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Biomedical subjects

K Steenland

Publications and source records attributed to K Steenland.

At least 19 recordsLinked to original sources
PubMed1999

Cancer, heart disease, and diabetes in workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

BACKGROUND: In 1997, the International Agency for Research on Cancer classified 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as a group 1 human carcinogen, based largely on four highly exposed industrial cohorts that showed an excess of all cancers combined. In this study, we extended the follow-up period for the largest of these cohorts by 6 years and developed a job-exposure matrix. METHODS: We did cohort mortality analyses involving 5132 chemical workers at 12 U.S. plants by use of life table techniques (U.S. population referent) and Cox regression (internal referent). We conducted exposure-response analyses for 69% of the cohort with adequate work history data and adequate plant data on TCDD contamination. All P values are two-sided. RESULTS: The standardized mortality ratio (SMR) for all cancers combined was 1.13 (95% confidence interval = 1.02-1.25). We found statistically significant positive linear trends in SMRs with increasing exposure for all cancers combined and for lung cancer. The SMR for all cancers combined for the highest exposure group was 1.60 (95% confidence interval = 1.15-1.82). SMRs for heart disease showed a weak increasing trend with higher exposure (P = .14). Diabetes (any mention on the death certificate) showed a negative exposure-response trend. Internal analyses with Cox regression found statistically significant trends for cancer (15-year lag time) and heart disease (no lag). CONCLUSIONS: Our analyses suggest that high TCDD exposure results in an excess of all cancers combined, without any marked specificity. However, excess cancer was limited to the highest exposed workers, with exposures that were likely to have been 100-1000 times higher than those experienced by the general population and similar to the TCDD levels used in animal studies.

Carcinogens↗
PubMed1998

Exposure to environmental tobacco smoke and risk factors for heart disease among never smokers in the Third National Health and Nutrition Examination Survey.

The relative risk of coronary artery disease among never smokers exposed to environmental tobacco smoke (ETS) versus never smokers not exposed to ETS is approximately 1.2 based on more than a dozen epidemiologic studies. Most of these studies have controlled for the major heart disease risk factors, but residual or uncontrolled confounding remains a possible explanation for the epidemiologic findings. The authors studied 3,338 never-smoking adults aged 17 years or older, who are representative of all US never smokers, in the 1988-1991 Third National Health and Nutrition Examination Survey (NHANES III) to determine whether selected risk factors for heart disease differ between ETS-exposed and -nonexposed persons. Both self-reported ETS exposure (at home and at work) and serum cotinine levels were available, the latter reflecting recent ETS exposure. After adjustments were made for age, sex, race, and education among adults aged 17 years or older, no significant differences were found between the ETS exposed and the nonexposed for any of 13 cardiovascular risk factors with the exception of dietary carotene, which was lower among the exposed. On the other hand, significant positive linear trends were found between serum cotinine and two risk factors (body mass index and alcohol consumption), and significant inverse trends were found with dietary carotene. There were also few differences between exposed and nonexposed never smokers among adults aged 40 years or older, who are most at risk of heart disease. In this group, however, there was an inverse linear trend between serum cotinine and high density lipoprotein cholesterol (p < 0.001). This finding could result from ETS exposure rather than be an indication of confounding; a similar inverse trend was found for children, confirming other results in the literature. Overall, these data suggest little potential for confounding by the heart disease risk factors studied here when ETS exposure is determined by self-report.

Adolescent↗
PubMed1998

Predicted lung cancer risk among miners exposed to diesel exhaust particles.

Several quantitative risk assessment models have been published for occupational and environmental exposures to diesel exhaust particles (DEP). These risk assessment models are reviewed and applied to predict lung cancer for miners exposed to DEP. The toxicologically based unit risk estimates varied widely (from 2 to 220 x 10(-6) per micrograms/m3). The epidemiologically based unit risk estimates were less variable and suggest higher risks (from 100 to 920 x 10(-6) per micrograms/m3). The wide range of risk estimates derived from these analyses reflects the strong assumptions and large uncertainties underlying these models. All of the models suggest relatively high risks (i.e., > 1/1,000) for miners with long-term exposures greater than 1,000 micrograms/m3. This is not surprising, given the fact that miners may be exposed to DEP concentrations similar to those that induced lung cancer in rats and mice, and substantially higher that the exposure concentrations in the positive epidemiologic studies.

Humans↗
PubMed1998

Diesel exhaust and lung cancer in the trucking industry: exposure-response analyses and risk assessment.

BACKGROUND: Diesel exhaust is considered a probable human carcinogen by the International Agency for Research on Cancer (IARC). The epidemiologic evidence rests on studies of lung cancer among truck drivers, bus drivers, shipyard workers, and railroad workers. The general public is exposed to diesel exhaust in ambient air. Two regulatory agencies are now considering regulating levels of diesel exhaust: the California EPA (ambient levels) and the Mine Safety Health Administration (MSHA) (occupational levels). To date, there have been few quantitative exposure-response analyses of diesel and lung cancer based on human data. METHODS: We conducted exposure-response analyses among workers in the trucking industry, adjusted for smoking. Diesel exhaust exposure was estimated based on a 1990 industrial hygiene survey. Past exposures were estimated assuming that they were a function of 1) the number of heavy duty trucks on the road, 2) the particulate emissions (grams/mile) of diesel engines over time, and 3) leaks from trucks' exhaust systems for long-haul drivers. RESULTS: Regardless of assumptions about past exposure, all analyses resulted in significant positive trends in lung cancer risk with increasing cumulative exposure. A male truck driver exposed to 5 micrograms/m3 of elemental carbon (a typical exposure in 1990, approximately five times urban background levels) would have a lifetime excess risk of lung cancer of 1-2% above a background risk of 5%. CONCLUSIONS: We found a lifetime excess risk ten times higher than the 1 per 1,000 excess risk allowed by OSHA in setting regulations. There are about 2.8 million truck drivers in the U.S. Our results depend on estimates about unknown past exposures, and should be viewed as exploratory. They conform reasonably well to recent estimates for diesel-exposed railroad workers done by the California EPA, although those results themselves have been disputed.

Humans↗
PubMed1998

Effect of age and height on vibrotactile threshold among 1,663 U.S. workers.

Assessment of vibrotactile threshold has gained application in studies of neuropathies induced by toxic substances, compression, and vibration. The effect of age and height on vibrotactile threshold is of interest for its own sake and for the purpose of confounder control. We have studied the relation between finger and toe vibrotactile thresholds and age and height in five studies carried out by the National Institute for Occupational Safety and Health with vibrometry data (N = 1,663). A unique property of the merged data set was its wide age range from 14 to 82 years (mean 42 years). We demonstrate a J-shaped increase in finger threshold value (expressed on a log scale) with age, with no increase up to age 35 and a linear increase thereafter. For finger threshold, height was not an important predictor. The data were sparser (n = 541) for toe threshold but suggested a linear increase with both age and height. While consistent with prior data, this study provides a better understanding of the relation between vibrotactile threshold and age and height than has been available before. The greater effect of age and height on toe rather than finger threshold is consistent with the hypothesis that the length of the nerve increases susceptibility to peripheral neuropathy.

Adolescent↗
PubMed1998

Exposure to dioxin and nonneoplastic mortality in the expanded IARC international cohort study of phenoxy herbicide and chlorophenol production workers and sprayers.

The authors studied noncancer mortality among phenoxyacid herbicide and chlorophenol production workers and sprayers included in an international study comprising 36 cohorts from 12 countries followed from 1939 to 1992. Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin or higher chlorinated dioxins (TCDD/HCD) was discerned from job records and company questionnaires with validation by biologic and environmental measures. Standard mortality ratio analyses suggested a moderate healthy worker effect for all circulatory diseases, especially ischemic heart disease, among both those exposed and those not exposed to TCDD/HCD. In Poisson regression analyses, exposure to TCDD/HCD was not associated with increased mortality from cerebrovascular disease. However, an increased risk for circulatory disease, especially ischemic heart disease (rate ratio [RR] 1.67, 95% confidence interval [Cl] 1.23-2.26) and possibly diabetes (RR 2.25, 95% Cl 0.53-9.50), was present among TCDD/HCD-exposed workers. Risks tended to be higher 10 to 19 years after first exposure and for those exposed for a duration of 10 to 19 years. Mortality from suicide was comparable to that for the general population for all workers exposed to herbicides or chlorophenols and was associated with short latency and duration of exposure. More refined investigations of the ischemic heart disease and TCDD/HCD exposure association are warranted.

Adult↗
PubMed1998

Health effects associated with sulfuryl fluoride and methyl bromide exposure among structural fumigation workers.

OBJECTIVES: This study assessed the health effects associated with occupational exposure to methyl bromide and sulfuryl fluoride among structural fumigation workers. METHODS: A cross-sectional study of 123 structural fumigation workers and 120 referents in south Florida was conducted. Nerve conduction, vibration, neurobehavioral, visual, olfactory, and renal function testing was included. RESULTS: The median lifetime duration of methyl bromide and sulfuryl fluoride exposure among workers was 1.20 years and 2.85 years, respectively. Sulfuryl fluoride exposure over the year preceding examination was associated with significantly reduced performance on the Pattern Memory Test and on olfactory testing. In addition, fumigation workers had significantly reduced performance on the Santa Ana Dexterity Test of the dominant hand and a nonsignificantly higher prevalence of carpal tunnel syndrome than did the referents. CONCLUSIONS: Occupational sulfuryl fluoride exposures may be associated with subclinical effects on the central nervous system, including effects on olfactory and some cognitive functions. However, no widespread pattern of cognitive deficits was observed. The peripheral nerve effects were likely caused by ergonomic stresses experienced by the fumigation workers.

Adult↗
PubMed1997

End-stage renal disease among silica-exposed gold miners. A new method for assessing incidence among epidemiologic cohorts.

OBJECTIVE: To examine the association between silica exposure and end-stage renal disease (ESRD). DESIGN: Retrospective cohort study. PARTICIPANTS: A cohort of 2412 white male gold miners was studied. Eligible gold miners worked underground for at least 1 year between 1940 and 1965 in a South Dakota gold mine and were alive on January 1,1977. Of primary interest was exposure to silica. METHODS: The ESRD Program Management and Medical Information System (PMMIS) was used to identify members of the gold mine cohort who had treated ESRD and to create a US rate file for treated ESRD. The ESRD incidence among the gold miners was compared with that in the US population. RESULTS: Based on the 11 cohort members identified with treated ESRD, the risk for ESRD in the cohort was elevated (standardized incidence ratio [SIR], 1.37; 95% confidence interval [CI], 0.68-2.46). The risk was greatest for nonsystemic ESRD (ESRD caused by glomerulonephritis or interstitial nephritis) for which the SIR was 4.22 (95% CI, 1.54-9.19), increasing to 7.70 (95% CI, 1.59-22.48) among workers with 10 or more years of employment underground. CONCLUSIONS: To our knowledge this is the first epidemiologic study to examine ESRD incidence in an occupational cohort. This study provides evidence that silica exposure is associated with an increased risk for ESRD, especially ESRD caused by glomerulonephritis. This study also demonstrates the usefulness of the ESRD PMMIS to assess ESRD risk among cohorts exposed to potential nephrotoxins.

Cohort Studies↗
PubMed1997

A follow-up study of job strain and heart disease among males in the NHANES1 population.

Several studies have associated heart disease with job strain, defined as low job control and high job demands. We have studied incident heart disease (519 cases) and job strain among 3,575 males in NHANES1 survey who were currently employed at baseline in the early 1970s, and followed through 1987. Scores for job control and job demands were assigned to each subject based on current occupation at baseline. Controlling for conventional risk factors, we found no excess risk for those with the highest strain (lowest control and highest demands, rate ratio 1.08). Those with highest job control did have significantly decreased risk (rate ratio 0.71, 95% CI 0.54-0.93). In blue-collar workers (58% of subjects) there was a significant inverse trend in risk with increasing job demands. Control for level of physical activity did not change this finding. A combination of high control and demand was protective among blue-collar workers (odds ratio 0.69, 0.48-0.99). Our findings suggest that class-specific analyses are needed in studying job stress, and that "active" blue-collar workers with high control and high demand are protected against heart disease. The "job demand" variable may measure whether work is challenging rather than fast-paced. Our findings are limited by the use of assigned job scores based on job title.

Follow-Up Studies↗
PubMed1997

Laryngeal cancer incidence among workers exposed to acid mists (United States).

In 1992, the International Agency for Research on Cancer (IARC) determined that sufficient evidence existed to classify sulfuric acid mists as a human carcinogen, based primarily on six human studies. Possible mechanisms include irritation of epithelial cells in conjunction with cigarette smoking, or a direct genotoxic effect due to a modification of cellular pH. We have followed 1,031 men exposed to acid mists in the steel industry in the United States, via mailed questionnaire and telephone interview, extending by 10 years a prior follow-up of this cohort. These workers averaged 9.2 years of exposure, with an average first year of exposure of 1949. The primary exposure was to sulfuric acid mist, although part of the cohort was exposed to other acid mists. Fourteen laryngeal cancers were observed in the cohort compared with 5.6 expected based on US rates, with follow-up through 1994. A 14 percent upward adjustment in expected cancers due to differences in tobacco and alcohol consumption led to 6.4 laryngeal cancers expected, yielding a rate ratio of 2.2 (95 percent confidence interval = 1.2-3.7). Our findings are consistent with previous findings from this cohort and from most other studies, and tend to confirm IARC's classification of acid mists as a human carcinogen. The occupational exposures of this cohort were at least an order of magnitude higher than usual ambient exposures in urban air.

Acids↗
PubMed1997

Silica, asbestos, man-made mineral fibers, and cancer.

Approximately three million workers in the United States are estimated to be exposed to silica, man-made mineral fibers, and asbestos. The lung is the primary target organ of concern. Each of these substances is composed predominantly of silicon and oxygen; asbestos and silica are crystalline, and asbestos and man-made mineral fibers are fibers. Man-made mineral fibers and asbestos are used as insulating agents, with the former having generally replaced the latter in recent years. Silica is used in foundries, pottery, and brick making, and is encountered by miners. A meta-analysis of 16 of the largest studies with well-documented silica exposure and low probability of confounding by other occupational exposures, indicates a relative risk (RR) of 1.3 (95 percent confidence interval [CI] = 1.2-1.4). Lung cancer risks are highest and most consistent for silicotics, who have received the highest doses (RR = 2.3, CI = 2.2-2.4, across 19 studies). The data for mineral fibers continue to support the International Association for Research on Cancer's 1988 judgment that mineral fibers are a possible human carcinogen (Group 2B). Recent epidemiologic studies provide little evidence for lung carcinogenicity for either glass wool or rock/slag wool. Ceramic fibers, a much less common exposure than glass wool and rock/slag wool, are of concern because of positive animal studies, but there are insufficient human data. Regarding asbestos, its carcinogenicity for the lung and mesothelium is well established. With regard to the controversy over chrysotile and mesothelioma, the data suggest chrysotile does cause mesothelioma, although it may be less potent than amphibole asbestos.

Animals↗
PubMed1997

Increased precision using countermatching in nested case-control studies.

Nested case-control studies in occupational cohorts are often used to estimate exposure effects when development of detailed exposure estimates for all cohort members is too costly. Duration of exposure, which can act as a surrogate for cumulative exposure, is often readily available for all cohort members. Langholz and others have recently proposed a method of control selection called countermatching, which uses data on the surrogate to determine which controls are selected from the risk set for a given case. This method may increase precision relative to the usual random sampling of the risk set. We compare countermatching with random sampling in a nested case-control study of silicosis among miners. Data on cumulative exposure were in fact available for all cohort members, enabling estimation of the parameter of interest in the full cohort. We conducted nested case-control analyses using 100, 20, 10, and 3 controls per case using random sampling and additional analyses using 3 controls per case with two different methods of countermatching. All analyses were replicated 50 times to explore the statistical properties of the estimated exposure parameter. We found that one of the countermatching methods markedly increased efficiency compared with random sampling. Countermatching using 3 controls per case yielded an approximate 25% increase in relative efficiency compared with random sampling; it was approximately equivalent to random sampling using 10 controls.

Case-Control Studies↗
PubMed1997

Identifying deaths before 1979 using the Social Security Administration Death Master File.

For cohort studies, the Social Security Administration (SSA) traditionally has been the principal source of deaths that occurred before 1979. In 1988, the SSA abolished a system that provided a relatively complete accounting of deaths and replaced it with the Death Master File. We examined the completeness of the SSA Death Master File by comparing it with the U.S. Vital Statistics records and by searching the SSA Death Master File for known decedents from seven cohorts. Overall, only 53% of reported U.S. deaths and 75% of known deaths in our seven cohorts were included in the SSA Death Master File. Ascertainment was better after 1975 (89-95%). A re-analysis of two cohorts that excluded deaths before 1979 not found in the SSA Death Master File resulted in 20-35% decreases in both standardized mortality ratios and dose-response trends. Although the SSA system before 1988 provided relatively complete vital status information, the SSA Death Master File is inadequate for vital status determination. New cohorts with a substantial number of deaths before the inception of the National Death Index in 1979 will be most seriously affected.

Cohort Studies↗
PubMed1997

Exposure-response analysis of risk of respiratory disease associated with occupational exposure to chrysotile asbestos.

OBJECTIVES: To evaluate alternative models and estimate risk of mortality from lung cancer and asbestosis after occupational exposure to chrysotile asbestos. METHODS: Data were used from a recent update of a cohort mortality study of workers in a South Carolina textile factory. Alternative exposure-response models were evaluated with Poisson regression. A model designed to evaluate evidence of a threshold response was also fitted. Lifetime risks of lung cancer and asbestosis were estimated with an actuarial approach that accounts for competing causes of death. RESULTS: A highly significant exposure-response relation was found for both lung cancer and asbestosis. The exposure-response relation for lung cancer seemed to be linear on a multiplicative scale, which is consistent with previous analyses of lung cancer and exposure to asbestos. In contrast, the exposure-response relation for asbestosis seemed to be nonlinear on a multiplicative scale in this analysis. There was no significant evidence for a threshold in models of either the lung cancer or asbestosis. The excess lifetime risk for white men exposed for 45 years at the recently revised OSHA standard of 0.1 fibre/ml was predicted to be about 5/1000 for lung cancer, and 2/1000 for asbestosis. CONCLUSIONS: This study confirms the findings from previous investigations of a strong exposure-response relation between exposure to chrysotile asbestos and mortality from lung cancer, and asbestosis. The risk estimates for lung cancer derived from this analysis are higher than those derived from other populations exposed to chrysotile asbestos. Possible reasons for this discrepancy are discussed.

Adult↗
PubMed1997

Thyroid hormones and cytogenetic outcomes in backpack sprayers using ethylenebis(dithiocarbamate) (EBDC) fungicides in Mexico.

Ethylenebis(dithiocarbamate) (EBDC) fungicides are used heavily in the United States. EBDCs (e.g., mancozeb, maneb) are metabolized to ethylene thiourea (ETU). The EPA classifies ETU as a carcinogen, based on thyroid and other cancers in rodents, and has restricted the use of EBDCs, while requiring workers to use protective equipment. There are no data on the potential carcinogenicity of EBDCs in humans, and there is only one study on human genotoxicity. ETU is known to cause decreases of thyroxine (T4) and increases in thyroid-stimulating hormone (TSH) in rodents. We have studied cytogenetic outcomes and serum thyroid hormone levels among 49 heavily exposed workers without protective equipment spraying EBDC on tomatoes in Mexico. We also studied 14 lightly exposed landowners and 31 nonexposed controls. Urinary ETU was used to compare exposure between groups. We found an increase in TSH (p = 0.05) among applicators compared to controls, but no decrease in thyroid hormone (T4). We found increases in sister chromatid exchange (p = 0.03) and in chromosome translocations (chromosome aberrations that persist through cell division) for applicators compared to controls (p = 0.05). However, the subset of reciprocal translocations showed a lesser increase (p = 0.24). Our data suggest that EBDCs affect the thyroid gland and the lymphocyte genome among heavily exposed workers. However, our data are limited to subclinical outcomes, are of borderline statistical significance, and should be interpreted with caution.

Adult↗
PubMed1997

Incidence of tuberculosis infection among New York State prison employees.

OBJECTIVES: This study examined tuberculosis skin test conversions among 24,487 New York State prison employees in 1992. METHODS: Conversions were analyzed by prison and by job category. RESULTS: The conversion rate was 1.9%. Employees in prisons with low and high numbers of prisoner cases had odds ratios for conversion of 1.67 (95% confidence interval [CI] = 1.27, 2.19) and 2.20 (95% CI = 1.69, 2.87), respectively, relative to employees in prisons with no prisoner cases. In prisons with cases, guards and medical personnel had odds ratios of 1.64 (95% CI = 1.11, 2.43) and 2.39 (95% CI = 1.40, 4.08), respectively, relative to employees with little prisoner contact. CONCLUSIONS: In 1992, approximately one third of new infections among New York State prison employees were due to occupational exposure.

Adult↗
PubMed1997

Effect of travel and rest on performance of professional basketball players.

We have studied 8,495 regular season games in the National Basketball Association over eight seasons (1987-1988 through 1994-1995) to analyze the effects of travel and rest on performance. We found that more time between games improved performance, an effect that was constant over time and statistically significant. More than 1 day between games increased the home team's score by 1.1 points and the visitor's by 1.6 points. Peak performance occurred with 3 days between games. The negative effects of little time between games may be due to lack of time for physical recovery, rather than any effects of circadian rhythm (jet lag). We found few consistent effects of distance traveled or direction of travel. We did find a suggestion of circadian rhythm effects in a subanalysis of games on either coast in which the visitor traveled across the country, while the home team did not travel (n = 101). In these games, the visiting team did four points better (p = 0.07) when they traveled west to east rather than east to west, almost nullifying the home-court advantage. This effect, like similar findings for Monday Night Football games, may be due to West Coast visitors playing night games at an earlier time according to their "internal clock". An incidental finding in our study was that the home-court advantage decreased over 8 years, from about six points to three points (due to relatively lower field-goal percentages and fewer free throws by the home team).

Basketball↗