AA Meharg

FAO/WHO

H Jennifer Redmon

JMRS Bandara

N Jayatilake

T. B. Ananda Jayalal

TBA Jayalal

BMC Nephrology

Crossref

Jayalal BMC Nephrology  (2015) 16:216 DOI 10.1186/s12882-015-0211-5CORRESPONDENCE Open AccessChronic kidney disease of uncertainaetiology: adding vital piece of informationto the national project team report ofSri LankaT. B. Ananda JayalalAbstractIn a recent study published by the National Project Team on chronic kidney diseases of unknown origin in Sri Lanka,identified cadmium as a major risk factor but strong conclusions were not made as the identified environmental toxinswere within the permissible levels.Sri Lankan food consumption pattern is different so that approach of total exposure of cadmium by food and waterbeen calculated. Such calculation point out that total exposure of cadmium exceed the provisional tolerable weeklyintake determined by international agencies.Keywords: Cadmium, Nephropathy, Chronic Kidney Disease of uncertain aetiology (CKDu), Provisional tolerable intake (PTWI)BackgroundIt is been estimated more than 40,000 cases of chronickidney disease patients in areas where chronic kidneydisease of uncertain aetiology (CKDu) prevails in SriLanka. Large proportions of these cases are due touncertain aetiology. National project team on chronickidney diseases has published that chronic exposure tolow levels of cadmium may be a causative factor inCKDu in Sri Lanka [1]. However, Jayatilake et al. findingon rice and pulses and water cadmium values seems tobe not supporting strongly as a causative factor as noneexceeds the permissible upper limits. Jayatilake et al. haveshown maximum cadmium levels in rice is 100 μg/kg andmaximum cadmium levels in water as 1.5 μg/L. TheCodex upper limit of cadmium for polished rice is400 μg/kg [2] whereas World Health Organizationupper limit for cadmium for drinking water is 3 μg/L[3]. However, in certain vegetables and freshwater fishJayatilake et al. has found levels above the internationalpermissible levels [1]. Nevertheless, Jayatilake et al. havesuspected people living in endemic area could be exposedto cadmium exceeding tolerable limits.Correspondence: jayalal313@yahoo.co.ukEnvironmental Health & Occupational Health, Ministry of Health, Colombo,Sri Lanka© 2015 Jayalal. Open Access This article is disLicense (http://creativecommons.org/licenses/medium, provided you give appropriate crediCommons license, and indicate if changes wecreativecommons.org/publicdomain/zero/1.0/Presence of cadmium in environmental samples similarto Jayatilake et al. are found by number of independentresearches. Jayalal [4] has quoted cadmium testing doneon environmental samples by Rice Research institute ofSri Lanka, National Water Supply and Drainage Board ofSri Lanka. Further, Bandara et al. [5, 6] and Andrew A.Meharg et.al. [7] also have shown presence of considerablyhigher levels of cadmium in their samples.From above findings it is apparent that in some areassoil, on which food crops are grown, is rich in cadmium,may be due to natural presence augmented by introduc-tion of fertilizers. It had been shown fertilizer “triplesuperphosphate” contain considerable levels of cadmiumas a contaminant. In addition, change of physical proper-ties of soil such as temperature, pH, and organic contentetc. may be playing a role in the increase absorption ofcadmium in to the food crops grown in those areas.It is the total exposure to any toxin that matters whenhealth impacts are considered. In heavy metal exposureand other environmental contaminants Food andAgriculture Organization (FAO) recommends the totaldiet study approach. Total exposure from total food in-take, water and smoking gives the required informationfor scientific evaluation of the question. Valuable find-ings of the Jayatilake et al. [1] can be further augmentedtributed under the terms of the Creative Commons Attribution 4.0 Internationalby/4.0/), which permits unrestricted use, distribution, and reproduction in anyt to the original author(s) and the source, provide a link to the Creativere made. The Creative Commons Public Domain Dedication waiver (http://) applies to the data made available in this article, unless otherwise stated.Jayalal BMC Nephrology  (2015) 16:216 Page 2 of 3by calculating the total exposure to cadmium by thestudy population.In addition hot spot sampling in areas with greaterreporting of CKDu prevalence could provide strong linkto risk factors [8]. Average values may not lead toconcrete evidence as done by Jayatilake et al. [1].MethodsSri Lankan diet is mainly consisting of rice, vegetablesand small amount of proteins from animal or aquaticorigin. Food made out of wheat also take minorproportion of the staple diet. From the available data, foran average 60 kg Sri Lankan living in endemic area it isassumed following food consumption values per week.Three kg of rice, 1.4 kg of vegetables and drinks 14 L ofwater per week. Other food categories not considered hereas cadmium contribution from them are proportionatelynegligible or data on cadmium are not available. Thefigures available in the cluster diets published byWHO [9] and data available from the ministry ofagriculture [10] were used with modification in thismodel food consumption values.Results and discussionIf the mean values of cadmium generated for food itemsby Jayatilake et al. are used for calculation of totalexposure, 3 kg of rice with 25 μg/kg Cadmium,1.4 kg of vegetables with 50 μg/kg of cadmium, and14 L of water with 0.5 μg/L of cadmium followingtotal weekly exposure of 152 μg of cadmium per weekis obtained. If the upper values i.e.100 μg, 70 μg,1.5 μg for rice, vegetables, and water respectivelytaken in to consideration exposure of 419 μg of cadmiumper week obtained. Therefore it can be assumed that 152to 419 μg of cadmium exposure per week occurs inendemic area only through food and water. Smokers areexposed to additional dose. The provisional tolerableweekly intake for cadmium for US and Europe declaredby the relevant authorities are 2.52 μg per Kg body weight[11, 12] and corresponding value declared by WHO is5.8 μg per Kg [13]. This correspond with 151.2 μg and348 μg per week respectively for a 60 kg man.The calculated cadmium exposure values exceed theprovisional tolerable weekly intake (PTWI) for cadmiumfor European standard and if the worst case scenarioconsidered exceeds the WHO recommendation (whichis higher) as well. As the smokers get added dose ofcadmium the actual exposure should be higher thanabove values. The contribution from smoking cannot beassessed in Sri Lanka as the adequate data not available.However, it is obvious from this calculations that certainnumber of people living in cadmium hot spots areexposed to doses exceeding the recommended tolerableintake of cadmium.DiscussionA wealth of data had been generated by Jayatilake et al.[1] to design the public health interventions to reducethe CKDu prevalence. However, Jayatilake et al. have notcome to firm conclusion as the food consumptionpattern and total exposure to the possible nephrotoxinswere not researched in to, perhaps it is not the objectiveof the research. The future research should fill this gap ofknowledge. However, present knowledge can be utilized ineffective public health interventions and operational re-search on such interventions may lead to firm establish-ment of causation of CKDu.Conclusions and recommendationsAbove calculations show that Sri Lankan populationliving in certain geological regions are exposed tocadmium from food and water in excess of provisionaltolerable weekly intake recommended by internationalagencies.As the cost of managing large number of people withterminal renal failure and the societal effects of prematuredeath and disability is detrimental, following interventionsare proposed which seems to be cost effective. However, itis suggested to consider the cost benefits in depth whichis beyond the scope of this paper.Future research need to be focused to confirm orexclude the causation of CKDu by cadmium. Followingoptions are suggested.1. Study the cadmium concentration in live orpostmortem kidney samples in CKDu and nonCKDu cases.2. Cohort study the urinary excretion of cadmium andsuitable biomarker of kidney damage afterappropriate intervention to lower the cadmiumintake. e.g. after provision of cadmium free water.In the present context what is required is implementa-tion of public health interventions to reduce thecadmium exposure of the population of the endemicarea. From the current data available, following mea-sures can be recommended.1. Drinking water of identified areas to be tested forcadmium and suitability for drinking should berecommended if cadmium cannot be detected by atest method with limit of detection (LOD) > 10−9/L.2. A national level programme to reduce cadmiumfrom the food chain need to be initiated with theinvolvement of the ministry of health and ministryof agriculture. Following interventions can beproposed from the current knowledge.a. All the major food varieties to be tested forcadmium and how cadmium concentrationsJayalal BMC Nephrology  (2015) 16:216 Page 3 of 3varies with the food type and geographicalvariation need to be identified. Rice varietieswith low cadmium concentration or best fieldsfor paddy cultivation need to be identified andagronomic practices that reduce cadmiumconcentration in rice and other major foodvarieties to be popularized among farmers.b. Anthropogenic activities which lead to increasecadmium levels in soil and food should beminimized to the extent possible.c. Proper disposal mechanism for e waste whichlead to decrease of cadmium concentration in theenvironment need to be implemented.d. More polished rice to be recommended forvulnerable groups of population while addressingthe micronutrient requirement as polishing hadbeen shown low cadmium in rice.3. To revise the Sri Lanka standard of potable water(SLS 614) and bottled or packaged drinking waterand bottled packaged natural mineral water in thepresent context. The permissible levels for cadmiumcan be lowered to undetectable by a sensitive testmethod. (Graphite Atomic absorption or moresensitive method)4. Coordinating mechanism on future research need tobe implemented.AbbreviationsCKDu: chronic kidney disease of uncertain aetiology; FAO: Food andAgriculture Organization of United Nations; PTWI: provisional tolerableweekly intake; WHO: World Health Organization.Competing interestsAuthor declare he has no competing interests.Authors’ contributionsThe author conceived the concept and design, analysis and interpretation ofdata, draft the manuscript, given final approval of the version to bepublished, and agree to be accountable for all aspects of the work.Authors’ informationAuthor is the former Director Environmental Health and Occupational Healthin the Ministry of Health of Sri Lanka. His primary degree is MBBS andobtained postgraduate degrees of MSc and MD in Medical Administration.Author took part in the activities of the national research project team forCKDu.AcknowledgementsMr. H. A. K. Amarakoon, Chief chemist of National Water Supply andDrainage Board of Sri Lanka and Dinaratna Sirisena of Rice Research Instituteof Sri Lanka, for providing data on cadmium.Received: 9 August 2015 Accepted: 15 December 2015References1. Jayatilake N, Mendis S, Maheepala P, Mehta FR, On behalf of the CKDuNational Research Project Team. Chronic kidney disease of uncertainaetiology: prevalence and causative factors in a developing country.BMC Nephrol. 2013;14:180. 1–13.2. FAO/WHO. Codex General Standard for Contaminants and Toxins in Foodand Feed. Food and Agriculture Organizaton of the United nation, JointFAO/WHO Food Standards Programme, Codex Alimentarius Commission.Rome: CODEX STAN; 2013. p. 193–1995.3. World Health Organization: Guidelines for drinking-water quality, fourthedition 2011. http://www.who.int/water_sanitation_health/publications/2011/9789241548151_ch08.pdf?ua=1(2011). Accessed 31 July 2015.4. Jayalal TBA. Chronic exposure to nephrotoxic doses of Cadmium throughSri Lankan diet. Sri Lanka J Med Admin. 2015;17:23–6.5. Bandara JMRS, Senevirathna DMAN, Dasanayake DMRSB, Herath V, BandaraJMPR, Abeysekara T, et al. Chronic Renal failure among farm families incascade irrigation systems in Sri Lanka associated with elevated dietarycadmium levels in rice and freshwater fish (Tilapia). Environ GeochemHealth. 2008;30:465–78.6. Bandara JMRS, Wijewardana HVP, Liyanage J, Upul MA, Bandara JMUA.Chronic renal failure in Sri Lanka caused by elevated dietary cadmium:Trojan horse of the green revolution. Toxicol Lett. 2010;198(1):33–9.7. Meharg AA, Norton G, Deacon C, Williams P, Adomako EE, Price A, et al.Variation in rice cadmium related to human exposure. Environ Sci Technol.2013;47:5613–8.8. Jennifer Redmon H, Elledge MF, Womack DS, Wickremashinghe R,Wanigasuriya KP, Peiris John RJ, et al. Additional perspectives on chronickidney disease of unknown aetiology (CKDu) in Sri Lanka – lessonslearned from the WHO CKDu population prevalence study.BMC Nephrol. 2014;15:125.9. World health Organization, Global Environment Monitoring System(GEMS/Food) http://www.who.int/nutrition/landscape_analysis/nlis_gem_food/en/(2012). Accessed 20 Dec 2015.10. Agriculture and Environment Statistics Division, Department of Census andStatistics, Sri Lanka. (2012) http://www.statistics.gov.lk/agriculture/Paddy%20Statistics/PaddyStatsPages/SelfsufficiencyRateofRice.html.Accessed 31 July 2015.11. Tox Guide for Cadmium. U.S. Department of Health and Human Services,Public Health Service, Agency for Toxic Substances and Disease Registry.2012. http://www.atsdr.cdc.gov/toxguides/toxguide-5.pdf (2012). Accessed31 July 2015.12. EFSA CONTAM Panel (EFSA Panel on Contaminants in the Food Chain),2009. Cadmium in food - Scientific opinion of the Panel on Contaminantsin the Food Chain. doi:10.2903/j.efsa.2009.980 (http://www.efsa.europa.eu/en/efsajournal/pub/980) 2011, Accessed 31 Jan 2015.13. FAO/WHO. Safety evaluation of certain food additives and contaminants,joint FAO/WHO expert committee on food additives (JEFCA). Geneva: WorldHealth Organization; 2011.•  We accept pre-submission inquiries •  Our selector tool helps you to find the most relevant journal•  We provide round the clock customer support •  Convenient online submission•  Thorough peer review•  Inclusion in PubMed and all major indexing services •  Maximum visibility for your researchSubmit your manuscript atwww.biomedcentral.com/submitSubmit your next manuscript to BioMed Central and we will help you at every step:

Chronic kidney disease of uncertain aetiology: adding vital piece of information to the national project team report of Sri Lanka

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Chronic kidney disease of uncertain aetiology: adding vital piece of information to the national project team report of Sri Lanka

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