| dc.description.abstract | The contamination of Agricultural products by harmful Heavy metals poses a significant global health concern, with potential links to severe public health issues such as cancer and neural impairment. Tomatoes (Lycopersicon esculentum Mill.), a dietary staple, can absorb and store both essential micronutrients and potentially harmful heavy metals, particularly in their consumable parts. Due to increased demand and value, many farmers have adopted modern farming methods which include application of Fertilizers, Pesticides, Compost manure, and Irrigation. Yet some of these Agricultural practices such as application of fertilizers and pesticides are known to increase the concentration of heavy metals in the soil. Some of these heavy metals such as Pb and Cd are toxic even at low concentrations while Cu and Cr though essential in the body, are toxic at high levels. This calls for monitoring to make sure that the levels of heavy metals do not exceed the threshold limits recommended by WHO/FAO due to their adverse health effects to human. This study therefore investigated the concentration of cadmium, lead, copper, and chromium in Fertilizers, tomatoes and corresponding soil samples from Kirinyaga County, Kenya. The findings will inform mitigation strategies for farmers and policymakers, promoting sustainable agriculture and food safety. Ultimately, the study supports soil preservation and long-term agricultural viability. A total of 27 tomato samples; 27 soil samples and 7 fertilizer samples were randomly collected from each of the three ecological zones of Kirinyaga County. Known weights of oven dried fertilizer, tomato and soil samples were digested using 4.0 mL of 35% HNO3 and 6.0 mL of H2O. The samples were digested using the dry ashing method and elemental analysis was performed using Microwave Plasma-Atomic Emission Spectroscopy (MP-AES). The mean concentrations of heavy metals in soil samples ranged from; cadmium: 0.0100±0.100 to 0.1133±0.0667, lead: 0.0570±0.0566 to 0.667±0.0367, copper: 0.8667±0.273 to 1.9±0.0577 and chromium 0.0670±0.0600 to 1.333±0.040 mg/Kg. The mean concentrations of heavy metals in tomatoes ranged from; cadmium: 0.00367±0.003 to 0.00867±0.01, lead: 0.00133±0.003 to 0.00667±0.02, copper: 0.00667±0.02 to 0.0667±0.003 and chromium: below detection limit to 0.027±0.035 mg/Kg. The mean concentrations of heavy metals in fertilizer samples ranged from; cadmium: 0.2±0.21 to 1.7±0.21, lead: below detection limit to 3.5±0.44, Copper: 0.8±0.18 to 2.1±0.18 and chromium 0.9±0.74 to 5.8±0.74 mg/Kg. The ANOVA results suggested that there was a significant difference (p = 0.05) in the levels of heavy metals between soil and tomatoes in all the regions. The correlation analysis between the concentration of metals in soil and tomatoes and the use of the inorganic fertilizer revealed relevance for the fertilizer NPK 27-10-16 + TE EASY GROW. The bioaccumulation index (BI) for cadmium, lead, copper, and chromium ranged from 4-12%, 0.7-4%, 2-5%, and 0.9-3%, respectively, suggesting that their accumulation in tomato fruits is low. The concentrations of the heavy metals in fertilizer, soils and tomatoes were significantly lower than the maximum concentrations set by the WHO/FAO. Although the tomatoes from the region are safe for human consumption regarding Cd, Pb, Cu, and Cr, repeated application of aforementioned fertilizer could put consumers at risk of exposure to these heavy metals. All the other sampled fertilizers were found to be safe for application on agricultural lands. There is a need to monitor the levels of heavy metals regularly to ensure they do not exceed acceptable limits. | en_US |
