Neuropsychological function in retired workers with previous long-term occupational exposure to solvents.

OBJECTIVES: It is plausible that neurodegenerative processes of aging might have a contributing role in the development of chronic effects of exposure to organic solvents. This study evaluated the risk for neuropsychological deficits among retired workers, relative to their histories of exposure to occupational solvents. METHODS: This cross sectional study evaluated retired male workers, 62-74 years of age, including 89 people with previous long-term occupational exposure to solvents (67 retired painters and 22 retired aerospace manufacturing workers), and 126 retired carpenters with relatively minimal previous exposure to solvents. Subjects completed a standardised neuropsychological evaluation and psychiatric interview, structured interviews for histories of occupational exposure and alcohol consumption, and questionnaires assessing neurological and depressive symptoms. RESULTS: By comparison with the carpenters, the painters on average reported greater cumulative alcohol consumption and had lower scores on the WAIS-R vocabulary subtest, usually presumed to reflect premorbid intellectual functioning. These findings, however, were not sufficient to account for the other study findings. Controlling for age, education, vocabulary score, and alcohol use, the painters had lower mean scores on test measures of motor, memory, and reasoning ability; and a subgroup of aerospace workers with moderate to high cumulative exposure to solvents (n = 8) had lower mean scores on measures of visuomotor speed, and motor, attention, memory, and reasoning ability. Subjects were more likely to have an increased number of relatively abnormal test scores (three or more outlier scores on 17 test measures) among both the painter group (odds ratio (OR), 3.1; 95% confidence interval (95% CI) 1.5 to 6.2) and the subgroup of aerospace workers with higher cumulative exposure (OR 5.6; 95% CI 1.0 to 38). The painters, but not the aerospace workers, reported significantly more neurological and depressive symptoms. CONCLUSIONS: The findings are consistent with residual central nervous system dysfunction from long-term exposure to organic solvents, persisting years after the end of exposure.

A case series of 71 patients referred to a hospital-based occupational and environmental medicine clinic for occupational asthma.

In a ten-year period at the Occupational and Environmental Medicine Program (OEMP) of the University of Washington in Seattle, 71 patients were determined by attending physicians to have work-related asthma. In this cross-sectional descriptive study, we describe these patients. Data were obtained from a database maintained by the OEMP and from chart reviews. We found that the three most common specific agents causing asthma were isocyanates, red cedar, and crabs. At least one pulmonary function study was available for all patients and was positive in 56 patients (79%). Among the 71 asthma cases reported in this article, 18 (25%) were attributed to reactive airways dysfunction syndrome (RADS); 19 (27%) to exacerbation of pre-existing asthma; 27 (38%) to sensitization; and 7 (10%) had undetermined causes. We conclude that occupational asthma presents as a result of diverse exposures in multiple work settings and with an array of characteristics. Prevention efforts need to recognize this diversity.

The National Occupational Research Agenda: a model of broad stakeholder input into priority setting.

OBJECTIVES: No single organization has the resources necessary to conduct occupational safety and health research to adequately serve the needs of workers in the United States. The National Institute for Occupational Safety and Health (NIOSH) undertook the task of setting research priorities in response to a broadly perceived need to systematically address those topics most pressing and most likely to yield gains to workers and to the nation. METHODS: NIOSH and its public and private partners used a consensus-building process to set priorities for the next decade for occupational safety and health research--the National Occupational Research Agenda. RESULTS: The process resulted in the identification of 21 research priorities grouped into 3 categories: disease and injury, work environment and workforce, and research tools and approaches. CONCLUSIONS: Although the field of occupational safety and health is often contentious and adversarial, these research priorities reflect a remarkable degree of concurrence among a broad range of stakeholders who provided input into a clearly defined and open process.

The CARET asbestos-exposed cohort: baseline characteristics and comparison to other asbestos-exposed cohorts.

The Carotene and Retinol Efficacy Trial (CARET) was a double-blind, placebo-controlled trial of the daily administration of 25,000 IU vitamin A and 30 mg beta-carotene for the prevention of lung cancer. Of close to 18,500 participants, more than 4,000 were asbestos-exposed men recruited from shipyard and construction trades at five study centers in the United States. While the primary endpoint of the trial was the incidence of lung cancer, a number of questions about the natural history of asbestos-related disease will also be addressed. The mean age at entry into the trial was 57 years and the mean duration of follow-up on active intervention was 4 years. With the exception of 133 never-smoker pilot participants (3%), all subjects recruited were by intention current (38%) or ex-smokers (58%), with a mean cumulative smoking exposure at entry of 43 pack-years. Mean years from first asbestos exposure were 35, and mean duration of asbestos exposure in a high-risk trade was 19 years. The distribution of radiographic abnormalities was as follows: normal, 34%; parenchymal opacities (ILO profusion score > 1/0) alone, 18%; pleural thickening alone, 27%; both parenchymal opacities and pleural thickening, 21%. The CARET cohort, when compared to previously reported asbestos-exposed cohorts, is characterized by substantial asbestos exposure and high proportion of asbestos-related radiographic findings. The active intervention was halted in 1996, after a mean duration of 40 years. Passive follow-up of the cohort will continue until the year 2000.

Work organization research at the National Institute for Occupational Safety and Health.

For 25 years, the National Institute for Occupational Safety and Health (NIOSH) has conducted and sponsored laboratory, field, and epidemiological studies that have helped define the role of work organization factors in occupational safety and health. Research has focused on the health effects of specific job conditions, occupational stressors in specific occupations, occupational difference in the incidence of stressors and stress-related disorders, and intervention strategies. NIOSH and the American Psychological Association have formalized the concept of occupational health psychology and developed a postdoctoral training program. The National Occupational Research Agenda recognizes organization of work as one of 21 national occupational safety and health research priority areas. Future research should focus on industries, occupations, and populations at special risk; the impact of work organization on overall health; the identification of healthy organization characteristics; and the development of intervention strategies.

Estimating underreported pesticide poisonings in Nicaragua.

We undertook to estimate the degree of underreporting to a regional pesticide poisoning registry, and to estimate the true incidence of poisoning in an agricultural region of Nicaragua. We surveyed 633 workers at 25 of 33 agricultural cooperatives and any nearby private forms in a area geographically convenient to the regional health headquarters with a short structured interview about pesticide poisonings. Eighty-three percent of workers described current use of pesticides. Twenty-five percent described a pesticide poisoning in the preceding 12 months, and almost one-half (48%) described having been made ill by pesticides at some point in time. Sixty-nine (11%) described a poisoning in the preceding month, 23 of whom had received medical attention. The names of the medically treated were sought in the Regional Pesticide Poisoning Registry for the survey year of 1988. Only 8 of the 23 subjects were found reported to the registry when a total of 1,143 human pesticide poisonings were reported in the entire region. Using 65% as an estimate of underreporting to the registry, we calculate that 3,300 (95% CI 2100-7500) poisonings had received treatment in the region in 1988, of whom more than 2,100 remained unreported. Based on the ratio of total poisonings (treated and untreated) to registry-reported poisonings among our survey respondents, we estimate that 6,700 (95% CI 4100-18000) systemic poisonings, occurred in 1988 in the region. Underreporting of pesticide poisonings disguises the enormity of the problem in developing countries. Even in a region with a strong emphasis on illness reporting for targeted conditions, underreporting is substantial. This method for estimating underreporting is easily applied and provides a rough estimate of registry underreporting and actual incidence for conditions identifiable by a community-applied questionnaire.

The future of intervention research at NIOSH.

The National Institute for Occupational Safety and Health (NIOSH) has recently made a commitment to increase both extramural and intramural support of control technology and intervention research. It is important for NIOSH to use intervention research more aggressively because it provides a mechanism to go beyond investigation, identification, and recommendations to actually determine if prevention has occurred. Intervention research can assess the effectiveness of the hierarchy of controls, workplace standards, and health and medical care, as well as provide important information on occupational disease and injury surveillance and health communication efforts. In pursuing intervention research, NIOSH will focus on enhancing its existing control technology and surveillance programs, seeking input from partners in industry and labor, pursuing interdisciplinary approaches, considering the cost and feasibility of controls, considering and integrating behavioral procedures, and widely disseminating the results.

Longitudinal pattern of reported respiratory symptoms and accelerated ventilatory loss in asbestos-exposed workers.

Studies investigating the relation between respiratory symptoms and change in ventilatory function have been limited by use of reported symptoms at a single point in time. To assess the relation between the longitudinal pattern of reported cough, phlegm, wheeze, and dyspnea and ventilatory loss, we prospectively investigated changes in FVC and FEV1 associated with development, resolution, or persistence of these symptoms over a 3- to 5-year period in 446 asbestos-exposed workers. Longitudinally reported symptoms changed frequently, with 52 to 61% of subjects reporting a specific symptom noting resolution or development of that symptom during follow-up. Initially reported symptoms were not predictive of accelerated loss of FVC or FEV1. In contrast, development of any new respiratory symptom, and to a lesser extent persistence of symptoms during follow-up, were associated with significantly greater ventilatory losses compared with asymptomatic individuals, ranging from 28 mL/yr in FEV1 for newly developed dyspnea, to 67 mL/yr in FVC for developed wheeze (p < 0.01). We conclude that development or persistence of respiratory symptoms over time, rather than the presence of symptoms per se, is predictive of future ventilatory loss. Recognition of interval changes in symptom reporting during surveillance of asbestos-exposed workers may effectively identify groups at risk for progressive ventilatory impairment.

Workers' compensation for nonmalignant asbestos-related lung disease.

Workers' compensation claims filed for occupational illness are generally more complicated to resolve than are injury claims, and they may therefore face higher likelihood of rejection. This study analyzed outcomes and predictive factors for claims filed from one clinic in Washington State between 1982 and 1986 by 157 male patients for nonmalignant asbestos-related lung disease. Among 50 federal Longshore claims, 46 (92%) were unresolved or could not be located by claims administrators. In contrast, 118 (89%) of State Fund claims had been resolved, with 48% accepted without consistent relationship to disease severity. Claims filed under both jurisdictions showed a twofold greater risk of rejection by the State Fund (relative risk, RR = 2.0; 95% confidence interval, 95% CI = 1.3-3.2). State Fund claims filed for nonwhite patients were rejected more often than those of white patients, although the association was explained at least partially by jurisdictional overlap (adjusted RR = 1.5; 95% CI = 1.05-2.1). This study indicates a need to scrutinize the handling of occupational disease claims by the federal Longshore system and to consider the adverse influences of jurisdictional conflicts and possible race-associated factors on compensation of occupational illness.

Proposal to reimburse occupational medicine disease and injury claims through third party health insurance.

The current system of compensation for the medical costs of occupational illnesses and injuries, a component of health insurance coverage for most workers in the United States, has recently come under scrutiny in the national health care reform debate. The cost of treatment of these conditions is significant, and there exist numerous disincentives for physicians and patients to use the workers' compensation system. Physicians who treat workers with occupationally related diseases may find compensation for a condition is disputed at the same time that it is excluded from payment by third party insurance coverage, leaving the patient selectively uninsured for at least some medical care services. In addition, most workers' compensation programs have been designed in a way that discourages efficient resource use by providers and claimants. We propose allowing health care providers to bill third party health insurers for all care, including work-related diseases and injuries. Insurers, in turn, would bill workers' compensation programs for associated treatment costs. The potential advantages of such a system include reductions in inefficiency and unfair burdens placed on providers and patients, in reporting bias, and in administrative costs balanced against the risks of insurers excluding workers in high risk occupations from obtaining low cost health insurance and shifting away from employers the administrative burden for workers' compensation.

The beta-carotene and retinol efficacy trial (CARET) for chemoprevention of lung cancer in high risk populations: smokers and asbestos-exposed workers.

CARET is a multicenter, two-armed, double-masked randomized chemoprevention trial in Seattle, Portland, San Francisco, Baltimore, Connecticut, and Irvine, to test whether oral administration of beta-carotene (30 mg/day) plus retinyl palmitate (25,000 IU/day) can decrease the incidence of lung cancer in high risk populations, namely, heavy smokers and asbestos-exposed workers. The intervention combines the antioxidant action of beta-carotene and the tumor suppressor mechanism of vitamin A. As of April 30, 1993, CARET had randomized 1,845 participants in the 1985-1988 pilot phase plus 13,260 "efficacy" participants since 1989; of these, 4,000 are asbestos-exposed males and 11,105 are smokers and former smokers (44% female). Accrual is complete everywhere except Irvine, which was the last center added (1991), and the safety profile of the regimen to date has been excellent. With 14,420 smokers, 4,010 asbestos-exposed participants, and 114,100 person-years through February 1998, we expect CARET to be capable of detecting a 23% reduction in lung cancer incidence in the two populations combined and 27, 49, 32, and 35% reductions in the smokers, female smokers, male smokers, and asbestos-exposed subgroups, respectively. CARET is highly complementary to the alpha-tocopherol-beta-carotene study in Finland and the Harvard Physicians Health Study (beta-carotene alone) in the National Cancer Institute portfolio of major cancer chemoprevention trials.

Elevated quantitative vibrotactile threshold among workers previously poisoned with methamidophos and other organophosphate pesticides.

To evaluate chronic effects of acute organophosphate pesticide poisoning, quantitatively determined vibrotactile thresholds were measured as an index of peripheral neuropathy among agricultural workers in Nicaragua. Thirty-six male workers were evaluated between 10 and 34 months after hospitalization for acute organophosphate poisoning and compared to an age- and sex-matched community reference group. Vibrotactile thresholds were measured quantitatively in right and left index fingers and right and left great toes. Study subjects were stratified into three groups: 1) never poisoned; 2) poisoned with organophosphates other than methamidophos, agents which have not been reported to cause peripheral neuropathy; and 3) poisoned with methamidophos, a peripheral neurotoxin. For all digits, there was a statistically significant trend of increasing age- and height-adjusted thresholds across these three exposure categories. Over one fourth of patients previously poisoned with methamidophos we studied had abnormal vibrotactile thresholds. These results suggest that previously reported cases of organophosphate-induced delayed polyneuropathy may represent only the worst disease in a spectrum of impairment, a sequela of exposure that may be much more common than previously thought.

Cancer incidence among firefighters in Seattle and Tacoma, Washington (United States).

In order to determine if exposure to carcinogens in fire smoke increases the risk of cancer, we examined the incidence of cancer in a cohort of 2,447 male firefighters in Seattle and Tacoma, (Washington, USA). The study population was followed for 16 years (1974-89) and the incidence of cancer, ascertained using a population-based tumor registry, was compared with local rates and with the incidence among 1,878 policemen from the same cities. The risk of cancer among firefighters was found to be similar to both the police and the general male population for most common sites. An elevated risk of prostate cancer was observed relative to the general population (standardized incidence ratio [SIR] = 1.4, 95 percent confidence interval [CI] = 1.1-1.7) but was less elevated compared with rates in policemen (incidence density ratio [IDR] = 1.1, CI = 0.7-1.8) and was not related to duration of exposure. The risk of colon cancer, although only slightly elevated relative to the general population (SIR = 1.1, CI = 0.7-1.6) and the police (IDR = 1.3, CI = 0.6-3.0), appeared to increase with duration of employment. Although the relationship between firefighting and colon cancer is consistent with some previous studies, it is based on small numbers and may be due to chance. While this study did not find strong evidence for an excess risk of cancer, the presence of carcinogens in the firefighting environment warrants periodic re-evaluation of cancer incidence in this population and the continued use of protective equipment.