Rice is the staple food of over three billion people. The rice plant is highly efficient at absorbing arsenic from soil and water, it is reported to be the highest arsenic-containing cereal. For Bangladeshi’s, rice is their staple food and they consume on average half a kilogramme of rice per day.
A team of scientists led by Dr Parvez Haris from DeMontfort University, Leicester, UK is carrying out research to identify ways of reducing human exposure to arsenic through diet.
Haris and his team have already demonstrated that exposure to the more toxic inorganic arsenic species is greater in people who eat more rice. In this latest work, published in Biomedical Spectroscopy and Imaging, the DeMontfort University team – along with Dr Michael Watts from the British Geological Survey, Keyworth, Nottingham, UK – has identified varieties that are low in arsenic but high in essential trace elements such as selenium and zinc.
Earlier studies showed high concentrations of arsenic in Bangladeshi rice, but the rice samples were mainly regions where the irrigation water contains higher levels of arsenic. The team carried out a detailed study on rice from the greater Sylhet region in the north-east of Bangladesh, which generally has a lower groundwater arsenic concentration. The team analysed 98 rice samples using a technique called Inductively Couple Plasma – Mass Spectromtetry (ICP-MS) to determine total arsenic and also arsenic species in a selected group of samples.
The results showed Sylheti rice to have a far lower arsenic concentration than similar types of rice form other regions of Bangladesh. Results also showed that the arsenic concentration in aromatic rice was 40% less than non-aromatic varieties and that it also contained higher concentrations of the essential elements selenium and zinc. This is very good news for millions of Bangladeshis who are exposed to high concentrations of arsenic through drinking water and rice and are also deficient in zinc and selenium. Several varieties of Sylheti aromatic rice even had lower arsenic than the well known Basmati aromatic rice from India and Pakistan.
For someone consuming 500 grams of non-aromatic or aromatic rice from Sylhet, the daily intake of arsenic from rice would be approximately 48% and 69% lower, respectively, compared with consuming no-aromatic rie from other parts of Bangladesh. Bangladeshis are proud of their diet and often refer to themselves as ‘mache bhathe Bangali’ which can be roughly translated as ‘fish and rice makes a Bengali’. The identification of rice with very low arsenic concentrations and higher concentrations of essential elements is good news for the Bangladeshis and other communities where rice is a staple food but it is important ot encourage a more diversified diet that is less dependent on rice.
Aromatic rice is generally cultivated during the wet (aman) season and therefore is less dependent on the use of groundwater for irrigation. It also requires less fertilizer and pesticides. Although the yield of aromatic rice is lower, the farmers will not need to spend much money on applying chemicals that could pollute the environment and harm their own health. Furthermore, energy costs (electricity or diesel) will be lower as there will be less need for them to pump groundwater for irrigation.
The impact of this finding may also have health implications for other groups of people who eat large quantities of rice daily. This type of rice could also be used in infant foods in stead of rice with higher arsenic concentrations. It could also benefit people suffering from celiac disease who consume rice-based foods on a regular basis. Therefore, it is essential that further research on aromatic rice from different parts of Bangladesh and other regions of the world are conducted.
Dr Parvez Haris, DeMontfort University
Shaban W. Al-Rmalli, Richard O. Jenkins, Michael J Watts, Parvez I. Haris, 2012. Reducing human exposure to arsenic and simultaneously increasing selenium and zinc intake, by substituting non-aromatic rice with aromatic rice in the diet. Watts and Parvez I. Haris. Biomedical Spectroscopy and Imaging Volume 1 / Issue 5. DOI: 1010.3233/BSI-120028.
Full text of the article has been made freely available at http://iospress.metapress.com/content/r81n381j34421481/fulltext.pdf