographic region showed a preponderance of disabling injuries among loggers in the West (similar to that shown in the HIS data) (Figure 1). Analysis by age revealed that the frequency rate of awards generally increased with increasing age; the 50- to 59-year age group experienced the highest rate (Table 3).
Findings of Mortality Studies in Two States. In both California and Washington, there was excess mortality among loggers from injuries caused by falling objects, when compared with the expected incidence of deaths from that cause for other occupational groups in those states. In California, from 1959 to 1961, 42 deaths were reported to result from injuries associated with a blow from a falling object; only one death from this cause had been expected. In Washington, in 1950-1971, 368 fatal injuries of this type were reported, with 34 deaths having been expected.
Findings Based on Data from Workers' Compensation Files in Two States. Cuts and lacerations were the most frequent injury (28%) among loggers for whom compensation claims were filed, with sprains and strains qualifying as a close second (26%) (Table 4). Fractures accounted for only 5% of all such claims. Discussion
The available statistical systems mentioned in this report provide only some of the data needed to characterize the epidemiology of injuries to workers engaged in logging. Obviously, these systems are at variance, measuring different outcomes in different cohorts to serve different objectives. For example, reports of severe and disabling injuries in the SSA-CDHS file stand in sharp contrast to the HIS data, which show that the category "dislocation without fracture" was the type of injury most frequently reported by the lumber and wood-product workers interviewed. Limitations result from having only one occupation and no industry recorded for each worker when, in reality, workers may change from one occupation or industry to another, and risk of injury in the same occupation may vary by industry. Moreover, associations between occupations and disabling conditions may be affected by demographic, socioeconomic, and environmental factors as well as physical or mental attributes of the workers. Without information on factors such as residence (urban vs. rural), life style, smoking habits, diet, hobbies, medical history, or previous jobs held, it is not possible to determine the extent, if any, of confounding of such factors in the relationship between disabling disease and selected occupations.
Nevertheless, the epidemiologic analyses summarized here do reveal differences in risk 1) by geography, with the Western Region showing the highest injury rates, and 2) by age, with older loggers being at the highest risk of disabling injuries. While the available data do not reveal the reasons for these differences, they compel further inquiry to determine: 1) what factors contribute to the apparent increased risk of injury to loggers in the West; 2) what characteristics of older loggers contribute to their apparent increased risk of injury; 3) what characteristics of logging equipment (e.g., chain saws and automated felling equipment) contribute to risk of injury (16) and whether characteristics differ by geography (17); 4) to what extent training (or, in the case of older loggers, retraining) could reduce logging injuries; 5) how behavior of workers affects risk and how behavior differs among older and younger workers or among workers from different regions; and 6) the influence of protective equipment (e.g., goggles).
The report also emphasizes the great opportunity and pressing need for basic descriptive epidemiology in the problem of work-related, traumatic injury. Perhaps no other major work-related health problem has received less epidemiologic study to date.
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