Arsenic contamination in polished and unpolished paddy rice: A study of geographical variation and health risk assessment in Cambodia

Abstract

The survey data from the study area provide valuable insights into respondents’ lifestyles, livelihoods, and farming practices, enabling a more comprehensive assessment of arsenic contamination in rice across different regions. A total of 155 participants were surveyed, including 79 from Kandal and 76 from Kampot. Respondents ranged in age from 18 to 65 years. Among them, 36.8% had completed only elementary education, 83.9% cultivated rice themselves, and 42% had a daily income of less than five dollars. Additionally, 56.1% consumed at least three meals of rice per day, 61.3% used tap water for cooking rice, 69.0% did not smoke cigarettes, and 69.7% had lived in the area for over 30 years. In Kandal province, a well-developed irrigation system is in place, with 63.29% (n = 50) of respondents regularly using groundwater for rice cultivation. In contrast, Kampot province relies primarily on rainwater, with 82.89% (n = 65) of respondents depending on this source. Farmers in both provinces frequently use agrochemicals. In Kandal, all respondents (100%, n = 79) reported applying pesticides, up to eight times per cropping cycle, while 51.89% (n = 41) applied herbicides at least three times per cycle. Additional agrochemical products were also used to support rice production. Arsenic is widespread in the environment and poses serious health risks, particularly through rice, which can accumulate arsenic up to 10 times that of other cereal crops under flooded growing conditions. As rice is the main staple food in Cambodia, this study assessed arsenic contamination in 110 polished and 100 unpolished rice samples collected from Kandal, Kampot, and Kep provinces. Total arsenic (tAs) was measured using acid digestion and inductively coupled plasma mass spectrometry (ICP-MS). Arsenic concentrations in polished rice ranged from 0.11 to 0.55 mg/kg, and in unpolished rice from 0.09 to 0.89 mg/kg. FAO/WHO limits were exceeded in many samples, especially in Kandal. Polished rice exceedances: 60% (Kandal), 15% (Kampot), 50% (Kep); unpolished: 45%, 5.6%, and 8.3%, respectively. Additionally, the Sen Kro Ob cultivar in Kandal and the Phka Rumduol and Phka Mlis cultivars from Kampot and Kep had the highest arsenic levels. Health risk assessments indicated elevated risks: chronic daily intake (CDI) exceeded the threshold of reference dose (RfD) (3.0E-04 mg/kg/day) which arsenic exposure may increase risks of hyperpigmentation, keratosis, and potential vascular complications; the hazard quotient (HQ) was above 1; and the incremental lifetime MS/EN 20231199 HEOM Phal (험 팔). Arsenic contamination in polished and unpolished paddy rice: A study of geographical variation and health risk assessment in Cambodia (캄보디아에서 생산된 쌀에 축적된 비소 모니터링과 이의 위해성 평가). College of Engineering. Department of Environment and Energy Engineering. 2026. 97p. Advisor Prof. Eunsuk Kim. cancer risk (ILCR) surpassed 1.0E-04 for both polished and unpolished rice. These findings highlight exposure risks associated with geography, rice types, rice cultivars, and farming methods. To reduce health risks, residents should prefer polished rice, while ongoing monitoring and education remain essential to mitigate arsenic’s long-term effects.