Human health risk assessment for exposure to BTEXN in an urban aquifer using deterministic and probabilistic methods: A case study of Chennai city, India

Bokam Rajasekhar; Indumathi M Nambi; Suresh Kumar Govindarajan

doi:10.1016/j.envpol.2020.114814

Human health risk assessment for exposure to BTEXN in an urban aquifer using deterministic and probabilistic methods: A case study of Chennai city, India

Environ Pollut. 2020 Oct;265(Pt B):114814. doi: 10.1016/j.envpol.2020.114814. Epub 2020 May 15.

Authors

Bokam Rajasekhar¹, Indumathi M Nambi², Suresh Kumar Govindarajan³

Affiliations

¹ Environmental and Water Resources Engineering, Department of Civil Engineering, Indian Institute of Technology Madras, 600036, India.
² Environmental and Water Resources Engineering, Department of Civil Engineering, Indian Institute of Technology Madras, 600036, India. Electronic address: indunambi@iitm.ac.in.
³ Reservoir Simulation Laboratory, Petroleum Engineering Programme, Department of Ocean Engineering, Indian Institute of Technology Madras, 600036, India.

PMID: 32505959
DOI: 10.1016/j.envpol.2020.114814

Abstract

The aquifer in Tondiarpet, Chennai, had been severely contaminated with petroleum fuels due to an underground pipeline leakage. Groundwater samples were analyzed quarterly for priority pollutants such as benzene, toluene, ethylbenzene, xylenes, and naphthalene (BTEXN) using purge and trap gas chromatography and mass spectrometer from 2016 to 2018. The maximum concentrations of BTEXN in groundwater at the site were found to be greater than the permissible limits significantly. Among the five sampling locations (MW1, MW2, MW3, MW4, and MW5), mean BTEXN levels were found to be higher near MW2, confirming the source location of petroleum leakage. Human health risk assessment was carried out using deterministic and probabilistic methods for exposure to BTEXN by oral and dermal exposure pathways. Risk analysis indicated that mean cancer and non-cancer risks were many times higher than the allowable limits of 1E-06 and 1 respectively in all age groups (children, teens, and adults), implying the adverse health effects. Oral exposure is predominately contributing (60-80%) to the total health risk in comparison to the dermal exposure route. Variability and uncertainty were addressed using the Monte Carlo simulations and the resultant minimum, maximum, 5th, 95th^, and mean percentile risks were predicted. Under the random exposure conditions to BTEXN, it was estimated that the risk would become unacceptable for >98.7% of the exposed population. Based on the sensitivity analysis, exposure duration, and ingestion rate are the crucial variables contributing significantly to the health risk. As part of the risk management, preliminary remediation goals for the study site were estimated, which require >99% removal of the BTEXN contamination for risk-free exposures. It is suggested that the residents of Tondiarpet shouldn't utilize the contaminated groundwater mainly for oral ingestion to lower the cancer incidence related to exposure to BTEXN.

Keywords: BTEX; Groundwater; Monte Carlo simulations; Petroleum spill; Probabilistic health risk assessment.

MeSH terms

Adolescent
Adult
Benzene
Benzene Derivatives
Child
Cities
Groundwater*
Humans
India
Risk Assessment
Toluene
Water Pollutants, Chemical / analysis*
Xylenes

Substances

Benzene Derivatives
Water Pollutants, Chemical
Xylenes
Toluene
Benzene