A quantitative analysis of chronic exposure of selected heavy metals in a model diet in a CKD hotspot in Sri Lanka

Abstract

Background Evidence of chronic low levels of exposure to heavy metals in Sri Lanka has emerged in a number of studies carried out in the recent past. The source and magnitude of such exposures have to be understood in order to assess the risk of adverse health effects of this exposure and to propose suitable public health interventions. Methods An assessment was carried out to quantify chronic exposure to cadmium, lead and arsenic through food in people living in an area in Sri Lanka, where prevalence of Chronic Kidney Disease of unknown origin (CKDu) is highest. First a dietary survey was carried out in the subjects to estimate the type and quantity of typical food items in order to estimate an average consumption. A model diet was formulated using this dietary consumption data; and this was thereafter used for estimation of chronic dietary exposure of selected contaminants. In parallel, the levels of contaminants of interest in the various identified food items: cadmium, lead and arsenic, were determined. Results Assuming the major route of intake is food, and based on the quantity and type of food items consumed, a 60 kg man is exposed to average doses of 83.7 μg cadmium, 924.1 μg lead, and 180.3 μg arsenic per week. The impact of chronic lead exposure was affirmed by a mean blood lead level of 3.0 μg/dL, with a maximum level of 8.8 μg/dL being observed in some cases. Conclusions Chronic low dose exposure of lead from food appears to be a public health concern in the studied population. Cadmium exposure through food appears to be of concern also. However, arsenic exposure through food appears to be within safe limits. As there are numbers of possible adverse health outcomes that can be associated with such estimated exposures of heavy metals, public health interventions are warranted to limit the described harmful exposures. Advocacy on dietary patterns and agronomic practices to lower the contaminants identified are the two broad strategies suggested.

Evidence of selected nephrotoxic elements in Sri Lankan human autopsy bone samples of patients with CKDu and controls

“…The existence of contamination of food by lead is further corroborated by the blood lead levels detected in exposed people. In a previous study, it had been shown that the study population had had a mean value of 3.35 ± 1.47 μg/dL of lead in their blood [13]. A similar result has been reported in another hotspot (Medirigiriya) with a mean of 3.6 μg/dL [10].…”

“…At present, a large of volume credible data is available that supports the presence of the contaminants tested in the study, in various constituents of environmental, food and biological samples in Sri Lanka [5][6][7][8][9][10][11][12][13][14][15]. Among these contaminants, a relatively higher amount of lead has been reported in the food of people living in hotspots of Chronic kidney disease of uncertain aetiology (CKDu) which is also known as Chronic Interstitial Nephritis in Agricultural Communities (CINAC).…”

“…Among these contaminants, a relatively higher amount of lead has been reported in the food of people living in hotspots of Chronic kidney disease of uncertain aetiology (CKDu) which is also known as Chronic Interstitial Nephritis in Agricultural Communities (CINAC). Lead is found in rice and vegetables, which are the main constituents of the local diet, exposing an individual of 60 kg to an amount of 924.1 μg lead per week based on a model diet of 3 kg of rice and 1 kg of vegetables per week [13].…”

“…Most of these are remote agricultural areas of the island. People living in these areas report having food habits that are different from their counterparts living in other areas of the country [13] due to geographical, socio-economic and other factors.…”

Longitudinal trends in renal function among first time sugarcane harvesters in Guatemala

“…There is the potential that the individuals evaluated here have had previous employment in other agricultural settings or participated in subsistence agriculture, which can differ by region, potentially explaining some of the differences we found between local and migrant workers. Limited research has been conducted to identify other differences in CKDu risk factors between local and migrant communities, but possible explanations could include differences in diets [33], airborne exposures [34], or water sources [35] which we showed to increase non-stable group assignment 6-fold and was highly associated with home of residence. Understanding differences in childhood and adolescent exposures may help determine why some young men enter the workforce with lower than expected eGFR and with elevated blood pressure.…”