Risk assessment before and after solar photocatalytic degradation of BTEX contaminated groundwater at a gas station site in Korea

Abstract

We assessed the incremental lifetime risks due to groundwater contamination with benzene, toluene, ethylbenzene, and xylene compounds (BTEX) for residents living on the site of a former gas station. Five remedial processes were applied to examine the degradation pattern of groundwater samples under similar weather conditions in winter: H2O2/solar light (action 1), immobilized TiO2/solar light (action 2), TiO2 slurry/solar light (action 3), immobilized TiO2/solar light/H2O2 (action 4), and TiO2 slurry/solar light/H2O2 (action 5). None of the remedial actions satisfied the criteria of acceptable risk (1 × 10−6 for carcinogens) using point estimation with both central tendency exposure (CTE) and reasonable maximum exposure (RME) for all pathways via designated exposure scenarios. Regarding the total hazard index (HI) for noncarcinogens, only action 5 satisfied all the exposure scenarios, both CTE and RME, for toluene, ethylbenzene, and xylene compounds, whereas the total health risk for benzene was between 10−5 and 10−6 for carcinogens. Results of probabilistic estimation before and after the treatment of benzene with action 5 using a Monte Carlo simulation were 68.1% for males (95% CI: 5.0 × 10−7 to 3.9 × 10−6) and 74.2% for females (95% CI: 5.0 × 10−7 to 4.6 × 10−6), exceeding the criteria of acceptable risk (10−6 for carcinogens). However, no adverse health risk was posed if remedial action 5 or an increased reaction time were applied. This study is a new attempt to integrate issues of groundwater contamination based on concentration and health risk assessment associated with different ex situ remedial actions. © 2008 American Institute of Chemical Engineers Environ Prog, 2008

Underestimated public health risks caused by overestimated VOC removal in wastewater treatment processes

“…18,20,25 The cancer risks were calculated by using the following two equations to determine the probability of an individual likely to acquire cancer due to his or her exposure to the VOCs during their lifetime. 6,26,27 Cancer risk ¼ LADD Â SF (1)…”

Comparative assessments of VOC emission rates and associated health risks from wastewater treatment processes

“…Cho et al assessed the incremental lifetime cancer risks due to groundwater contamination with benzene, toluene, ethylene, and xylenes for residents living on the site of a former gas station. 25 Studies focusing on concentration trends and the associated environmental risk assessment of atmospheric VOCs in specific areas or cities are available. [26][27][28] Besides the geographical characteristics, preceding studies have also assessed the possible health risks from exposure to selected VOCs emitted from different sources.…”

Trends of groundwater data from the Korean National Groundwater Monitoring Stations: indication of any change?

“…Beside Daegu city, very high EC values were also found in many metropolitan areas including Busan, Incheon and Seoul, which indicated extensive deep groundwater contamination in urban areas of the country (Baek and Lee, 2011). Frequently occurring contaminants in urban groundwater were BTEX (benzene, toluene, ethylene and xylenes), TCE (trichloroethylene), PCE (tetrachloroethene), and many inorganic materials (Chae et al, 2008;Cho et al, 2008). The high EC values in western coastal areas were partly attributed to enhanced seawater intrusion by heavy pumping (Park et al, 2005;Lee and Song, 2007).…”