Heavy metal is defined as metallic element usually toxic in nature with high density and atomic weight. As they are toxic in nature they accumulate in different parts of the vegetables and lead to several health complications in humans. Some of these metals are of nutritionally important for human health in minute quantities and referred as trace elements. Lead, cadmium, nickel and chromium are among the major toxicants in vegetables which may cause chronic diseases in the kidney and liver of humans and causes disruption of numerous biochemical processes leading to cardiovascular, nervous, kidney and bone diseases. Leafy vegetables like mint has more chances of infestation in suburbs due to waste water irrigation as compared to intact skin vegetables especially grown away from suburbs. Waste water contains sufficient amount toxic heavy metals which cause clinical problems.In Pakistan farmers are openly using the sewage water for cultivation. Food safety is serious issue these days in Pakistan as many foodborne diseases occur due to consumption of vegetables growing in sewage water. Cultivation of crops by contaminated water is of bigger concern regarding food safety issue. Use of polluted water in fields for long terms without any treatment is liable to cause diseases.
Total 36 samples of vegetables, 4 samples of water and 8 soil composite samples were collected from four different places surrounding Hudiara drain in Lahore for one month. Sampling was done for 3 months (May, June and July).Soil samples were taken from two different depths (0-6 inches and 6-12 inches with the help of soil auger. For three months, total of 144 samples were analyzed for desired study. The heavy metals Pb, Cd, Ni and Cr in tomato, lady finger and mint (from various places around Hudiara drain Lahore) were determined in washed, dried and digested vegetable samples using Atomic Absorption Spectrophotometer. The data was brought to presentable from by applying Two-way ANOVA through SPSS Version 16.0. Mean and S.D was also calculated for every ANOVA to discuss in detail. Results exhibited significant values in water, soil and vegetable samples. Lead, cadmium, nickel and chromium showed significant values in some samples of water, soil and vegetables. Lead was found above permissible limit in tomatoes and lady finger. The data showed that there is continuous bio-accumulation of heavy metals from waste-water to soil, which is causing uptake of heavy metals from soil to plant. Continuous cultivation with affected water will make the land unfit for irrigation and vegetables for consumption. Proper treatment is required of water which is being used for cultivation in surroundings of Hudiara drain in Lahore.