Industrial Hygiene Surveys Research Articles

An outbreak of work-related asthma and silicosis at a US countertop manufacturing and fabrication facility.

Outbreaks of severe silicosis have affected workers who fabricate artificial stone countertops. Work-related asthma (WRA) has not been a prominent feature of those prior outbreaks. This report describes an outbreak of WRA and silicosis at a facility that manufactures and fabricates chemical-resistant countertops comprised of sand, epoxy resin, and phthalic anhydride (PA), a known respiratory sensitizer. The multi-disciplinary investigation included clinical examinations of workers, an industrial hygiene survey with qualitative and quantitative exposure assessments, and a cross-sectional questionnaire. Engineering controls and personal protective equipment were inadequate. Some workers were exposed to PA or silica above permissible exposure limits established by the Occupational Safety and Health Administration (OSHA). Clinical and epidemiologic investigations identified 16 workers with confirmed or suspected WRA. Two years later, after OSHA began to enforce its new silica standards, 12 workers received medical surveillance for silicosis. Of these 12 workers, four (33.3%) were diagnosed with silicosis based on abnormal chest computed tomography examinations. Artificial stone countertop workers can develop asthma or silicosis. Risk of asthma may be highest in workers exposed to asthmagens such as PA and epoxy resins while manufacturing the artificial stone material.

Occupational Exposure to Flour Dust. Exposure Assessment and Effectiveness of Control Measures.

The adverse effects associated with exposure to flour dust have been known since the 1700s. The aim of the study was to assess the occupational exposure to flour dust in Italian facilities, identify the activities characterized by the highest exposure, and provide information to reduce workers’ exposure. The study was performed in different facilities such as flourmills (n = 2), confectioneries (n = 2), bakeries (n = 24), and pizzerias (n = 2). Inhalable flour dust was assessed by personal and area samplings (n = 250) using IOM (Institute of Occupational Medicine) samplers. The results showed personal occupational exposure to flour dust over the American Conference of Governmental Industrial Hygiene (ACGIH) and the Scientific Committee on Occupational Exposure Limit (SCOEL) occupational limits (mean 1.987 mg/m3; range 0.093–14.055 mg/m3). The levels were significantly higher for dough makers in comparison to the dough formers and packaging area subjects. In four bakeries the industrial hygiene surveys were re-performed after some control measures, such as installation of a sleeve to the end of pipeline, a lid on the mixer tub or local exhaust ventilation system, were installed. The exposure levels were significantly lower than those measured before the introduction of control measures. The exposure level reduction was observed not only in the dough making area but also in all bakeries locals.

Asbestos Exposure of Chrysotile Miners and Millers in Balangero, Italy.

The largest chrysotile mine in Western Europe was active in Balangero (Italy) from 1917 to 1990. We quantitatively assessed exposure to asbestos in the framework of a cohort study on mortality of Balangero miners and millers. Using documents filed at the Italian State Archive we reconstructed the job-histories of cohort members. The concentration of asbestos fibres by work-area was derived from industrial hygiene surveys since 1968 and monitoring programs since 1975. Earlier exposures had been estimated based on the experimental reconstruction of past working conditions. In the mine concentrations of about 20 fibres per millilitre (f/ml) were initially present, decreasing to 5 in the mid-1950s and to <1 in late 1970s. In milling areas higher levels were present and did not fall below 1 f/ml until the mid-1980s. Cumulative exposure of cohort members, as the sum over their job-history of their year- and area-specific exposures, were <10 fibre/millilitre years (f/ml-y) in 18% of workers, 10-100 in 32%, 100-1000 in 37%, and >1000 in 13%. Compared with recently published estimates for the Russian chrysotile mine in Asbest, fibre concentrations in Balangero were higher during the 1950s and 1960s. Such difference may be partly accounted for by difficulties in converting dust measurements to fibre concentrations in the Russian study and the need to rely on the experimental reconstruction of exposures before 1968 in our study.

Application of occupational health risk assessment model in a glyphosate manufacturing enterprise

Objective To assess the occupational hazard risks of glyphosate in a pesticide factory by MOM and ICMM models, and to explore the suitable method. Methods A large glyphosate enterprise was selected and an industrial hygiene survey was conducted. MOM and ICMM models were applied to evaluate the occupational hazard risks, which were compared with the site testing results and verified by the national occupational hazard classification for workplaces. Results There were poor occupational health protection facilities in the plant. The concentrations of glyphosate in drying and packaging posts were beyond occupational exposure limit. And the maximum individual detection values were 5.32 mg/m3 and 49.59 mg/m3, respectively. The results of MOM and ICMM risk rating method were consistent. The main posts were low and medium risk. The quantitative method of ICMM judged that nearly all posts were unacceptable risks. There was no difference in the risk ratio between MOM and risk rating method as well as work grading criteria (F=3.960, P>0.05) , while the result calculated by quantitative method in evaluating the production process of IDA technology was obviously higher than that of the former three methods (F=4.096, P<0.05) . Conclusion Both MOM and ICMM models can appropriately predict and assess the occupational health risk of glyphosate. Besides, the judgment results may be more precise than the classification of occupational hazards. Due to the relatively simple operation, easy evaluation parameters, ICMM model maybe more convenient for glyphosate production plants. Key words: Glyphosate; Occupational health; Risk assessment

Standardizing industrial hygiene data collection forms used by workers’ compensation insurers

Workers’ compensation (WC) insurers collect large amounts of industrial hygiene (IH) data in the United States. The data collected is not easily accessible for research or surveillance purposes. Individual WC insurers are using computerized systems to standardize and store the IH data, leaving a gap in standardization among the different WC insurers. This study sought to standardize IH data collection among WC insurers and to determine the feasibility of pooling collected IH data. IH air and noise survey forms were collected from WC insurers. Data fields on the forms were evaluated for importance and a study list of core fields was developed. The core study list was presented to an IH review panel for review before finalization. The final core study list was compared to recommendations published by the American Conference of Governmental Industrial Hygienists (ACGIH) and the American Industrial Hygiene Association (AIHA). Fifty-nine forms from 10 organizations were collected. Industrial hygienists from research organizations, state-based WC insurers, and private WC insurers participated in the data field evaluation and on the review panel. For both air and noise survey forms, more than half the data fields (55% and 54%, respectively) were ranked as “essential.” Three of the four fields in the worker and control observations category ranked “essential” were found less than half of the time on both types of survey forms. The study list of core data elements consisted of more than half of the data fields from both the air and noise survey forms. Three additional fields were added based on the comparison to the ACGIH-AIHA recommendations. Data fields essential to standardizing IH data collection were identified and verified. The “essential” data fields will be made available and have the potential to be incorporated into WC insurers electronic IH data management systems. Future research should focus on other IH survey forms, such as those used in ergonomic assessments and specific chemical exposures, and methods to transfer data fields to electronic platforms.

Elemental properties of coal slag and measured airborne exposures at two coal slag processing facilities

ABSTRACTIn 1974, the National Institute for Occupational Safety and Health recommended a ban on the use of silica sand abrasives containing >1% silica due to the risk of silicosis. This gave rise to substitutes including coal slag. An Occupational Safety and Health Administration investigation in 2010 uncovered a case cluster of suspected pneumoconiosis in four former workers at a coal slag processing facility in Illinois, possibly attributable to occupational exposure to coal slag dust. This article presents the results from a National Institute for Occupational Safety and Health industrial hygiene survey at the same coal slag processing facility and a second facility. The industrial hygiene survey consisted of the collection of: (a) bulk samples of unprocessed coal slag, finished granule product, and settled dust for metals and silica; (b) full-shift area air samples for dust, metals, and crystalline silica; and (c) full-shift personal air samples for dust, metals, and crystalline silica.Bulk samples consisted mainly of iron, manganese, titanium, and vanadium. Some samples had detectable levels of arsenic, beryllium, cadmium, and cobalt. Unprocessed coal slags from Illinois and Kentucky contained 0.43–0.48% (4,300–4,800 mg/kg) silica. Full-shift area air samples identified elevated total dust levels in the screen (2–38 mg/m3) and bag house (21 mg/m3) areas. Full-shift area air samples identified beryllium, chromium, cobalt, copper, iron, nickel, manganese, and vanadium. Overall, personal air samples for total and respirable dust (0.1–6.6 mg/m3 total; and 0.1–0.4 mg/m3 respirable) were lower than area air samples. All full-shift personal air samples for metals and silica were below published occupational exposure limits. All bulk samples of finished product granules contained less than 1% silica, supporting the claim coal slag may present less risk for silicosis than silica sand. We note that the results presented here are solely from two coal slag processing facilities, and more in-depth air monitoring is needed to better characterize occupational exposure to coal slag dust, metals, and silica at similar facilities.

Occupational Lung Disease Risk and Exposure to Butter-Flavoring Chemicals after Implementation of Controls at a Microwave Popcorn Plant

After an outbreak of severe lung disease among workers exposed to butter-flavoring chemicals at a microwave popcorn plant, we determined whether or not lung disease risk declined after implementation of exposure controls. National Institute for Occupational Safety and Health staff performed eight serial cross-sectional medical and industrial hygiene surveys at the plant from November 2000 through August 2003. Medical surveys included standardized questionnaires and spirometry testing. Industrial hygiene surveys measured levels of production-related air contaminants, including butter-flavoring chemicals such as diacetyl. All diacetyl concentrations above detectable limits were corrected for the effects of absolute humidity and days to sample extraction. Ventilation and isolation of the production process resulted in one to three orders of magnitude reductions in diacetyl air concentrations in different areas of the plant. Workers with past high exposures had stable chest symptoms over time; nasal, eye, and skin irritation symptoms declined. New workers had lower symptom prevalences and higher lung function than workers with past high exposures, and they did not worsen over time. In workers who had at least three spirometry tests, those with past high exposures were more likely to experience rapid declines in lung function than new workers. Implemented controls lowered exposures to butter-flavoring chemicals and decreased lung disease risk for much of the plant workforce. Some workers with continuing potential for intermittent, short-term peak and measurable time-weighted exposures remain at risk and should use respiratory protection and have regularly scheduled spirometry to detect rapid lung function declines that may be work-related. Close follow-up of such workers is likely to yield additional information on risks due to peak and time-weighted exposure levels.

Cananea Copper Mine: An International Effort to Improve Hazardous Working Conditions in Mexico

A team of international occupational health and safety professionals evaluated the working conditions and health status of miners at a giant open-pit copper mine in Cananea, Mexico. Workers in the ore processing plants were exposed to levels of crystalline silica 10 times the Mexican regulatory limit, high levels of acid mist and noise, and numerous safety hazards, including unguarded machinery and malfunctioning 10- and 15-ton cranes. Lung function testing and interviews with physicians showed a substantial percentage of miners with adverse respiratory symptoms including shortness of breath (46%), wheezing (12%), coughing (12%), and elevated sputum production (10%). The mine owner, Grupo Mexico, violated Mexican law by failing to conduct an industrial hygiene survey sufficient to identify, evaluate, and control health hazards including exposure to mineral dust (including silica), acid mists, airborne solvents, high noise levels, high vibration levels, and extreme temperatures.

Exposure to Chrysotile Asbestos Associated with Unpacking and Repacking Boxes of Automobile Brake Pads and Shoes

Industrial hygiene surveys and epidemiologic studies of auto mechanics have shown that these workers are not at an increased risk of asbestos-related disease; however, concerns continue to be raised regarding asbestos exposure from asbestos-containing brakes. Handling new asbestos-containing brake components has recently been suggested as a potential source of asbestos exposure. A simulation study involving the unpacking and repacking of 105 boxes of brakes (for vehicles ca. 1946-80), including 62 boxes of brake pads and 43 boxes of brake shoes, was conducted to examine how this activity might contribute to both short-term and 8-h time-weighted average exposures to asbestos. Breathing zone samples on the lapel of a volunteer worker (n = 80) and area samples at bystander (e.g., 1.5 m from worker) (n = 56), remote area (n = 26) and ambient (n = 10) locations collected during the unpacking and repacking of boxes of asbestos-containing brakes were analyzed by phase contrast microscopy and transmission electron microscopy. Exposure to airborne asbestos was characterized for a variety of parameters including the number of boxes handled, brake type (i.e. pads versus shoes) and the distance from the activity (i.e. worker, bystander and remote area). This study also evaluated the fiber size and morphology distribution according to the International Organization for Standardization analytical method for asbestos. It was observed that (i) airborne asbestos concentrations increased with the number of boxes unpacked and repacked, (ii) handling boxes of brake pads resulted in higher worker asbestos exposures compared to handling boxes of brake shoes, (iii) cleanup and clothes-handling tasks produced less airborne asbestos than handling boxes of brakes and (iv) fiber size and morphology analysis showed that while the majority of fibers were free (e.g. not associated with a cluster or matrix), <30% were respirable and even fewer were of the size range (>20 microm length) considered to pose the greatest risk of asbestos-related disease. It was found that average airborne chrysotile concentrations (30 min) ranged from 0.086 to 0.368 and 0.021 to 0.126 f cc(-1) for a worker unpacking and repacking 4-20 boxes of brake pads and 4-20 boxes of brake shoes, respectively. Additionally, average airborne asbestos exposures (30 min) at bystander locations ranged from 0.004 to 0.035 and 0.002 to 0.011 f cc(-1) when 4-20 boxes of brake pads and 4-20 boxes of brake shoes were handled, respectively. These data show that a worker handling a relatively large number of boxes of brakes over short periods of time will not be exposed to airborne asbestos in excess of its historical or current short-term occupational exposure limits.

Past Occupational Exposure to Airborne Manganese in a Manganese Alloy Plant

A retrospective exposure assessment of a group of manganese (Mn) alloy workers was performed in conjunction with a 2004 follow-up study, 14 years after cessation of exposure, to evaluate the long-term effects of occupational Mn exposure on neurobehavioral functions. The ferro- and silico-Mn alloy plant opened in 1973 and closed in 1991. The airborne total Mn (TMn) exposures for job groupings were established using personal sampling data from a 1991 industrial hygiene survey. Historical short-term total dust (TDust) data were used to estimate past TDust exposure for job groupings and plant areas. Relationships between Mn content and TDust from the 1991 survey, supported by sparse historical data, were used to estimate TMn content in the historical TDust data. Results showed past personal TDust exposure levels much higher than those found in 1991. Changes in TDust levels and corresponding TMn levels were a function of changes in ventilation, work practices, and operations, not of product (ferro- or silico-Mn). Relationships between TMn and respirable Mn (RMn) from area sampling in 1991 were used to estimate RMn exposure for the job groups. Work histories for 112 workers were developed from payroll records, questionnaires, and interviews and combined with Mn exposure estimates to develop cumulative exposure indices (CEIs). The TMn CEI ranged from 0.27 mg/m 3 × years to 100.24 mg/m 3 × years, with an AM of 24.40 mg/m 3 × years and a GM of 14.06 mg/m 3 × years. The RMn CEI had an AM of 2.95 mg/m 3 × years and a GM of 1.78 mg/m 3 × years with a range of 0.05–12.03 mg/m 3 × years. Overall average TMn exposure intensity, the TMn CEI divided by time worked in years for each worker, had an AM of 1.6 mg Mn/m 3 , a GM of 1.0 mg Mn/m 3 , range 0.02–6.2 6 mg Mn/m 3 . The results of the 2004 follow-up study showed several concentration-response relationships between TMn CEI and neurobehavioral outcomes, which suggest that increase in cumulative TMn exposure level has long-term consequences on the nervous system.

A case–control study relating railroad worker mortality to diesel exhaust exposure using a threshold regression model

A case–control study of lung cancer mortality in U.S. railroad workers in jobs with and without diesel exhaust exposure is reanalyzed using a new threshold regression methodology. The study included 1256 workers who died of lung cancer and 2385 controls who died primarily of circulatory system diseases. Diesel exhaust exposure was assessed using railroad job history from the US Railroad Retirement Board and an industrial hygiene survey. Smoking habits were available from next-of-kin and potential asbestos exposure was assessed by job history review. The new analysis reassesses lung cancer mortality and examines circulatory system disease mortality. Jobs with regular exposure to diesel exhaust had a survival pattern characterized by an initial delay in mortality, followed by a rapid deterioration of health prior to death. The pattern is seen in subjects dying of lung cancer, circulatory system diseases, and other causes. The unique pattern is illustrated using a new type of Kaplan–Meier survival plot in which the time scale represents a measure of disease progression rather than calendar time. The disease progression scale accounts for a healthy-worker effect when describing the effects of cumulative exposures on mortality.

Airborne Concentrations of Asbestos Onboard Maritime Shipping Vessels (1978–1992)

The exposure of shipyard workers to asbestos has been frequently investigated during the installation, repair or removal of asbestos insulation. The same level of attention, however, has not been directed to asbestos exposure of maritime seamen or sailors. In this paper, we assemble and analyze historical industrial hygiene (IH) data quantifying airborne asbestos concentrations onboard maritime shipping vessels between 1978 and 1992. Air monitoring and bulk sampling data were compiled from 52 IH surveys conducted on 84 different vessels, including oil tankers and cargo vessels, that were docked and/or at sea, but these were not collected during times when there was interaction with asbestos-containing materials (ACMs). One thousand and eighteen area air samples, 20 personal air samples and 24 air samples of unknown origin were analyzed by phase contrast microscopy (PCM); 19 area samples and six samples of unknown origin were analyzed by transmission electron microscopy (TEM) and 13 area air samples were analyzed by scanning electron microscopy (SEM). In addition, 482 bulk samples were collected from suspected ACMs, including insulation, ceiling panels, floor tiles, valve packing and gaskets. Fifty-three percent of all PCM and 4% of all TEM samples were above their respective detection limits. The average airborne concentration for the PCM area samples (n = 1018) was 0.008 fibers per cubic centimeter (f cc(-1)) (95th percentile of 0.040 f cc(-1)). Air concentrations in the living and recreational areas of the vessels (e.g. crew quarters, common rooms) averaged 0.004 f cc(-1) (95th percentile of 0.014 f cc(-1)), while air concentrations in the engine rooms and machine shops averaged 0.010 f cc(-1) (95th percentile of 0.068 f cc(-1)). Airborne asbestos concentrations were also classified by vessel type (cargo, tanker or Great Lakes), transport status (docked or underway on active voyage) and confirmed presence of ACM. Approximately 1.3 and 0% of the 1018 area samples analyzed by PCM exceeded 0.1 and 1 f cc(-1), respectively. This data set indicates that historic airborne asbestos concentrations on these maritime shipping vessels, when insulation-handling activities were not actively being performed, were consistently below contemporaneous US occupational standards from 1978 until 1992, and nearly always below the current permissible exposure limit of 0.1 f cc(-1).

A study of airborne chrysotile concentrations associated with handling, unpacking, and repacking boxes of automobile clutch discs

Although automotive friction products (brakes and manual clutches) historically contained chrysotile asbestos, industrial hygiene surveys and epidemiologic studies of auto mechanics have consistently shown that these workers are not at an increased risk of developing asbestos-related diseases. Airborne asbestos levels during brake repair and brake parts handling have been well-characterized, but the potential exposure to airborne asbestos fibers during the handling of clutch parts has not been examined. In this study, breathing zone samples on the lapel of a volunteer worker ( n = 100) and area samples at bystander ( n = 50), remote area ( n = 25), and ambient ( n = 9) locations collected during the stacking, unpacking, and repacking of boxes of asbestos-containing clutches, and the subsequent cleanup and clothes handling, were analyzed by phase contrast microscopy (PCM) and transmission electron microscopy (TEM). In addition, fiber morphology and size distribution was evaluated using X-ray diffraction, polarized light microscopy, and ISO analytical methods. It was observed that the (1) airborne asbestos concentrations increased with the number of boxes unpacked and repacked, (2) repetitive stacking of unopened boxes of clutches resulted in higher asbestos concentrations than unpacking and repacking the boxes of clutches, (3) cleanup and clothes handling tasks yielded very low asbestos concentrations. Fiber size and morphology analyses showed that amphibole fibers were not detected in the clutches and that the vast majority (>95%) of the airborne chrysotile fibers were less than 20 μm in length. Applying the ratio of asbestos fibers:total fibers (including non-asbestos) as determined by TEM to the PCM results, it was found that 30-min average airborne chrysotile concentrations (PCM adjusted) were 0.026 ± 0.004 f/cc or 0.100 ± 0.017 f/cc for a worker unpacking and repacking 1 or 2 boxes of clutches, respectively. The 30-min PCM adjusted average airborne asbestos concentrations at bystander locations ranged from 0.002 ± 0.001 f/cc and 0.004 ± 0.002 f/cc when 1 or 2 boxes of clutches were handled, respectively. Estimated 8-h TWA asbestos exposures for a worker handling 1 or 2 boxes of clutches over a workday ranged from 0.002 to 0.006 f/cc. The 30-min PCM adjusted average airborne asbestos concentration for a worker continuously stacking unopened boxes of clutches was 0.212 ± 0.014 f/cc; the 8-h TWA was 0.013 f/cc. Additionally, 30-min PCM adjusted average airborne asbestos concentrations following cleanup and clothing handling were 0.002 ± 0.001 f/cc and 0.002 ± 0.002 f/cc, respectively, both resulting in estimated 8-h TWA asbestos exposures of 0.0001 f/cc. The results of this study indicate that the handling, unpacking, and repacking of clutches, and the subsequent cleanup and clothes handling by a worker within a short-term period or over the entire workday, result in exposures below the historical and current short-term and 8-h occupational exposure limits for asbestos.

Evaluation of Bricklayer Exposures to Airborne Asbestos in Steel Mills (1972-1981)

P-609 Introduction: Although there have been a number of studies of worker exposure to chemicals in steel mills, less attention has been devoted to characterizing the exposure of craftsman in these facilities. For example, the exposure to asbestos by bricklayers in steel mills has been suggested as being possibly significant. The objective of this analysis was to characterize the airborne concentrations of asbestos of these craftsmen as reflected in samples collected in two steel mills between 1972 and 1981. Methods: An asbestos air monitoring database was created from industrial hygiene surveys conducted during repair and/or maintenance work on open hearth furnaces and stoves. Personal (n=110) samples were collected while bricklayers and bricklayer helpers handled asbestos millboard and asbestos expansion allowance sheets. Some area (n=11) samples were collected in the vicinity of the work environment. The sample durations for all personal and area samples averaged 22 min (range 9-50 min) and 37 min (range 13-95 min), respectively. Most air samples were analyzed using phase contrast microscopy (PCM). Descriptive summary statistics were conducted to characterize both personal and area airborne asbestos concentrations. These data were combined with time-motion information to estimate 8-hour time-weighted average (TWA) concentrations, and these were compared to the contemporaneous OSHA permissible exposure limit (PEL) for asbestos. Results: Results of all personal air samples ranged from 0.03-3.2 f/cc (average: 0.3 f/cc; standard deviation (SD): 0.5 f/cc). These samples were collected during the periods of the day during which exposure was expected to be the highest and don't reflect the 8 hr-TWA. Of all the personal samples, six had results greater than or equal to 1 f/cc, but all were below the contemporaneous OSHA 15-min ceiling limit of 10 f/cc. Four of these relatively high samples were associated with the relining of a stove and the remaining two were associated with relining an open hearth furnace. Neither task is normally performed by bricklayers or masons. The estimated 8-hr TWA concentrations for these workers ranged from 0.04-1.34 f/cc (average: 0.33 f/cc; SD: 0.348 f/cc) for those days when mason were rebuilding furnaces. These values can not be used to depict the typical daily exposures of masons since fraction of their careers were involved in lining furnaces. Conclusions: Based on these results, it appears that bricklayer exposure to airborne asbestos, in these steel mills during this period of time, were generally below the contemporaneous OSHA permissible exposure limits (PELs).

Exposure Assessment Methods for a Study of Mortality and Cancer Morbidity in Relation to Specific Petroleum Industry Exposures

In 1987 a Canadian company implemented an exposure tracking and health information system. The exposure tracking method aligned closely with published concepts for describing workplace exposure, with over 1800 similar exposure groups being used to describe occupational exposures. The database has been actively maintained and is subject to a number of quality checks. Recently, the company initiated a cancer morbidity study, with one objective being to examine whether the exposure tracking data could be used to reconstruct exposure estimates for the cohort. Five agents—hydrogen sulfide, petroleum coke/spent catalyst, hydrocarbon solvents and fuels, hydrocarbon lubricants, and an index for exposure to operations derived from noise exposure—were selected for development of occupational exposure estimates for each cohort member. The cohort consisted of workers first employed between January 1964 and December 1994 and who were employed for at least 1 year. Work history records were associated with a similar exposure group, using human resources data and knowledge of local industrial hygienists. Only employees with > 90% duration of their work history assigned were kept in the cohort (25,292 people out of a possible 25,617). For each similar exposure group inventory, the substances were identified that contributed to each of the five agents being studied. Exposure estimates before 1987 were modified using historic occupational exposure limits. Rules were created to sum the exposure from multiple substances found in any one similar exposure group. The validity of exposure estimates was tested via comparison with results documented in industrial hygiene survey reports. Industrial hygienists who were unaware of the derived exposure estimates evaluated several hundred industrial hygiene surveys and prepared benchmark information. The two lists were then evaluated for concordance, which was found to be significantly different from that occurring by chance. We conclude that the process described can create valid exposure estimates for use in epidemiology studies.

Benzene exposure in the shoemaking industry in China, a literature survey, 1978–2004

This article presents a summary of benzene exposure levels in the shoemaking industry in China reported in the Chinese medical literature between 1978 and 2004. A comprehensive search identified 182 papers reporting such exposure data. These papers could be classified into two categories: benzene poisoning case reports and industrial hygiene surveys. From each paper, the following information was abstracted whenever available: location and year of occurrence, occupation and/or task involved, benzene content in adhesives/solvents, work environment, working conditions, working hours, diagnosis, and air monitoring data of benzene. A total of 333 benzene measurements (88 averages, 116 minimums, 129 maximums) in the shoemaking industry were reported in the 182 papers identified. The data were analyzed in terms of geographical location, time period, type of ownership (state, township, or foreign), type of report (benzene poisoning reports vs. industrial hygiene surveys), and job title (work activity) or process. The reported data covered a wide range; some measurements were in excess of 4500 mg/m 3. Thirty-five percent of the reported benzene concentrations were below 40 mg/m 3, which was the national occupational exposure limit (OEL) for benzene between 1979 and 2001. The remaining 65% measurements, which exceeded the national OEL in effect at the time, and were distributed as follows: 40–100 mg/m 3, 11%; 100–300 mg/m 3, 21%; 300–500 mg/m 3, 13%; and 500+ mg/m 3, 20%. However, only 24% of the reported measurements after 2002 were below 6 mg/m 3, i.e., Permissible Concentration-Time Weighted Average (PC-TWA) and 10 mg/m 3, i.e., Permissible Concentration-Short Term Exposure Limit (PC-STEL), the newly amended benzene OELs in effect after May 2002. The data demonstrated that the majority of the facilities in the shoemaking industry reported in the literature were not in compliance of the OEL for benzene in effect at the time. Overall, the data show a clear downward trend of benzene exposure levels over the years, particularly after the introduction of the new lower OEL in 2002. Even though substantially lower when compared to levels in the past, current benzene exposure measurements from the literature review suggest that many facilities in the shoemaking industry in China have benzene concentrations that are still above the new OEL. The reported data, stratified by job, year and survey reason, can be used as part of the information and analysis for developing a job-exposure matrix in retrospective exposure assessment and thus may be part of the information used in developing historical exposure estimates in epidemiologic studies of shoe workers.

An overview of published benzene exposure data by industry in China, 1960–2003

This article presents an overview of occupational benzene exposures in China based on data published in Chinese medical journals. The data were derived from 384 reports of benzene poisoning or industrial hygiene surveys published in Chinese medical journals between 1960 and 2003. The following information was extracted whenever available: industry, occupation, task, date, benzene levels, sampling location, workplace descriptions and, for case reports, medical diagnosis. Each paper provided one or more sets of benzene data, each set representing a sampling location or job title with one to several measurements including, mainly, breathing zone area concentration measurements, and much less frequently personal monitoring. Two criteria based on data quality were applied to select suitable data for analyses. The selected exposure data were analyzed by industry and time period. Nine hundred five sets of benzene measurements from 72 industries were reported in the 384 papers selected for this review, and 621 sets (68.6%) presented average benzene concentrations, which covered 55 industries. The distribution of the reported average benzene exposures was skewed with a median of 51.5 mg/m 3. The average benzene concentrations were below 100 mg/m 3 for 406 (65%) of the 621 reported average concentrations. The medians of the reported averages in mg/m 3 for the five industries with the highest exposures were: 124.8 for leather products, 98.7 for electronic devices, 75.4 for machinery, 50.4 for shoes, and 50.3 for office supplies and sports equipment manufacturing. These data describe the concentrations and changing patterns of occupational benzene exposure by industry and time period in China.

Environmental Mycological Study and Allergic Respiratory Disease among Tobacco Processing Workers

This study presents the results of an investigation of respiratory symptoms, lung function, chest X-ray examinations, analysis of specific IgE antibodies and skin prick tests to fungi on 130 tobacco-processing workers and 112 control workers. Industrial hygiene survey and environmental mycological studies were also performed. The average dust concentrations ranged from 13.76 to 29.55 mg/m(3) in the tobacco processing workshops. Also, the numbers of fungi colonies in the processing environments were much higher than those in the control environments. The prevalences of chronic respiratory or nasal symptoms in exposed workers were significantly higher than those in control workers (p<0.05 or p<0.01). The prevalences of lung function abnormalities in the exposed workers were significantly higher than those in control workers (p<0.05). The positive prevalences of specific IgE reactions to fungi (26.92% for A.fumigatus and 51.54% for Rhizopus nigricans) in exposed workers were also significantly higher than those in control workers (p<0.01). The positive prevalences of the skin prick test showed that 18.46% of the exposed workers were positive to A. fumigatus and 23.85% were positive to Rhizopus nigricans. Our results suggested that tobacco processing workers may develop respiratory diseases related to tobacco dust and we consider that fungi might be one of the allergens causing allergic respiratory or nasal diseases in tobacco processing workers.

Risk of breast cancer among enlisted Army women occupationally exposed to volatile organic compounds

The military presents a unique opportunity to study the incidence of disease in a population with complete knowledge of person-time and occupation. Women in the Army are employed more frequently in non-traditional, industrial jobs such as auto mechanic and motor transport operators than in the general US population, increasing the probability of exposure to industrial chemicals. A cohort to investigate the risk of breast cancer among active duty Army women occupationally exposed to volatile organic chemicals (VOCs) was constructed. Age-adjusted incidence rates for breast cancer were calculated for more than 270,000 enlisted women who served between 1980-1996. Twenty-one VOCs, described in previously published literature as having a potential risk of breast cancer, were identified in an Army industrial hygiene survey database. Job title histories were linked to workplace chemical evaluations conducted by Army industrial hygienists, which included a subjective exposure potential rating (high, medium, low, and none) for each VOC. Poisson regression analysis was used to evaluate the association between the exposure rating by job title and breast cancer. The incidence of breast cancer in the cohort was significantly elevated in women younger than 35 years of age, especially among black women, when compared to the age-specific rates in the general population. Women who worked in occupations with a moderate to high exposure potential to at least one VOC had a 48% increased risk (P < 0.05) of breast cancer while on active duty between 1980-1996 when compared to those women with low to no exposure potential. This study provides preliminary evidence that exposure to one or more of the study VOCs is associated with an increased risk of breast cancer. Further substance-specific, quantitative analyses are warranted.

Airborne Concentrations of Methylene Diphenyl Diisocyanate (MDI) in North American Wood Mills During the Manufacturing of Oriented Strand Board (OSB)

Air monitoring data were collected from industrial hygiene surveys over an 8-year period in oriented strand board (OSB) mills. Personal samples were taken to evaluate potential employee exposures to MDI. Area samples were taken to determine the effectiveness of control measures used in the mills to prevent fugitive emissions of wood dust, MDI, and MDI-coated wood dust from the OSB manufacturing process. Personal sampling results (578 samples covering 11 different job categories) ranged from 0.0002–0.524 mg/m3, with a GM = 0.001 and GSD = 3.71. Area sampling results (1657 samples covering 14 stationary locations in the mills) ranged from 0.0002–2.5 mg/m3, with a GM = 0.004 and GSD = 5.52. The statistical range of the data suggests high variability. While exposures to MDI above the established limits (0.051 mg/m3, 8-hour time-weighted average, 0.2 mg/m3, ceiling) can and do occur when engineering controls are not maintained and/or proper work practices and personal protective equipment are not followed/used for certain high exposure potential tasks, the data indicate that over 97% of the personal and 92% of the area sampling results are less than 0.051 mg/m3. Wipe testing was performed to determine the presence of removable, unreacted diisocyanates (NCO functional groups) from various surfaces. Positive results were found in about 13% of the wipe tests on surfaces confined to the blender, forming line, and hopper deck process areas.