Health risk assessment of arsenic from blended water in distribution systems

ABSTRACT

In a water distribution system with different sources, water blending occurs, causing specific variations of the arsenic level. This study was undertaken to investigate the concentration and cancer risk of arsenic in blended water in Xi'an city. A total of 672 tap water samples were collected from eight sampling points in the blending zones for arsenic determination. The risk was evaluated through oral ingestion and dermal absorption, separately for males and females, as well as with respect to seasons and blending zones. Although the arsenic concentrations always fulfilled the requirements of the World Health Organization (WHO) (≤10 μg L⁻¹), the total cancer risk value was higher than the general guidance risk value of 1.00 × 10⁻⁶. In the blending zone of the Qujiang and No.3 WTPs (Z2), the total cancer risk value was over 1.00 × 10⁻⁵, indicating that public health would be affected to some extent. More than 99% of the total cancer risk was from oral ingestion, and dermal absorption had a little contribution. With higher exposure duration and lower body weight, women had a higher cancer risk. In addition, due to several influential factors, the total cancer risk in the four blending zones reached the maximum in different seasons. The sensitivity analysis by the tornado chart proved that body weight, arsenic concentration and ingestion rate significantly contributed to cancer risk. This study suggests the regular monitoring of water blending zones for improving risk management.

KEYWORDS:

• Arsenic
• blended water
• cancer risk
• risk assessment
• water distribution system

Acknowledgments

The authors would like to thank the editors and reviewers for the valuable comments and suggestions.

Funding

This study was supported by the National Natural Science Foundation of China (No. 51508452), Teaching reform project of Xi'an University of Architecture and Technology (JG021510), and Research team on enhanced purification of drinking water and water quality assurance of Xi'an University of Architecture and Technology.