Inhalation exposure to carbonyl compounds and BTEX and health risk assessment of gas station workers in Bangkok metropolitan

Abstract

The study aimed to evaluate potential occupational exposure of gas station workers to carbonyl compounds and BTEX via inhalation pathway and to estimate their health risk. The sampling was divided into 2 parts based on area focusing. The first sampling was performed in 6 gas stations located in Pathumwan district representing the inner city of Bangkok during May – June 2010, and the second sampling was performed in 6 gas stations located in different districts representing the widespread area of Bangkok in November 2010. 2, 4 DNPH active cartridge and a charcoal glass tube connected to a personal air pump with the air flow rate of 100 ml/min was used for collecting the carbonyl compounds and BTEX, respectively. This device was attached within the breathing zone of the workers to collect the personal exposure and was taken place inside in the center of gas station at the height of approximately 1.5 m during 8 work hours (6.00 am–2.00 pm). The 2,4 dinitrophenylhydrazine (DNPH) cartridge and charcoal glass tube were extracted by acetonitrile and carbondisulfide, and the samples were analyzed by HPLC/UV and GC/FID, respectively. The gas station workers exposure to benzene, toluene, ethylbenzene, m,p-xylene and o-xylene (BTEX) from both samplings were in range of 36.93 – 292.52, 69.21 – 490.38, 7.86 – 52.42, 22.33 – 154.14 and 5.28 – 49.90 µg/m3, respectively, and their exposure to nine major species of carbonyl compounds namely formaldehyde, acetaldehyde, acetone, propionaldehyde, crotonaldehyde, butylraldehyde, benzaldehyde, valeraldehyde and hexanaldehyde were in range of 3.40 – 39.76, 1.59 – 35.33, 3.49 – 104.90, 0.27 – 4.78, 0.34 – 19.11, 0.12 – 7.57, 0.13 – 4.57, 0.04 – 3.09 and 0.18 – 3.96 µg/m3, respectively. Only eight compounds including benzene, ethylbenzene, formaldehyde, acetaldehyde, toluene, m,p-xylene, o-xylene and propionaldehyde can be estimated the health risks. The results show that the lifetime cancer risks of gas station workers exposure to benzene, formaldehyde, ethylbenzene and acetaldehyde were in the range of 4.14×10-5 - 4.99×10-4, 4.28×10-6 - 5.72×10-5, 1.47×10-6 - 1.26×10-5 and 8.46×10-7 - 2.03×10-5, respectively. The hazard quotients for non-carcinogenic compounds of gas station workers exposure to toluene, m,p-xylene, o-xylene and propionaldehyde were found in range of 0.0044 - 0.0313, 0.0714 - 0.4927, 0.0169 - 0.1595 and 0.0106 - 0.1910, respectively. The high cancer risk of the gas station workers especially exposure to benzene leading to leukemia was determined greater than 10-6. Otherwise, the overall workers were not posed to increase risk of some adverse health effects from exposure to non-carcinogenic compounds due to hazard quotients were less than 1.