Linear-no-threshold concept for evaluating arsenic toxicity in rice grains

Area of Science:

• Environmental Science
• Toxicology
• Food Science

Background:

• Arsenic (As) is a major carcinogen entering the human diet through rice, a global staple.
• Rice cultivation areas are often contaminated with arsenic, posing a significant public health concern.

Purpose of the Study:

• To assess arsenic levels in rice grains from Mumbai/Navi-Mumbai.
• To evaluate the health risks associated with dietary arsenic intake from rice.
• To investigate the efficacy of traditional Indian cooking methods in reducing arsenic accumulation in rice.

Main Methods:

• Market survey of 500 rice grain samples from 41 locations.
• Categorization of rice samples based on arsenic accumulation (low, medium, high).
• Health risk assessment using hazard quotient and dietary intake estimations.
• Analysis of arsenic reduction using parboiling and absorption-based cooking.
• In vitro study on the effects of rice extracts on murine lymphocytes (ROS and GSH levels).

Main Results:

• A significant proportion of rice samples, even below the WHO permissible limit, indicated a health risk (Hazard Quotient > 1).
• Traditional Indian cooking methods (parboiling and absorption) reduced arsenic accumulation by approximately 0.4-fold.
• Kolam rice extracts induced oxidative stress (increased ROS, decreased GSH) in murine lymphocytes, suggesting redox imbalance.

Conclusions:

• Arsenic contamination in rice presents a health risk, necessitating careful evaluation.
• Traditional cooking methods are effective in mitigating arsenic exposure from rice.
• The linear-no-threshold model is recommended for assessing the safety of arsenic-contaminated rice for human consumption.