Evaluation of particle and volatile organic compound emissions during the use of 3D pens.

This study investigated particle and volatile organic compound (VOC) emission rates (ER) from 3D pens, which are increasingly popular in children's toys. Nine filaments and two 3D pens were evaluated using a flow tunnel, a scanning mobility particle sizer, a proton-transfer-reaction time-of-flight mass spectrometer for particles, and a thermal desorption-gas chromatography-mass spectrometer for VOCs. Results showed that the ERs varied with the pen type, filament, and brand. The particle ER was highest for acrylonitrile butadiene styrene (ABS), followed by polylactic acid (PLA) and polycaprolactone (PCL). Notably, ERs of 83 % and 33 % of ABS and PLA filaments exceeded the maximum allowable particle ER (MAER; 5 × 109 particles/min) for 3D printers but were lower than the VOC MAER (173 µg/min in the office). Different filaments emitted diverse VOCs; ABS emitted styrene and benzene, PLA emitted lactide, and PCL emitted phenol. While particle ERs from 3D pens were comparable to those from printers, the total VOC ERs from 3D pens were slightly lower. Caution is warranted when using 3D pens because of potential health risks, especially their prolonged use, proximity to the breathing zone, and usage by children. This study highlights the need for considering particles and VOCs when assessing the safety of 3D pens, emphasizing awareness of potential hazards, particularly in child-oriented settings.

Dose-response relationship between lung function and chest imaging response to silica exposures in artificial stone manufacturing workers.

BACKGROUND: Occupational exposure to artificial stone, a popular material used for countertops, can cause accelerated silicosis, but the precise relationship between silica dose and disease development is unclear. OBJECTIVES: This study evaluated the impact of silica exposure on lung function and chest imaging in artificial stone manufacturing workers. METHODS: Questionnaire and spirometry assessments were administered to workers in two plants. A high-exposure subset underwent further evaluation, including chest CT and DLco. Weighting factors, assigned as proxies for silica exposure, were based on work tasks. Individual cumulative exposures were estimated using area concentration measurements and time spent in specific areas. Exposure-response associations were analyzed using linear and logistic regression models. RESULTS: Among 65 participants, the mean cumulative silica exposure was 3.61 mg/m3-year (range 0.0001 to 44.4). Each 1 mg/m3-year increase was associated with a 0.46% reduction in FVC, a 0.45% reduction in FEV1, and increased lung function abnormality risk (aOR = 1.27, 95% CI = 1.03-1.56). Weighting factors correlated with cumulative exposures (Spearman correlation = 0.59, p < 0.0001), and weighted tenure was associated with lung function abnormalities (aOR = 1.04, 95% CI = 1.01-1.09). Of 37 high-exposure workers, 19 underwent chest CT, with 12 (63%) showing abnormal opacities. Combining respiratory symptoms, lung function, and chest X-ray achieved 91.7% sensitivity and 75% specificity for predicting chest CT abnormalities. CONCLUSION: Lung function and chest CT abnormalities occur commonly in artificial stone workers. For high-exposure individuals, abnormalities on health screening could prompt further chest CT examination to facilitate early silicosis detection.

The effect of cumulative noise exposure on distortion product otoacoustic emissions.

OBJECTIVE: This study aimed to identify the characteristics of distortion product otoacoustic emissions (DPOAEs) that can be used to differentiate noise-induced hearing loss (NIHL) from age-related hearing loss. A potential index to detect NIHL was defined in terms of its susceptibility to cumulative noise exposure but not to age. DESIGN: In this cross-sectional cohort study, a job-exposure matrix was used to calculate the cumulative noise exposure. Multivariate linear regression models were used to examine how age and cumulative noise exposure associated with DPOAEs at individual frequencies after adjusting for hypertension, dyslipidaemia, tobacco use and alcohol consumption. STUDY SAMPLE: The pure-tone audiometry and DPOAEs data collected from 239 male workers in a steel factory. RESULTS: DPOAEs and DPOAE signal-to-noise ratios (SNRs) at all frequencies were found to be correlated with age, and those at 2, 3, 4 and 6 kHz were correlated with both age and noise exposure. The difference between DPOAE SNR at 1 and 3 kHz showed significant correlation with noise exposure but not with age. CONCLUSIONS: The results showed that this DPOAE index, the DPOAE SNR at 1 kHz minus the DPOAE SNR at 3 kHz, could add values to audiometric evaluation of NIHL.

Application of Standardized Proportional Mortality Ratio to the Assessment of Health Risk in Relatively Healthy Populations: Using a Study of Cancer Risk in Telecommunication Workers with Excess Exposure to Acid Mists as an Example.

When a study population is relatively healthy, such as an occupational population, epidemiological studies are likely to underestimate risk. We used a case study on the cancer risk of workers with exposure to acid mists, a well-documented carcinogen, to demonstrate that using proportional mortality ratios (PMRs) is more appropriate than mortality ratios in assessing risk in terms of mortality. The study included 10,229 employees of a telecommunication company who worked in buildings with battery rooms. In these buildings, the battery rooms had the highest levels of sulfuric acid in the air (geometric mean = 10.7 µg/m3). With the general population in Taiwan as a reference, a decreased standardized mortality ratio (0.42, p < 0.01) from all causes combined, between 1 January 1985 and 31 December 1996, was observed, indicating a healthy worker effect. When we reanalyzed the data using standardized PMR, elevated risks were observed for all cancers combined (1.46, p = 0.01) and cancers of the digestive organs and peritoneum (1.61, p = 0.02), especially stomach cancer (2.94, p = 0.01). The results showed that PMR can detect increases in mortality when a study population is generally healthier than the comparison population and call for further studies on the possible carcinogenic effects of low-level acid mist exposures on the stomach.

Physical and psychological stress along with candle fumes induced-cardiopulmonary injury mimicking restaurant kitchen workers.

Restaurant kitchens are work areas where involve strict and hierarchal environments that promote opportunity for bullying and workplace aggression and violence. These physical and psychological stress and fumes ultimately trigger severe occupational stress by disrupting the body's homeostasis that might induce cardiopulmonary injury. The study aimed to investigate the physical and psychological stress and candle fumes on cardiopulmonary injury in an animal model mimicking a restaurant kitchen worker. Social disruption stress (SDR) mice were exposed to scented candle fumes (4.5 h/d, 5 d/wk) in an exposure chamber for 8 weeks. Exposure to burning scented candles failed to reduce serum corticosterone level and increased proinflammatory cytokines levels and NF-ƙB activity in the lung. In addition, burning scented candle fumes synergistically increased SDR-induced serum LDH, CPK, CKMB levels, proinflammatory cytokines production as well as NF-ƙB activation in the lung and heart. Further, cardiac HIF-1α and BNP levels were also increased. We conclude that the physical and psychological stress along with candle fumes might induce cardiopulmonary injury in mice. These results could be extrapolated to restaurant kitchen workers.

Respiratory health effects of the fiberglass-reinforced plastic lamination process in the yacht-building industry.

Objectives Fiberglass-reinforced plastics (FRP) manufacturing has been related to cases of severe airway obstruction and elevated risk of respiratory mortality. But the specific job content risk is not clear. This study evaluated the respiratory health effects of the FRP lamination process. Methods A questionnaire was used to evaluate respiratory symptoms of workers in two yacht-building plants. Pre-shift (07:30-08:30 hours) and post-shift (17:00-18:00 hours) lung function was measured, while post-shift induced sputum was collected on the first day of the week. The participants were grouped into FRP laminators and non-laminators. Linear and logistic regression was used to investigate the effects of the lamination process on lung function. Results Laminators had a higher prevalence of chronic cough, lower pre-shift forced expiratory volume in first second (FEV1) and FEV1/force vital capacity (FVC) (-3.3% and -1.5%), lower post-shift FVC and FEV1 (-3.6% and -4.9%), and larger post-shift reduction of FVC (-2.1%) compared to non-laminators. The laminators also had higher risk of early obstructive and overall (obstructive plus restrictive) lung function impairment, and post-shift reduction of FVC >10% [odds ratio (OR) 5.98, 4.98, and 3.87, respectively). They also had higher percentages of neutrophils and lymphocytes in the induced sputum. Conclusion Laminators should undergo regular check-ups of respiratory symptoms and lung function. Further toxicologic studies are warranted to identify the specific causal agent in the FRP lamination process.

Effect of Implementing Electronic Toll Collection in Reducing Highway Particulate Matter Pollution.

Highway vehicle emissions can result in adverse health problems to nearby residents and workers, especially during traffic congestion. In response, the policy to implement electronic toll collection (ETC) has helped alleviate traffic congestion, as compared to manual toll collection (MTC) and has led to reduced air pollution and improved public health. However, the effect of ETC in reducing particulate matter polluting the air is not well understood, especially in the ultrafine particle (UFP) range (particle diameter <100 nm). To the best of our knowledge, this is the first study to investigate how ETC affects the traffic pattern and air quality, especially UFP and PM2.5. We selected a site in Tainan, Taiwan, and measured UFP and PM2.5 concentrations before and after the construction of the ETC system. The computed traffic volumes during peak travel periods (7:00 AM to 9:00 AM and 4:00 PM to 6:00 PM) respectively, accounted for approximately 23-25% and 14-18% before and after the implementation of ETC, indicating that peak traffic volumes were more homogeneous after ETC. Moreover, the results indicate that the full implementation of ETC can help reduce UFP number concentrations and PM2.5 mass concentrations in the highway downwind area by 4 × 103 #/cm3 and 20.5 µg/m3, respectively. After the full implementation of the ETC, significant reductions in both the UFP number concentration and PM2.5 mass concentration were seen. Furthermore, excessive lifetime cancer risks (ELCR) from exposure to PM2.5 and UFP together were reduced 49.3% after the implementation of the ETC. Accordingly, ETC not only helps alleviate traffic congestion but also reduces traffic emissions and lifetime cancer risk for people living or working near highways.

Will daytime occupational noise exposures induce nighttime sleep disturbance?

BACKGROUND: Nighttime environmental noise affects sleep quality. However, the effects of daytime occupational noise remain unclear. METHODS: A quasi-experiment of 48 participants who had been employed for at least six months in two hospital cafeterias. The participants were randomly designated to be assessed on high- and low-noise workdays for 8 h or low- and high-noise workdays, separated by a washout period of 14 days. Subsequently, pure tone audiometry, autonomic nervous system (ANS) function tests, serum cortisol tests, and polysomnography were conducted. RESULTS: For the 40 participants in the study, the 8-h time-weighted average of personal noise exposed on high- and low-noise workdays was 76.8 dBA (standard deviation, SD: 6.2) and 61.0 dBA (SD: 7.1), respectively. Participants with higher personal noise exposure during the day were found to have a lower percentage of slow wave sleep (percent change of mean value: -1.287%; 95% CI: -2.602%, -0.037%) and lower sleep efficiency (-0.267%; 95% CI: -0.525%, -0.008%). In addition, after work, personal noise exposure was revealed to be related to increased serum cortisol levels (1.698%; 95% CI: 0.887%, 2.528%), and sympathetic activity as measured by low frequency/high frequency (3.000%; 95% CI: 1.294%, 4.706%) and blood pressures by cold pressor test (systolic: 5.163%; 95% CI: 2.780%, 7.537%) (diastolic: 3.109%; 95% CI: 1.604%, 4.614%). CONCLUSIONS: Daytime occupational noise exposure had sustained effects on nighttime sleep quality, specifically on slow wave sleep and sleep efficiency. These disturbances could be partially explained by post-shift elevated cortisol and ANS activity. The psychosocial and metabolic consequences of poorer sleep quality induced by occupational noise exposure warrant further investigation.

An instantaneous spatiotemporal model for predicting traffic-related ultrafine particle concentration through mobile noise measurements.

People living near roadways are exposed to high concentrations of ultrafine particles (UFP, diameter < 100 nm). This can result in adverse health effects such as respiratory illness and cardiovascular diseases. However, accurately characterizing the UFP number concentration requires expensive sets of instruments. The development of an UFP surrogate with cheap and convenient measures is needed. In this study, we used a mobile measurement platform with a Fast Mobility Particle Sizer (FMPS) and sound level meter to investigate the spatiotemporal relations of noise and UFP and identify the hotspots of UFP. UFP concentration levels were significantly influenced by temporal and spatial variations (p < 0.001). We proposed a Generalized Additive Models to predict UFP number concentration in the study area. The model uses noise and meteorological covariates to predict the UFP number concentrations at an industrial site in Taichung, Taiwan. During the one year sampling campaign from fall 2013 to summer 2014, mobile measurements were performed at least one week for each season, both on weekdays and weekends. The proposed model can explain 80% of deviance and has coefficient of determination (R2) of 0.77. Moreover, the developed UFP model was able to adequately predict UFP concentrations, and can provide people with a convenient way to determine UFP levels. Finally, the results from this study could help facilitate the future development of noise mobile measurement.

PM2.5 components and outpatient visits for asthma: A time-stratified case-crossover study in a suburban area.

The effects of fine particles (PM2.5) on asthma have been widely confirmed by epidemiological research studies. However, a limited number of studies have investigated the relationship between exposure to different PM2.5 components and asthma. We characterized the PM2.5 components in a suburban site of central Taiwan and conducted a time-stratified case-crossover study to elaborate the effects of daily concentration of each PM2.5 component on asthma outpatient visits. We retrieved asthma outpatient claims for individuals less than 20 years old with a residential address in the Shalu district, Taiwan, from the National Health Insurance Research Database during 2000-2010. Multiple linear regression models were used to back extrapolate the historic concentration of individual components of PM2.5 from 2000 through to 2010, including black carbon (BC) and eight ions, namely, sulfate, nitrate (NO3-), ammonium, chloride, potassium (K+), magnesium, calcium, sodium. The odds ratio (OR) with a 95% confidence interval (CI) of individual PM2.5 components on asthma was estimated by conditional logistic regression. A total of 887 asthma outpatient visits with individuals who have an average age of 7.96±3.88 years were selected. After adjusting for confounders, we found an interquartile range (IQR) increase in BC level, an IQR increase in NO3- level, and an IQR increase in K+ level that were all associated with the increased risk of asthma outpatient visits from the current day (OR = 1.18, 95% CI: 1.05-1.34; OR = 1.11, 95% CI: 1.01-1.21; and OR = 1.16, 95% CI: 1.04-1.30, respectively). The effects of these components on asthma were stronger in the cold season than in the warm season. However, we did not find any lagging effects. The results suggest that exposure to NO3-, BC, and K+ derived from industry-related combustion or motor vehicles emission sources may increase the risk of asthma outpatient visits, particularly during the cold season.

Estimation of respiratory heat flows in prediction of heat strain among Taiwanese steel workers.

International Organization for Standardization 7933 standard provides evaluation of required sweat rate (RSR) and predicted heat strain (PHS). This study examined and validated the approximations in these models estimating respiratory heat flows (RHFs) via convection (C res) and evaporation (E res) for application to Taiwanese foundry workers. The influence of change in RHF approximation to the validity of heat strain prediction in these models was also evaluated. The metabolic energy consumption and physiological quantities of these workers performing at different workloads under elevated wet-bulb globe temperature (30.3 ± 2.5 °C) were measured on-site and used in the calculation of RHFs and indices of heat strain. As the results show, the RSR model overestimated the C res for Taiwanese workers by approximately 3 % and underestimated the E res by 8 %. The C res approximation in the PHS model closely predicted the convective RHF, while the E res approximation over-predicted by 11 %. Linear regressions provided better fit in C res approximation (R 2 = 0.96) than in E res approximation (R 2 ≤ 0.85) in both models. The predicted C res deviated increasingly from the observed value when the WBGT reached 35 °C. The deviations of RHFs observed for the workers from those predicted using the RSR or PHS models did not significantly alter the heat loss via the skin, as the RHFs were in general of a level less than 5 % of the metabolic heat consumption. Validation of these approximations considering thermo-physiological responses of local workers is necessary for application in scenarios of significant heat exposure.

Comparison of Real Time Nanoparticle Monitoring Instruments in the Workplaces.

BACKGROUND: Relationships among portable scanning mobility particle sizer (P-SMPS), condensation particle counter (CPC), and surface area monitor (SAM), which are different metric measurement devices, were investigated, and two widely used research grade (RG)-SMPSs were compared to harmonize the measurement protocols. METHODS: Pearson correlation analysis was performed to compare the relation between P-SMPS, CPC, and SAM and two common RG-SMPS. RESULTS: For laboratory and engineered nanoparticle (ENP) workplaces, correlation among devices showed good relationships. Correlation among devices was fair in unintended nanoparticle (UNP)-emitting workplaces. This is partly explained by the fact that shape of particles was not spherical, although calibration of sampling instruments was performed using spherical particles and the concentration was very high at the UNP workplaces to allow them to aggregate more easily. Chain-like particles were found by scanning electron microscope in UNP workplaces. The CPC or SAM could be used as an alternative instrument instead of SMPS at the ENP-handling workplaces. At the UNP workplaces, where concentration is high, real-time instruments should be used with caution. There are significant differences between the two SMPSs tested. TSI SMPS showed about 20% higher concentration than the Grimm SMPS in all workplaces. CONCLUSIONS: For nanoparticle measurement, CPC and SAM might be useful to find source of emission at laboratory and ENP workplaces instead of P-SMPS in the first stage. An SMPS is required to measure with high accuracy. Caution is necessary when comparing data from different nanoparticle measurement devices and RG-SMPSs.

Particulate Matter Exposure in a Police Station Located near a Highway.

People living or working near roadways have experienced an increase in cardiovascular or respiratory diseases due to vehicle emissions. Very few studies have focused on the PM exposure of highway police officers, particularly for the number concentration and size distribution of ultrafine particles (UFP). This study evaluated exposure concentrations of particulate matter (PM) in the Sinying police station near a highway located in Tainan, Taiwan, under different traffic volumes, traffic types, and shift times. We focused on periods when the wind blew from the highway toward the police station and when the wind speed was greater than or equal to 0.5 m/s. PM2.5, UFP, and PM-PAHs concentrations in the police station and an upwind reference station were measured. Results indicate that PM2.5, UFP, and PM-PAHs concentrations in the police station can be on average 1.13, 2.17, and 5.81 times more than the upwind reference station concentrations, respectively. The highest exposure level for PM2.5 and UFP was observed during the 12:00 PM-4:00 PM shift while the highest PAHs concentration was found in the 4:00 AM-8:00 AM shift. Thus, special attention needs to be given to protect police officers from exposure to high PM concentration.

Emissions of Nanoparticles and Gaseous Material from 3D Printer Operation.

This study evaluated the emissions characteristics of hazardous material during fused deposition modeling type 3D printing. Particulate and gaseous materials were measured before, during, and after 3D printing in an exposure chamber. One ABS and two PLA (PLA1 and PLA2) cartridges were tested three times. For online monitoring, a scanning mobility particle sizer, light scattering instrument, and total volatile organic compound (TVOC) monitor were employed and a polycarbonate filter and various adsorbent tubes were used for offline sampling. The particle concentration of 3D printing using ABS material was 33-38 times higher than when PLA materials were used. Most particles were nanosize (<100 nm) during ABS (96%) and PLA1 (98%) use, but only 12% were nanosize for PLA2. The emissions rates were 1.61 × 10(10) ea/min and 1.67 × 10(11) ea/g cartridge with the ABS cartridge and 4.27-4.89 × 10(8) ea/min and 3.77-3.91 × 10(9) ea/g cartridge with the PLA cartridge. TVOCs were also emitted when the ABS was used (GM; 155 ppb, GSD; 3.4), but not when the PLA cartridges were used. Our results suggest that more research and sophisticated control methods, including the use of less harmful materials, blocking emitted containments, and using filters or adsorbents, should be implemented.

Cancer Attributable to Asbestos Exposure in Shipbreaking Workers: A Matched-Cohort Study.

PURPOSE: Long-term follow-up studies of asbestos-related cancer in shipbreaking workers are lacking. This study examines the relationship between cancer incidence and asbestos exposure among former Taiwan shipbreaking workers. METHODS: A total of 4,427 shipbreaking workers and 22,135 population-based matched controls were successfully followed in this study. The study cohort was linked to the Taiwan Cancer Registry for new cancer cases. The adjusted hazard ratio (aHR) for cancer was calculated for the shipbreaking workers with Total Exposure Potential Scores (TEP) for asbestos. RESULTS: Follow-up generated 109,932 person-years, with 940 deaths and 436 cancer cases, among 4,427 shipbreaking workers from 1985 to 2008. The high asbestos exposure group also had a statistically significant increase in the risk of overall cancer (aHR= 1.71; 95% CI: 1.42-2.05), esophagus cancer (aHR= 2.31; 95% CI: 1.00-5.41), liver and intrahepatic bile duct cancer (aHR= 1.60; 95% CI: 1.08-2.36), and trachea, bronchus, and lung cancer (aHR= 3.08; 95% CI: 1.80-5.25). Mesothelioma cases were found in the high asbestos exposure group. Moreover, overall cancer, esophagus cancer, and trachea, bronchus, and lung cancer were seen in a dose-dependent relationship with asbestos exposure. CONCLUSIONS: This study presented the elevated trend of asbestos exposure with cancer incidence for overall cancer, esophagus cancer, and trachea, bronchus, and lung cancer among shipbreaking workers. Those workers previously exposed to asbestos should receive persistent monitoring in order to early detect adverse health outcomes.

An integrated approach to assess exposure and health-risk from polycyclic aromatic hydrocarbons (PAHs) in a fastener manufacturing industry.

An integrated approach was developed to assess exposure and health-risk from polycyclic aromatic hydrocarbons (PAHs) contained in oil mists in a fastener manufacturing industry. One previously developed model and one new model were adopted for predicting oil mist exposure concentrations emitted from metal work fluid (MWF) and PAHs contained in MWF by using the fastener production rate (Pr) and cumulative fastener production rate (CPr) as predictors, respectively. By applying the annual Pr and CPr records to the above two models, long-term workplace PAH exposure concentrations were predicted. In addition, true exposure data was also collected from the field. The predicted and measured concentrations respectively served as the prior and likelihood distributions in the Bayesian decision analysis (BDA), and the resultant posterior distributions were used to determine the long-term exposure and health-risks posed on workers. Results show that long term exposures to PAHs would result in a 3.1%, 96.7%, and 73.4% chance of exceeding the PEL-TWA (0.2 mg/m3), action level (0.1 mg/m3), and acceptable health risk (10-3), respectively. In conclusion, preventive measures should be taken immediately to reduce workers' PAH exposures.

Prioritizing factors associated with thermal stresses imposed on workers in steel and iron casting industries using the Monte Carlo simulation and sensitivity analysis.

OBJECTIVES: The aims of this study were to develop approaches for monitoring and prioritizing factors associated with thermal stresses imposed on workers in iron and steel casting industries, and to eventually purpose effective control strategies. METHODS: The whole study was completed in the furnace areas of two steel casting and two iron casting plants, where the air temperature (Ta), radiant temperature (Tr), air velocity (Va) and partial water vapor pressure (Pa) were measured continuously during two consecutive work cycles. Simultaneously, the metabolic rates (M) of all workers in the furnace area were also measured. RESULTS: Using the WBGT as an index for screening purposes, our results suggest that all furnace area workers in both types of casting plants might experience severe heat stress. The predicted heat strain (PHS) model proposed by ISO 7933 was further adopted for detailed analysis from the physiological aspect. Through use of the Monte Carlo simulation and sensitivity analysis, both M and Tr were found to be the two most important factors associated with workers' thermal hazard. Therefore, two effective control strategies were suggested, including reducing workloads of workers and reducing radiant heat transmitting from furnaces to workplace environments. CONCLUSIONS: The approach developed in the present study would be beneficial to many other industries for initiating strategies to avert the thermal hazard imposed on workers.

Cancer incidence of Taiwanese shipbreaking workers who have been potentially exposed to asbestos.

BACKGROUND: Shipbreaking remains one of the most dangerous jobs worldwide. Shipbreaking workers are exposed to many hazardous chemicals, especially asbestos. Unfortunately, long-term follow-up studies of cancer incidence patterns in shipbreaking workers are lacking. This study examines whether there is an increased risk of cancer among male shipbreaking workers over a 24-year follow-up period. METHODS: 4155 male shipbreaking worker's information was retrospectively collected from Kaohsiung's Shipbreaking Workers Union database from 1985. The study cohort was linked to the Taiwan Cancer Registry from 1985 to 2008 for new cancer cases. The expected number of cancers for shipbreaking workers was calculated by using the age (5-year intervals) and calendar time-specific annual rates of cancer incidence with reference to the general population of Taiwan from 1985 to 2008. Standardized incidence ratios (SIRs) were calculated as relative risk estimates. The hazard ratio (HR) for cancer was calculated for the shipbreaking workers with Total Exposure Potential Scores for asbestos. RESULTS: After consideration of a 5-year latency period, an elevated incidence of overall cancer (N=368; SIR=1.13 (1.01-1.25)), oral cavity cancer (N=83; SIR=1.99 (1.58-2.46)), and trachea, bronchus, and lung cancers (N=53; SIR=1.36 (1.02-1.78)) was found among male shipbreaking employees. Moreover, mesothelioma cases were found in those who had the occupation of flame cutter. The high asbestos exposure group was associated with an increased SIR of developing overall cancer and oral cancer, whether we considered a 5-year or 10-year latency period. CONCLUSION: Asbestos-related diseases, including lung cancer and mesothelioma, were seen in excess in these shipbreaking workers and some cases appeared to have a dose-dependent relationship. Preventative measures among male shipbreaking workers should be researched further.

Developing a semi-quantitative occupational risk prediction model for chemical exposures and its application to a national chemical exposure databank.

In this study, a semi-quantitative occupational chemical exposure risk prediction model, based on the calculation of exposure hazard indexes, was proposed, corrected, and applied to a national chemical exposure databank. The model comprises one factor used to describe toxicity (i.e., the toxicity index), and two factors used to reflect the exposure potential (i.e., the exposure index and protection deficiency index) of workers exposed to chemicals. An expert system was used to correct the above proposed model. By applying the corrected model to data obtained from a national occupational chemical hazard survey program, chemical exposure risks of various manufacturing industries were determined and a national control strategy for the abatement of occupational chemical exposures was proposed. The results of the present study would provide useful information for governmental agencies to allocate their limited resources effectively for reducing chemical exposures of workers.