Hyderabad : Arsenic levels in rice raise health concerns
HYDERABAD: Concerns over pesticide residues in food have been growing, but a World Health Organization (WHO) report has now flagged the presence of arsenic in food items including rice and fish. It found elevated arsenic levels particularly in rice, a staple consumed widely in India.
Long-term exposure to high levels of arsenic could increase the risk of health problems affecting the heart, kidneys, skin and lungs, the report said.
Rice emerges as major source of arsenic exposure
The Joint FAO/WHO Expert Committee on Food Additives (JECFA) studied toxic contaminants in food, including rice, across several countries, including India. Kolkata was selected for the study in India.
The study found arsenic in several food items, including rice, fish and vegetables. While arsenic contamination has largely been associated with water, the study found that the contaminant also enters paddy cultivated using such water.
Paddy plants remain in standing water for long periods and absorb arsenic from it. The contaminant consequently enters the rice grain and eventually the food consumed by people.
The report warned that exposure to high levels of arsenic could increase the risk of heart and kidney diseases and serious lung-related illnesses. Researchers also identified an association with skin diseases, including skin cancer, and gangrene.
Exposure exceeds identified risk benchmark
According to the report, exposure to inorganic arsenic at 0.3 micrograms per kg of body weight per day is associated with a benchmark corresponding to a 0.5% increase in the incidence of heart disease. At exposure of one microgram, the risk of lung cancer is higher, it said.
Rice contains an average of 100 to 112 micrograms of arsenic per kg, while the corresponding average in India is 92 to 94 micrograms per kg, according to the report.
Even in areas without significant contamination, children consume between 0.05 and 0.8 micrograms of inorganic arsenic per kg of body weight per day, while exposure among adults ranges from 0.1 to 0.55 micrograms.
The report said the upper end of this exposure range exceeds the 0.3-microgram benchmark identified by JECFA.
In areas where water is contaminated with arsenic, exposure can be 2.5 to 175 times higher, it said.
Rice accounts for between 30% and 70% of exposure to inorganic arsenic, the more hazardous form of the contaminant. In areas where groundwater contains 10 micrograms of arsenic, water can account for 80% to 90% of the risk, according to the report.
Arsenic residues have particularly been detected in crops cultivated in the Ganga basin and in areas irrigated by polluted rivers.
In West Bengal, adults consume an estimated 1.06 micrograms of arsenic per kg of body weight, while exposure among children is higher at 1.27 micrograms per kg of body weight, the report said.
The report does not specifically mention Telangana. However, the source report notes that paddy is extensively cultivated in the state and says crops grown in the Musi catchment could also face a risk of contamination.
Cooking and farming practices can cut arsenic exposure
WHO has suggested measures to reduce arsenic exposure, including changes in the way rice is cooked.
Rice should be washed thoroughly two or three times before cooking. The practice of draining excess cooking water, or ganji, has declined as more people use pressure cookers. Draining the water after cooking can reduce arsenic exposure by 50% to 70%, according to the source report.
Arsenic levels are higher in rice bran, and polishing can therefore reduce exposure to some extent. However, polishing also removes nutrients. The report suggests using a method called hot-water percolation to address this issue.
Changes in farming practices can also reduce arsenic accumulation in rice. Paddy fields should not remain continuously flooded and farmers can instead follow the alternate wetting and drying method. The practice can reduce arsenic levels in rice by up to 50%, according to the source report.
The use of silicon fertilisers can also help prevent paddy plants from absorbing arsenic.
