Exposure to isocyanates and organic solvents, and pulmonary-function changes in workers in a polyurethane molding process

Five annual observations of respiratory findings in gun factory workers exposed to solvents

OBJECTIVE

We investigated whether long-term, low-level exposures to solvents had adverse longitudinal effects on pulmonary functions.

METHODS

The study was performed on 1091 workers 5 years ago and then on 697 workers 5 years later. Chronic respiratory symptoms were recorded using a questionnaire on respiratory symptoms.

RESULTS

The annual decrease in forced expiratory volume in 1 second in the workers exposed to solvents was not significantly different from that of the unexposed workers (69.7 +/- 89.9 vs 75.8 +/- 87.6 mL/yr, P = 0.5, respectively). In 453 workers who were exposed to solvents 5 years ago, the prevalence rate of asthma was 1.1%. Five years later, it was 3.6% in 193 workers from the same group. The difference was statistically significant (P = 0.03).

CONCLUSIONS

Longitudinally, the chronic exposure to low doses of solvents does not adversely affect the pulmonary functions, whereas it increases the asthma prevalence.

A survey of airborne and skin exposures to chemicals in footwear and equipment factories in Thailand

This research reports on a pilot industrial hygiene study that was performed at four footwear factories and two equipment factories in Thailand. Workers in these factories were exposed through inhalation and dermal contact to a large number of organic vapors from solvents and cements that were hand applied. In addition, these workers were exposed to highly toxic isocyanates primarily through the dermal route. A total of 286 personal air samples were obtained at the four footwear factories using organic vapor monitors; individual job tasks were monitored using a real-time MIRAN Spectrometer. A total of 64 surface, tool, or hand samples were monitored for isocyanates using surface contamination detectors. Real-time measurements were also obtained for organic vapors in two equipment factories. From 8% to 21% of the workers sampled in each footwear factory were overexposed to mixtures of chemicals from solvents and cements. Up to 100% of the workers performing specific job tasks were overexposed to mixtures of chemicals. From 39% to 69% of the surface samples were positive for unreacted isocyanates. Many of the real-time measurements obtained in the equipment factories exceeded occupational exposure limits. Personal protective equipment and engineering controls were inadequate in all of the factories.

Respiratory findings in gun factory workers exposed to solvents

OBJECTIVE

Gun factory workers are exposed to many solvents (toluene, acetone, butanol, xylene, benzene, trichloroethylene). We investigated whether chronic exposure to solvents had adverse effect on respiratory system.

MATERIAL AND METHODS

The workers were questionnaired by modified Medical Research Council's respiratory questionnaire before morning start shift. Then physical examination and measurement of pulmonary functions by portable dry rolling spirometer were performed. The study group consisted of 1091 gun factory workers. The workers were grouped according to their smoking habits (smokers, [exposed n: 353 vs. unexposed n: 339] and non-smokers [exposed n: 58 vs. unexposed n: 341]). Asthma-related symptoms were defined as either definite asthma, probable asthma, and possible asthma.

RESULTS

In non-smokers, the report of asthma-related symptoms was more prevalent in exposed workers than unexposed (39.7% vs. 21.7% OR 2.4[1.3-4.3], respectively P = 0.003). In smokers, the report of asthma-related symptoms was more common in exposed group than unexposed (50.7% vs. 42.5% OR 1.4[1.0-1.9], respectively P = 0.03). Logistic regression analysis showed that smoking (OR 2.8[2.0-3.8] P = 0.00001) and exposure to solvents (OR 1.4[1.1-1.9] P = 0.01) were independent risk factors for asthma-related symptoms, after adjusting for age. Logistic regression analysis identified that smoking (OR 3.3[2.3-4.6] P = 0.00001) was independent risk factors for chronic bronchitis. Multiple linear regression analysis of lung-function parameters (% forced expiratory volume (FEV1), FEV1/forced vital capacity, FEF(25-75)) indicated significant effects of smoking.

CONCLUSION

Present study indicated significant effects of smoking and exposure to solvents, with the smoking effect being the most important on asthma-related symptoms of gun factory workers.

Diesel exhaust, solvents, and other occupational exposures as risk factors for wheeze among farmers

Farmers engage in activities that result in exposure to diesel exhaust, solvents, welding fumes, and other respiratory irritants. Using the Agricultural Health Study, a cohort of pesticide applicators in Iowa and North Carolina, we evaluated the odds of wheeze associated with nonpesticide occupational exposures. We used logistic regression models controlling for age, state, smoking, and history of asthma or atopy to evaluate odds of wheeze in the past year among the 20898 farmers who provided complete information on all covariates. Driving diesel tractors was associated with elevated odds of wheeze (odds ratio = 1.31; 95% confidence interval = 1.13, 1.52); the odds ratio for driving gasoline tractors was 1.11 (95% confidence interval = 1.02, 1.21). A duration-response relationship was observed for driving diesel tractors but not for driving gasoline tractors. Activities involving solvent exposure, including painting and use of solvents for cleaning, were associated with an increased odds of wheeze in a duration-dependent fashion. The highest odds of wheeze for farm activities were for daily painting (odds ratio = 1.82; 95% confidence interval = 0.89, 3.73), an indication of daily solvent exposure. These results add to the growing body of evidence of adverse respiratory effects of diesel exposure on the lung and suggest exposure to solvents may contribute as well.

Investigation of pulmonary function among employees exposed to low levels of monomeric isocyanates and solvents at an automobile finishings plant

There have been reports in the literature of decrements in pulmonary function associated with long-term, low-level monomeric isocyanate exposure combined with solvent exposure. This cross-sectional study examines the relationship between these exposures and pulmonary function in an automobile paint and coating (finishes) plant. A job exposure matrix was developed for isocyanate and solvent exposure; years in a work task were used as a surrogate for exposure. Recent pulmonary function tests were used as the outcome variables; specifically the difference between predicted and actual FEV1 and FVC. The results of the analysis demonstrated no statistically significant relationship between combined isocyanate and solvent exposure and decline in pulmonary function. There was a statistically significant negative correlation between solvent exposure and FEV1 and FVC.

Effects of long-term solvent exposure on blood cytokine levels and antioxidant enzyme activities in house painters

The aim of this study was to examine solvent-associated effects on blood cytokine levels, antioxidant enzyme activities, and malondialdehyde (MDA) concentration in house painters. Trace element (Cu and Zn) and nitrite and nitrate levels as well as protein concentrations in erythrocytes and serum were determined. Thirty male house painters and 30 male clerical workers were included in the study. There were 13 smokers and 17 nonsmokers in each group. Hemoglobin concentrations were significantly lower in house-painter blood compared to controls. House painters had significantly higher concentrations of erythrocyte protein (excluding hemoglobin), whereas no significant difference was observed between serum protein levels. Proinflammatory cytokine levels, such as tumor necrosis factor-alpha and interleukin-8, were significantly increased in house painters' sera. Interleukin-6 was below the detection limit of the assay in both groups. Interleukin-1beta and cytokine receptor interleukin 2R concentrations were not significantly affected. Furthermore, a three- to fourfold increase in nitrite and nitrate concentrations was found in house painters' sera. Serum superoxide dismutase (SOD) and glutathione peroxidase (GSHPx) activities were significantly lower in house painters compared to controls. Malondialdehyde (MDA) concentration, a measure of lipid peroxidation, was found to be significantly elevated. In house painters, erythrocyte carbonic anhydrase and catalase activities were elevated approximately 11- fold and 2-fold, respectively. Zinc levels were significantly decreased in house painters' sera. Smoking was not found to be a major confounder for the association between solvent exposure and blood parameters.

Prevalence of neuropsychiatric and mucous membrane irritation complaints among Palestinian shoe factory workers exposed to organic solvents and plastic compounds

BACKGROUND

Long-term exposure to organic solvents is associated with neuropsychiatric and mucus membrane irritation. In developing countries, efforts to secure a good working environment are inadequate and protection against chemical exposures is often neglected.

METHODS

In a cross-sectional survey, the prevalence of self-reported health complaints and the association with long-term exposure to solvents and plastic materials in the work environment was studied among 167 shoe-factory workers. Prevalences and adjusted prevalence ratios (PR)were calculated in Cox regression. 95% confidence intervals were estimated for PRs of adverse health effects.

RESULTS

Overall, the workers reported high prevalences of neuropsychiatric and mucus membrane complaints: headache (65%), mental irritability (53%), tingling of limbs (46%), and sore eyes (43%). Cleaning work was associated with tingling of limbs (PR = 1.8, 1.0-3.2), sore eyes (PR = 1.9, 1.1-3.3), and breathing difficulty (PR = 2.0, 1.0-3.9); plastic work was associated with tingling of limbs (PR = 1.8, 1.2-2.9)and sore eyes (PR = 1.7, 1.1-2.7); and varnishing was associated with breathing difficulty (PR = 1.9, 1.1-3.5).

CONCLUSIONS

The high prevalence of self-reported health complaints and the exposure-outcome association could be due to volatile organic solvents (dichloromethane, n-hexane)and plastic compounds (isocyanates and polyvinyl chloride). Absence of a satisfactory work environment is likely to contribute to high exposure levels.

Exposure biomarkers and risk from gluing and heating of polyurethane: a cross sectional study of respiratory symptoms

OBJECTIVES

To define the relation between exposure to polyurethane (PUR) glue, biomarkers of exposure and effect, and work related symptoms that occur at least once a week.

METHODS

In a cross sectional study, 152 workers and 14 clerks in a factory with exposure to sprayed and heated PUR glue containing 4, 4'-diphenylmethane (MDI) or 1,6-hexamethylene (HDI) di-isocyanate were examined with gas chromatography-mass spectrometry (GC-MS) for metabolites of MDI in plasma (P-MDX) and urine (U-MDX), 2,4- and 2, 6-toluene di-isocyanate (TDI; P-TDX, U-TDX) and HDI in plasma and urine, specific serum IgG (S-IgG-MDI, S-IgG-HDI, and S-IgG-TDI, respectively) and IgE (S-IgE-MDI). Work related symptoms of the eyes and airways (nose or lower airways, or both), and lung function were also evaluated.

RESULTS

P-MDX was detected in 65% of the workers, U-TDX in 47%, HDX in none. Three per cent were positive for S-IgE-MDI, 33% for S-IgG-MDI, 32% for S-IgG-TDI, and 12% for S-IgG-HDI. A few clerks had metabolites, and some had antibodies. Most metabolites and immunoglobulins were slightly correlated-for example, P-MDX v S-IgG-MDI: r(s)=0.21. Workers who heated glue had increased P-MDX (odds ratio (OR)=12 for a value above the median) and S-IgG-MDI (OR=3.7), sprayers P-2,4-TDX (OR=6.2) and P-2,6-TDX (OR=16). Twenty six per cent of the workers had work related symptoms of the airways, 21% from the nose, 11% from the lower airways. Spraying of glue increased the risk of work related symptoms and slightly decreased lung function. U-MDX was associated with work related symptoms from the airways (OR=3.7) and P-2,6-TDX with work related symptoms from the lower airways (OR=6.6). S-IgG-MDI was related to work related symptoms from the airways (OR=2.6).

CONCLUSIONS

There were relations between exposures to sprayed and heated PUR glue based on MDI and HDI, concentrations of metabolites of MDI and TDI in plasma and urine, specific IgG serum antibodies against MDI, TDI, and HDI, and work related symptoms.

Weight change and lung function: implications for workplace surveillance studies

This study evaluated the relationship between weight change and longitudinal measurement of lung function among 361 men providing at least five pulmonary function tests. The men in this study were participants in a workplace pulmonary surveillance program for subjects with exposure to refractory ceramic fibers (RCFs). Occupational and environmental studies are generally designed to evaluate factors suspected of causing excess decline in lung function. Failure to adequately account for all significant factors may lead to erroneous conclusions regarding change in lung function. This study utilized two different statistical models to evaluate longitudinal changes in a cohort of RCF workers. What was unique to this study was the modeling of longitudinally measured initial weight, weight change, and longitudinal exposure before and during the period of observation. Results showed a strong relationship between weight gain and longitudinal loss in lung function that approximated forced vital capacity declines of 16 mL for every kilogram of weight gain per year in both models. This value is comparable or greater in magnitude and significance to other factors known to be inversely related to lung function, such as age and pack-years smoking to time of initial testing. In conclusion, weight gain was found to have a significant impact on longitudinal change in lung function. Therefore, weight gain becomes a very important variable that requires consideration whenever longitudinal studies of pulmonary function are conducted.