Field evaluation of a portable photoionization detector for assessing exposure to solvent mixtures.

To evaluate a portable photoionization detector for assessing personal exposure to solvent mixtures, a set of 26 side-by-side, time-weighted average (TWA) personal breathing zone samples were collected during various construction painting tasks by two different sampling methods: (1) standard charcoal sorbent tubes analyzed by gas chromatography (CST/GC), and (2) a direct-reading photoionization detector coupled with an extended data-logger (PID). The TWA concentrations of the hydrocarbons detected by CST/GC analysis were summed for comparison with the TWA concentration obtained from the direct-reading PID. Based on linear regression between the log TWA concentrations of the two sampling methods, the data were highly correlated (r2 = 0.95). Since the solvents had effects that may be considered additive, threshold limit values (TLVs) for mixtures were developed using American Conference of Governmental Industrial Hygienists formulas to evaluate solvent exposure. The logs of the TLV mixture data from the sampling methods were highly correlated (r2 = 0.94). Based on the linear regression analyses, the response of the portable PID was highly correlated to the CST/GC results for hydrocarbon mixtures encountered during various painting tasks. Due to the short duration of tasks, highly fluctuating exposures, and complexity of the mixtures, the PID may provide the most cost-effective, detailed exposure assessment for solvent mixtures.

Exposures of geotechnical laboratory workers to respirable crystalline silica.

Geotechnical laboratory testing involves the determination of the physical properties of soil, rock, and other building materials for engineering purposes. Individuals working in these laboratories are exposed to airborne soil, rock, and other dusts during the preparation and testing of these materials. Crystalline silica as quartz is a common constituent of these materials and represents a potential hazard to geotechnical laboratory workers when airborne as a respirable dust. The authors conducted an examination of the potential for geotechnical laboratory workers to be exposed to respirable dust and respirable quartz during the performance of three routine laboratory tasks. A task-based exposure assessment strategy was used. Although respirable dust was generated during the performance of each of these tasks, its impact on exposures was generally overridden by the presence of respirable quartz in the dust. Quartz content in the respirable dust ranged from below the detection limit to greater than 50 percent. Mean exposure to respirable quartz, based on the duration of the task and assuming no other exposures for the rest of the 8-hour day, exceeded the National Institute for Occupational Safety and Health (NIOSH) "action level" (the exposure level at which certain actions must be taken) of 0.025 mg/m3. If exposure was assumed to continue for the rest of the 8-hour day at the measured concentration, mean exposure to respirable quartz exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) time-weighted average (TWA), the Occupational Safety and Health Administration (OSHA) PEL, and the NIOSH REL. Seven percent of 57 individual task exposure measurements exceeded the TLV-TWA and the PEL, 18 percent exceeded the REL, and another 12 percent exceeded excursion limits as defined by ACGIH. The results of this study support the conclusion that geotechnical laboratory workers are potentially exposed to respirable crystalline silica as quartz at levels that may be harmful. Because the quartz content of the materials being tested in these laboratories is highly variable and is almost never determined prior to testing, all materials being tested in the geotechnical laboratory should be assumed to contain quartz. Appropriate controls should be used to protect workers from inhaling dusts generated from these materials.

Association of semen quality and occupational factors: comparison of case-control analysis and analysis of continuous variables.

OBJECTIVE: To compare two statistical approaches, case-control and analysis of continuous parameters of semen, in examining the relationship between occupational exposures and male reproductive function. DESIGN: Case-control study. SETTING: Males providing semen samples at a university infertility clinic. PATIENT(S): Nonvasectomized males who provided at least one semen sample at an infertility clinic. MAIN OUTCOME MEASURE(S): Standard clinical semen analysis. RESULT(S): Analyses using a dichotomous dependent variable did not uncover significant associations between any occupational factor and infertility case status. However, linear models incorporating continuous variables identified a number of occupational factors that were associated with specific parameters of semen. A reduction in percentage of progressive sperm and an increase in percentage of coiled tail sperm defects in welders, compared with unexposed subjects, were found. Significant dose-response relationships between level of perceived job stress and percentage of progressive sperm, total motile count, morphology, abnormal heads, and coiled tail defects were found. CONCLUSION(S): The findings suggest that subtle changes in semen variables, possibly associated with workplace exposure, may be detected only with parametric analyses of continuous variables of semen.

The HomeSafe Pilot Program: a novel approach to injury prevention in residential construction.

Workers in the residential construction industry face unacceptably high risk of injury, disability and death. Attempts to implement comprehensive health and safety programs in this industry have met with little success. The HomeSafe Pilot Program is a novel residential construction safety program developed and sponsored by the Occupational Safety and Health Administration (OSHA) Region VIII and the Home Builders Association of Metropolitan Denver (HBA). Test subjects represent over 7475 persons employed in residential construction in the six county Denver Metro area of Colorado. The HomeSafe Pilot Program includes primary behavioral, engineering and administrative interventions to improve safe work practices in residential construction. It has some unique features of brevity, specificity and incentives not seen elsewhere in the construction industry. Its overall goal is to guide residential construction companies along a path of progressive development of comprehensive safety and health programs. The HomeSafe Pilot Program is introduced and compared to other safety and health program models developed by OSHA and the HBA. This study began in January 1997 and will continue through the millennium.

Development of an on-site, behavior-based safety audit for the residential construction industry.

The purpose of this study was to describe the development and implementation of an on-site, behavior-based safety audit based on a safety program designed specifically to reduce injuries and fatalities in the residential construction industry. The audit was used to assess safety hazards and safety compliance on residential construction work sites. Safety behaviors were scored as all-or-none. A high score was related to high safety compliance. A total of 195 audits were performed on residential construction companies from varying trades. Analysis of mean total scores indicated that companies that had received some form of safety training scored significantly higher than companies that had not received any (P<0.01). Analysis of mean total scores between company trades indicated that masonry/stucco application companies had significantly lower scores than most other trades represented (P<0.01). Challenges in designing, administering and analyzing the safety audits are discussed.

Evaluation of HomeSafe: an injury and illness prevention program in residential construction.

OBJECTIVES: To design a program evaluation to determine the effectiveness of a novel safety and health program in residential construction. STUDY DESIGN: The overall program evaluation incorporates five separate studies with designs including: pre-test-post-test control group designs for determining program effects on safety culture and safe work behaviors, and cohort designs to assess longitudinal changes in injury rates and workers compensation costs. RESULTS: Preliminary data from 252 respondents who completed a two-page questionnaire after attending an initial training session indicated that the innovative HomeSafe Program has been well received. Companies who have joined the program to date are not representative of the broader population of businesses in the residential construction industry, as they generally are larger with heightened concerns for health and safety. CONCLUSIONS: Evaluating a safety and health program being introduced into the dynamic residential construction industry presents numerous challenges which are discussed.

Variability in biological exposure indices using physiologically based pharmacokinetic modeling and Monte Carlo simulation.

By using physiologically based pharmacokinetic (PBPK) modeling coupled with Monte Carlo simulation, the interindividual variability in the concentrations of chemicals in a worker's exhaled breath and urine were estimated and compared with existing biological exposure indices (BEIs). The PBPK model simulated an exposure regimen similar to a typical workday, while exposure concentrations were set to equal the ambient threshold limit values (TLVs) of six industrial solvents (benzene, chloroform, carbon tetrachloride, methylene chloride, methyl chloroform, and trichloroethylene). Based on model predictions incorporating interindividual variability, the percentage of population protected was derived using TLVs as the basis for worker protection. Results showed that current BEIs may not protect the majority or all of the workers in an occupational setting. For instance, current end-expired air indices for benzene and methyl chloroform protect 95% and less than 10% of the worker population, respectively. Urinary metabolite concentrations for benzene, methyl chloroform, and trichloroethylene were also estimated. The current BEI recommendation for phenol metabolite concentration at the end-of-shift sampling interval was estimated to protect 68% of the worker population, while trichloroacetic acid (TCAA) and trichloroethanol (TCOH) concentrations for methyl chloroform exposure were estimated to protect 54% and 97%, respectively. The recommended concentration of TCAA in urine as a determinant of trichloroethylene exposure protects an estimated 84% of the workers. Although many of the existing BEIs considered appear to protect a majority of the worker population, an inconsistent proportion of the population is protected. The information presented in this study may provide a new approach for administrative decisions establishing BEIs and allow uniform application of biological monitoring among different chemicals.

Parental occupations as risk factors for craniosynostosis in offspring.

In a population-based case-control study, we examined relations between maternal and paternal occupations and the risk of infant craniosynostosis. Cases were 212 children born to Colorado residents and diagnosed during 1986-1989 with radiographically confirmed synostosis of unknown etiology. Controls were 291 children randomly selected from state birth records and frequency matched to cases on month and year of birth. Trained staff conducted telephone interviews of mothers of case and control children. Information was obtained about each job held by either parent during the pregnancy, and any job that the father held during the 3 months before the last menstrual period before conception. Jobs were coded using 1980 Census occupation and industry codes. We found no strong associations for maternal occupations. Of paternal occupations, two groups were associated with moderately increased odds ratios after adjustment for maternal smoking and altitude: agriculture and forestry (odds ratio = 2.3; 95% confidence interval = 1.0-5.2), and mechanics and repairmen (odds ratio = 2.7; 95% confidence interval = 1.2-6.1). For both, the odds ratios were higher for males.