Potential Environment and Public Health Risk Due to Contamination of Heavy Metals from Industrial Waste Water in Lam Thao, Phu Tho, Vietnam

Abstract

Problem statement: In Vietnam, rice cultivation plays an important role in national economic development and food security. However, rice production is facing many problems associated with rapid industrialization and urbanization in the country. Resultant emissions of solid and liquid wastes are often untreated and discharged directly to agricultural land. These practices have potential impacts on the environment and human health. Approach: The research was carried out within the frame of the collaborative research project "Towards the mitigation of environment and public health risks due to heavy metal contamination in irrigated rice-based systems of Vietnam" in 2006-2010. The study was implemented in the Lam Thao district, Phu Tho province with the aim to assess the effects of wastewater and other contamination sources on the environment and public health. Results: Surface water and soil in the field showed signs of significant contamination by wastewater from the industrial zones. Bio-indicators (DO, COD, BOD5) in the surface water were also strongly affected by waste. Paddy fields around the industrial zones had an elevated risk of heavy metal contamination (Cu, Zn, As, Cd and Pb), with concentrations exceeding Vietnamese Maximum Acceptable Concentrations (MACs) for Cu, Zn, Cd and Pb. Soil contamination with heavy metals was resulting in elevated concentrations in rice grain. Where consumption of locally-produced food was high, exposure of individuals to heavy metals could present a public health risk. The partial Hazard Quotient (HQ; a ratio derived from comparing estimated exposure to heavy metals, i.e., Cd, (with toxicologically-derived„ safe’ daily doses) for rice and vegetables (water spinach) and the integrated Hazard Quotient of rice and vegetables (HQi) was consistently greater in areas with soil contamination than in the reference area using Red River water for irrigation. The HQi for Cd was particularly high for children below the age of 13 and it was slightly higher for females than for males. While toxicologically-derived ‘safe’ daily doses are very conservative to account for inherent uncertainty in their derivation, this issue should be raised with famers and policy makers. Conclusion/Recommendations: Due to unrestricted discharge of industrial waste, the soil and water environment has been contaminated, which is demonstrated by accumulation of heavy metals in surface soils. This may in some circumstances pose a risk to public health. Policies should be developed that enable authorities to mitigate negative environmental impacts of industry and empowers communities to nurture a safer environment whilst maintaining the economic benefits of development.