By Dilrukshi Handunnetti
A recent study by an international group of scientists has included among its most startling disclosures that rice samples from Sri Lanka and Bangladesh contained the dreaded toxic metal, cadmium. The 12-nation study yielded that Sri Lanka only came second to Bangladesh in the level of toxicity. Other countries surveyed include parts of Cambodia – a massive rice producing country, two European nations – France and Italy, the United States, Spain, Ghana in West Africa, two Asian countries – Japan and Thailand, and four South Asian countries – India, Nepal, Bangladesh and Sri Lanka. These toxic revelations were published online by Environmental Science and Technology magazine of the American Chemical Society on 13 May 2013.
Cadmium contamination In this large-scale survey that focused on possible cadmium contamination in rice in the 12 countries of study, samples were gathered from 12 districts in Bangladesh, representing one fourth of the country. The Sri Lankan samples were gathered from Padaviya, Medawachchiya, Kebitigollewa, Rambewa, Sripura and Parakramapura in the North Western Province where CKDue records a high prevalence. Additional samples were from selected areas in Kamburupitiya in the Matara District, and Ambalantota and Daragama in the Hambantota District which were tested for both cadmium and arsenic.
The samples showed lower levels of cadmium when compared with the Bangladeshi samples, but supported the view that it could be one of the main causes for the high prevalence of Chronic Kidney Disease of Uncertain Etiology (CKDue) that plagues the North Central Province at present and has begun to spread to three other provinces, according to the World Health Organization (WHO). The abstract available online reads: "From a survey of 12 countries on four continents, cadmium and arsenic levels in rice grain were the highest in Bangladesh and Sri Lanka, with both these countries also having high per capita rice intakes. For Bangladesh and Sri Lanka, there was high weekly intake of cadmium and arsenic from rice, leading to intakes deemed unsafe by international and national regulators. While genetic variance, and to a lesser extent milling, provide strategies for reducing cadmium in rice, caution has to be used, as there is environmental regulation as well as genetic regulation of cadmium accumulation within rice grains.
For countries that import rice, grain cadmium can be controlled from where that rice is sourced, but for countries with subsistence rice economies that have high levels of cadmium in rice grain, agronomic and breeding strategies are required to lower grain cadmium."
The average daily consumption of rice in Bangladesh is said to be around 400-500 gm, among the highest per capita rice consumption rates in the world, causing severe cadmium exposure. Sri Lankan rice consumption is also significantly high though less than Bangladesh, given slight variations in food consumption patterns.
According to the Sri Lankan researcher associated with the recent study, Dr. Mangala C. S. de Silva, who is a Senior Lecturer in Environmental Toxicology, University of Ruhuna, further studies into arsenic contamination in Sri Lankan samples are on-going. Head of the Chemistry Department, Kelaniya University, Prof. Priyani Paranagama, attributed the detection of high cadmium content in rice to multiple factors including soil conditions and runoff, amongst others. The World Health Organization (WHO) has issued a ceiling for cadmium in rice to be 200 micrograms per one kg, but samples taken from Bangladesh and Sri Lanka far exceeded the set limit, with an alarming 1,000 micrograms of cadmium per one kg of rice.
Call for toxic-free rice The scientists through this survey do not want to instill fear amongst the people and cause them to avoid their staple, rice. They insist that the idea is to call for the production of toxic-free rice, which is a prime health requirement. Dr. de Silva said, "It is not because we want to promote other options such as wheat flour, etc; that cadmium contamination is highlighted. Sri Lankans have eaten rice for centuries with no problem and cadmium seemed to be recent phenomenon. But what we eat should be safe," he asserted. Through various studies, it has been indicated that the island has one of the highest consumption rates of fertilizer use in the entire region and among the rice-growing nations in the world, with a sustained fertilizer subsidy system promoting heavy use, to the detriment of the population. Agro-chemicals have been cited regularly as a source for other toxic substances, including arsenic, with serious harmful impacts to the human body. Meanwhile, the promotion of the non-use of fertilizers or a highly reduced use, is a policy the Sri Lankan State is not yet willing to consider, given the high production potential when chemical fertilizers are used in rice cultivation. Refuting the theory that Sri Lankan paddy fields have shown high levels of toxicity due to cadmium and possibly arsenic contamination, Minister of Agriculture, Mahinda Yapa Abeywardene said, there was no question of abnormal levels of cadmium being recorded in homegrown rice. "With this cadmium scare linking farmers' health and paddy fields being contaminated by heavy metals, we have had samples tested both in Sri Lanka and overseas to verify matters. This is not true," he said.
Sri Lanka rice safe? According to Yapa Abeywaredene, rice samples have been specially collected from areas with widespread CKDue including Medawchchiya, Padaviya-Sripura and Mahawa. Other samples came from Bathalegoda, Sammanthurai, Labuduwa, Bombuwala, Galle and Ambalantota, where the history of paddy cultivation exceeds several decades, without the use of agro-chemicals. Through different studies but primarily through the WHO study last year, the CKDue prevalent areas were clearly identified, causes notwithstanding. They are, the North Central, North Western, Uva and Eastern Provinces. According to the WHO findings, some 400,000 kidney patients were found within just two provinces – North Central and Uva. The vulnerable age group was identified as 15-70 years. In the past 20 years, some 22,000 people had also died due to CKDue, the researchers stated, confirming that approximately 2.15% of the Sri Lankan population suffered from kidney disease in some form or the other. In Bangladesh, a few years ago, a survey supported the hypothesis that as opposed to the consumption of aromatic rice, people should be encouraged to consume non-aromatic, which was considered a healthier option.