Judy Sparer

Liver Disease Associated with Occupational Exposure to the Solvent Dimethylformamide

STUDY OBJECTIVE to characterize an outbreak of liver disease among workers in a fabric coating factory; and to determine the outbreaks cause and natural history and strategies for clinical recognition, treatment, and prevention. DESIGN clinical-epidemiological investigation. SETTING academic medical center, Occupational Medicine Clinic, and worksite. PATIENTS fifty-eight of sixty-six workers participated in the study. All had standard liver function tests at least once. Forty-six workers completed a questionnaire; 27 had more extensive clinical evaluation for recognized liver abnormalities. RESULTS a plant-wide outbreak of liver disease was recognized after a new employee presented with signs and symptoms of hepatitis. Evaluation of the worksite showed that dimethylformamide, a widely used industrial solvent and known hepatotoxin, was being used to coat fabric in poorly ventilated areas without appropriate skin protection. No other major hepatotoxic exposure was identified. Overall, 36 of 58 (62%) workers tested had elevations of either aspartate aminotransferase (AST) or alanine aminotransferase (ALT) levels. Enzyme abnormalities occurred almost exclusively in production workers (35 of 46 were abnormal), whereas only 1 of 12 nonproduction workers showed any elevations in enzyme levels (P less than 0.0001). Serologic tests excluded known infectious causes of hepatitis in all but 2 workers and changes characteristic of toxic liver injury were confirmed by histologic examinations of biopsy specimens from 4 workers. The ratio of AST to ALT levels was one or less in all but 1 worker. After modification of work practices and removal of workers most severely affected from exposure, improvement in liver enzyme abnormalities and symptoms in most patients were seen, although some patients showed persistent elevations of enzyme levels. CONCLUSIONS an outbreak of toxic liver disease has been associated with exposure to dimethylformamide in the workplace. The diagnosis of toxic liver disease was established by the clinical histories, negative viral serologies, an enzyme pattern of ALT levels being greater than AST levels, epidemiologic data on coworkers, and liver biopsy specimens. The high prevalence of unsuspected liver enzyme abnormalities in these workers suggests that occupational liver disease may occur more frequently than is generally recognized.

Isocyanate Exposures in Autobody Shop Work: The SPRAY Study

Isocyanates, known to cause respiratory sensitization and asthma, are widely used in automotive refinishing where exposures to aliphatic polyisocyanates occur by both inhalation and skin contact. The work reported here, the characterization of isocyanate exposure in the autobody industry, was part of an epidemiologic study of workers in 37 autobody shops in Connecticut. This article describes workplaces, tasks, and controls, and outlines the frequency, duration, and intensity of isocyanate exposures. Personal air samples taken outside of respirators had median concentrations of 66.5 μg NCO/m3 for primer, 134.4 μg (NCO)/m3 for sealer, and 358.5 μg NCO/m3 for clearcoat. Forty-eight percent of primer, 66% of sealer, and 92% of clearcoat samples exceeded the United Kingdom Health and Safety Executive guideline for isocyanate, though none exceeded the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit for monomer. Nonisocyanate-containing primers and sealers are used in more than half the shops, but nonisocyanate clearcoats are rare. Eighty-two percent of personal samples taken within a spray booth exceeded the U.K. guideline: 81% of those in downdraft spray booths, 74% in semidowndraft booths, and 92% in crossdraft booths. Only 8% of shops reported that spraying is done exclusively in spray booths. All painters wore some type of respirator. In 30% of shops, painters used supplied air respirators; the rest relied on half face organic vapor cartridge respirators with N95 overspray pads. All shops provided some type of gloves, usually latex, not recommended for isocyanate protection. Despite improvements in autobody shop materials, practices, and controls, there are still opportunities for substantial exposures to isocyanates.

Characterization of clinical tolerance to inhaled zinc oxide in naive subjects and sheet metal workers.

Clinical tolerance to the acute effects of zinc oxide inhalation develops in workers during periods of repeated exposure. The aims of this study were to determine whether clinical tolerance is accompanied by a reduction in the acute pulmonary inflammatory and cytokine responses to zinc oxide exposure and whether tolerance can be demonstrated in sheet metal workers who chronically inhale low levels of zinc oxide. Naive (never-exposed) subjects inhaled 5 mg/m3 zinc oxide on 1 or 3 days and underwent bronchoalveolar lavage 20 hours after the final exposure. Sheet metal workers inhaled zinc oxide on 1 day and control furnace gas on another day. Among naive subjects in whom tolerance was induced, bronchoalveolar lavage fluid percent neutrophils and interleukin-6 (IL-6) levels were significantly decreased compared with subjects who underwent only a single exposure. Sheet metal workers were much less symptomatic, but they still experienced a significant increase in plasma IL-6. The results indicate that clinical tolerance to zinc oxide is accompanied by reduced pulmonary inflammation and that chronically exposed sheet metal workers are not clinically affected by exposure to zinc oxide fume at the Occupational Safety and Health Administration Permissible Exposure Limit. The increase in IL-6 levels observed in the clinically responsive, and to a lesser extent, tolerant, states following zinc oxide inhalation is consistent with the dual role of IL-6 as a pyrogen and anti-inflammatory agent.

Peripheral and central auditory dysfunction induced by occupational exposure to organic solvents

Objective: To examine the effects of solvent exposure on hearing function, through an audiological test battery, in a population not occupationally exposed to high levels of noise. Methods: One hundred ten workers from a coating factory were studied. Jobs at the factory were divided into three different levels of solvent exposure. Hearing status was assessed with a test battery including pure-tone hearing thresholds (0.5–8 kHz), high-frequency hearing thresholds (12 and 16 kHz), and dichotic listening measured through dichotic digits test. Multiple linear regression models were created to explore possible association between solvent exposure and each of the hearing outcomes. Results: Significant associations between solvent exposure and the three hearing outcomes were found. Covariates such as age, gender, race, and ethnicity were also significantly associated with the studied hearing outcomes. Conclusions: Occupational exposure to solvents may induce both peripheral and central auditory dysfunction. The dichotic digits test seems as a sensible tool to detect central auditory dysfunction associated with solvent exposure. Hearing loss prevention programs may use this tool to monitor hearing in solvent-exposed workers.

Respiratory Protection from Isocyanate Exposure in the Autobody Repair and Refinishing Industry

This study, part of the Survey of Painters and Repairers of Auto bodies by Yale (SPRAY), evaluated the effectiveness of respiratory protection against exposure to aliphatic polyisocyanates. A total of 36 shops were assessed for respiratory protection program completeness; 142 workers were measured for respirator fit factor (FF) using PortaCount Plus respirator fit tester. Twenty-two painters from 21 shops were sampled using NIOSH method 5525 to determine the workplace protection factor (WPF) of negative pressure, air-purifying half-facepiece respirators equipped with organic vapor cartridges and paint prefilters during spray-painting and priming activities. Only 11 shops (30%) had written respiratory protection programs. Eighty percent of all fit tested workers passed the test on the first try with FF ≥ 100, and 92% passed the second test after respirator use training. Overall geometric mean (GM) FF was 1012 for all fit tested workers. Significant differences on pass rate (92% vs. 72%) and on FF (1990 vs. 736) were found between previously fit tested workers vs. nontested workers. Twenty-nine WPF samples were collected. The outside facepiece GM concentration of total isocyanate group (NCO) was 378.4 μ g NCO/m3 with 96% concentrations exceeding the U.K. short-term exposure limit, 70 μ g NCO/m3, but no in-facepiece concentrations exceeded the limit. The GM WPF of total NCO was 319 (GSD 4) and the 5th percentile was 54. WPF of total NCO was positively correlated with the duration of painting task. FF positively correlated with WPF when FF was ≤450 but negatively correlated with WPF when FF was >450. We conclude that negative pressure, air-purifying half-facepiece respirators equipped with organic vapor cartridges and paint prefilters provide effective protection against isocyanate exposure in spray and priming operations if workers are properly trained and fitted.

Slow Curing of Aliphatic Polyisocyanate Paints in Automotive Refinishing: A Potential Source for Skin Exposure

Two-component, polyurethane paints containing aliphatic isocyanates are widely used in autobody spray painting. Such isocyanates can cause asthma, and skin exposure may be an important route of sensitization and may contribute to the development of isocyanate asthma. Autobody workers are frequently in contact with recently painted, dried auto parts. It is not known how fast the newly painted car surfaces are fully cured, that is, for how long unbound, isocyanate species remain on painted surfaces after initial drying. To address this question, scrap sections of auto bodies were painted and dried by autobody shop painters following regular practice. Routinely used paints were sprayed 23 different times on the parts. Drying was accomplished by baking the part in a paint spray booth by heating it with a heat lamp or air drying in the shop. The 23 sprayed surfaces were sampled at regular time intervals after drying to determine the presence of free NCO groups using the semiquantitative SWYPE technique. Quantitative isocyanate analysis was also performed on two sprayed parts using NIOSH method 5525. Geometric mean curing time of 23 painted surfaces was 56.4 hr (range: 0.8 hrs to 32 days). Unbound isocyanate species of similar composition to the original bulk material remained present on the majority of sampled painted surfaces for up to 120 hours for typical paint formulations and for 1 month for others. The actual curing of polyurethane paints in autobody refinishing can be a slow process. Unbound isocyanates may remain on the surface of painted car parts for prolonged periods (days to weeks) after dried. Such surfaces are an under-recognized potential source of skin exposure to autobody workers.

Field Comparison of Impingers and Treated Filters for Sampling of Total Aliphatic Isocyanates with the MAP Reagent

Results of a comparative field study on the performance of 25-mm inhalable samplers (Institute of Occupational Medicine [IOM]) and midget impingers for the collection of total isocyanates in air using the 1-(9-anthracenylmethyl)piperazine (MAP) reagent are presented. Air sampling and analysis was performed according to the National Institute for Occupational Safety and Health MAP draft method 5525. Midget impingers filled with 15 mL of 1 x 10(-4) M MAP in butyl benzoate were operated at 1 L/min. IOM cassettes loaded with 25-mm quartz fiber filters impregnated with 500 microg MAP, were operated at 2 L/min. Filters were field extracted with 10 mL of 1 x 10(-4) M MAP in acetonitrile. Thirty-four impinger-IOM pairs were collected in three autobody shops during spray painting tasks. Regression analysis [Ln (IOM) = 1.0 Ln (impinger), R2 = 0.98] and a paired t-test (Pr > 0.9) demonstrated that impingers and IOMs perform equally in their collection efficiency for the monomer and total oligomeric hexamethylene diisocyanate (HDI). IOM performance did not deteriorate at longer sampling times compared with the impinger performance. Within-sampler variability was calculated from the individual coefficients of variation (CV) of the 17 pairs of like samplers. The mean of CVs (SD)% for the monomer and total oligomeric HDI was approximately 12 (12)% and 15 (13)% for the IOM and the impinger sampler, respectively. Poor correlation (Pearson correlation coefficient < 0.3) and statistically nonsignificant differences (P > 0.74 two-sided) were found for the between-sampler CVs. Factors that might have influenced the observed sampler agreement are also discussed. It is concluded that MAP impregnated filters can be successfully used for sampling of slow curing total aliphatic isocyanates in air.

Skin Exposure to Aliphatic Polyisocyanates in the Auto Body Repair and Refinishing Industry: III. A Personal Exposure Algorithm

OBJECTIVES Isocyanate skin exposure may play an important role in sensitization and the development of isocyanate asthma, but such exposures are frequently intermittent and difficult to assess. Exposure metrics are needed to better estimate isocyanate skin exposures. The goal of this study was to develop a semiquantitative algorithm to estimate personal skin exposures in auto body shop workers using task-based skin exposure data and daily work diaries. The relationship between skin and respiratory exposure metrics was also evaluated. METHODS The development and results of respiratory exposure metrics were previously reported. Using the task-based data obtained with a colorimetric skin exposure indicator and a daily work diary, we developed a skin exposure algorithm to estimate a skin exposure index (SEI) for each worker. This algorithm considered the type of personal protective equipment (PPE) used, the percentage of skin area covered by PPE and skin exposures without and underneath the PPE. The SEI was summed across the day (daily SEI) and survey week (weekly average SEI) for each worker, compared among the job title categories and also compared with the respiratory exposure metrics. RESULTS A total of 893 person-days was calculated for 232 workers (49 painters, 118 technicians and 65 office workers) from 33 auto body shops. The median (10th-90th percentile, maximum) daily SEI was 0 (0-0, 1.0), 0 (0-1.9, 4.8) and 1.6 (0-3.5, 6.1) and weekly average SEI was 0 (0-0.0, 0.7), 0.3 (0-1.6, 4.2) and 1.9 (0.4-3.0, 3.6) for office workers, technicians and painters, respectively, which were significantly different (P < 0.0001). The median (10th-90th percentile, maximum) daily SEI was 0 (0-2.4, 6.1) and weekly average SEI was 0.2 (0-2.3, 4.2) for all workers. A relatively weak positive Spearman correlation was found between daily SEI and time-weighted average (TWA) respiratory exposure metrics (microg NCO m(-3)) (r = 0.380, n = 893, P < 0.0001) and between weekly SEI and TWA respiratory exposure metrics (r = 0.482, n = 232, P < 0.0001). CONCLUSIONS The skin exposure algorithm developed in this study provides task-based personal daily and weekly average skin exposure indices that are adjusted for the use of PPE. These skin exposure indices can be used to assess isocyanate exposure-response relationships.

A laboratory investigation of the effectiveness of various skin and surface decontaminants for aliphatic polyisocyanates

Isocyanates may cause contact dermatitis and respiratory sensitization leading to asthma. Dermal exposure to aliphatic isocyanates in auto body shops is very common. However, little is known about the effectiveness of available commercial products used for decontaminating aliphatic polyisocyanates. This experimental study evaluated the decontamination effectiveness of aliphatic polyisocyanates for several skin and surface decontaminants available for use in the auto body industry. The efficiency of two major decontamination mechanisms, namely (i) consumption of free isocyanate groups via chemical reactions with active hydrogen components of the decontaminant and (ii) physical removal processes such as dissolution were studied separately for each decontaminant. Considerable differences were observed among surface decontaminants in their rate of isocyanate consumption, of which those containing free amine groups performed the best. Overall, Pine-Sol(R) MEA containing monoethanolamine was the most efficient surface decontaminant, operating primarily via chemical reaction with the isocyanate group. Polypropylene glycol (PPG) had the highest physical removal efficiency and the lowest reaction rate with isocyanates. All tested skin decontaminants performed similarly, accomplishing decontamination primarily via physical processes and removing 70-80% of isocyanates in one wiping. Limitations of these skin decontaminants are discussed and alternatives presented. In vitro testing using animal skins and in vivo testing with field workers are being conducted to further assess the efficiency and identify related determinants.

Risk factors for tuberculin skin test positivity in an industrial workforce results of a contact investigation.

Objective:The objective of this study was to determine the prevalence of and risk factors for tuberculin skin test (TST) positivity among an industrial workforce employing many foreign-born workers after one employee was hospitalized for active tuberculosis (TB). Methods:A contact investigation was performed. We used crude odds ratios and a multivariate model to assess risk factors for TST positivity. Results:The rate of TST positivity was 37.1% (N = 97). Twenty-nine of 36 (80.6%) workers from higher TB prevalence countries versus seven of 61 (11.5%) workers born in low-prevalence countries were positive. Workplace risk factors included using the lunchroom, carpooling with the case, or working on the same or subsequent shift. A total of 66.7% of immigrant workers denied previous screening. Conclusion:TB contact investigations should probe into workplace transmission. Workplaces with workers from higher TB prevalence countries should consider preplacement TB screening.