Attached
Rice is the staple food in Sri Lanka with a per
capita consumption of about 108 kg of milled rice per
year.1 Presence of toxic metals/metalloids in rice above
the threshold limit is detrimental to human life. Hence,
systematic investigations leading to determination of
toxic metals/metalloids in rice are important. In the
present study, ten varieties of rice including traditional
rice varieties (TRV) and newly improved hybrid rice
varieties (NIHRV) were cultivated in two regions; one
in Anuradhapura - Rambewa (an area where CKDu is
prevalent) and the other, Kurunegala (an area where
CKDu is not known to exist). The study was carried out
under two different agricultural management systems;
organic and conventional using split-plot design
consisting of three replicates.
A total of 120 rice samples were collected from
farming sites in these two regions of paddy plants at
maturity stage. They were processed and microwave
digested according to US EPA 3052 method and
analyzed for the selected toxic metals; Cd, Pb and Cr
using Hitachi ZA 3000 Polarized Zeeman graphite
furnace atomic spectrometer.2 Cd and Pb were analyzed
in the presence of the matrix modifiers; Mg(N03)2 and
(NH4)2HP04 respectively. Certified reference material
IRMM-804 RICE FLOUR was analyzed for validation
of the analytical method. Method recoveries were in the
range of86% to 121 %.
Cadmium content in rice samples analyzed (Bg
300, 366, 352, 358, 360, Suwandel, Madathawalu,
Kuruluthuda, PachchaPerumal, KaluHeeneti) were in
the range between 5.7 pg kg'1 and 184.0 pg kg'1 and it
does not exceed the maximum allowed limit of200 pg
kg'1 set by Codex Alimentarious commission.3 Further,
compared to NIHRV, two selected TRVs; Pachcha Perumal and Madathawalu showed low levels of trace
metals at both regions under the two different
agricultural management conditions. Cd contents in
these two varieties were in die range5.9 pg kg'1 to 99.5
pg kg'1. Pb was undetectable in all rice samples
analyzed. Crcontentwere in the range of 13.8 pgkg'1 to
290.8 pg kg'1 which is approximately one tenth of the
maximum allowed limit o f2000 pg kg'1 set by Codex
Alimentarious commission.4 The findings shows that
the rice grown in two regions do not contain the above
metals beyond the safe levels.
