Arsenic in water and rice, a silent killer

Arsenic, a dangerous chemical element, poses a serious threat to public health. Its absorption leads to poisoning and can cause cancer. Scientists alert that more than 30 percent of the of the world’s population live in areas where arsenic concentrations in drinking water exceed acceptable standards set by the World Health Organization (WHO). Particularly affected regions such as China, Bangladesh and Pakistan, where rice is a dietary staple, face the challenge of ensuring food and water safety for their citizens. This begs the question: why is arsenic so dangerous to health?

Poisonous rice?

Rice contains phosphorus, magnesium and B vitamins, so it is classified as the grain most easily absorbed by the human body. However, as it turns out, consuming it can have serious health consequences, because compared to other cereals, it contains more inorganic arsenic compounds (iAs), which are more toxic than organic compounds. The risk of poisoning increases when rice cooked in water containing iAs at levels above 10 µg L ^-1 is consumed.

A study by researchers from the Institute for Sustainable Food and the Department of Geography at the University of Sheffield has proven that some countries’ failure to comply with current WHO limits poses a threat to some 32 percent of the world’s food supply. world population.

Lack of restrictive regulations on arsenic concentrations in Asia and Africa

Manoj Menon, head of research on the presence of arsenic, stated: “Rice and drinking water in the UK are subject to regulations on the presence of arsenic, but in Asia and Africa these regulations are rarely followed (…) As many as 40 countries allow more than 10 µg of L ^-1 arsenic in drinking water, and in 19 WHO standards do not exist at all.” Dr. Menon added, “The UN aims to ensure that every person has access to clean water and sanitation, without which it is impossible to live healthily. It is therefore necessary to implement arsenic standards in countries where such limits do not operate.”

India as an example for other countries in Asia and Africa

India is facing the problem of elevated arsenic concentrations, which is why it adopted a concentration standard of 10 µg L ^-1 a few years ago and is striving to maintain it, setting a good example for other countries that are not yet in compliance with this limit. The likelihood of poisoning increases in proportion to the amount of grain consumed. As Dr. Menon said, “In the study, we assessed the probability of poisoning the population of Bangladesh, where each resident consumes approx. 170 kg of rice per year. We found that almost all age groups are at serious risk of arsenic poisoning.”

The best method for cooking rice has been discovered

The effects of two cooking methods on arsenic and nutritional elements in white, parboiled and brown rice were investigated. As-safe tap water (0.18 μg L ^-1) and enriched iAs (10 or 50 μg L ^-1) were used. Exposure risk was calculated using the margin (MOE) for countries with low (UK) and high (Bangladesh) per capita rice consumption. Micronutrient and macronutrient content was measured by ICP-MS (inductively coupled plasma mass spectrometry). Liquid chromatography-ICP-MS (LC-ICP-MS) was used to quantify arsenic concentrations.

The EW (boiling with excess water at a rice-to-water ratio of 1:6-12) and PBA (steamed and absorbed method at a rice-to-water ratio of 1:4) methods have similar potential for effective removal of iAs (54-58 percent) contained in white and brown rice. It should be noted that EW (∼50 percent) eliminated this harmful element from the steamed grain better than PBA (∼39 percent). The study further showed that brown rice, when cooked in iAs-enriched water, contained more nutrients and fewer iAs than other types of this cereal. The risk assessment showed that cooking rice with 50 μg L ^-1 increases the probability of As poisoning in the Bangladeshi population due to the high per capita rice consumption rate.

What can be done to reduce the risk of arsenic poisoning?

The PBA method is not recommended for As-contaminated water. Risk assessment by MOE indicates that cooking rice in water with 10 μg L ^-1 iAs increases the probability of poisoning adults and children in Bangladesh due to high per capita rice consumption. To achieve the UN Sustainable Development Goals of “good health and well-being” and “clean water and sanitation,” WHO limits must be implemented in countries where arsenic concentrations are not controlled.