Researchers Prove Link Between Arsenic In Rice and DNA Damage
Rice is a staple in diets around the world, but tests have recently detected alarming and worrisome levels of arsenic in hundreds of rice products ranging from infant cereals to rice cakes, rice pastas, rice drinks and rice itself. The Rice Industry says arsenic occurs naturally and concerns are unwarranted. However, researchers have now proven a causal link between high levels of arsenic and chromosomal damage.
The report looked into more than two hundred rice products found across the U.S. It discovered levels of arsenic that the report calls "worrisome", especially considering that arsenic is a known poison and Group 1 carcinogen. And many of those products are on the shelves.
Rice comes from all over the world and is grown very differently from region to region, which may greatly vary the levels of arsenic within the same kind of product.The most contaminated rice comes from Taiwan and China. Rice from the Czech Republic, Bhutan, Italy, India and Thailand also had potentially harmful levels.
Many people in parts of Asia have been poisoned by drinking groundwater laced with arsenic -- not introduced by humans, but leached naturally from sediments, and now being tapped by shallow drinking wells.
Despite the warnings and based on all the available data and scientific literature available, FDA still does not recommend that consumers change their consumption of rice and rice products at this time. The fact that the FDA has been monitoring arsenic levels in rice for more than 20 years should cause some red flags for consumers since their researchers will only measure whether current levels of arsenic represent toxic forms according to old and inaccurate data. The FDA actually has no established limit.
There is no safe level of arsenic, but, as of 2012, a limit of 10 parts per billion has been established in the United States for drinking water, twice the level of 5 parts per billion originally proposed by the EPA. Consumption of one serving of some varieties of rice gives more exposure to arsenic than consumption of 1 liter of water that contains 5 parts per billion arsenic; however, the amount of arsenic in rice varies widely with the greatest concentration in brown rice and rice grown on land formerly used to grow cotton.
Arsenic is released from volcanoes and from the erosion of mineral deposits. It is found throughout the environment--in water, air and soil, however human activities add enormous amount of arsenic to our natural environment through burning coal, oil, gasoline and wood, mining, and the use of arsenic compounds as pesticides, herbicides and wood preservatives.
The biotech industry is now pushing the envelope further on the need for genetically modified rice by highlighting recent evidence that rice imported from certain countries contains high levels of arsenic and lead that could pose health risks, particularly for infants and children, who are especially sensitive to lead's effects. Genetic Threat
University of Manchester scientists, working in collaboration with scientists at CSIR-Indian Institute of Chemical Biology in Kolkata, have proven a link between rice containing high levels of arsenic and chromosomal damage, as measured by micronuclei* in urothelial cells, in humans consuming rice as a staple.
The researchers discovered that people in rural West Bengal eating rice as a staple with greater than 0.2 mg/kg arsenic showed higher frequencies of micronuclei than those consuming rice with less than this concentration of arsenic.
The study, published in Nature Publishing Group's Scientific Reports, looked at the frequency of 'micronuclei' -- a tell-tale sign of chromosomal damage (that has been shown by others previously to be linked to cancer) by screening more than 400,000 individual cells extracted from urine samples from volunteers.
The team, funded by the UK India Education and Research Initiative (UKIERI), chose a study population with relatively similar dietary and socio-economic status that was not otherwise exposed to arsenic, for example, through drinking water.
They demonstrated that the trend of greater genetic damage with increasing arsenic in rice was observed for both men and women, for tobacco-users and non-users, and for those from three different locations within the study area. The pattern observed was broadly similar to that previously seen for people exposed to arsenic through drinking high arsenic well waters, which has caused devastating health impacts, including cancers, in many parts of the world.
The authors say their work raises considerable concerns about health impacts of consuming high arsenic rice as a staple, particularly by people with relatively poor nutritional status -- perhaps as many as a few hundred million people. How directly relevant the results are to people in the UK, with a generally lower consumption of rice and better nutritional status, remains to be fully determined but is an obvious focus for further research.
Professor David Polya, who led the Manchester team in the University's School of Earth, Atmospheric and Environmental Sciences, said: "Although concerns about arsenic in rice have been raised for some time now, to our knowledge, this is the first time a link between consumption of arsenic-bearing rice and genetic damage has been demonstrated. As such, it vindicates increasing concerns expressed by the European Food Safety Authority and others about the adequacy of regulation of arsenic in rice.
"In the absence of contamination, rice is an easily stored food that provides essential energy, vitamins and fibre to billions of people around the world, but a small proportion of rice contains arsenic at concentrations at which we have observed significant genetic damage in people who consume it as a staple food. We hope that our work will encourage efforts to introduce regulatory standards for arsenic in food, and particularly in rice, which are more consistent and protective of human health."
Dr Ashok K Giri, who led the Indian research team, added: "We can avoid high arsenic rice by taking proper mitigation strategies for rice cultivation; moreover, one CSIR institute in India has already identified a number of Indian rice varieties which accumulate lower concentrations of arsenic, so we can easily address future human health risks with proper mitigation strategies. Results of this study will not only help to understand the toxic effects caused by this human carcinogen but also these results will help the scientists and regulatory authorities to design further extensive research to set improved regulatory values for arsenic in rice, particularly for those billions of people who consume 10 to 50% rice in their daily diet."
* Most human cells have one nucleus which contains 46 human chromosomes but when any of these chromosomes are damaged, the part of the chromosome not able to participate in cell division typically remains as small 'micronuclei' in any daughter cells. Increased frequency of these micronuclei has been shown by other groups to be linked to the development of cancers.
Natasha Longo has a master's degree in nutrition and is a certified fitness and nutritional counselor. She has consulted on public health policy and procurement in Canada, Australia, Spain, Ireland, England and Germany.