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Appl Occup Environ Hyg [journal]
- Current chemical exposures among Ontario construction workers. [Journal Article, Research Support, Non-U.S. Gov't]
- Appl Occup Environ Hyg 2003 Dec; 18(12):1031-47.
Current occupational exposures to chemical agents were assessed as part of an epidemiological study pertaining to the cancer and mortality patterns of Ontario construction workers. The task-based exposure assessment involved members from nine construction trade unions. Air samples were taken using personal sampling pumps and collection media. A DustTrak direct-reading particulate monitor was also employed. Exposure assessments included measurements of airborne respirable, inhalable, total, and silica dust; solvents; metals; asbestos; diesel exhaust and man-made mineral fibers (MMMF). In total, 396 single- or multi-component (filter/tube), 798 direct-reading, and 71 bulk samples were collected. The results showed that Ontario construction workers are exposed to potentially hazardous levels of chemical agents. The findings are similar to those reported by other researchers, except for silica exposure. In our study, silica exposure is much lower than reported elsewhere. The difficulty associated with assessing construction workers' exposures is highlighted.
- Exposure to inhalable flour dust in Canadian flour mills. [Journal Article, Research Support, Non-U.S. Gov't]
- Appl Occup Environ Hyg 2003 Dec; 18(12):1022-30.
In 1999, the American Conference of Governmental Industrial Hygienists (ACGIH(R)) proposed a Threshold Limit Value (TLV(R)) of 0.5 mg/m(3) for flour dust with a sensitization notation. The Labour Program of the Department of Human Resources Development Canada (HRDC), following notice of the intention to set a TLV, conducted a study of the levels of exposure to flour dust in flour mills across Canada to verify existing conditions, as well as to decide whether to adopt the proposed TLV or reference some other value. As part of the study, a relationship between flour dust concentrations obtained by using Institute of Occupational Medicine (IOM) samplers and closed-face 37-mm cassettes was examined and the literature on the health effects of exposure to flour dust was reviewed. A total of 104 millers, packers, sweepers, bakery mix operators, and others (mixed tasks) from 14 flour mills were sampled over an 8-hour work shift using IOM samplers. The results indicate that 101 employees (97.1%) were exposed to levels exceeding 0.5 mg/m(3), 66 employees (67.3%) to levels exceeding 5 mg/m(3), and 44 employees (42.3%) to levels exceeding 10 mg/m(3). For comparison purposes, flour dust measurements were also taken in a highly automated flour mill using state-of-the-art technology. The results suggest that even with the most up-to-date technology and proper cleaning operations in place, the flour milling industry may not be able to reduce the flour dust levels to below the TLV of 0.5 mg/m(3). According to the measurements of inhalable and total dust concentrations, the IOM sampler appears to be a more efficient collector of inhalable airborne particles up to 100 microm than the closed-face 37-mm cassette.
- Characterization of chemical exposures in hairdressing salons. [Journal Article]
- Appl Occup Environ Hyg 2003 Dec; 18(12):1014-21.
Workers in hairdressing salons are exposed to several hundred chemicals, of which a few are possibly detrimental to pregnant workers or their fetuses. In Quebec, a government program provides protective reassignment for exposed pregnant workers. This study was set up to assist public health physicians by describing the exposure levels for ingredients that were measurable (i.e., airborne), selected from a list of possibly detrimental hairdressing ingredients. Twenty-six salons were sampled in Montreal, Canada, between June 1996 and December 1997. At the time of sampling, information on certain work conditions (e.g., chemical services offered, number of clients, average CO(2) level during the day) was also noted. Fifty percent of the salons provided additional services other than hairdressing, such as manicures, pedicures, or beauty treatments. Almost half of the salons were quite small, with less than 5 employees. Average temperature ranged between 17 and 26 degrees C, relative humidity between 18 and 59 percent and average CO(2) concentrations from 583 to 4301 mg/m(3). Duration of samples varied between 15 minutes and 8 hours. The most prevalent chemicals were alcohols: ethanol, at an average personal concentration of 39.9 mg/m(3), and isopropanol at an average personal concentration of 3.1 mg/m(3). Acetone, toluene, and acetates, all related to manicure services, were also measured in small quantities. An empirical mathematical model brought in evidence that CO(2) levels explained 46 percent of variation in the concentration of ethanol; when number of permanent waves done during the day and relative humidity and temperature were added, the resulting model explained 68 percent of the variations in ethanol. Thus, although the measured concentrations of chemicals were fairly low in this study, it appears possible that on very busy days, especially if other chemical services are performed in the salon, the total mixture of airborne chemicals could reach significant concentrations.
- Epidemiological adaptation of quartz exposure modeling in Swedish aluminum foundries: nested case-control study on lung cancer. [Journal Article, Research Support, Non-U.S. Gov't]
- Appl Occup Environ Hyg 2003 Dec; 18(12):1006-13.
In a recent cohort study in aluminum foundries and remelting plants an unexpectedly high risk of lung cancer was found in workers in sand foundries. On the basis of present and historical measurement data, we developed a statistical model for exposure to total dust and crystalline quartz for different jobs and time periods. Cumulative dose estimates of total dust and crystalline quartz were calculated and used in a nested case-control study in the cohort. From the cohort of foundry workers (n = 5016), 46 cases of lung cancer were identified. The final analysis was performed on 31 cases and 233 controls with one year or more of employment. Historical measurement data from the 1960s and onward were collected, totaling 203 total dust and 103 crystalline quartz exposure observations. Regression models, using the determinants of job title, time period, type of foundry, and size of production, were developed for assessing historical total dust and crystalline quartz air concentrations. These estimates were used to calculate individual cumulative exposure in the case-control study. In the multiple linear regression analysis, the determinants explained much of the variations in dust level (r(2) = 0.58). The explained variation in crystalline quartz was much lower (r(2) = 0.13). The regression coefficients for the type of foundry, time period, and size of production were statistically significant for total dust. On the basis of the regression analysis, the final models were used to calculate individual cumulative exposures. The calculated cumulative dust and quartz exposures averaged 33 mg/m(3) * year and 0.42 mg/m(3) * year, respectively. The odds ratios (ORs) were not significant, but showed dose-response trends for both dust and crystalline quartz.
- An exploratory study of whole-body vibration exposure and dose while operating heavy equipment in the construction industry. [Journal Article, Research Support, Non-U.S. Gov't]
- Appl Occup Environ Hyg 2003 Dec; 18(12):999-1005.
Whole-body vibration measurements were recorded for various types of heavy equipment used within the construction industry. The purpose of these measurements was to provide more information about the potential levels of whole-body vibration experienced by equipment operators in the construction industry, as well as to identify types of equipment warranting further research. In total, 67 pieces of equipment were tested from 14 different equipment types. Testing took place at various construction sites including corporate, public, and residential work projects. Measurements were made (following the 1997 International Standards Organization's 2631-1 whole-body vibration standards) for 20-minute testing periods using a Larson Davis HVM100 vibration monitor and a triaxial accelerometer. The mobile equipment tested was associated with greater levels of whole-body vibration than the stationary equipment. When whole-body vibration levels were compared to the International Standards Organization's 2631-1 standards, wheel loaders, off-road dump trucks, scrapers, skid steer vehicles, backhoes, bulldozers, crawler loaders, and concrete trowel vehicles exceeded the recommendations based on measured vibration dose values. Further research incorporating larger sample sizes and controlled testing conditions is required to better understand the levels of exposure experienced by operators as well as the amount to which seating, terrain, mobility, and vehicle structure might affect whole-body vibration.
- Benzene exposure measurement in shoe and glue manufacturing: a study to validate biomarkers. [Journal Article, Research Support, U.S. Gov't, P.H.S., Validation Studies]
- Appl Occup Environ Hyg 2003 Dec; 18(12):988-98.
This article reports an extensive program to monitor individual personal exposures of subjects recruited for a study conducted in a Chinese occupational population to determine whether selected biological markers of exposure to benzene are reliable and sensitive enough to detect low-level benzene exposure in people. The monitoring program reported here was to assure an appropriate range of exposure for subject selection as well as to provide data for the exposure response assessment. The overall study resulted in correlation of the measured exposures with the measured concentrations of two minor urinary benzene metabolites, trans,trans-muconic acid and S-phenylmercapturic acid. The study design and evaluation of biological end points are presented in separate publications. Recruitment of 130 exposed subjects was based on personal exposure measurements collected with passive organic vapor monitors at weekly intervals for 3 to 4 weeks prior to collection of biological samples. Two monitors, side by side, were used for all of the personal monitoring in the first year of the study and about 10 percent of subsequent monitoring. One of each pair was analyzed immediately in Beijing at the Institute of Occupational Medicine, and the other was shipped to the United States and analyzed at the New York University Institute of Environmental Medicine. Exposure concentrations measured over 4-5 weeks were reasonably stable with average coefficients of variation of 0.58, 0.59, and 0.46 for benzene, toluene, and xylene, respectively. Benzene exposure averaged 10 +/- 13 ppm benzene with a median of 3.8 ppm for the recruited exposed workers. Excellent correlation was obtained between samples analyzed for benzene at the two laboratories. The extensive effort to document exposures was important to the exposure-response relationship demonstrated in the full study, which concluded that S-phenylmercapturic acid appears to be a good biomarker for detecting and evaluating benzene exposure at concentrations less than 0.25 ppm.
- Assessment of silica exposure and engineering controls during tuckpointing. [Journal Article, Research Support, U.S. Gov't, P.H.S.]
- Appl Occup Environ Hyg 2003 Dec; 18(12):977-84.
- DNA-based methodologies for rapid detection, quantification, and species- or strain-level identification of respiratory pathogens (Mycobacteria and Pseudomonads) in metalworking fluids. [Journal Article, Research Support, U.S. Gov't, P.H.S.]
- Appl Occup Environ Hyg 2003 Nov; 18(11):966-75.
Mycobacteria and pseudomonads occurring in modern metalworking fluids (MWF) have been implicated in occupational health hazards as causal agents for hypersensitivity pneumonitis (HP) and other respiratory illnesses in machine workers exposed to these fluids and their aerosols. Unlike the conventional cultural and biochemical methods, which are often slow and ambiguous and detect only culturable cells, DNA-based methods offer a time-saving alternative for reliable detection and identification of both culturable and nonculturable bacteria in MWF and for selective quantification of individual genera of pathogens of interest in these fluids. This is the first report on DNA-based direct detection of mycobacteria and pseudomonads in MWF without culturing. Genus-specific PCR approach was successfully applied for screening of field MWF samples originating from different industrial users for detection of mycobacteria or pseudomonads including both culturable and nonculturable cells. PCR in combination with amplicon DNA sequencing led to the identification of Mycobacterium chelonae, Pseudomonas nitroreducens, and an undefined Pseudomonas species from these fluids. Genome fingerprinting by pulsed-field gel electrophoresis (PFGE) on Mycobacterium isolates further showed that the isolates represented three strains of M. chelonae although the possibility of one of the strains being clonal with M. immunogenum cannot be excluded. In parallel efforts, a quantitative competitive PCR method developed based on the Pseudomonas-specific PCR was applied to quantify total P. fluorescens cells in contaminated metalworking fluid and MWF aerosol without culturing. The DNA-based protocols developed in this study will allow rapid screening of field MWF samples for the presence of both culturable and nonculturable cells and thus facilitate effective fluid management and timely exposure assessment.
- Observations on the relationship between triazines and mycobacteria in metal removal fluids. [Comparative Study, Journal Article]
- Appl Occup Environ Hyg 2003 Nov; 18(11):961-5.
The purpose of the study was to determine whether hexahydrotriazine ("triazine") bactericides increase the likelihood of elevated mycobacteria growth in metal removal fluids (MRFs). In reaction to an outbreak of hypersensitivity pneumonitis (HP) at a transmission manufacturing facility, machining plants of a large automobile manufacturer were directed to increase the testing of MRF, especially testing for mycobacteria. A working hypothesis was developed that triazine bactericides cause an increase in mycobacteria contamination, which in turn may lead to an increased risk of HP for workers exposed to MRF aerosols. Test results for 277 central MRF systems from nine machining facilities were analyzed for various MRF properties including the presence and type of both bactericide in the MRF formula and bacterial contamination of the MRF. The study included data reflecting usual operating conditions of all of the 277 large MRF systems in the company. The study does not evaluate the effect of tank-side biocide addition. The results show that soluble oils, semi-synthetic, and synthetic MRFs are all capable of supporting mycobacterial growth. The results also demonstrate a highly significant association between routine use of triazine bactericides and mycobacterial contamination of MRF. Based on the hypothesis that mycobacteria are a likely causative agent of hypersensitivity pneumonitis from MRF exposure, it is concluded that elimination of triazines from MRF formulae may be protective against HP in the machining environment.
- Evaluation of hypersensitivity pneumonitis among workers exposed to metal removal fluids. [Case Reports, Journal Article, Research Support, U.S. Gov't, P.H.S.]
- Appl Occup Environ Hyg 2003 Nov; 18(11):953-60.
Hypersensitivity pneumonitis (HP) was identified among employees in an automobile parts manufacturing facility. Mycobacteria immunogenum (MI) was identified as a metal removal fluid (MRF) contaminant at this facility and had been identified as a contaminant in other facilities where HP had occurred. We therefore questioned whether measurement of MI-specific cell-mediated immunity would be associated with HP in this facility. We also questioned whether measures of cell-mediated immunity would be more informative about the presence of HP than evaluation of serum anti-MI antibody levels. Workers were categorized for exposure and disease status by questionnaire and review of medical records. Cell-mediated immunity to MI was assessed by measuring in vitro secretion of cytokines (interleukin 8, tumor necrosis factor alpha, and interferon-gamma) from peripheral blood mononuclear cells or anticoagulated whole blood induced by culture with MI antigen. Serum antibodies against MI were also measured. Six study participants met our survey definition for HP and 48 did not. As has been reported for various agents causing HP, serum antibody levels against MI were increased in both exposed workers and workers with HP. Serum antibodies did not distinguish between the two. When expressed as a percentage of secretion induced by lipopolysaccharide, MI induced a significant increase in interleukin-8 secretion in exposed participants' whole blood cultures. There were trends for increased MI-induced secretion of interferon-gamma by peripheral blood mononuclear cells from both exposed workers and workers with HP. However, these trends did not attain statistical significance. Thus, several measures of immunity to MI distinguished between exposed and unexposed workers but not between workers with and without HP. These evaluations of cell-mediated immunity were not more informative than measurement of serum antibodies. As was done at this facility, institution of a comprehensive safety and health plan for MRF is necessary to eliminate (or minimize) health effects related to occupational exposures in the machining environment.