Biomedical subjects
H Weill
Publications and source records attributed to H Weill.
Silicosis risk: Canadian and South African miners.
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Blue-collar normative spirometric values for Caucasian and African-American men and women aged 18 to 65.
Normative spirometric values were derived from 5,042 white (of mainly European ancestry) and black (of mainly African ancestry) men and women paper plant workers who are never-smokers, with no respiratory symptoms or diagnoses and no history of occupational exposure to fibrogenic dusts or irritant chemicals. This cohort was selected from a much larger population under long-term respiratory surveillance (n > 50,000 at 50 plants). Standardized equipment, procedures, and data reduction methods complied with ATS recommendations. Data were collected by the medical departments of the participating companies as part of their routine health surveillance, and the graphic and numeric test results were transmitted to the Tulane University Section of Environmental Medicine for centralized quality assurance, interpretation, and archiving. The large numbers allow derivation of gender- and race-specific reference values. Lower limits of normal were derived and depend upon residual variation and any changes in variation with age. The results indicate that polynomial regression equations provide a significantly better fit than linear regressions with breakpoints. In addition to being more biologically plausible, the polynomial model more closely matches observed longitudinal changes in lung function with age. The age range of the cohort, 18 to 65, provides a regression that more closely matches the observed values in this range, because it does not include "supernormal" elderly survivors, which can lessen the slope of the regression and artifactually increase the predicted values of 50 to 65 yr olds. The regression equations derived for black men and women do not support the use of a single race adjustment (0.85 or 0.88) for all age, sex, height, and spirometric test parameter combinations. These race- and gender-specific regression equations, with their respective lower limits of normal, should improve the detection and quantification of adverse health effects in working individuals and populations.
Crystalline silica: risks and policy.
Since the International Agency for Research on Cancer labeled crystalline silica a probable carcinogen in 1988, government regulations have required sand and other products to contain warning labels and researchers have attempted to quantitatively assess low-exposure risks. The uncertainties are unlikely to diminish any time soon, and little value exists in calculating such risks, as low exposures to this ubiquitous mineral are commonplace in both urban and rural areas due to many uncontrollable activities. What is certain is that regulatory resources targeted at continuing high-level occupational exposures would be much more likely to have beneficial public health consequences than continued attempts to assess low-exposure risks quantitatively.
Review of the Kilburn and Warshaw Chest article--airways obstruction from asbestos exposure.
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Potency versus importance in fiber pathogenicity.
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Biological effects: asbestos-cement manufacturing.
Fourteen cohorts of asbestos-cement workers have been studied. These studies have demonstrated exposure-response relationships for lung cancer, mesothelioma and asbestosis. For lung cancer, relatively consistent results have been observed, with risk two-fold or less in 13 of the 14 cohorts. Among New Orleans workers, excess risk was restricted to those with X-ray evidence of asbestosis. Workers employed at least 21 years but without X-ray abnormalities, experienced no elevated risk, while those with small opacities (1/0 or higher) had substantially elevated risk (SMR > 400). Exposures in these two groups had been similar. These results suggest that asbestosis may be a necessary precursor for asbestos-induced lung cancer; if so, then the no-threshold model for lung cancer risk is inappropriate since there is general agreement that very low exposures will not result in radiologically detectable lung fibrosis. Further data on this potential link are needed. As in other industries, mesothelioma risk was strongly related to amphibole exposure, especially to crocidolite in asbestos-cement pipe manufacture. A cluster of cases has recently been reported in a family amosite-cement business. Among New Orleans workers, risk of asbestosis was related to cumulative exposure but there was little evidence of risk below 30 f ml-1-years. Progression of asbestosis in these workers was slow, related to past cumulative exposure and not related to lung function decline. Asbestosis risk is therefore not likely to develop in workers under current controlled exposure conditions.
Abnormal lung function in polyurethane foam producers. Weak relationship to toluene diisocyanate exposures.
Exposures to toluene diisocyanate (TDI) were studied for effects on respiratory health of workers in two plants manufacturing polyurethane foams. Intensive personal monitoring was used to characterize job exposures. Of 4,845 12-min personal samples, 9% exceeded 5 ppb and 1% exceeded 20 ppb. Initial questionnaire and spirometry were obtained in 386 workers (88.7% of target population). Current smoking was associated with lower mean FEV1 and FEF25-75, but percent predicted (% pred) means were normal in all smoking categories. Multiple regression showed significant adverse effects of cumulative TDI exposure on initial level of FVC and FEV1 of current smokers, and an effect at borderline significance (p less than 0.063) on FEF25-75 over all smoking categories. Logistic regression showed that chronic bronchitis was more prevalent among those with higher cumulative exposures, after controlling for smoking, age, and sex. Methacholine (MCh) reactivity was associated with reduced airway function, -8.5% pred for FEV1 and -20.0% pred for FEF25-75. In 227 with adequate follow-up, the slopes of annual change were abnormal, for example, FEV1 of -67 ml/yr in current and -53 ml/yr in never smokers. Men had worse FEV1 declines than did women, -71 ml/yr versus -43 ml/yr. TDI exposure, lifetime or concurrent, had no significant effect on slopes, despite its demonstrated effects on initial level of lung function and on prevalence of chronic bronchitis.
Asbestosis as a precursor of asbestos related lung cancer: results of a prospective mortality study.
A prospective mortality study of 839 men employed in the manufacture of asbestos cement products in 1969 examined lung cancer risk in relation to lung fibrosis seen on chest x ray film, controlling for age, smoking, and exposure to asbestos. Twenty or more years after hire, no excess of lung cancer was found among workers without radiographically detectable lung fibrosis, even among long term workers (greater than or equal to 21.5 years); nor was there a trend in risk by level of cumulative exposure to asbestos among such workers. By contrast, employees with small opacities (greater than or equal to 1/0; ILO classification) experienced a significantly raised risk of lung cancer (nine observed deaths v 2.1 expected), even though their exposures to asbestos were similar to the exposures of long term workers without opacities. In this population, excess risk of lung cancer was restricted to workers with x ray film evidence of asbestosis, a finding consistent with the view that asbestos is a lung carcinogen because of its fibrogenicity.
Exposure-related declines in the lung function of cotton textile workers. Relationship to current workplace standards.
To evaluate the effectiveness of the current workplace standards in preventing chronic health effects from cotton dust exposure, a 5-yr longitudinal study of a large multimill population of cotton textile and synthetic process workers, employed at a major U.S. textile company, was conducted. To control for and assess the effect of type of work area on annual change in lung function, we limited the analysis to those 1,817 subjects who, throughout their textile work history at the company, worked exclusively in cotton yarn manufacturing or slashing and weaving, or in synthetic textile mills. The expected effect of smoking on average annual change in lung function was demonstrated for both cotton and synthetic workers. Despite lower overall dust exposure, cotton yarn workers exhibited steeper annual declines in lung function than did workers in slashing and weaving; this difference persisted within each smoking category, indicating a dust potency effect. There were mill differences in annual change in lung function among cotton workers, potentially masking an exposure effect. A smoking-work area interaction persisted after adjusting for mill differences, with the largest annual declines observed in cotton yarn workers who smoke. A significant dose-response relationship was seen in cotton yarn manufacturing between annual declines in FEV1, FVC, and FEF25-75 and average exposure by mill, and the larger declines were found in mills using the highest percentage and lowest grade of cotton. Synthetic textile workers had larger declines than did cotton textile workers, which were not explained by smoking or duration of employment. Unrecognized and unmeasured causative exposures or selection bias could explain this result.(ABSTRACT TRUNCATED AT 250 WORDS)
Progression of asbestos effects: a prospective longitudinal study of chest radiographs and lung function.
From an original prospective cohort of 244 current and ex-workers in two asbestos cement plants, longitudinal radiographic data covering ten years were available for 165 and lung function data covering about six years for 150. Estimates of average and cumulative dust exposure were available for each participant, all men. Radiographic progression (onset or worsening) was assessed by comparing earliest and latest films side by side. Annual changes in lung function were computed by fitting regression lines to all the data points. Small opacities (ILO category 1/0 or higher) were found in 16% of initial films, and progression of small opacities occurred in 13% of film pairs. Average and cumulative dust exposure were each significant determinants of the initial presence of small opacities, and were determinants of the progression of both parenchymal and pleural abnormalities. There was greater likelihood of progression if an abnormality was initially present, and a greater likelihood of progression in the plant that had systematic use of some crocidolite. Initial levels of lung function were related to smoking, exposure to dust, and initial radiographic status. Mean annual declines in lung function were modest (FVC-0.017 l/y, FEV1-0.020 l/y) and were related to smoking but not exposure to dust, initial radiographic status, or radiographic progression. Both plants used mainly chrysotile asbestos and exposure levels declined severalfold after 1960. Our findings suggest a waning effect of the larger remote dust exposures on recent annual change in lung function. This accords with human and experimental pathology data showing the relatively low resistance of chrysotile fibres to chemical alteration and clearance.
Role of inhalation challenge testing in the diagnosis of isocyanate-induced asthma.
Results of isocyanate challenge tests performed on 63 workers referred with a diagnosis of probable isocyanate asthma between 1974 and 1988 were reviewed. Thirty (48 percent) had an acute episode of asthma with a greater than 20 percent decline in FEV1 following subirritant exposure to isocyanates. No difference in the frequency or type of respiratory complaints between isocyanate reactors and nonreactors was found. No differences in lung function results were present when comparing smoking and ex-smoking reactors and nonreactors. In never-smokers with complaints consistent with isocyanate-induced asthma, the presence of obstructive lung disease increased the likelihood that isocyanate-induced asthma was present. Bronchial responsiveness to methacholine occurred in nearly all isocyanate reactors but predicted isocyanate-induced asthma in only 68 percent of the workers. In nearly all cases of challenge-confirmed toluene diisocyanate (TDI)-induced asthma, a 15-min exposure to 20 ppb of the commercial TDI mixture (80:20 2,4:2,6) provoked asthma. Conversely, in the absence of an asthmatic response following exposure to this dose for this duration, a second exposure at this concentration for a longer time would be reasonable to confirm the absence of isocyanate-induced asthma. Among workers employed in the production of polyurethane foam and confirmed to have TDI-induced asthma by inhalation challenge to the different TDI isomers, there appeared to be increased airway reactivity to the 2,6 isomer. This may have relevance to the frequency and intensity of respiratory symptoms that workers with TDI-induced asthma develop in differing industrial settings.
Development and use of asbestos risk estimates.
Several groups of researchers, at the request of government agencies in various countries, have reviewed the literature on the health effects of asbestos exposure and derived quantitative estimates of the risks from such exposures. Because of differences in the area of responsibility of the different agencies, these estimates have inevitably been based on different assumptions concerning exposure (concentration, number of years of exposure, initial age, and number of hours per week). The lifetime cancer risk estimates derived in 6 reports are compared here, after adjustment to a common set of exposure assumptions appropriate for students attending schools containing asbestos products. Estimates are found to be reasonably similar, remaining differences being primarily due to differences in assumptions concerning parameter values of the models and the background risk of lung cancer. The various administrative processes used by the US agencies are also compared, and recommendations made for US government agencies involved in the derivation of risk estimates for exposures of general public concern.
Asbestos health effects: resolving the scientific uncertainties.
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Mortality of workers employed in two asbestos cement manufacturing plants.
In a study of the mortality experience of 6931 employees of two New Orleans asbestos cement products manufacturing plants over 95% were traced. Chrysotile was the primary fibre used in both plants. Plant 1 also used small amounts of amosite and, later, crocidolite irregularly whereas plant 2 used crocidolite steadily in pipe production. Previously reported exposure concentration estimates were revised, based on additional air sampling data and re-evaluation of these data. Workers in the two plants had similar duration of employment (overall, a mean of 3.8 years) and estimated exposure concentration (a mean of 7.6 million particles per cubic foot (mppcf)). Mortality was similar for these plants and comparable with Louisiana rates for all causes combined, nonmalignant causes, and primary cancers of specified sites other than lung. Short term workers from both plants showed raised and similar risk of lung cancer, but risk among longer term workers differed--for example, for workers employed over one year there was no excess in plant 1 (16 observed, 17.2 expected) but a significant excess in plant 2 (52 observed, 28.9 expected, p less than 0.001). After excluding short term workers, risk of lung cancer in plant 2 showed a significant trend with estimated cumulative asbestos exposure; using a conversion of 1.4 fibres/ml = 1 mppcf, the slope of the line was 0.0076. The slope for plant 1 was 0.0003. Among all workers (the 6931, plus 167 early employees) ten mesotheliomas had occurred up to 1984: two from plant 1, eight from plant 2. In plant 2 a case-control analysis found a relation between risk of mesothelioma and duration of employment (p less than 0.01) and proportion of time spent in the pipe area (p less than 0.01), thus adding to the evidence of a greater risk of mesothelioma from crocidolite than chrysotile asbestos. A review of the mortality findings of eight cohorts of asbestos cement workers is presented.
Spirometry: quantitative test criteria and test acceptability.
Quantitative test criteria have been developed to assess the acceptability of spirometric tracings. Most automated spirometers have been programmed with the criteria in order to assist in data collection. These instruments compare computed parameters from the collected tracings with the criteria and, after 3 acceptable FVC maneuvers have been collected, print out a statement indicating that "tests meet acceptability criteria." Technicians, nurses, and even their medical supervisors are beginning to rely on these statements as assuring overall test quality. However, a review of actual curves indicates that unacceptable results can be obtained from tests that comply with these standards. Although quantitative test criteria are a positive step toward quality assurance, they should be treated as they were developed, as "minimum" criteria. All curves should be inspected for visible defects, especially if the results are used to follow subjects longitudinally.
Synergy of lung biology and medicine: the NHLBI from the perspective of the pulmonary community.
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