Monitoring of toxic metals (cadmium, lead, arsenic and mercury) in vegetables of Sindh, Pakistan

Abstract

A monitoring study was carried out with the aim to assess the level of toxic metals i.e., lead (Pb), cadmium (Cd), arsenic (As) and mercury (Hg) in different vegetables grown in Sindh province of Pakistan during 2007-2008. Two hundred ten samples of twenty one vegetables were collected from farmers' field of Sindh and exporters at Karachi. These samples were grouped into four categories viz., leafy, root and tuberous, cucurbits and fruity. The samples in duplicate were digested with nitric and perchloric acid mixture with 3:1 ratio. Cadmium and Pb were analyzed with Graphite Furnace Atomic Absorption Spectrophotometer and As and Hg on Atomic Absorption using Vapor and Hydride Generation Assembly. Average concentration of Cd, Pb, As and Hg in leafy vegetables was found 0.083 μgg^-1, 0.05 μgg^-1, 0.042 μgg^-1 and 0.008 μgg^-1 respectively, in roots and tuberous vegetables was 0.057 μgg^-1, 0.03 μgg^-1, 0.045 μgg^-1 & 0.004 μgg^-1 respectively, in cucurbit vegetables was 0.021 μgg^-1, 0.051 μgg^-1, 0.056 μgg^-1 and 0.0089 μgg^-1 respectively and in fruity vegetables was 0.035 μgg^-1, 0.067 μgg^-1, 0.054 μgg^-1 and 0.007 μgg^-1 respectively. In leafy vegetables, the concentration of cadmium, lead and mercury were found comparatively higher than other three groups of vegetables. However, concentration of heavy metals found in the samples of all four categories of vegetables, was within the permissible limits and safe to consume.