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Biomedical subjects

T G Robins

Publications and source records attributed to T G Robins.

At least 37 records · Page 2Linked to original sources
PubMed1993

Renal effects of naphtha exposure among automotive workers.

As part of a study on health effects of naphtha exposure, the association between naphtha exposure and urinary excretion of total protein, albumin, beta-N-acetyl-D-glucosaminidase (beta-NAG), and beta 2-microglobulin was assessed prospectively over 1 year among workers at an automotive plant that used naphtha to calibrate fuel injectors. Participants consisted of 248 workers who provided spot urine samples in June 1988 among whom 181 workers provided specimens again in June 1989. Naphtha air concentrations at the plant ranged from 6 to 790 mg/m3 and the length of exposure ranged from 0.8 to 7.3 years. In both 1988 and 1989, the overall distribution of the four measures of renal function appeared consistent with that of an unexposed population. In cross-sectional analyses, there were no statistically significant associations in the expected direction between cumulative or recent naphtha exposure and the measures of renal function. In longitudinal analyses, the change in beta-NAG was positively associated with the change in recent naphtha exposure (P = .009). The effect of the naphtha exposure during 1 workweek was assessed among 17 workers who provided urine samples Monday preshift, Monday postshift, and Friday postshift. No associations were found. The results of this study do not provide strong evidence of naphtha-associated renal effects at these levels of exposure.

Adult↗
PubMed1993

Longitudinal and cross sectional analyses of exposure to coal mine dust and pulmonary function in new miners.

The association between exposure to dust and pulmonary function was studied by longitudinal and cross sectional analyses in a group of United States underground coal miners beginning work in or after 1970. Quantitative estimates of exposure to respirable coal mine dust were derived from air samples taken periodically over the entire study period. The cohort included 977 miners examined both in round 2 (R2) (1972-5) and round 4 (R4) (1985-8) of the National Study of Coal Workers' Pneumoconiosis. Multiple linear regression models were developed for both cross sectional (pulmonary function at R2 and R4) and longitudinal (change in pulmonary function between R2 and R4) analyses with exposure partitioned into pre-R2 and post-R2 periods and controlled for covariates including smoking history. The results indicate a rapid initial (at R2) loss of FVC and FEV1 in association with cumulative exposure of the order of 30 ml per mg/m3-years. Between R2 and R4 (about 13 years) no additional loss of function related to dust exposure was detected although the percentage of predicted FVC and FEV1 did decline over the period. After some 15 years since first exposure (at R4), a statistically significant association of cumulative exposure with FEV1 of about -5.9 ml per mg/m3-years was found. These results indicate a significant non-linear effect of exposure to dust on pulmonary function at dust concentrations present after regulations took effect. The initial responses in both the FVC and FEV1 are consistent with inflammation of the small airways in response to exposure to dust.

Adult↗
PubMed1992

Exposure-response relationships for coal mine dust and obstructive lung disease following enactment of the Federal Coal Mine Health and Safety Act of 1969.

Underground U.S. coal miners were studied cross-sectionally for the association of respirable coal mine dust exposure with pulmonary function and symptoms of airways obstruction. The study group included 1,185 miners participating in Round 4 of the National Study of Coal Workers' Pneumoconiosis who had started mining in or after 1970 when comprehensive exposure regulations first came into effect. Quantitative estimates of cumulative exposure, derived using respirable dust measurements taken by the Mine Safety and Health Administration over the entire study period, were used in linear and logistic regression models on indicators of pulmonary function and chest symptoms while controlling for smoking status, pack-years, and other potential confounders. Statistically significant associations between log cumulative exposure and decrements in FVC, FEV1, and FEV1/FVC were observed. In logistic models, statistically significant associations of cumulative exposure with increasing prevalence of FEV1 and FEV1/FVC less than 80% predicted and symptoms including chronic phlegm, chronic bronchitis, breathlessness, wheeze, and wheeze with shortness of breath were found. It is concluded that exposures to respirable coal mine dust present in U.S. mines since 1970 continue to affect respiratory health in underground miners.

Adult↗
PubMed1992

A longitudinal study of the relation of lead in blood to lead in air concentrations among battery workers.

The relation between lead in air (PbA) and lead in blood (PbB), concentrations was investigated among 44 workers in five major operations in a United States high volume, lead acid battery plant. The study covered a 30 month period in which workers received frequent PbA and PbB determinations, workers remained in a single job, and PbA concentrations averaged below the US Occupational Safety and Health Administration (OSHA) permissible exposure limit of 50 micrograms/m3. In both univariate and multivariable linear regressions, longitudinal analyses averaging PbA concentrations over the 30 month study period appeared superior to cross sectional analyses using only six month PbA averages to model PbB concentrations. The covariate adjusted coefficient (alpha value) for PbA (mu/m3) in models of PbB (micrograms/100 g) was 1.14. This figure is strikingly higher than that reported in previous studies in the lead acid battery industry in all of which PbA concentrations were substantially higher than in the current study. Plausible explanations for the difference in alpha values include non-linearity of the PbA-PbB curve, a higher fraction of large size particulate associated with higher PbA concentrations, survivor bias among workers exposed to higher PbA concentrations, and the cross sectional designs of most previous studies. Despite previously reported problems with the model used by OSHA to predict PbA-PbB relations, the findings of this study are in good agreement with the predictions of that model.

Chemical Industry↗
PubMed1991

Renal function in dry cleaning workers exposed to perchloroethylene.

Perchloroethylene (PCE) is a widely used dry cleaning and degreasing solvent. Although there is evidence in animals and humans for renal effects at extremely high doses, there are few studies of its potential renal toxicity at typical occupational concentrations. This study reports on the relationship of PCE in breath and estimates of chronic exposure with the urinary ratios of total urinary protein, albumin, and n-acetyl-glucosaminidase (NAG) to creatinine in dry cleaning workers exposed to PCE. Regression models including one or more exposure variables, demographic variables, mean arterial blood pressure (MAP), and the presence of diseases affecting kidney function were examined. Urine samples, breath samples, exposure histories, and medical histories were obtained from 192 dry cleaning workers. The results failed to demonstrate any consistent relationship between exposure and renal outcome variables. However, protein/creatinine and albumin/creatinine were significantly, although weakly and positively, associated with MAP; NAG/creatinine was weakly but significantly positively associated with age; mean NAG/creatinine was also higher in non-whites. The reasons why an association between exposure and renal outcome was not found are discussed.

Acetylglucosaminidase↗
PubMed1991

The effect of airborne lead particle size on worker blood-lead levels: an empirical study of battery workers.

Theoretical models and experimental data suggest that the particle size distribution of lead aerosols should affect the lead dose absorbed by exposed workers. In the present study, 44 workers in five major operations in a high-volume, lead-acid battery plant were studied for the influence of lead aerosol size on lead-in-blood (PbB) levels. A multiple linear regression analysis based on particle size assumptions made in the model used by the Occupational Safety and Health Administration to help select the permissible exposure level (PEL) for lead showed no improvement in prediction of PbB over that already present without any consideration of particle size. The use of the American Conference of Governmental Industrial Hygienists (ACGIH) regional size-selective criteria also failed to improve the prediction of PbB. However, when deposition models developed by Heyder et al were used in which the lead aerosol was separated into alveolar and extra-alveolar fractions, corresponding to what is considered respirable and ingestible lead, the coefficient of determination (R2) associated with the fractionated lead particulate increased approximately 25% over that attributable to only the total lead concentration. In addition, the deposition model, which closely matched the ACGIH reference worker criteria, resulted in ratios of the coefficients for the respirable to ingestible lead contributions to PbB that appeared to agree with experimental data, suggesting approximately a 10 to 1 ratio in absorption efficiency of the lung versus the gastrointestinal tract.

Aerosols↗
PubMed1991

Influence of high past lead-in-air exposures on the lead-in-blood levels of lead-acid battery workers with continuing exposure.

We investigated the relationship between air lead levels and blood lead levels in 132 lead-acid battery workers in two plants who were followed for 30 months between 1983 and 1985 with frequent air lead and blood lead determinations. Both plants converted to more modern, expanded-metal battery manufacturing technologies around 1978 with associated reductions in mean air lead exposures from greater than 100 to less than 30 micrograms/m3. In multiple regression analyses including consideration of job category, seniority, age, ethnicity, gender, and smoking habit as covariates, there was a highly significant association of blood lead in micrograms/dL with air lead in micrograms/m3 (partial R2 = .20, P less than .0001) among the 68 workers in plant B but no association (P = .91) in plant A. Restriction of the regression analysis to those 44 workers in plant B with less than or equal to 22 years of seniority yielded the most significant air lead-blood lead association (partial R2 = .36, P less than .0001). Among the remaining 24 plant B workers, seniority, but not air lead, had a significant positive association with blood lead. Despite very stable air lead levels over the 30-month study, the 51 workers in plant A with more than 20 years' seniority had a mean decline of 0.04 microgram/dL in mean blood lead over the study period, whereas the 13 workers in plant A with less than or equal to 20 years' seniority had a mean increase of 7.6 microgram/dL.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants, Occupational↗
PubMed1991

Lymphocytopenia, T-lymphocyte subsets, and colorectal polyps in automotive pattern and model makers.

Several studies have found pattern and model makers to be at increased risk for colorectal polyps and colorectal cancers. One study found an increased prevalence of lymphocytopenia. The association of total lymphocyte, CD4 (T-helper cell), CD8 (T-suppressor cell), CD2 (total T-cell), and CD16 (natural killer cell) counts with biopsy-proved colorectal polyp status was investigated in 70 patternmakers participating in one or more of four sequential screenings. In logistic regression analyses after adjusting for age or trade years, pack-years smoked, and material worked with most, a history of any type of polyp was significantly associated with total lymphocyte count (odds ratio of 2.01 for a 500 cell/cc decrease, P = 0.03), and somewhat associated with decreased CD4 and CD2 counts (P values of 0.06 and 0.07, respectively). In linear regression models adjusted for age, pattern and model makers had (regardless of polyp status) significantly lower CD4, CD8, CD2, and CD16 counts than did laboratory reference controls (P value less than 0.01 for each comparison). These findings appear consistent with a sequence of carcinogenesis initiated by pattern and model makers' work-place exposures that depress immune surveillance thus promoting the development of colorectal polyps as a precursor of carcinoma.

Adenocarcinoma↗
PubMed1990

Respiratory morbidity of pattern and model makers exposed to wood, plastic, and metal products.

Pattern and model makers are skilled tradespersons who may be exposed to hardwoods, softwoods, phenol-formaldehyde resin-impregnated woods, epoxy and polyester/styrene resin systems, and welding and metal-casting fumes. The relationship of respiratory symptoms (wheezing, chronic bronchitis, dyspnea) and pulmonary function (FVC% predicted, FEV1% predicted, FEV1/FVC% predicted) with interview-derived cumulative exposure estimates to specific workplace agents and to all work with wood, plastic, or metal products was investigated in 751 pattern and model makers in southeast Michigan. In stratified analyses and age- and smoking-adjusted linear and logistic regression models, measures of cumulative wood exposures were associated with decrements in pulmonary function and dyspnea, but not with other symptoms. In similar analyses, measures of cumulative plastic exposures were associated with wheezing, chronic bronchitis, and dyspnea, but not with decrements in pulmonary function. Prior studies of exposure levels among pattern and model makers and of respiratory health effects of specific agents among other occupational groups support the plausibility of wood-related effects more strongly than that of plastic-related effects.

Adult↗
PubMed1990

Assessment of potential biases in the application of MSHA respirable coal mine dust data to an epidemiologic study.

Systematic errors in exposure data will result in biased estimates of the exposure-response relationship derived from epidemiologic analyses. Thus, adjustment of exposure data to account for identified errors may provide for a more accurate assessment of effect. In preparing to apply respirable coal mine dust exposure data collected by the Mine Safety and Health Administration (MSHA) to a study of the pulmonary status of underground coal miners, an assessment of potential systematic errors was undertaken. Potential errors stemming from adjustment of controls during sampling, concentration-dependent sampling, truncation of sampling results, identified sampling equipment problems, and a disproportionate number of low concentration samples in mine operator-collected samples were identified and evaluated. Methods to account for these errors and adjust mean exposures by mine, occupation, and year are given.

Bias↗
PubMed1990

Perchloroethylene exposure assessment among dry cleaning workers.

Perchloroethylene (Perc), the most widely used solvent in dry cleaning, is toxic to the liver, kidneys, and central nervous system and may be a human carcinogen. In the Detroit area, as part of a project investigating the health status of dry cleaning workers, an exposure assessment was carried out in dry cleaning plants using perchloroethylene. Breath samples were obtained from each participant, and time-weighted average (TWA) breathing zone air samples were obtained using passive dosimeters on a subset expected to experience a range of exposures. Perc in breath and Perc in air were highly correlated (r2 = 0.75, p less than 0.0001). On average, operators of dry cleaning equipment experienced significantly more exposure than nonoperators. Also, employees working in shops that use transfer equipment (requiring physical transfer of Perc-saturated clothing from washers to dryers) showed significantly higher exposure than those in shops utilizing dry-to-dry machinery (permitting washing and drying in one machine in a single cycle). One or more air samples in every transfer shop exceeded the recently revised Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) of 25 ppm, while no air samples in dry-to-dry shops exceeded this limit. The results suggest concern for exposures to operators in transfer shops and that compliance with the PEL is achievable by engineering controls with presently existing technology.

Adult↗
PubMed1990

Implementation of the Federal Hazard Communication Standard: does training work?

A joint labor-management training program intended to bring a large US manufacturing firm into compliance with the training requirements of the Federal Hazard Communication Standard appeared to achieve increases in employee knowledge and improved work practices. The program also evidenced positive indirect effects on management's institution of hazard control measures and organizational handling of health and safety issues. Most observed effects were maintained over a 2-year period after the training. More interactive, trainer-intensive delivery methods to smaller groups were associated with more positive effects on reported training usefulness and changes in work practices and working conditions.

Hazardous Substances↗
PubMed1990

Solvent nephrotoxicity in humans and experimental animals.

Evidence from human case reports, epidemiologic studies and animal experiments have suggested that exposure to organic solvents is associated with a wide spectrum of renal disorders, including tubular necrosis, interstitial disease, glomerulonephritis and neoplasia. This review summarizes what is known about solvent-induced renal damage in humans and experimental animals, with emphasis on hypothesized mechanisms by which this broad range of disorders may occur.

Animals↗
PubMed1990

Chronic noise exposure, high-frequency hearing loss, and hypertension among automotive assembly workers.

The prevalence of hypertension and mean blood pressure was studied in 150 white men and 119 black men exposed to industrial noise of 85 dBA or greater for a minimum of 5 years. Mean decibel loss at 4000 Hz was 28.3 among the black workers and 45.3 among the white workers. 31.9% of the black men and 22.0% of the white men had hypertension, defined as diastolic blood pressure greater than 90 mm Hg and/or currently taking hypertensive medication. After controlling for several potential confounding factors, hearing loss at 4000 Hz and years worked in high-noise departments were significantly associated with mean blood pressure and hypertension among the black workers. No correlation between mean blood pressure or the presence of hypertension and hearing loss at 4000 Hz or years worked in high-noise departments was found among the white workers.

Adult↗
PubMed1989

Relationship of cumulative trauma disorders of the upper extremity to degree of hand preference.

The degree of hand preference, ie, the extent to which the use of one upper extremity is obligate, has not been studied previously as a possible risk factor for the development of upper extremity cumulative trauma disorders (UECTDs). This case-control study was designed to test the hypothesis that strong hand preference, whether left or right, would be associated with UECTDs in a working population. Case subjects were drawn from workers who presented to one of two acute care clinics for treatment of work-related cumulative trauma disorders of the upper extremity. Control subjects were drawn from job applicants presenting for preplacement examinations at the same two clinics. The degree of hand preference was determined by the Edinburgh Handedness Inventory of Oldfield. The 48 case subjects evidenced a higher absolute value of the mean handedness score (indicative of a stronger degree of hand preference) than the 134 control subjects (P = .01). As a dichotomized variable, being "strong"-handed versus "weak"-handed was a significant risk factor for UECTD (P = .01, odds ratio = 2.48). Among the 48 case subjects, 83% had a UECTD ipsilateral to the side of hand preference. This study found that workers who develop cumulative trauma disorders of the upper extremity are more likely to exhibit a strong hand preference than a group of applicants entering the work force. These findings suggest that the endogenously determined obligate use of one extremity may be a significant risk factor for the development of upper extremity cumulative trauma disorders.

Adult↗
PubMed1988

Respiratory morbidity in workers exposed to asbestos in the primary manufacture of building materials.

Former employees (214) of a plant that manufactured asbestos-containing building materials (wallboard and acoustic tile) from 1958 through 1974 were screened for asbestos-related pulmonary disease. Results are presented on 182 union members whose names appeared on a 1966 seniority list in one of six departments believed to have had substantial asbestos exposure. The study population demonstrated a high frequency of pulmonary abnormalities often associated with asbestos exposure: low mean forced vital capacity percent of predicted (FVC % predicted), low mean forced expiratory volume at one second percent of predicted (FEV1 % predicted), presence of parenchymal abnormalities (40.1% with profusion scores of 1/0 or higher), and 30.5% with bilateral pleural abnormalities on chest roentgenograms. In addition, râles in two or more locations were found in 22.8% on examination of the chest, 30.6% gave a history of chronic bronchitis, and 34.8% of dyspnea grade two or higher. Calculated asbestos exposure scores, based upon participant recall, were not found to be associated with these abnormalities. The abnormal findings were not adequately explained by potential confounders such as cigarette smoking. Other notable findings in this study include the presence of smoking-adjusted decrements in pulmonary function associated with moderate profusion scores (i.e., 1/0 and 1/1) and the presence of a substantial degree of obstructive lung disease (19.2%) in this population.

Adult↗
PubMed1988

The use of geometric and arithmetic mean exposures in occupational epidemiology.

In constructing quantitative measures of exposure for the study of chronic occupational disease, researchers have generally used a cumulative exposure calculated as the sum of the products of period-specific exposure concentrations and the time each individual spent in each exposure category. There has been some disagreement and lack of clarity about the use of the geometric or arithmetic mean of exposure for this calculation. This paper explores the difference in the use of the two measures and defines a relative bias introduced with the geometric vs. the arithmetic mean. The magnitude of the bias is calculated in two linear models of possible exposure-response relationships. The theoretical basis for the choice of one mean over the other is then explored. It is suggested that when adopting a linear exposure response model, the arithmetic mean is the more appropriate measure. In other models, such as a linear-log (outcome is proportional to the logarithm of exposure) model, the geometric mean would be more appropriate.

Chronic Disease↗