Longitudinal and Cross-sectional Analyses of Lung Function in Toluene Diisocyanate Production Workers

Longitudinal Evaluation of Lung Function in Gulf War I Veterans Exposed to Depleted Uranium

OBJECTIVE

Gulf War I (GWI) Veterans exposed to depleted uranium (DU) have undergone biennial surveillance to assess for DU-related health effects. No DU-specific respiratory effects have been observed cross-sectionally, but longitudinal lung function decline has not been assessed.

METHODS

A dynamic cohort of 71 Veterans underwent spirometry testing between 1999 and 2019. Longitudinal rates of decline of spirometry values were compared among Veterans with high versus low uranium levels using a linear mixed model.

RESULTS

There was no significant difference in rate of decline of spirometry values between Veterans with high versus low uranium levels. The overall rate of decline was similar to that of the general population.

CONCLUSIONS

In 20 years of follow-up, there does not appear to be an accelerated rate of decline of lung function among veterans exposed to depleted uranium.

How Is Work Ability Shaped in Groups of Shift and Non-Shift Workers? A Comprehensive Approach to Job Resources and Mediation Role of Emotions at Work

There is much less research on the relationship between shift work and positive states experienced in the workplace, e.g., emotions and work ability. Using the job demands-resources model, conservation of resources theory and the broaden-and-build theory as theoretical frameworks, the direct and indirect (mediated via positive and negative emotions) relations between the complex of job resources and work ability were tested in the group of shift and non-shift workers. Three types of resources related to task, leadership and interpersonal relations were taken into account. Data were collected among 1510 workers. Structural equation modelling (SEM) showed that only leadership was directly related to high work ability in both occupational groups. Indirect effects of positive and negative emotions were strongly supported. Both of them mediate the effects of the three analysed job resources on work ability, but individual job resources impacted were different. Leadership resources led to "good" work ability by the intensification of positive and reduction of negative emotions. Interpersonal resources decrease negative emotions. Task resources, conversely, intensified positive emotions, which in turn increased work ability. These research results shed more light on the ways of shaping work ability among shift and non-shift workers.

Spirometric Measurement among Polyurethane Foam Mattress-making Workers of India

Background:

The polyurethane foam (PUF) mattress-making workers are exposed to isocyanates which are known respiratory toxicants and cause effect on pulmonary volumes and flows. Thus, the study was with a rationale to measure the changes in pulmonary flow and volumes due to isocyanates among PUF mattress-making workers.

Materials and Methods:

The study included 183 male workers from seven PUF making units of western and northern India. Using the interview technique as a tool for data collection, demographic and occupational details of the subjects were recorded on the predesigned and pretested pro forma. The mean of spirometric parameters was compared using one-way ANOVA and t-test. The relation between spirometric parameters and anthropometric parameters was analyzed using the correlation coefficient.

Results:

The spirometry showed that out of 183 participants, 165 (90.2%) subjects had normal spirometry, 13 (7.1%) had restrictive impairment, and 4 (2.2%) had obstructive impairment. All the mean spirometric values showed a declining trend with increasing age, while only forced expiratory volume in first second and forced vital capacity_25%–75% showed a declining trend with increasing duration of employment. The spirometric measurements had a negative correlation with age and positive correlation with height.

Conclusion:

The spirometric values representing the airway flow were affected. The associated factors include age and duration of exposure.

The Effect of Exposure to Rubber Production Emissions and Physical Activity on Pulmonary Function Indices among Tyre Manufacturing Employees in Iran

Background:

Exposure to rubber production emissions can cause respiratory problems. There is some evidence that physical activity might have protective effects against respiratory obstruction.

Aims:

This study, was investigated the effect of physical activity on potential respiratory damages induced by the exposure to rubber production chemicals.

Methods:

This cross-sectional study was carried out during 2019 on the staff of a rubber manufacturing company in Khorasan, Iran. Employees of a rubber manufacturing company were recruited in this cross-sectional study (n = 385), and were classified into exposed (n = 266) and unexposed (n = 119) groups. Baecke Physical Activity Questionnaire (BPAQ) was used to assess the level of physical activity. Logistic regression was used to evaluate the effects of exposure, physical activity and confounding variables on pulmonary function test (PFT) results.

Results:

Work, leisure time and total physical activity scores were significantly higher in exposure group compared with control group subjects. Although no significant differences were observed between the exposure and control groups in most spirometric parameters, FEF25-75 was significantly lower in the exposure group (P = 0.035). Abnormal PFT was observed in 93 participants (24.2%) and in the multivariate model was significantly associated with exposure (OR = 1.80, CI95: 1.01-3.22) and age (OR = 1.08, CI95: 1.02-1.14) but not physical activity score.

Conclusion:

Exposure to rubber manufacturing chemicals nearly doubles the odds of abnormal PFT, and the self-reported level of physical activity had no protective effect against these occupational hazards.

Practical learnings from an epidemiology study on TDI-related occupational asthma: Part II-Exposure without respiratory protection to TWA-8 values indicative of peak events is a good indicator of risk

The anonymized data of an epidemiology study on the incidence of toluene diisocyanate (TDI)-related occupational asthma in three US-based TDI production facilities have been reanalyzed to identify where to best focus exposure reduction efforts in industrial practice in order to reduce the risk of sensitization to TDI. In Part I, it was demonstrated that cumulative exposure is not a good indicator of the risk of developing TDI-related occupational asthma. In this Part II, an alternative model was developed based on net exposure parameters (i.e. samples taken when no respiratory protection was used). A statistically significant relationship was determined between asthma incidence and the frequency of exposure to TDI levels indicative of peak events that are expressed as time-weighted average-8 (TWA-8) values greater than 3 ppb during which no respiratory protection was used. This relationship suggests a threshold to induction of TDI-related asthma. The findings also highlight the importance of a comprehensive program for controlling workplace atmosphere in the plant by technical measures (e.g. selection of equipment, cleaning procedures) and controlling exposure by organizational measures and situational awareness (e.g. training, use of in-the-field direct reading indicators) during high potential exposure scenarios (e.g. line breaking, spills) to encourage or enforce the appropriate use of respiratory protection.

Practical learnings from an epidemiology study on TDI-related occupational asthma: Part I-Cumulative exposure is not a good indicator of risk

The anonymized data of an epidemiology study on incidence of toluene diisocyanate (TDI)-related occupational asthma in three US-based TDI production facilities have been reanalyzed to identify where to best focus exposure reduction efforts in industrial practice to reduce the risk of sensitization to TDI. Since the induction of sensitization has sometimes been attributed to cumulative exposure, this relationship was examined first. Gross cumulative exposure values (i.e. not taking into account whether respiratory protection was used or not) and net cumulative exposure values (i.e. accounting for the use of respiratory protection) per participant were calculated based on the duration of their study participation and the average time-weighted average value of the exposure group to which they belonged. These two sets of cumulative exposure data were compared with asthma incidence using logistic regression. Incidence was zero among workers who rarely come into contact with open plant systems (e.g. during maintenance or spills). Notwithstanding, no statistically significant relationship between asthma incidence and either gross or net cumulative exposure could be determined. This is shown to be consistent with the results of several other epidemiology studies on TDI-related occupational asthma. In conclusion, cumulative exposure values are not a good indicator of the risk of developing TDI-related occupational asthma.

Incidence of Occupational Asthma and Exposure to Toluene Diisocyanate in the United States Toluene Diisocyanate Production Industry

Objective

This study examines asthma risk in facilities producing toluene diisocyanate (TDI).

Methods

A total of 197 workers were monitored from 2007 to 2012. TDI air concentrations were used to estimate exposures.

Results

The incidence of cases consistent with TDI-induced asthma was 0.009 per person-years (seven cases) or consistent with TDI-induced asthma or asthma indeterminate regarding work-relatedness was 0.012 (nine cases). Increased risk of cases consistent with TDI asthma was observed for cumulative (odds ratio [OR] = 2.08, 95% confidence interval [CI] 1.07 to 4.05) per logarithm parts per billion-years and peak TDI exposures (OR = 1.18, 95% CI 1.06 to 1.32) (logarithm parts per billion). There was a weak association with cumulative and peak exposures for decline of short-term forced expiratory volume in one second (FEV₁). Asthma symptoms were associated with workers noticing an odor of TDI (OR 6.02; 95% CI 1.36 to 26.68).

Conclusions

There is evidence that cumulative and peak exposures are associated with TDI-induced asthma.

Medical Monitoring for Occupational Asthma Among Toluene Diisocyanate Production Workers in the United States

OBJECTIVE

The aim of this study was to describe a study of medical monitoring methods and lessons learned in detecting health outcomes in U.S. plants producing toluene diisocyanate (TDI).

METHODS

A multidisciplinary team implemented a medical and environmental monitoring program in three TDI plants.

RESULTS

Of 269 eligible workers, 197 (73%) participated and 42 (21%) met symptom and/or lung function criteria that would trigger evaluation for possible asthma over 5 years of data collection. Subsequent evaluation was delayed for most, and a web-based data collection system improved timeliness.

CONCLUSION

Medical monitoring of TDI workers identified workers triggering further assessment per study protocol. Systems and/or personnel to ensure rapid follow-up are needed to highlight when triggering events represent potential cases of asthma needing further evaluation. Implementation of a research protocol requires resources and oversight beyond an occupational health program.