Applied occupational and environmental hygiene最新文献

This article describes a new method for (1) systematically prioritizing needs for intervention on hazardous substance exposures in manufacturing work sites, and (2) evaluating intervention effectiveness. We developed a checklist containing six unique sets of yes/no variables organized in a 2 x 3 matrix of exposure potential versus protection (two columns) at the levels of materials, processes, and human interface (three rows). The three levels correspond to a simplified hierarchy of controls. Each of the six sets of indicator variables was reduced to a high/moderate/low rating. Ratings from the matrix were then combined to generate a single overall exposure prevention rating for each area. Reflecting the hierarchy of controls, material factors were weighted highest, followed by process, and then human interface. The checklist was filled out by an industrial hygienist while conducting a walk-through inspection (N = 131 manufacturing processes/areas in 17 large work sites). One area or process per manufacturing department was assessed and rated. Based on the resulting Exposure Prevention ratings, we concluded that exposures were well controlled in the majority of areas assessed (64% with rating of 1 or 2 on a 6-point scale), that there is some room for improvement in 26 percent of areas (rating of 3 or 4), and that roughly 10 percent of the areas assessed are urgently in need of intervention (rated as 5 or 6). A second hygienist independently assessed a subset of areas to evaluate inter-rater reliability. The reliability of the overall exposure prevention ratings was excellent (weighted kappa = 0.84). The rating scheme has good discriminatory power and reliability and shows promise as a broadly applicable and inexpensive tool for intervention needs assessment and effectiveness evaluation. Validation studies are needed as a next step. This assessment method complements quantitative exposure assessment with an upstream prevention focus.

The relationship between asbestos exposure and disease has been well documented, although questions persist as to variation in risk by the type and length of fiber. For a series of jobs with potential asbestos exposure, the primary fiber type (e.g., amosite, anthophylite, chrysotile, crocidolite, or tremolite) and fiber length were identified and the relative exposure intensity was estimated. The resulting job exposure matrix may be useful in epidemiological studies where asbestos is an exposure of interest.

The release of asbestos during maintenance and removal of resilient floor covering is of concern to health professionals and many regulators. This study assesses the asbestos levels observed during removal of resilient floor covering products using the "Recommended Work Practices" (1995) of the Resilient Floor Covering Institute or other methods requiring containment (Controls). The 1995 "work practices" require wet removal or dry heat removal but do not require the use of respirators. Wet removals of sheet vinyl/separated backing, 12" x 12" vinyl asbestos tile/mastic, and 9" x 9" asphalt tiles/mastic were conducted and the air was sampled during each procedure. Settled dust samples were collected at the sites of RFCI square tile removal and pieces of each type of tile were broken in a mini-enclosure to evaluate asbestos emissions. Analyses of the air samples collected during the removals showed that the RFCI methods did not produce asbestos counts significantly different from the Control methods requiring containment. Only a small number (0.7%) of fibers and structures, counted and measured by Analytical Transmission Electron Microscopy, would have been counted using the rules for Phase Contrast Microscopy in the 7400 method specified by Occupational Safety and Health Administration regulations. This indicates workers in similar situations without respirators are likely to have unknown exposure levels. A high percentage of these fibers and structures are 5 micrometers or less in length, smaller than 0.5 micrometer in diameter, and are easily inhaled. The RFCI air sample and settled dust data may cause regulators to consider requiring respiratory protection, cleanup procedures, and methods to control asbestos migration. Other areas that might be addressed are clearance levels and their measurement, removal area size, bulk sample analysis by transmission electron microscopy if polarized light microscopy reports less than 1 percent asbestos, better worker exposure evaluation, and supervisor/worker training in accordance with the Model Accreditation Plan.

Findings are reported on the first two years of an active injury surveillance project designed to test the utility of active injury investigations in identifying causes of injury among a large cohort of carpenters who did residential building and drywall installation. Occupational Safety and Health Administration recordable injuries were reported by participating contractors. Injured union carpenters were interviewed by experienced journeymen trained in a standard questionnaire protocol. Enumeration of workers and hours worked were provided by the union. These data allowed the definition of a dynamic cohort of 4429 carpenters, their hours worked, detailed information on the circumstances surrounding recordable injuries, and possible preventive measures from the perspectives of the injured worker and an experienced journeyman investigator. The overall estimated injury rate (16.9 per 200,000 hours worked) was considerably higher than recent Bureau of Labor Statistics rates despite less than complete ascertainment of injuries. Injuries most commonly involved being struck by or against something, manual materials handling injuries, and falls. Manual materials handling injuries often involved very heavy objects or tasks and were injuries carpenters most often reported needs for adequate help and coordinated team work to prevent. Falls from heights occurred from a variety of surfaces and were not just injuries of inexperience. Carpenters reported the need for more attention to common fall protection practices, such as the use of more toe boards and guardrails. Poor housekeeping was involved in the majority of same level falls, as well as some manual materials handling injuries.

Video exposure assessments were conducted in a comparative anatomy laboratory using formaldehyde-preserved sharks and cats. Work in the facility using time-integrated samplers indicated personal and area concentrations generally below the current OSHA permissible exposure limit. However, complaints about room air quality were frequent and routine. Using a photoionization detector with an integral data logger, total ionizables present were sampled as a surrogate for formaldehyde. After synchronizing time tracks from the datalogger concentrations with simultaneously created videotapes of laboratory tasks, composite video exposure overlays were generated. Use of this video exposure method revealed very short-lived, excessively high peak exposure events, whereas conventional time-weighted averages indicated the majority (30/32) of personal exposures were below the OSHA limit of 0.75 ppm. These legally acceptable exposure levels were associated with self-reported symptoms of burning nose and eyes and eye irritation. Thus, transient peak formaldehyde concentrations not detected by longer term averaging studies could be responsible for the health effects reported. The video exposure monitoring method demonstrated that close dissection work, opening peritoneal cavities, and specimen selection activities were most likely the causes of elevated student exposures. Teaching assistants' exposures were the highest, exceeding OSHA limits on several occasions. The utility of the video monitoring method for conducting enhanced, critical task exposure assessments is discussed.

This study investigated the bias introduced by an inlet sampling line on a respirable mass monitor. The 1.5-m electrically conductive, flexible sampling line conducts aerosol at a flow rate of 2.2 Lpm from a helmet-mounted inlet to a waist-mounted sensor for mass concentration measurement. Particulate transport was modeled for each section of the sampling line and considered the effects of diffusion, gravitational settling, and inertial impaction. An estimate of respirable mass concentration measured with the sampling line was determined by integrating assumed workplace aerosols with the transport curves. The bias introduced by the sampling line was then calculated by dividing the difference between the respirable mass concentration with and without the sampling line by that without the sampling line. For the current sampling line, in which the inner diameter is 4.83 mm, bias was calculated as -0.3 percent, -2.4 percent, -4.6 percent, and -6.7 percent for four test aerosols with mass median aerodynamic diameters of 0.6 microm, 4 microm, 12 microm, and 30 microm, respectively. Optimization studies suggest that increasing the sampling line with a larger inner diameter by a factor of 1.25 to 1.75 will minimize bias to below -3.0 percent. An experimental study confirmed that bias due to the presence of the sampling line is small.

Injury and illness among youth working on farms are important problems. The types of farm tasks performed by children and the ages at which they begin these activities have not been well characterized. This cross-sectional study characterized agricultural work performed by adolescents in a rural Iowa county to better understand the patterns and extent of exposures to agricultural risk factors. This information will help to develop prevention strategies for agriculture-related injury and illnesses for children working on farms. The Keokuk County Rural Health Study is a prospective cohort study of randomly selected households in Iowa. In Round 2, all youth, aged 12 to 17 years participating in this population-based study, were asked about their use of farm machinery, work with livestock, pesticide handling, and other farm activities. The age at which they actually began these activities, the age they believed youth should start these activities, and sources of health and safety training they received were also ascertained. Adults in the study were asked the same questions about youth. Matched parental reports and opinions were compared to their children's reports and opinions using McNemar's chi-square tests. A total of 143 youth and 684 adults with farming experience completed the interviews. There were 118 pairs of parents and youth. Fifty percent of male youth, and 18 percent of females had performed agricultural work at some time in their life. Twenty-five percent of all male youth, and 5 percent of females were currently working on farms. Close to 30 percent had driven tractors, all-terrain vehicles, and pick-up trucks. Despite the legal prohibition of hazardous work by children under age 16, several younger children reported that they had driven a self-propelled combine, worked in silos, or handled and applied fertilizers in the past 12 months. Youth began riding on tractors at a mean age of 7. The mean ages for driving tractors and all-terrain vehicles were 11 and 10, respectively. The mean age for driving a self-propelled combine was 13. Children began applying or handling fertilizers at the age of 12. There were discrepancies between parent and youth reports regarding the frequencies, starting age, and opinions relative to performing agricultural tasks. These results suggest the need for implementing guidelines, particularly for age appropriate agricultural tasks.