# Occupational Inhalation Health Risk Assessment of TCE Exposure in the Korean Manufacturing Industry
## 4 Discussion  
Workers involved in various processes that use TCE, especially degreasing processes, may be exposed to higher levels of TCE than the general population. High levels of TCE have been measured in environments where TCE is used as an industrial solvent. The metal industry traditionally used TCE for degreasing in the 1970s, and metal cleaning accounted for approximately 65% of the total metal processing in the USA [59]. In this study, the manufacturing of fabricated metal products was found to be the industry with the highest AM (4.67) and the industry with the second-largest number of measurements (1175) in Korea. Exposure to TCE as a metal cleaner or degreaser is prevalent in Korea, as well as in other countries. The average TCE concentration of 30 dry cleaners in Iran was much higher than that of the non-occupationally exposed group [60]. In Denmark, 69% of the measurements from 150 companies between 1947 and 1989 were in the steel and metal industry, indicating higher concentrations than in all other industries [61]. In a watch manufacturing factory in Thailand, 171 workers used TCE to clean the surfaces of the metal parts of watches [62]. The average exposure to TCE in the workplace air was 27.83 \(\pm\) 6.02 ppm [62]. In the United States, AM, including both individual and area measurements, was 39.6 ppm (\(n=867\)) of trichloroethylene exposure in degreasing operations [59]. In a study by [PERSON] et al., when measuring the TCE concentration by occupation in Shanghai, China, the air concentration of metal processing workers using TCE as a degreasing agent was found to be exposed to GM at levels of 29-34 mg/m\({}^{3}\)[63]. The TCE exposure level at several electroplating and electronics facilities in China was 58.63 mg/m\({}^{3}\) for TCE in the degreasing group, and 58.63 mg/m\({}^{3}\) for TCE in the washing group [31]. These results are consistent with the fact that TCE use is decreasing in the United States and Europe due to its toxicity but is increasing in some Asian countries due to increasing demand for degreasing agents [3]. TCE use in China increased from 4 to 5 kilotons in 1980-1990 to 40 kilotons in 2000 and 165 kilotons in 2010, of which 60-75% was used for degreasing [3]. Additionally, a study from China analyzed 212 workers and found that the C-TWA exceedance rate for TCE was 80.7% [64]. Therefore, it can be concluded that such high levels of TCE exposure are due to the country's usage and the industries where it is used. According to the non-carcinogenic risk assessment, the 95 th percentile of HQ indicates high-concentration exposure, with 60% of the 20 manufacturing industries showing an unacceptable risk. The results of the carcinogenic risk assessment in this study showed that the HQ exceeded 1 in all industries at the 95 th percentile, indicating exposure to high concentrations. Additionally, 85% of industries at the 50 th percentile HQ, corresponding to average exposure, showed unacceptable risk. In China, 14 electroplating companies and 6 electronics companies conducted risk assessments for non-carcinogenic and carcinogenic risks for workers who used TCE for degreasing work [31]. The HQ for non-carcinogenic risks was 18,000, while the HQ for workers involved in cleaning work was 33,000 [31]. The unacceptable risk ratio for car