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A comprehensive survey of respirable dust and respirable silica in Ontario gold mines was conducted by the Ontario Ministry of Labor during 1978–1979. The aim was to assess the feasibility of introducing gravimetric sampling to replace the assessment method which used konimeters, a device which gave results in terms of number of particles per cubic centimeter (ppcc) of air. The study involved both laboratory and field assessments. The field assessment involved measurement of airborne respirable dust and respirable silica at all eight operating gold mines of the time. This article describes the details of the field assessment. A total of 288 long-term (7–8 hr) personal respirable dust air samples were collected from seven occupational categories in eight gold mines. The respirable silica (α-quartz) was determined by x-ray diffraction method. The results show that during 1978–1979, the industry wide mean respirable dust was about 1 mg/m3, and the mean respirable silica was 0.08 mg/m3.The mean% silica in respirable dust was 7.5%. The data set would be useful in future epidemiological and health studies, as well as in assessment of workers’ compensation claims for occupational diseases such as silicosis, chronic obstructive pulmonary disease (COPD), and autoimmune diseases such as renal disease and rheumatoid arthritis. [ABSTRACT FROM PUBLISHER]

The objective of this study was to determine the concentration of nickel, cadmium, and lead in the autopsied lungs of 29 hardrock miners. It involved chemical analysis of the lungs, where each lung was divided horizontally into 3 sections and analyzed by an atomic absorption spectrophotometer equipped with a graphite furnace. The grand mean levels of nickel, cadmium, and lead were found to be 1.84, 1.74, and 2.75 μg/g of dry tissue, respectively. The effect of smoking was also examined. The ratios using the mean values between smoker and nonsmoker for nickel, cadmium, and lead were found to be 0.7, 5.4, and 1.4, respectively. The level of cadmium in smokers was significantly higher than nonsmokers. This study provides an estimate of retained metals in the lungs of the Ontario hardrock miners as a result of occupational exposure to hardrock mining environment. [ABSTRACT FROM AUTHOR]

The article discusses a study that aimed to identify and quantify asbestos in the lungs of subjects occupationally exposed to it. Occupational exposure to asbestos can cause asbestosis, mesothelioma and lung cancer. Estimation of asbestos levels in lungs can aid diagnosis. Quantification using ATEM analysis with a microfilm reader also showed the presence of chrysotile, amosite, crocidolite, and tremolite.

A study of past silica and respirable dust exposures in the Vermont granite industry was conducted to develop a job exposure matrix (JEM) that used 5204 industrial hygiene measurements made from 1924-2004. The construction of the JEM involved data entry from several original sources into an Excel database that was reviewed later to ensure accuracy. Exposure measurements by job or location were grouped in two broad categories of quarry or shed and then into 22 job classes. Missing exposure data by time period were computed, taking into account improvements in dust control and periods of significant reduction in dustiness. Percent free silica (α-quartz) in respirable dust was estimated to be 11.0% based on previous published studies in Vermont and on data in the current database. About 60% of all measurement data (primarily from years prior to 1972) were obtained using the impinger and expressed in millions of particles per cubic foot (mppcf), which were converted to equivalent respirable free silica concentrations using the conversion of 10 mppcf = 0.1 mg/m3 of respirable silica. For impinger data, respirable dust was calculated by multiplying respirable silica by a factor of 9.091 to reflect that the respirable silica was 11.0% respirable dust. This JEM has been used in a recent epidemiologic study to assess mortality in Vermont granite workers and to examine the relationships among mortality from silicosis, lung cancer, and other nonmalignant respiratory diseases. [ABSTRACT FROM AUTHOR]

The aim of the study described in this companion paper was to assesses relationships among inhalable, thoracic, and respirable aerosol fractions of metalworking fluids. A RespiCon sampler, which simultaneously collects all three fractions, was used at four Ontario plants to collect 37 samples of 120 to 400 min duration. The ratios of the slopes of the lines of a regression model forced through the origin between inhalable and thoracic, inhalable and respirable, and thoracic and respirable were 1.38, 1.51, and 1.13, respectively. These ratios would be useful in assessing metalworking fluid airborne exposure data based on different aerosol fractions and for interpreting occupational exposure standards based on different fractions. [ABSTRACT FROM AUTHOR]

The article focuses on an industrial hygiene laboratory and its quality control (QC). Quality assurance (QA) and QC are used interchangeably as QC is a component of QA. The system of QA includes training of personnel with proper qualifications, sample login, sample processing, reporting structure, data handling, record keeping and audit procedures in addition to QC procedures.

This article summarizes an assessment of air sampling and analytical methods for both oil and water-based metalworking fluids (MWFs). Three hundred and seventy-four long-term area and personal airborne samples were collected at four plants using total (closed-face) aerosol samplers and thoracic samplers. A direct-reading device (DustTrak) was also used. The processes sampled include steel tube making, automotive component manufacturing, and small part manufacturing in a machine shop. The American Society for Testing and Materials (ASTM) Method PS42-97 of analysis was evaluated in the laboratory. This evaluation included sample recovery, determination of detection limits, and stability of samples during storage. Results of the laboratory validation showed (a) the sample recovery to be about 87%, (b) the detection limit to be 35 μg, and (c) sample stability during storage at room temperature to decline rapidly within a few days. To minimize sample loss, the samples should be stored in a freezer and analyzed within a week. The ASTM method should be the preferred method for assessing metalworking fluids (MWFs). The ratio of thoracic aerosol to total aerosol ranged from 0.6 to 0.7. A similar relationship was found between the thoracic extractable aerosol and total extractable aerosol. The DustTrak, with 10-μm sampling head, was useful in pinpointing the areas of potential exposure. MWF exposure at the four plants ranged from 0.04 to 3.84 mg/m 3 with the geometric mean ranging between 0.22 to 0.59 mg/m 3 . Based on this data and the assumption of log normality, MWF exposures are expected to exceed the National Institute for Occupational Safety and Health recommended exposure limit of 0.5 mg/m 3 as total mass and 0.4 mg/m 3 as thoracic mass about 38% of the time. In addition to controlling airborne MWF exposure, full protection of workers would require the institution of programs for fluid management and dermal exposure prevention. [ABSTRACT FROM AUTHOR]

Past reviews of occupational exposure limit (OEL) adjustments have covered both decision logic and calculation methods to derive factors to assure protection of workers on extended (also known as unusual) work shifts. The approaches reviewed included several Haber's rule based methods, several variants of single compartment toxicokinetic (TK) models, and physiologically based pharmacokinetic modeling. These models calculate OEL adjustment factors based on the work shift and the uptake and elimination of the toxicant. A key parameter of the TK models is the biologic half-life of the toxicant, but reliable data for the half-life are not available for all substances of concern. A spreadsheet is presented that implements TK calculations, with one of the presented TK calculation alternatives not dependent on half-life data. This half-life data independent approach is suggested as a viable option for situations when the toxicant's half-life is unknown or uncertain. [ABSTRACT FROM AUTHOR]

A simultaneous job- and task-based exposure study was conducted for tanker drivers delivering petroleum products from several bulk terminals and an agency to retail outlets. Full-shift (job-based) samples and job component tasks samples were collected simultaneously. The tasks sampled included loading, unloading, and travel. Three hundred sixty-six personal charcoal tube samples were collected. Full-shift visual observations of work practices and real-time monitoring using a datalogging hydrocarbon analyzer were also conducted. Multiple measurements per worker were made, which permitted an assessment of sampling variability within and between workers. The highest exposures for drivers occurred during unloading at the agency. The mean benzene exposure for agency drivers was 0.88 ppm for full-shift time-weighted average, 2.86 ppm for unloading, and 0.54 ppm for loading. For bulk terminal drivers, the mean benzene level without vapor control was 0.12 ppm for time weighted average, 0.24 ppm for unloading, and 0.33 ppm for loading. The time-weighted average exposure of the agency and bulk terminal drivers based on the data collected and the lognormal model can be expected to exceed threshold limit value-time weighted average of 0.5 ppm for benzene about 70 and 2% of the time, respectively. Agency drivers' unloading and loading tasks accounted for approximately 30% and 7% of the total time, and 95% and 4% of total exposure, respectively. For the bulk terminal drivers, mean unloading and loading tasks constituted 24% and 12% of the total time, and 68% and 19% of the total exposure, respectively. Travel activity accounted for an average of 63% of the total time for agency and 64% for bulk terminal drivers, but only contributed < 1 and 13% of the total exposure, respectively. The actual job-based time-weighted average concentration and the calculated time-weighted average derived from the time-weighted summation of the components tasks are in very good agreement. Within-worker variability was generally higher than between-worker variability. Exposure control strategies are required primarily for unloading at the agencies. Vapor control technology at the terminal effectively reduces exposure (by almost 50%) and fugitive emissions. [ABSTRACT FROM AUTHOR]

Current occupational exposures to man-made mineral fibers (MMMF), including refractory ceramic fibers (RCF), were measured as part of an exposure assessment program for an epidemiological study pertaining to cancer and mortality patterns of Ontario construction workers. The assessments were carried out at commercial and residential sites. A total of 130 MMMF samples (104 personal and 26 area) was collected and included 21 RCF (16 personal and 5 area). The samples were analyzed by the World Health Organization method in which both respirable and nonrespirable airborne fibers are counted. The results show that Ontario construction workers' full-shift exposure to MMMF (excluding RCF) is generally lower than the American Conference of Governmental Industrial Hygienists' (ACGIH®) recommended threshold limit value-time-weighted average (TLV®-TWA) of 1 fibers/cc and thus should not present any significant hazard. However, approximately 40% of the occupational exposures to RCF are higher than ACGIH's TLV-TWA of 0.2 fibers/cc and present a significant potential hazard. Workers generally wore adequate approved respiratory protection, especially while performing particularly dusty tasks such as blowing, spraying, and cutting, so the actual exposure received by workers was lower than the reported values. Adequate control measures such as ventilation and respiratory protection should always be used when work involves RCF. [ABSTRACT FROM AUTHOR]

Presents several letters to the editor. Comment on an article about the exposure assessment literature; Views on an article which discussed ways for assigning quartz exposure levels using current and past exposure data.

The article presents a case study on the occupational exposures of construction crane operators to whole-body and hand-arm vibrations and noise. It says that vibration and noise testing were conducted using cranes operated by training center instructors. It adds that exposure to hand-arm vibration was assessed following the Standard 5349-1 of the International Standards Organization (ISO). It mentions that the exposure levels were below the European Directive Exposure Limit Value (ELV).