# Occupational Inhalation Health Risk Assessment of TCE Exposure in the Korean Manufacturing Industry
## 1 Introduction  
Trichloroethylene (TCE) is a non-flammable, volatile, colorless, sweet-smelling organic solvent. In the workplace, 80-95% is used for degreasing and cleaning metal machine parts [1; 2]. In Republic of Korea (referred to as Korea), TCE is applied in automotive and engine parts, electrical materials, computers, radio-televisions, communication equipment, metal products, glass and optical instrument cleaning, various cleaning activities, and degreasing of rubber and leather products [1; 3; 4; 5]. In 2019, 515 manufacturing establishments with 5 or more employees handled TCE, totaling 7236 tons [6]. TCE diffuses primarily as vapor; therefore, respiratory exposure is the primary route, and skin absorption is limited under normal working conditions [7]. TCE vapors flow through the bloodstream and affect the central nervous system, causing headaches, dizziness, vomiting, drowsiness, and in severe cases, loss of consciousness or death [8; 9; 10; 11; 12; 13; 14]. Long-term exposure can cause nervous system symptoms, such as memory loss, loss of motivation, emotional instability, and permanent damage to the liver or kidneys [8; 11; 12; 13; 14]. In addition, there have been several case reports indicating that severe systemic dermatitis may occur. This typically manifests as generalized exfoliative dermatitis, such as Stevens-Johnson syndrome or toxic epidermal necrolysis. Case reports have indicated that toxic hepatitis is frequently concurrent with this type of generalized exfoliative dermatitis [15]. High concentrations of trichloroethylene fumes cause deaths [8]. There have been cases of deaths resulting from inhalation of abnormally high levels of TCE vapor in the workplace [8]. TCE is a human carcinogen [8; 9; 10; 11; 12; 13]. Strong evidence for kidney cancer is found in the existing human data [8]. TCE is described as a group 1 carcinogen by the InternationalAgency for Research on Cancer (IARC) and a group A2 carcinogen by the American Conference of Governmental Industrial Hygienists (ACGIH) [8; 16]. There is sufficient evidence that TCE causes kidney cancer in humans [9; 17]. Several independent studies have observed an effect on liver cancer due to occupational exposure to TCE. In 9 of 15 studies, in which occupational TCE exposure was identified in individual subjects, the relative risk (RR) ranged from 0.93 to 1.39 for overall exposure to TCE [18; 19; 20; 21; 22; 23; 24; 25], and in 8 studies, in which exposure to TCE was more likely than the overall population, the RR ranged from 1.04 to 1.79 [18; 20; 21; 22; 23; 24; 25]. Additionally, the most estimated RR in 15 of the 24 studies reporting kidney cancer risk was between 1.10 and 1.90 for overall exposure to TCE [27; 28; 29; 30]. There are also risk assessment studies on TCE used in industry [31; 32; 33], but they are insufficient compared to epidemiological studies. In January 2006 in Korea, a male worker performing TCE cleaning in the electronics parts manufacturing industry died because of Stevens-Johnson syndrome, an acute form of TCE poisoning. Around the same time, a woman who worked in the inspection and packaging process following TCE cleaning in the mobile phone parts manufacturing industry developed Stevens-Johnson syndrome and died [1]. In 2008, three workers were hospitalized for toxic hepatitis [34]. Despite the numerous health risks mentioned above, TCE is widely used in the workplace because of its excellent solubility in oils, fats, and resins, volatility, non-flammability, and low cost [14]. In Korea, the occupational exposure limits (OEL) of TCE are defined as a Threshold Limit Value-Time-Weighted Average (TLV-TWA) of 50 ppm, and a Threshold Limit Value Short-Term Exposure Limit (TLV-STEL) of 200 ppm [35; 36]. These were subsequently revised on 17 February 2016 and are currently TLV-TWA 10 ppm and TLV-STEL 25 ppm, as proposed by the ACGIH [35; 36].