Exposure to toluene and methyl ethyl ketone among workers in a rubber shoe manufacturing factory in Bangkok, Thailand: evaluation using personal sampling

Objectives: This cross-sectional study aims to verify the concentrations of toluene and methyl ethyl ketone (MEK) in personal sampling of air and worker’s urine samples to create a safety/health strategy for a rubber shoe manufacturing factory in Bangkok, Thailand. Methods: Target workers were 180 workers in the rubber shoe manufacturing factory. The data were obtained through an interview using a questionnaire sheet, collection of air and urine samples to measure the toluene and MEK levels, and a walking observation survey. Air samples were individually collected by an organic vapor monitor (n = 20). Urine samples were also individually measured (n = 165). Results: Among 180 participants, 65.6% always used personal respiratory protective equipment (PPE), but all of them used a carbon cloth mask. Median toluene level was 681 ppb and MEK level was 7.23 ppm in air samples. Median toluene level was 3.14 μg/L and MEK level was 82.7 μg/L in urine samples. In 27 cases, toluene level in urine samples exceeded the exposure limit recommended by the ACGIH (30 μg/L). More than 10% of participants answered that they often had forgetfulness and dyspnea. Dyspnea was significantly positively related to MEK level in urine samples. There were seven cases with lower toluene and MEK levels in air samples but higher levels in urine samples. They sat in the leeward position and used no PPE and no rubber gloves while working. Conclusions: These results suggest that education, correct and suitable PPE, and strict work control should be implemented while working in rubber shoe manufacturing.