Assessment of Heavy Metal Concentration in the Environment and Perceived Health Risks by the Community around Kadhodeki Dumpsite, Nairobi county
Njagi, Joan Murugi
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Solid wastes constitute a disaster for human health and environmental degradation. Dumpsites in Kenyan urban settlements are used as sources of nutrient rich soils for cultivating crops without regard to the risks of perceived toxic heavy metal pollution from the wastes. Water sources near the dumpsites are used as domestic water source for the people living near such sites. This water is often contaminated by toxic heavy metals leaching from the dumpsite. Heavy metals are known to accumulate in the plants then passed to the humans through the food chain. Prolonged consumption of unsafe concentrations of heavy metals through foodstuffs may lead to the accumulation of heavy metals in the humans causing disruption of numerous biochemical processes. The aim of this study was to determine the level of heavy metals in the vegetables, soil and water samples collected around Kadhodeki dumpsite. The study also sought to assess the knowledge, attitude and perceptions of the health risks posed by the site to the residents of the village. Heavy metal determination samples collected was carried out using X- ray fluorescence (XRF) analytical method. A descriptive cross sectional survey was carried out to assess the knowledge, attitudes and perceptions of people living around the study area. The analytical data was subjected to statistical tests of significance using ANOVA and post hoc analysis by Tukeys test (P<0.05) to determine whether there was any significant difference between the study sites. Chi square was used to determine if there were associations between the study variables in the survey. The research found that the vegetables under study had low levels of essential metals Fe, Mn, Zn and Cu while they had higher levels of Ni, Co, V, and more than maximum allowable levels (MAL) of Hg and Pb. V, Mn, Cu, Ni, Hg concentrations in the soil were higher than MAL for agricultural soils while Fe, Zn were within the limits. The water was contaminated by high than allowed levels of Mn (366-856 μg/l) and Fe (5132-12402 μg/l) in drinking water while Zn (40-336 μg/l) was below the WHO limits. The people living in Kadhodeki village had inadequate knowledge about the health risks which was significantly associated with the level of education (χ2 = 20.86 df=1 P<0.01). A significant association between level of education and perception was also revealed (χ2=13.57, df=1, p<0.01). Insignificant associations between age and the number of years the participants had lived in the village were found for the variables of knowledge, attitude and perception. Health education to the people living in Kadhodeki village on the dangers posed by the vegetables grown around the dumpsite should be done to prevent further consumption of contaminated crops. Farmers growing edible crops around the site should be advised to stop doing so and instead encouraged to grow other crops which can provide some earning and at the same time reclaim the land.