Arsenic in rice: Playing God

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by Upali Samarajeewa

(June 24, Colombo, Sri Lanka Guardian) Statements made by a group of scientists from universities have provoked much debate, arguments and concerns among the public, as well as responsible groups of scientists, private sector commercial organizations and concerned politicians. It is the expected norm among the scientists, and in the culture of science, to verify the validity of such statements themselves, before releasing their findings into the public domain. The objective of article is to bring to the attention of concerned, the issues that should be carefully examined before making or accepting such statements.

Presence of arsenic in organic and inorganic forms in soil and water is a common feature in many part of the world, both in developed and developing countries. Arsenic is absorbed from water into plants including rice, and may get concentrated in rice. From a regulatory point of view tolerance limits of arsenic for rice is not well documented. There are no limits of tolerance established specifically for arsenic in the US, the UK or in the EU countries due to well known scientific reasons, although they have common limits for a variety of toxic metals in food. China has established a limit of 0.15 parts per million (ppm = micrograms/gram or mg/kg) for rice. Studies done in the US have shown presence of arsenic at average concentrations of 0.3 ppm in samples from certain locations. Other studies have shown concentrations of similar range for rice elsewhere. According to the information released to the press by the scientists who claim presence of arsenic in Sri Lankan rice, they have detected concentrations of 0.1 ppm. According to the information released by ITI concentrations of 0.334, 0.166 and 0.370 have been reported for 3 out of 28 samples tested and the Agriculture Department has indicated that those breed lines reported by ITI to be high, would be withdrawn. While these findings indicate presence of arsenic, the detected concentrations need not be used to create a public alarm, rather than addressing at the forum of scientists to bring in necessary controls, if required.

Concentrations of arsenic in food, and for that matter any toxic trace metal, would never be uniformly distributed. In such a situations what matters are the distribution patterns of arsenic, meaning how many samples out of a few hundred tested show unacceptable levels (at least using the Chinese standard). This brings in two very important questions which the responsible scientists should answer. How many samples of rice have they examined and what was the distribution of arsenic on the basis of concentrations and in relation to types of rice and locations of cultivation before sensitizing the population of the country? If alarm was raised without adequate data, the scientists concerned cannot be forgiven. It is their primary duty to release the results for the benefit of science and country. The second most important issue is the method they used for testing. There are very specific test methods designed and accepted by the global scientific community after long periods of validation studies for each of toxic trace metals including arsenic. Apparently, the scientists responsible for the statement at issue have not divulged the test methods; they have only said that it is a new method. The very fact that it is a new method makes it incumbent upon the scientists to indicate whether they have carried out validation studies for the method and what the results of the validation experiments are before going public. When a new method is developed it is the primary responsibility of the scientists to present the method to the scientific community for peer evaluation. There are enough opportunities in Sri Lanka for the scientists to present their observations at annual sessions like that of the Sri Lanka Association for the Advancement of Science, Institute of Chemistry, Ceylon etc. or published in recognized journals locally or abroad, so that their scientific contributions become refined and acceptable. Newspapers are not the vehicle through which to publicise highly sophisticated and socially sensitive findings before they are accepted by scientific community. (It must be mentioned here that a similar finding by an eminent Sri Lankan scientist was published in the internationally recognized journal, Nature, and the scientists who tried to apply the method found that it was flawed. The designer of the method had to humbly accept his error, preventing scientific and global community moving in the wrong direction!) This I believe, is the very reason why Sri Lanka gives special awards to scientists and special allowance to those practising science properly at the national level. Science has always developed on sound thinking, logical arguments and interactive discussions, but not on divine revelations.

With sophistication of analytical methods in science, analysts detect potentially hazardous substances present at extremely low concentrations in foods, hitherto undetected by conventional methods, though such concentrations never posed threats to human life in the past. Thus governments had to change the guidelines and regulations addressing food safety in developed countries, especially the US. Today, the whole world is viewing the presence of potentially hazardous substances from an angle of risk assessment and risk management. In Pakistan, where arsenic concentrations are high in surface water, special filters made of clay and packed with charcoal are made available for household use in an effort to manage the risk. Decisions based on analytical reports coming from nowhere, without basic background information is a thing of the past. In our alleged case of arsenic, we need to establish the concentrations in all types of rice and in relations to the locations of cultivation. I urge the scientists to do so early. Then it is the duty of the medical scientists to find whether there are any signs of diseases related to arsenic in the population to consider it a risk. In Bangladesh, where the incidence of arsenic in rice is high, diseases of the lung, bladder and skin have been established as the resulting effects. Our effort to link arsenic with kidney disease prevalent in North Central Province, which is a completely a different kettle of fish, could only be considered an effort to join the bandwagon rather than to come out with a valid scientific theory supported by sound scientific findings. Similar statements linking the problem in North Central Province to presence of toxic trace metal, cadmium, appeared in the press sometimes back, based on incorrect and unscientific estimations. It is the job of the toxicologists to link a disease with a hazardous substance.

It is time the scientists who made the claims on arsenic revisited their test methods through scientific validation studies and re-examined the samples expanding it to an acceptable number of samples.

Leaving science out for a minute, the questions raised by the ordinary public are: "We all eat rice in Sri Lanka, which is supposed to be contaminated with arsenic and how come only the people in the North Central Province have been affected by arsenic? What will be the fate of our cattle eating the paddy straw?" Should we stop drinking local milk too?

The author of this article is former Senior Professor in Food Science & Technology at University of Peradeniya, and currently an International Expert in Laboratory Accreditation addressing the food safety issues associated with global trade. He could be contacted at smrjee@yahoo.com