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Toxic heavy metal in rice: Lanka second in 12 country list
Suspected cadmium caused CKDu now spreading to South?
Sri Lanka comes in second, just behind Bangladesh, for having the highest levels of the toxic heavy metal cadmium in rice, in a study of 12 countries across the world, with both countries also having heavy intakes of rice by the people. This latest study follows close on the heels of disturbing reports that the mysterious kidney disease earlier thought to be felling farmers mainly in the North Central Province (NCP) and adjacent areas may now be raising its head in the south as well. Cadmium levels in rice were the highest in Bangladesh and Sri Lanka. The high weekly intake of cadmium in rice leads to intakes “deemed unsafe by international and national regulators”, the survey of the 12 countries across four continents has found.
The latest study, ‘Variation in Rice Cadmium Related to Human Exposure’ published in a high-impacting science journal in the United States of America on May 13 (last month), has been carried out in Bangladesh, Sri Lanka, Cambodia, France, Ghana, India, Italy, Japan, Nepal, Spain, Thailand and the United States of America. Field studies had also been conducted in China.
The Sri Lankan researcher involved in the study, Dr. P. Mangala C.S. De Silva of the University of Ruhuna, told the Sunday Times that the findings should send clear danger signals about the rice we eat. There is “no big difference” in the cadmium levels in areas affected by the mysterious kidney disease and others areas. However, this is not to dissuade people from eating rice but to get the authorities to make the rice safer, he stressed.
This study conducted in 2011 and 2012 and published in the ‘Environmental Science and Technology’ magazine of the American Chemical Society cements and builds on earlier studies which proved that cadmium was present in the rice that Sri Lankans eat as their staple food.
The Sri Lanka Government-World Health Organization (WHO) study of the Chronic Kidney Disease of unknown aetiology (CKDu) killing people mainly in the Dry Zone stated: “We found significantly higher urine cadmium excretion in healthy people in the endemic area compared to those living in a non-endemic area. These findings support the contention that chronic exposure to low levels of cadmium may be playing a role in the causation of CKDu in Sri Lanka.” (See graphic)
The 75 rice samples, in the latest research, were taken from Padaviya, Medawachchiya, Kebitigollewa, Rambewa and Sripura and Parakramapura in the Anuradhapura and Polonnaruwa areas where CKDu is rampant and from several villages in Kamburupitiya in the Matara area and Ambalantota and Daragama in the Hambantota area which were the control groups, the Sunday Times learns.
The tests were for both cadmium and arsenic, says Dr. De Silva who is a Senior Lecturer of the Department of Zoology, Faculty of Science of the Ruhuna University.
With Sri Lankans, especially in the villages eating rice for all three meals, it is obvious that more cadmium is getting into their systems, he explains, hastening to reiterate that there is no intention of urging Sri Lankans to reduce their rice intake. Our forefathers also ate rice for all three meals but didn’t have this problem, according to him, so this is a recent issue.
Whenever researchers come up with evidence-backed findings about cadmium or arsenic in rice, there are major accusations that they are promoting wheat flour, he said, rejecting that contention strongly. “We don’t want people to stop eating rice but we just want the rice to be free of toxic substances,” Dr. De Silva added.
Among earlier studies on CKDu are ‘Chronic renal failure among farm families in cascade irrigation systems in Sri Lanka associated with elevated dietary cadmium levels in rice and fresh water fish (tilapia)’ in 2007; and ‘Chronic kidney disease of uncertain etiology (CKDue) in Sri Lanka: Geographic distribution and environmental implications’ and ‘Natural radionuclides and trace elements in rice field soils in relation to fertilizer application: Study of chronic kidney disease area in Sri Lanka’ both in 2010. The last study also focused on uranium.
Substandard fertiliser to blame
To the crucial question of how cadmium has got into Sri Lanka’s rice, Dr. De Silva points an accusing finger at substandard phosphate fertilisers.
In other countries the source of cadmium is mining and industrial pollution, he says but in Sri Lanka and Bangladesh it is due to triple superphosphates (TSP).
Both fertilizer (pohora) and synthetic pesticides including weedicides (palibodha nashaka) fall under ‘agrochemicals’, which are “chemicals used in agriculture”, according to him.
Sri Lanka has the highest “consumption” of synthetic fertilizer for a less amount of land in South Asia and other rice-growing countries in Southeast Asia, points out this scientist, quoting the World Bank. The other countries studied were Bangladesh, Pakistan, India, Maldives, Bhutan, Nepal, Thailand, Myanmar, Vietnam and Cambodia.
Farmers get fertilizer more or less free. Due to the government subsidy, they pay only about Rs. 300 when the actual price would be Rs. 1,500-2,000. Therefore, they apply fertilizer excessively, Dr. De Silva has found during extensive field studies.
Kidney disease spreading to other areas
Is CKDu spreading its tentacles to Tissamaharama, Wellawaya, Lunugamvehera and Tanamalwila in Hambantota and Moneragala areas?
The curse of CKDu began way back in 1994 starting in the upper regions of Padaviya, Kebitigollewa and Medawachchiya in the Anuradhapura district, then spreading down to Rambewa, Maha Wilachchiya and Horowupotana, says Dr. Channa Jayasumana of the Rajarata University who has studied this issue in-depth.
Later CKDu was diagnosed in Hingurakgoda and Medirigiriya in the Polonnaruwa district, Girandurukotte in the Badulla district and Dehiattakandiya in the Ampara district, said this Lecturer in Pharmacology of the Faculty of Medicine, Rajarata University. A heavy pocket of victims has also been identified in Polpitigama, Giribewa and Nikawewa in the Kurunegala district.
Now there seems to be indications that it is coming up in the south, he said. Chronic Kidney Disease (CKD) seems to be an emerging illness in the south, said Moneragala Judicial Medical Officer (JMO), Dr. K.S. Dahanayake when contacted by the Sunday Times.
Dr. Dahanayake who is in touch with other doctors in the south who are disturbed by this trend, said that he is planning to conduct a study shortly.
WHO report lists contributory causes
Critical of Agriculture Ministry moves to palm off the blame for CKDu on imported food such as sugar, Dr. De Silva said the WHO report was clear in its findings that cadmium, arsenic and nephrotoxic pesticides commonly used in Sri Lanka may be contributory factors.
The ministry’s allegations that residues of pesticides never used in Sri Lanka have been found in specimens of CKDu victims only indicates ignorance, he said. All scientists know that over time chemicals such as pesticides become degradation products.
Some old hypotheses of Sri Lankan researchers also need to change, he said, adding that some believe that if statistically significant amounts of arsenic are not found in urine, then one of the causes of CKDu may not be arsenic.
What they forget is that there are four stages of CKDu and when specimens are taken if the kidneys are already damaged and cannot perform their usual functions, the body cannot pass arsenic in urine. This arsenic would then get deposited in hair and fingernails, as found by the Government-WHO study.
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