Background

The goal of this study is to develop a general population job-exposure matrix (GPJEM) on asbestos to estimate occupational asbestos exposure levels in the Republic of Korea.

Methods

Three Korean domestic quantitative exposure datasets collected from 1984 to 2008 were used to build the GPJEM. Exposure groups in collected data were reclassified based on the current Korean Standard Industrial Classification (9^th edition) and the Korean Standard Classification of Occupations code (6^th edition) that is in accordance to international standards. All of the exposure levels were expressed by weighted arithmetic mean (WAM) and minimum and maximum concentrations.

Results

Based on the established GPJEM, the 112 exposure groups could be reclassified into 86 industries and 74 occupations. In the 1980s, the highest exposure levels were estimated in "knitting and weaving machine operators" with a WAM concentration of 7.48 fibers/mL (f/mL); in the 1990s, "plastic products production machine operators" with 5.12 f/mL, and in the 2000s "detergents production machine operators" handling talc containing asbestos with 2.45 f/mL. Of the 112 exposure groups, 44 groups had higher WAM concentrations than the Korean occupational exposure limit of 0.1 f/mL.

Conclusion

The newly constructed GPJEM which is generated from actual domestic quantitative exposure data could be useful in evaluating historical exposure levels to asbestos and could contribute to improved prediction of asbestos-related diseases among Koreans.

Background

Few studies have examined ambulatory cardiovascular physiological parameters of taxi drivers while driving in relation to their occupational hazards. This study aims to investigate and quantify the impact of worksite physical hazards as a whole on ambulatory heart rate of professional taxi drivers while driving without their typical worksite psychosocial stressors.

Methods

Ambulatory heart rate (HR_driving) of 13 non-smoking male taxi drivers (24 to 67 years old) while driving was continuously assessed on their 6-hour experimental on-road driving in Los Angeles. Percent maximum HR range (PMHR_driving) of the drivers while driving was estimated based on the individual HR_driving values and US adult population resting HR (HR_rest) reference data. For analyses, the HR_driving and PMHR_driving data were split and averaged into 5-min segments. Five physical hazards inside taxi cabs were also monitored while driving. Work stress and work hours on typical work days were self-reported.

Results

The means of the ambulatory 5-min HR_driving and PMHR_driving values of the 13 drivers were 80.5 bpm (11.2 bpm higher than their mean HR_rest) and 10.7 % (range, 5.7 to 19.9 %), respectively. The means were lower than the upper limits of ambulatory HR and PMHR for a sustainable 8-hour work (35 bpm above HR_rest and 30 % PMHR), although 15-27 % of the 5-min HR_driving and PMHR_driving values of one driver were higher than the limits. The levels of the five physical hazards among the drivers were modest: temperature (26.4 ± 3.0 °C), relative humidity (40.7 ± 10.4 %), PM_2.5 (21.5 ± 7.9 μg/m³), CO₂ (1,267.1 ± 580.0 ppm) and noise (69.7 ± 3.0 dBA). The drivers worked, on average, 72 h per week and more than half of them reported that their job were often stressful.

Conclusions

The impact of physical worksite hazards alone on ambulatory HR of professional taxi drivers in Los Angeles generally appeared to be minor. Future ambulatory heart rate studies including both physical and psychosocial hazards of professional taxi drivers are warranted.