Arsenic in rice: state of knowledge and perceptions in Cambodia

As a strategy to reduce risk associated with seasonal drought and enhance cropping intensity, farmers in the Lower Mekong and Bassac River basins of Cambodia have resorted to exploiting groundwater resources through shallow tube wells. This approach offers distinct advantages over poorly designed surface-based irrigation systems that were constructed during the Pol Pot era in Cambodia in the 1970s.

While farmers’ access to groundwater resources allows for individual approaches to on-farm water management and greater flexibility, it does hold potential risks in the Lower Mekong basin due to the presence of naturally occurring pockets of arsenic-bearing ground water which can have extremely elevated levels of up to and over 500 micrograms (μg) per litre, which pose a threat to human health.

The Cambodian government has been promoting the intensification of rice farming through an additional crop in the dry season, and Cambodian rice farmers are increasingly accessing groundwater to fully irrigate paddy. Under these flooded anoxic conditions, underground arsenic deposits in the form of arsenite (As^III) become increasing available and are readily taken up by rice plants, thereby entering the food chain. This has health implications for households regularly consuming contaminated rice over extended periods.

While the impacts of arsenic on human health, including cancer and skin lesions, became evident in the early 2000s as Cambodians turned to groundwater as a source of cleaner drinking water, the potential impact of arsenic entering the human food chain through the consumption of rice grain in Cambodia has only recently been considered.

The paper explores two research questions:

1. How do different stakeholders understand and perceive the issue of arsenic in rice, in terms of public health, potential mitigation measures, and policy?
2. What are the major knowledge gaps regarding rice in arsenic that would affect policy-making?

It outlines the state of academic knowledge on arsenic in rice, and reviews stakeholder perceptions of arsenic in Cambodia based on key informant interviews and a roundtable on public health and mitigation measures.