Abstract:
CKDu appeared mainly in North Central province in Sri Lanka, and recently, it materialized in Uva
province. Soil can be gripped as a main environmental source for the phenomenon of this kidney
failure, as it is a material that is frequently used by people in the areas with CKDu generality, and
soil has a direct correlation between food crops and water sources. Therefore, the present study
explores the potentially toxic levels and soil quality in Rideemaliyadda-South Grama Niladari
Division (a CKDu hotspot), Badulla district, Uva province, Sri Lanka, to explore the risk factors
associated with the phenomenon of CKDu. Triplicated thirty soil samples were collected using the
random stratified sampling method (Thirteen home gardens, nine cultivated areas, five forested
areas, and three tank sediment samples) under the land use patterns in this area and evaluated
using ArcMap 10.2.2 software. Cation concentrations including Cr, Mn, Cu, Zn, Cd, Pb, and As in
collected soil and sediment samples were analyzed using inductively coupled plasma–mass
spectrometry (ICP-MS) followed by Microwave digestion using concentrated nitric acid. The
average concentration of selected heavy metals including Chromium (Cr), Manganese (Mn),
Copper (Cu), Zinc (Zn), Cadmium (Cd), Lead (Pb), and Arsenic (As) in soil (in mg/kg) were
43.62±6.19, 411.60±35.60, 15.74±1.76, 52.30±11.00, 0.01±0.01, 8.85±0.71 and 0.04±0.04,
respectively. According to the toxicological studies, all existing concentrations were below the
permissible levels considering the nephrotoxic heavy metal contents in soil (Cd, Pb, Cr, and As are
proven as nephrotoxic heavy metals according to the toxicological studies), instead of that, Mn (p
= 0.020), Cu (p = 0.036), and Zn (p = 0.042) were significantly higher in the CKDu hotspot than the
reference levels of Mn, Cu, and Zn in soil (in mg/kg) were 476.00, 36.00, and 50.00, respectively.
The average content of Zinc in soil exceeded the permissible levels given by WHO. Hypothesizing
the Phosphates as an interactive anion to the availability of cations in soil, the phosphate
concentrations in soil and sediment samples were measured using Ion Chromatography (IC). The
average concentration of phosphate in soil was 7.08±1.29 mg/kg. Pearson correlation coefficients
indicated a negative correlation between the existing cadmium (Cd) concentrations and the
phosphate (PO4
3-) concentrations (-0.093) in soil and sediments. The mean soil pH in the CKDu
hotspot showed a slightly acidic condition which was 6.78±0.15, and it was within permissible
soil pH limits. The mean conductivity was compiled with the acceptable conductivity range, which
was 118.20±25.20 µS cm-1. Lead, Chromium, Arsenic, and Cadmium were nephrotoxic heavy
metals and were proved by toxicology chemistry. According to the results, the spatial distribution
of Pb and Cr within the CKDu hotspot showed a clustered pattern, and those clustered appeared
especially related to the agricultural lands in the area. Whether those heavy metal concentrations
were below the permissible levels, lower concentrations can cause nephrotoxicity with long-term
exposure.
