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Problem statement: In Vietnam, rice cultivation plays an important ro le in national economic development and food security. However, rice production is facing many problems associated with rapid industrialization and urbaniz ation in the country. Resultant emissions of solid and liquid wastes are often untreated and discharge d directly to agricultural land. These practices ha ve potential impacts on the environment and human health. Approach: The research was carried out within the frame of the collaborative research proj ect "Towards the mitigation of environment and public health risks due to heavy metal contaminatio n 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 contamin ation sources on the environment and public health. Results: Surface water and soil in the field showed signs o f 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 industri al zones had an elevated risk of heavy metal contamination (Cu, Zn, As, Cd and Pb), with concent rations 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 estima ted exposure to heavy metals, i.e., Cd, (with toxicologically-derived" safe' daily doses) for ric e and vegetables (water spinach) and the integrated Hazard Quotient of rice and vegetables (HQi) was co nsistently greater in areas with soil contamination than in the reference area using Red River water fo r irrigation. The HQi for Cd was particularly high for children below the age of 13 and it was slightl y higher for females than for males. While toxicologically-derived 'safe' daily doses are very conservative to account for inherent uncertain ty 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 t o public health. Policies should be developed that enable authorities to mitigate negative environment al impacts of industry and empowers communities to nurture a safer environment whilst maintaining the economic benefits of development. |
