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.

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.

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

OBJECTIVE: The aim of this study was to investigate lung function among toluene diisocyanate (TDI) production workers. METHODS: One hundred ninety-seven U.S workers performed spirometry from 2006 through 2012. Results were compared within the study cohort and with U.S. population measures. A mixed-effects model assessed factors affecting repeated forced expiratory volume in 1 second (FEV1) measurements. RESULTS: The cohort's mean FEV1 and forced vital capacity (FVC) percent reference values, although greater than 90%, were significantly lower and the prevalence of abnormal spirometry (predominantly restrictive pattern) was significantly higher than in the U.S. POPULATION: Differences in lung function among workers with higher cumulative TDI exposure were in the direction of an exposure effect, but not significant. CONCLUSION: We found little evidence of an adverse effect of TDI exposure on longitudinal spirometry in these workers. The association between TDI exposure and the increasing prevalence of a restrictive pattern needs further exploration.

Developing a registry of workers involved in nanotechnology: BASF experiences.

OBJECTIVE: To assist BASF in the establishment of a registry of workers involved in nanotechnology. METHODS: The initial step was a complete inventory of nanomaterials and sites of use. Guidance was developed to clarify which particulate nanomaterials were to be included in the survey. Site management was then contacted by the medical department to obtain a list of workers. RESULTS: The time line for collecting data ranged from several months to a year, depending on the information needed, and presented challenges based on the lack of global definition and labeling of nanomaterials. Less than 50 nanomaterials are used as raw materials in less than 10% of the sites globally. In North America, less than 5% of sites and 5% workers use nanomaterials. CONCLUSIONS: Further work is required to integrate the inventory, registry, and exposure assessments.

Investigation of cancer occurrences associated with an herbicide manufacturing facility.

This study evaluated cancer incidence and mortality among 251 employees of a facility that synthesized a benzothiadiazin herbicide between 1979-1987. It was initiated in response to a perceived cancer cluster. Cancers were identified mainly by review of occupational medical records and personal interviews. Standardized incidence ratios (SIRs) were computed using comparison data provided by the Louisiana Tumor Registry. Overall mortality was less than expected and did not vary by job type or duration of assignment in the facility. Total cancer incidence was marginally elevated [SIR = 1.4; 95% Confidence Interval (CI): 0.9-1.9] and was highest among men assigned to the unit during 1979 [SIR = 2.1; 95% CI: 1.3-3.3]. Thirteen of 20 cancers among these men were either prostate (9) or digestive system (4) cancers. Increased medical examinations and cancer awareness may have contributed to the detection of cancers at earlier ages than would be seen in a general population. No specific workplace agents were identified to account for the findings although a workplace role cannot be ruled out.

Experience with early detection of toluene diisocyanate-associated occupational asthma.

There is good reason to expect that regular respiratory surveillance and early removal of workers who develop toluene diisocyanate (TDI)-associated occupational asthma can effectively protect these workers from accelerated pulmonary function decline. Application of this simple principle in operating industrial workplaces presents numerous challenges. The experience of one corporation is presented. One approach is to remove from future diisocyanate work, all workers who develop symptoms consistent with occupational asthma. However, the experience within this one corporation concurs with earlier, more carefully controlled investigations that such a strategy would be unduly restrictive of workers' occupational options. Fewer than half of the workers, who might have triggered such a practice, have required removal after more thorough occupational medical evaluation. Diisocyanates are such well known occupational asthmagens that other exposures tend to be ignored when considering respiratory health problems in a workplace. A small series of workers with work-related respiratory symptoms will be discussed. The usual industrial hygiene air monitoring demonstrated excellent control of the polyisocyanate hazard. Further investigation demonstrated poor control of a mold-release solution. Control of that exposure has allowed previously restricted workers to return to their former work making polyurethane parts. The number of cases available for analysis and discussion from this single, albeit large, corporation is small. Significant advances in understanding whether time-weighted average (TWA), task-specific, or dermal exposures to TDI and other polyisocyanates are most hazardous will require either many more years of experience within one corporation, or pooling of experience across the industry.