Health risk assessment of exposure to ambient concentrations of benzene, toluene and xylene in Pretoria West, South Africa

Abstract

Benzene, toluene and xylene (BTX) are part of the volatile organic group of pollutants and are seen as international environmental priority air pollutants that can constitute a threat to public health. This study assessed the non-carcinogenic and carcinogenic risks of exposure to BTX in an industrial area located in Pretoria West, South Africa. The study comprised two parts, namely ambient air monitoring and the application of a Human Health Risk Assessment (HHRA) model. The study included sampling data for the 2014 calendar year (January – December). Sampling frequency were hourly samples of ambient concentrations of BTX. Estimate of the possible non-carcinogenic risk of BTX and carcinogenic risk of benzene were determined using the hazard quotient (HQ) and lifetime cancer risk (LCR) respectively. Annual average concentration (µg/m³) of BTX was 0.9 ± 0.9, 2.2 ± 2.5 and 0.8 ± 0.6, respectively, with higher concentrations during winter months. The HQ indicated no likelihood of adverse health effects on children and adults. The HQ of exposure to BTX were <1 for both children (0.094 µg/m³) and adults (0.38 µg/m³). The LCR of exposure to benzene among children (4.4 × 10⁻⁷) as well as adults (1.8 × 10⁻⁶) was lower than those stipulated by regulatory organizations.

Keywords:

• benzene
• toluene, and xylene
• carcinogenic and non-carcinogenic risks
• risk assessment

Acknowledgment

The authors would like to thank the South African Weather Service, the South African Air Quality Information System and the Environmental Management Services Department of the City of Tshwane for granting permission for and the release of the data used in this study.