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Biomedical subjects

J A Merchant

Publications and source records attributed to J A Merchant.

At least 55 records · Page 3Linked to original sources
PubMed1990

Asbestos-induced pleural fibrosis and impaired lung function.

To assess the clinical significance of asbestos-induced pleural fibrosis, we evaluated the relationship between radiographic evidence of pleural fibrosis and spirometric values in 1,211 sheet metal workers. Of those with pleural fibrosis (n = 334), 78% had circumscribed plaques and 22% had diffuse pleural thickening involving the costophrenic angle. Factors that were found to be associated with the presence and type of pleural fibrosis included increased age (p less than 0.001), more years in the trade (p less than 0.0001), more years since first exposure to asbestos (p less than 0.0001), more pack-years of cigarette smoking (p less than 0.01), and the presence and degree of interstitial fibrosis (p less than 0.0001). After controlling for these potential confounders (age, years in the trade, latency, pack-years of smoking, and ILO profusion category), linear multivariate regression models demonstrated that both circumscribed plaques (p = 0.007) and diffuse pleural thickening (p = 0.008) were independently associated with decrements in FVC but not with decrements in the FEV1/FVC ratio. Furthermore, our data indicate that the effect of diffuse pleural thickening on decrements in FVC is approximately twice as great as that seen with circumscribed pleural plaques. We conclude that the presence and type of pleural fibrosis among asbestos-exposed workers is independently associated with a pattern of spirometry that is suggestive of an underlying restrictive defect in lung function.

Asbestos↗
PubMed1990

Human epidemiology: a review of fiber type and characteristics in the development of malignant and nonmalignant disease.

Consideration of the human epidemiology of diseases arising from exposure to naturally occurring and man-made mineral fibers encompasses the several forms of asbestos (chrysotile, crocidolite, amosite, anthophyllite, tremolite-actinolite), other naturally occurring silicates (talc, sepiolite, erionite, attapulgite, vermiculite, and wollastonite), and man-made mineral fibers (glass continuous filament, glass/rock/slag insulation wools, ceramic and other refractory fibers, and glass microfibers). The diseases arising from exposures to some of these fibers include pleural thickening (plaques, diffuse pleural thickening, and calcification), pulmonary fibrosis, lung cancers, mesothelioma of the pleura and peritoneum, and other cancers). Risk factors important in assessing these diseases include assessment of latency, duration of exposure, cumulative exposure, fiber origin and characteristics (length and diameter), other possible confounding occupational or environmental exposures, and smoking. Methodological issues commonly presenting problems in evaluation of these data include assessment of the adequacy of environmental exposures, particularly in regard to fiber identification, distribution, and concentration over the duration of exposure, and the adequacy of study design to detect health effects (disease frequency, latency, and cohort size). Research priorities include further assessment and standardization of pleural thickening relative to fiber exposure, uniform mesothelioma surveillance, further epidemiological assessment of certain silicate and man-made mineral fiber cohorts with emphasis given to assessment of tremolite and small diameter glass and ceramic fibers. Further assessment of possible health risks of the general public should await improved definition of relevant fiber exposure in ambient air.

Asbestos↗
PubMed1988

Acute systemic reactions to carbonless copy paper associated with histamine release.

We report two cases of recurrent episodes of hoarseness, cough, flushing, pruritus, and rash occurring within 30 minutes of topical exposure to carbonless copy paper. Provocative challenges revealed that alkylphenol novolac resin was the ingredient responsible. Video endoscopy of the larynx was performed and plasma histamine levels were obtained prior to and 30 minutes after cutaneous challenge of a patient with alkylphenol novolac resin. We documented marked laryngeal edema and a sixfold increase in plasma histamine levels after challenge. We conclude that topical exposure to carbonless copy paper may cause mast cell/basophil-mediated acute systemic and potentially life-threatening reactions in susceptible patients.

Adult↗
PubMed1987

Occupational disease surveillance data sources, 1985.

Health department epidemiologists in 50 states, New York City, and the District of Columbia were surveyed in 1985 about seven potential data sources for occupational disease surveillance. Reported sources of occupational disease data were: automated workers' compensation claims (63 per cent of the 52 respondents); provider reports (62 per cent); death certificates with occupation or industry (60 per cent); cancer registries with occupational histories (35 per cent); birth certificates with parent's occupation (27 per cent); non-cancer disease registries (13 per cent); and hospital or insurance records (8 per cent).

Birth Certificates↗
PubMed1985

Medical and industrial hygiene characterization of the cotton waste utilization industry.

We studied 260 workers in the cotton waste utilization industry and 310 "blue-collar" control workers from nondusty industries in the same geographic area of the United States by respiratory symptom questionnaire and by pre- and postshift spirometry. We excluded 75 cotton workers and 75 control workers from statistical analysis because of prior hazardous occupational exposures. Plant-wide, 8-hour time-weighted average exposures ranged from 0.28 mg/m3 to 7.80 mg/m3. The overall prevalence of symptoms compatible with byssinosis was 5.9% in cotton workers and 4.7% in the controls. Cotton workers with less than 2 years of employment had a significantly greater prevalence of bronchitis than their control counterparts. The cotton workers with 2 years or more of employment had significantly greater prevalences of bronchitis, shift decrement in forced expiratory volume in 1 second (FEV1) of greater than or equal to 10%, and FEV1/FEV1-predicted less than 80%, than their control counterparts. Regression analysis showed that for matched cotton and control workers, the percentage decrement in FEV1 over the shift was significantly greater for cotton workers; and that in all cotton workers, longevity in industry had a negative effect on the before-shift forced vital capacity (FVC). This study suggests that there are both acute and chronic effects of cotton exposure in the cotton waste utilization industry.

Adult↗
PubMed1985

Cigarette smoking and health.

Cigarette smoking is the major preventable cause of increased mortality and premature disability in the United States. Smoking is a proven cause of coronary heart disease, chronic bronchitis and emphysema, and lung and other cancers. Maternal smoking is associated with low infant birth weight, increased perinatal mortality, and several complications of pregnancy. Passive smoking is associated with increased incidence of lower respiratory tract infections in very young children and may increase the risk of lung cancer in the nonsmoker. Smoking cessation is difficult because of nicotine addiction and psychological and social factors. Physicians and other health professions must be active both in helping people quit smoking and in preventing nonsmokers from starting. We recommend a national effort focused on preventing young people from starting to smoke.

Cardiovascular Diseases↗
PubMed1983

Roentgenographic evidence of asbestos exposure in a select population of railroad workers.

A volunteer population of 266 current and former railroad workers was examined with posteroanterior and oblique chest roentgenograms, and a comprehensive occupational smoking history. Seventy-five percent of participants were over the age of 60, and 80% had fewer than 10 years of railroad-related asbestos exposure. Roentgenographic evidence of asbestosis was found in only six workers (2%), whereas 20% had one or more pleural changes. Radiological abnormalities were related to latency period, age, and occupation, but not to smoking habit. While selection factors qualify the results of this study, the findings support the exposure and suggest a past and future history of asbestos mortality and morbidity among steam era railway workers.

Aged↗
PubMed1982

The detection of thoracic abnormalities using posterior-anterior (PA) vs PA and oblique roentgenograms.

A reading trial was conducted as part of the 1978 Bay Area Asbestos Screening Project to evaluate the utility of adding oblique-view roentgenograms to standard posterior-anterior (PA) views. Chest films from a sample of 555 workers with histories of long-term asbestos exposure were read twice as PA and twice as PA + oblique sets, providing a basis for assessing reliability through intrareader, interreader, and intermethod agreement. The ancillary use of oblique view films resulted in higher rates of detection of asbestos-related abnormalities than with PA films alone, but the increased rates were gained at the expense of reliability in the interpretation process. Depending on the source of this unreliability, which requires further study, different remedial actions might be indicated. A reader's lack of experience could indicate the need for additional training, the use of several readers, an average over several reader judgements, or the development of standards for evaluating obliques. If, on the other hand, no way is found to reduce the unreliability, the use of oblique films in routine screening programs ought to be discouraged on the basis of measurement theory, since reliability is a prerequisite to validity.

Asbestos↗
PubMed1981

Mount St Helens eruptions, May 18 to June 12, 1980. An overview of the acute health impact.

Thirty-five known deaths were caused by the landslide and lateral blast of the May 18 eruption of Mount St Helens and at least 23 persons are missing. In 18 of 23 cases that reached autopsy, asphyxiation from ash inhalation was the cause of death. A rapidly established hospital surveillance system detected increases in the number of emergency room (ER) visits and admissions for asthma and bronchitis in communities with the heaviest ashfall after the May 18 eruption and the eruptions on May 25 and June 12. There were also increases in the number of ER visits for ash-related eye complaints in some areas. laboratory studies indicated that the May 18 ash was not acutely toxic, but the respirable portion contained 3% to 7% of crystalline free silica, a potential pneumoconiosis hazard to certain heavily exposed occupational groups. Continuing volcanic activity of Mount St Helens and future eruption of other volcanoes in the Cascade Range may pose a variety of health hazards, including blast, ashfalls, flooding, damage to public utilities, and possible psychosocial effects.

Asphyxia↗
PubMed1981

Silicosis in silica flour workers.

In July 1979, the health of 86 current and ex-workers at 2 silica mining and milling operations in southern Illinois was examined using a respiratory questionnaire, spirometry, and chest radiographs. None of 25 current workers with less than 1 yr of exposure to silica dust had radiographic evidence of silicosis. For 61 current workers and ex-workers with 1 or more yr of exposure, chest radiographs showed 16 (26%) with simple silicosis and 7 (11%) with progressive massive fibrosis. Of these 23, 8 with simple silicosis and 3 with progressive massive fibrosis began work after the first Mine Safety and Health Administration inspection in 1973. These data and a review of federal dust inspection results between 1973 and 1979 showed that these cases of silicosis could have been prevented by effecting compliance with the existing dust standard.

Adult↗
PubMed1981

The use of pulmonary function testing and questionnaires as epidemiologic tools in the study of occupational lung disease.

Pulmonary function testing and questionnaires are valuable tools in epidemiologic studies of occupational lung disease. Accurate equipment and standardized methodology are vital to obtain reproducible responses. For spirometry, the FVC and FEV show the least intrasubject variability and on questionnaires, occupational and smoking history are more reproducible than symptoms. The limitations of any method used to define a lower limit of normal should be kept in mind and, whenever possible, groups should be compared by use of the distribution of observations in the two groups--not just the prevalence of "abnormal" findings.

Adult↗