Why does rice contain arsenic?

British scientists have identified the best method for cooking rice to reduce the concentration of arsenic in the finished product. Thus, cooking rice for five minutes in boiling water and then replacing it with clean cold water can reduce the concentration of the substance by 54 percent in brown rice and by 73 percent in white rice compared to the dry product. An article describing the method was published in the journal Science of the Total Environment. Deep groundwater contains large quantities of arsenic, which is toxic to the human body—therefore, residents of regions that use groundwater for water supply and crop irrigation are at high risk of poisoning. You can be poisoned by arsenic not directly through water, but indirectly, for example, through the consumption of cereals, among which rice can be especially dangerous: according to researchers, it absorbs ten times more arsenic than other crops. The risk of arsenic poisoning from rice can be reduced by thoroughly washing it, but this may not be enough – so Manoj Menon from the University of Sheffield and his colleagues set out to find the most effective method of cooking rice that would minimize the concentration of arsenic in the finished product. The scientists took several eight-gram samples of brown and white rice and boiled them in deionized water in a standard ratio of 1:4. In total, the researchers tested four cooking methods: in cold water without prior rinsing, with rinsing, with soaking the rice for half an hour before cooking, and with changing the water during the cooking process. When using the latter method, the rice was thrown into boiling water, drained after five to five minutes of cooking and replaced with cold deionized water – and then cooked in the standard way until tender. After cooking, all the rice was cooled to 60 degrees Celsius and placed in an oven with a temperature of 50 degrees for two days to dry. The dried rice was ground into flour, mixed with nitric acid and diluted with clean water to obtain 20 and 50 milliliters of solution. The first was used to analyze the content of phosphorus, potassium, magnesium, zinc and manganese in rice, the second was used to analyze the content of arsenic: organic (dimethylarsinic and methylarsinic acids) and inorganic (arsenates and arsenites) forms. In both cases, the inductively coupled plasma mass spectrometry method was used. For comparison, the analysis was also carried out on dry, uncooked rice. The latter cooking method—draining the boiling water and replacing it with clean water—proved to be the most effective: Compared to the dry product, rice cooked this way had 54 percent and 73 percent less arsenic for brown and white rice, respectively. Other cooking methods also reduced arsenic concentrations, but not significantly for brown rice: given that most arsenic is contained in rice husks, from which brown rice is not purified, proper cooking is especially necessary for it. As for the other elements considered, in brown rice they remained in higher concentrations after any cooking method than in white rice, although magnesium disappeared from both brown and white rice after cooking, but in both rice in full zinc was retained in the volume. However, this did not depend on the cooking method. Based on the permissible levels of arsenic for adult men and women, as well as children aged seven and one year, the scientists also calculated the maximum amount of brown and white rice that can be eaten without harm to health, depending on the cooking method. So, the bottom line is that a one-year-old child can eat 15 grams of white and 11 grams of brown rice per kilogram of body weight per day; if the rice is cooked using the proposed method, then the child will be able to eat 57 grams of white and 23 grams of brown rice per day (also in dry matter). So, to reduce the risk of arsenic poisoning, scientists recommend preparing rice as follows: boil four glasses of water for one glass of rice, add rice to boiling water, cook for another five minutes, then drain the water, add two more glasses of cold water for one glass of rice and cook over medium heat until tender (until all the water is absorbed). In the future, the researchers plan to test this cooking method on different varieties and types of rice, as well as using water of different qualities. Rice and other grains make up a significant part of the Japanese diet: as Japanese scientists found out several years ago, following it can even help prolong life. Elizaveta Ivtushok
Found a typo? Select a fragment and press Ctrl+Enter.
Warming has reduced mammal diversity in Canadian and US cities
Scientists soon predicted the same thing for cities in the tropics Warming is exacerbating the loss of biodiversity caused by urbanization. Scientists came to these conclusions after studying the diversity of mammals in 20 cities in the USA and Canada. They noted that this could be a marker of a new biodiversity crisis in the tropics, where urbanization is now increasing in hot climates. The results of their research were published in the journal Nature Ecology & Evolution. Cities are challenging sites for biodiversity research. The habitat within any urbanized area is variable and heterogeneous due to the complex landscape, the nature of the development and the characteristics of the urban climate, such as the presence of an urban heat island. Among animals in cities, the diversity of birds is best studied (due to the ease of observing them), and the diversity of mammals is the worst studied, because in urban conditions they tend to lead a secretive lifestyle. Scientists led by Jeffrey Haight from the University of Arizona assessed the diversity and abundance of mammals living in urbanized areas of North America. To do this, they used images from 725 camera traps installed in 20 cities in the United States and Canada and operating there from 336 to 2531 days. In total, 37 species of mammals were recorded, including black bears, chipmunks, skunks, mountain beavers, cougars and white-tailed deer. The authors of the study concluded that warming, suppression of vegetation cover and sealing of the surface are depriving mammals of suitable habitat. Contrary to the popular belief that warmer regions have higher biodiversity, the continent’s hot cities have lower diversity. Indicators characterizing biodiversity (total number of species, Shannon index, and others) also turned out to be negatively associated with sparse vegetation and urbanization—the average percentage of impervious (i.e., paved) surface in areas. Large mammals were most affected by these factors. The authors noted that urbanization in the world is now growing mainly in low latitudes in warm climates, and judging by the results of the study, this may mean a new round of the biodiversity crisis in tropical regions. Previously, zoologists discovered that due to global warming, viviparous lizards began to age even before birth: heat stress shortens the telomeres of their females, which reduces survival and ultimately leads to the extinction of entire populations.

© 2024 N + 1 Online publication / Certificate of registration of mass media El No. FS77-67614

The use of all text materials without modification for non-commercial purposes is permitted with reference to N + 1. All audiovisual works are the property of their authors and copyright holders and are used only for educational and informational purposes. If you are the owner of a particular work and do not agree with its placement on our website, please write to [email protected] The site mojet soderjat content, ne prednaznachennyy dlya lits mladshe 18 let. Scientists from the University of Manchester (UK) announced a connection between rice consumption and the risk of developing cardiovascular diseases. According to scientists, this risk is higher in those who consume rice in large quantities and for a long time. A study published in the journal Science of the Total Environment found a link between rice consumption in England and Wales and cardiovascular disease caused by arsenic exposure. The findings show that the 25% of people in England and Wales who eat the most rice are at greater risk of cardiovascular mortality, compared with the 25% of those who eat the least. Researchers also note that long-term exposure to arsenic increases the risk of other dangerous diseases, including cancer. FAQ As scientists have found, over the past few years, the concentration of arsenic in the soil and water of regions where rice is grown has increased significantly. Experts suggest that arsenic in rice may be responsible for more than 50 premature deaths annually. Despite a number of useful substances, scientists advise consuming this product in moderation and eating a varied diet.

How does arsenic get into rice?

Arsenic enters the human body in large quantities mainly through the consumption of drinking water obtained from groundwater with a high natural level of inorganic arsenic, consumption of food prepared with such water, as well as through agricultural crops irrigated with water containing arsenic. significant concentration. According to the researchers, arsenic penetrates rice grains from the soil, from where it is absorbed by the roots of the plant. The arsenic content in rice also depends on the area where the crop is grown. The greatest threat to human health is arsenic contained in groundwater. According to the World Health Organization (WHO), at least 140 million people in 50 countries drink water with arsenic concentrations above the WHO recommended level of 10 micrograms/liter. Inorganic arsenic is present in high concentrations in groundwater in a number of countries, including Argentina, Bangladesh, India, China, Mexico, the United States of America and Chile. Related Article As stated in a report from the Consumer Union of the United States, all products that contain rice also contain arsenic. Brown rice contains more of it than white rice, and concentrated forms of brown rice – flour, rice syrup and similar products – have the highest levels of the dangerous substance. From groundwater, rice can accumulate not only arsenic, but also various metals, including copper, lead, zinc, iron, manganese and silicon dioxide.

How does arsenic affect the human body?

Arsenic can lead to cancer and cardiovascular diseases. In China, it is believed that arsenic-induced myocardial infarction, in particular, may be the cause of so-called “black leg disease,” which is a severe blood vessel disease that leads to gangrene. Scientists have also shown that arsenic can cause chromosome damage in humans. In addition, with long-term exposure to high concentrations of inorganic arsenic (for example, through drinking water or food), people may develop skin lesions and hardening of the skin on the palms and soles (hyperkeratosis). The WHO advisory states that these symptoms appear after exposure for at least five years and may be a warning sign of skin cancer. Related Article In addition to skin cancer, long-term exposure to this inorganic chemical may also cause bladder and lung cancers, as well as adverse pregnancy outcomes and infant mortality. Doctors note that exposure to arsenic during fetal development and early life leads to an increase in mortality among young people caused by various types of cancer, lung diseases, heart attacks and kidney failure. Arsenic also has a negative impact on mental development, intelligence and memory.

How can you reduce arsenic in rice?

The arsenic content in rice can be reduced by 30-50% if you first wash the grain and then cook it in a large amount of water (similar to how beans are cooked: for 1 part rice you need to take 6 parts water). The remaining water after cooking should be drained. Another way to reduce arsenic in rice is to thoroughly rinse the grains before cooking. Experts also recommend soaking rice for 48 hours before cooking to reduce arsenic levels. During soaking, the water should be drained and the grains washed every 8-12 hours.