Old and new reflections on dioxin.
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Dioxins↗
Biomedical subjects
W E Halperin
Publications and source records attributed to W E Halperin.
Colon and stomach cancer mortality among automotive wood model makers.
Automotive wood model makers have been reported to be at excess risk for colon and other cancers in recent epidemiologic studies. To further explore these risks, we conducted a retrospective cohort mortality study, with follow-up from 1940 through 1984, of 2294 white male wood model makers employed at any time until 1980 by three US auto makers. Using US mortality rates for comparison, we found elevated standardized mortality ratios of 1.2 (95% CI, 0.8-1.9) for colon cancer and 1.6 (95% CI, 0.9-2.6) for stomach cancer. We also conducted nested case-control studies for 20 colon and 17 stomach cancer cases and 543 age-matched controls. We found no trend of increased risk for colon or stomach cancer mortality with increased exposure to wood dust or to duration employed in wood model making.
Automobiles↗
Video display terminals and the risk of spontaneous abortion.
BACKGROUND: The relation between spontaneous abortion and the use of video display terminals (VDTs) is of great public health concern. Previous investigators of this issue have reported inconsistent findings. METHODS: To determine whether electromagnetic fields emitted by VDTs are associated with an increased risk of spontaneous abortion, a cohort of female telephone operators who used VDTs at work was compared with a cohort of operators who did not use VDTs. To obtain reliable estimates of exposure, we determined the number of hours of VDT use per week from company records and measured electromagnetic fields at VDT workstations and, for purposes of comparison, at workstations without VDTs. Operators who used VDTs had higher abdominal exposure to very-low-frequency (15 kHz) electromagnetic fields (workstations without VDTs did not emit very-low-frequency energy). Abdominal exposure to extremely-low-frequency fields (45 to 60 Hz) was similar for both operators who used VDTs and those who did not. Among 2430 women interviewed, there were 882 pregnancies that met our criteria for inclusion in the study. RESULTS: We found no excess risk of spontaneous abortion among women who used VDTs during the first trimester of pregnancy (odds ratio = 0.93; 95 percent confidence interval, 0.63 to 1.38), and no dose-response relation was apparent when we examined the women's hours of VDT use per week (odds ratio for 1 to 25 hours per week = 1.04; 95 percent confidence interval, 0.61 to 1.79; odds ratio for greater than 25 hours per week = 1.00; 95 percent confidence interval, 0.61 to 1.64). There continued to be no risk associated with the use of VDTs when we accounted for multiple pregnancies, conducted separate analyses of early abortion, late abortion, and all fetal losses, or limited our analyses to spontaneous abortions for which a physician was consulted. CONCLUSIONS: The use of VDTs and exposure to the accompanying electromagnetic fields were not associated with an increased risk of spontaneous abortion in this study.
Abortion, Spontaneous↗
Cancer mortality in workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin.
BACKGROUND: In both animal and epidemiologic studies, exposure to dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, or TCDD) has been associated with an increased risk of cancer. METHODS: We conducted a retrospective cohort study of mortality among the 5172 workers at 12 plants in the United States that produced chemicals contaminated with TCDD. Occupational exposure was documented by reviewing job descriptions and by measuring TCDD in serum from a sample of 253 workers. Causes of death were taken from death certificates. RESULTS: Mortality from several cancers previously associated with TCDD (stomach, liver, and nasal cancers, Hodgkin's disease, and non-Hodgkin's lymphoma) was not significantly elevated in this cohort. Mortality from soft-tissue sarcoma was increased, but not significantly (4 deaths; standardized mortality ratio [SMR], 338; 95 percent confidence interval, 92 to 865). In the subcohort of 1520 workers with greater than or equal to 1 year of exposure and greater than or equal to 20 years of latency, however, mortality was significantly increased for soft-tissue sarcoma (3 deaths; SMR, 922; 95 percent confidence interval, 190 to 2695) and for cancers of the respiratory system (SMR, 142; 95 percent confidence interval, 103 to 192). Mortality from all cancers combined was slightly but significantly elevated in the overall cohort (SMR, 115; 95 percent confidence interval, 102 to 130) and was higher in the subcohort with greater than or equal to 1 year of exposure and greater than or equal to 20 years of latency (SMR, 146; 95 percent confidence interval, 121 to 176). CONCLUSIONS: This study of mortality among workers with occupational exposure to TCDD does not confirm the high relative risks reported for many cancers in previous studies. Conclusions about an increase in the risk of soft-tissue sarcoma are limited by small numbers and misclassification on death certificates. Excess mortality from all cancers combined, cancers of the respiratory tract, and soft-tissue sarcoma may result from exposure to TCDD, although we cannot exclude the possible contribution of factors such as smoking and occupational exposure to other chemicals.
Bronchial Neoplasms↗
Targeting of workplace inspections for lead.
The prevention of occupational lead poisoning requires identification of worksites with ongoing excessive lead exposures. The utility of different sources of surveillance data in identifying worksites was evaluated by comparing a list of companies inspected by the Occupational Safety and Health Administration (OSHA) for lead with 1) Ohio Bureau of Workers' Compensation (BWC) claims for lead poisoning, and 2) the New York Health Department's Heavy Metal Registry (NYHMR) reports of individuals with elevated blood lead levels. For the period 1981 through 1985, the NYHMR identified 179 companies with at least one employee having an elevated blood lead level. Of the 134 OSHA inspections conducted in New York during the same time period, 23 (17%) companies were identified by the NYHMR. In Ohio from 1979 through 1985, 50 companies had workers' compensation claims filed against them involving documented elevated blood lead levels. OSHA inspected 306 companies; 23 (7.5%) were identified by the BWC. In both states, companies inspected by OSHA were concentrated in larger industries with traditional, well-recognized lead hazards (e.g., primary metal and fabricated metals). Companies identified by compensation claims and laboratory reports tended to be in industries dominated by smaller establishments where lead is not a primary part of the industrial process (e.g., automotive repair and construction). Sources of surveillance data, such as workers' compensation claims and laboratory reports, identify worksites that tend not to be routinely inspected by OSHA and which need intervention to prevent excessive lead exposure. To maximize the impact of public health resources devoted to the elimination of occupational lead poisoning, follow-up efforts at companies identified by state health departments and workers' compensation systems offer an important opportunity to complement OSHA's inspection efforts.
Environmental Monitoring↗
Evaluation of chronic bronchitis, chronic obstructive pulmonary disease, and ventilatory function among workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin.
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is produced as an undesirable contaminant in the manufacture of 2,4,5-trichlorophenol (TCP) and its derivatives. There is considerable concern about the health effects that may be associated with exposure to TCDD-contaminated substances. A cross-sectional medical study that included a comprehensive medical history, medical examination, and measurement of pulmonary function was conducted on workers employed more than 15 yr earlier in the manufacture of NaTCP and its derivatives at two chemical plants. The workers had substantial exposure to substances contaminated with TCDD, as evidenced by a mean serum TCDD level, lipid adjusted, of 200 ppt compared with a mean of 7 ppt in the unexposed reference group. The comparison group consisted of individuals with no occupational exposure to phenoxy herbicides who lived in the same communities as the workers. A total of 281 workers and 260 unexposed referents participated in the medical examination. Logistic and linear regression analyses, which contained categorical and continuous measures of TCDD exposure, were performed to control for important confounders, including cigarette and alcohol consumption. No difference was found between workers and referents in the risk for chronic bronchitis or COPD. Analysis of the ventilatory function data revealed no association between history of exposure to substances contaminated with TCDD and the forced expiratory volume at one second (FEV1), forced vital capacity (FVC), or the ratio of FEV1 to FVC (FEV1/FVC%).
Bronchitis↗
Weight of the evidence on the human carcinogenicity of 2,4-D.
The phenoxy herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is widely used to control the growth of weeds and broadleaf plants. We convened a panel of 13 scientists to weigh the evidence on the human carcinogenicity of 2,4-D. The panel based its findings on a review of the toxicological and epidemiological literature on 2,4-D and related phenoxy herbicides. The toxicological data do not provide a strong basis for predicting that 2,4-D is a human carcinogen. Although a cause-effect relationship is far from being established, the epidemiological evidence for an association between exposure to 2,4-D and non-Hodgkin's lymphoma is suggestive and requires further investigation. There is little evidence of an association between use of 2,4-D and soft-tissue sarcoma or Hodgkin's disease, and no evidence of an association between 2,4-D use and any other form of cancer. Scientists on the panel were asked to categorize 2,4-D as a "known," "probable," "possible," or "unlikely" carcinogen or as a noncarcinogen in humans. The predominant opinion among the panel members was that the weight of the evidence indicates that it is possible that exposure to 2,4-D can cause cancer in humans, although not all of the panelists believed the possibility was equally likely: one thought the possibility was strong, leaning toward probable, and five thought the possibility was remote, leaning toward unlikely. Two panelists believed it unlikely that 2,4-D can cause cancer in humans.
2,4-Dichlorophenoxyacetic Acid↗
Enhancing the quality of epidemiologic studies.
Three principles can improve epidemiologic studies (1) Conduct open scientific review of research protocols and final reports, (2) Disseminate study results to all appropriate parties, and (3) Incorporate new scientific methods into the research and utilize expertise from other disciplines. The procedures we describe are used within the Industrywide Studies Branch of the National Institute for Occupational Safety and Health to implement these principles.
Clinical Protocols↗
The epidemiology of populations exposed to dioxin.
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Carcinogens, Environmental↗
Testicular cancer, dimethylformamide, and leather tanneries.
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Dimethylformamide↗
Surveillance of occupational skin diseases: a method utilizing workers' compensation claims.
In order to determine the feasibility of using workers' compensation claims (WCC) for surveillance of occupational skin diseases, we reviewed all WCC received in the state of Ohio from 1980 through 1984. A total of 4,214 WCC for occupational skin diseases were filed by 2,610 Ohio companies, of which 1,656 (63%) companies were classified in Standard Industrial Classification (SIC) categories with average annual WCC rates above the overall state average for skin diseases. During the five year study period, 102 companies filed six or more WCC, of which 85 (83.3%) companies were classified in SICs with above-average WCC rates. WCC from 65 (63.7%) of these 102 companies implicated either the same occupation or causal agent in 50% or more of WCC received from each respective company. Using SIC classifications with WCC rates above the state average and six or more filed WCC as measures of risk, there was good correlation between company risk ranking by SIC categorization and number of WCC filed. This study suggests that active intervention strategies to prevent occupational skin diseases can be based on primary identification of companies filing WCC, followed by secondary identification of high-risk occupations or causal agent exposures within these companies.
Environmental Monitoring↗
Chloracne associated with employment in the production of pentachlorophenol.
To evaluate the association between exposure to pentachlorophenol (PCP) and the occurrence of chloracne, we studied the medical and personnel records for individuals employed in the manufacturing of PCP. Forty-seven cases of chloracne were identified among 648 workers (7.0%) assigned to PCP production at a single plant between 1953 and 1978. The annual incidence rate varied considerably, ranging from 0 (in 1953) to 1.46 (in 1978). No linear trend in the risk of chloracne was observed with the duration of employment in the pentachlorophenol department. Workers with a documented episode of direct skin contact with PCP had a significantly increased risk of chloracne compared with workers who did not have a documented episode of direct skin contact (cumulative incidence ratio = 4.6; 95% confidence interval 2.6-8.1). Our results confirm that chloracne is associated with exposure to PCP contaminated with hexachlorinated, heptachlorinated, and octachlorinated dibenzo-p-dioxins and dibenzofurans.
Acne Vulgaris↗
Lung cancer mortality among nonsmoking uranium miners exposed to radon daughters.
Radon daughters, both in the workplace and in the household, are a continuing cause for concern because of the well-documented association between exposure to radon daughters and lung cancer. To estimate the risk of lung cancer mortality among nonsmokers exposed to varying levels of radon daughters, 516 white men who never smoked cigarettes, pipes, or cigars were selected from the US Public Health Service cohort of Colorado Plateau uranium miners and followed up from 1950 through 1984. Age-specific mortality rates for nonsmokers from a study of US veterans were used for comparison. Fourteen deaths from lung cancer were observed among the nonsmoking miners, while 1.1 deaths were expected, yielding a standardized mortality ratio of 12.7 with 95% confidence limits of 8.0 and 20.1. These results confirm that exposure to radon daughters in the absence of cigarette smoking is a potent carcinogen that should be strictly controlled.
Adult↗
Levels of polychlorinated dibenzo-p-dioxins and dibenzofurans in workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin.
Review of employment and chemical production records at a Missouri chemical plant and of questionnaires with self-reported occupational exposure to 2,3,7,8-tetrachloro-dibenzo-p-dioxin (2,3,7,8-TCDD) for 16 Missouri workers has explained the wide diversity of 2,3,7,8-TCDD levels previously reported in the workers' adipose tissue (3.5-750 ppt on whole-weight basis). We show that the highest exposures reported to date in the United States occurred in a group of nine production workers who made products contaminated with 2,3,7,8-TCDD. The nine workers had adipose tissue levels with a mean of 246 ppt and a range of 42 to 750 ppt. Seven persons who worked at the same chemical company, but not in the 2,3,7,8-TCDD-contaminated process, had a mean of 8.7 ppt and a range of 3.5 to 25.8 ppt. We also report serum levels of 2,3,7,8-TCDD in these individuals. The adipose tissue from a subset of four production workers with elevated levels of 2,3,7,8-TCDD and seven Missouri residents with normal 2,3,7,8-TCDD levels was also analyzed for other isomers of the PCDDs and PCDFs. The mean adipose tissue level of 2,3,7,8-TCDD in the subset of production workers was 45 times higher than the mean level in the unexposed Missouri residents, but similar levels of the other PCDDs and PCDFs were found in both groups.
Adipose Tissue↗
Cluster of oligospermia among four men occupationally exposed to methylene chloride (MeCl)
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Adult↗
Semen quality in workers exposed to 2-ethoxyethanol.
To evaluate whether long term exposure to 2-ethoxyethanol (2EE) may affect semen quality, a cross sectional study was conducted among men exposed to 2EE used as a binder slurry in a metal castings process. Full shift breathing zone exposures to 2EE ranged from non-detectable to 24 ppm (geometric mean 6.6 ppm). Because of the potential for substantial absorption of 2EE through skin exposure, urine measurements of the metabolite of 2EE, 2-ethoxyacetic acid (2EAA) were conducted, showing levels of 2EAA ranging from non-detectable to 163 mg 2EAA/g creatinine. Only 37 exposed men (50% participation) and 39 non-exposed comparison (26% participation) from elsewhere in the plant provided a sperm sample. A questionnaire to determine personal habits, and medical and work histories, and a physical examination of the urogenital tract were also administered. The average sperm count per ejaculate among the workers exposed to 2EE was significantly lower than that of the unexposed group (113 v 154 million sperm per ejaculate respectively; p = 0.05) after consideration of abstinence, sample age, subjects' age, tobacco, alcohol and caffeine use, urogenital disorders, fever, and other illnesses. The mean sperm concentrations of the exposed and unexposed groups did not significantly differ from each other (44 and 53 million/ml respectively). No effect of exposure to 2EE on semen volume, sperm viability, motility, velocity, and normal morphology or testicular volume was detected, although some differences in the proportion of abnormal sperm shapes were observed. These data suggest that there may be an effect of 2EE on sperm count among these workers, although the possibility that other factors may be affecting the semen quality in both exposed and unexposed men in this population or that the results reflect bias introduced by the low participation rates cannot be excluded.
Acetates↗
Reducing knee morbidity among carpetlayers.
Carpetlayers have a high prevalence of occupational knee morbidity, partly attributable to their use of the knee kicker to stretch carpet for wall-to-wall installation. While a mechanical alternative "power stretcher" is available, knee kickers are still widely used. A questionnaire survey indicated that unavailability of the mechanical stretcher at installation sites was a major factor for continued use of the knee kicker. Strategies to reduce use of the knee kicker are discussed.
Floors and Floorcoverings↗
Surveillance of occupational skin disease using the Supplementary Data System.
The utility of the Supplementary Data System (SDS) compiled by the Bureau of Labor Statistics (BLS) in conducting surveillance of occupational skin disease was evaluated by examining 14,703 workers' compensation cases reported to the SDS for the year 1981. Combined with state employment denominators obtained from the BLS Employment and Earnings Program, rates of illness (cases of dermatitis/10,000 employed) calculated for eight major industrial divisions varied significantly according to the criteria used for reporting cases. Despite quantitative variations in the rate of skin disease that depended on specific reporting criteria, the relative ranking of the major industrial divisions remained unchanged, with highest rates of skin disease consistently found in three major industry divisions: agriculture, manufacturing, and construction. This ranking of major industry divisions by rate of dermatitis corresponded extremely well with rankings generated from the 1981 Annual Survey (Spearman rank correlation = .98, p less than .01). At the two-digit level of the Standard Industrial Classification, the rankings based on the SDS had a 77% rank correlation with those from the Annual Survey. Two-digit SIC codes identified from the top 10 in both sets of rankings included crop and livestock production from the agricultural division and leather products, food products, rubber and plastic products from the manufacturing division.
Dermatitis, Occupational↗