In this study, the health risk caused by heavy metals exposure to communities along Mubi-Yola highways was evaluated. Samples from Mubi, Hong, Gombi, Song, and Gerei were collected and analyzed for Lead (Pb), Cadmium (Cd), Chromium (Cr), Zinc (Zn), Cupper (Cu), and Nickel (Ni) using Atomic Absorption Spectrophotometer (AAS). The mean concentrations of the metals used for the risk assessment were observed to fall in this order Zn>Pb>Ni>Cu>Cd>Cr. The noncarcinogenic risk based on the target hazard quotient (THQ) and human health index (HI) values for each exposure pathway and for each metal were observed to be less than (<) 1 which means, exposure to the heavy metals has no immediate risks for both the adults and children in the settlements. The lifetime cancer risk (CRI) for the metals for both the ingestion (CRI Ing ) and inhalation (CRI Inh ) exposure pathways were observed to pose no lifetime carcinogenic risk. The CRI for all the exposure pathways and for all age categories were <10 -4. Similarly, the combine Bwatanglang et al.; JSRR, 23(1): 1-13, 2019; Article no.JSRR.48137 2 effect or total cancer risk (TCRI) for each exposure pathway show high probability for carcinogenic risk by ingestion route compared to exposure by inhalation. The order of exposure were observed to be adults

Environmental pollution by heavy metals has become a global issue in the recent years as it affects public health. Especially with the continue increase in anthropogenic activities such as industries and urbanization which releases pollutants in to the environment without control and effects remedies. Among the numerous environmental pollutants, heavy metals plays an important role as its concentrations in air, soil and water are continuously increasing due to anthropogenic activities. Heavy metal is any metal that is toxic regardless of their density or atomic mass. Heavy metals occur naturally in the soil environment from the pedogenetic processes of weathering of parent materials and from anthropogenic sources such as traffic emission, industrial and energy production, waste disposal, vehicle exhaust as well as coal and fuel combustion. Excess of metal pollutants deposited on soils may be transformed and transported to vegetation and from plants they pass on to animals and human being through the food chain. Excessive levels of heavy metal can be damaging to the organism and plants by disrupt metabolic functions of vital organs and glands. Also they displace the vital nutritional minerals from their original place, thereby, hindering their biological function. Therefore it is important to continually assess and monitor the levels of heavy metals in an environment due to increase in anthropogenic activities for evaluation of human exposure and for sustainable environment The aim of this paper is to discuss illustratively environmental (air, soil and water) pollution by heavy metals. Sources of heavy metals in an environment as well as their effects on organisms and plants were examined. Different methods of assessing their level of pollution were also considered and remedies were presented.

This work was designed to explore the phytochemicals, elemental and proximate analysis of Maerua angolensis Stem bark were determined using standard analytical methods. The phytochemical screening showed alkaloid (271.30 mg /100 g), tannins (340.25 mg /100 g), flavonoid (176.85 mg /100 g), reducing sugar (41.20 mg /100 g), glycosides (184.30 mg /100 g), steroids (112.30 mg /100 g), anthraquinones (167.85 mg /100 g) and saponin (225.61 mg /100 g). Also the elemental analysis carried out revealed that the concentration of Manganese (0.02 9 mg/kg), Copper (0.059 mg/kg), Calcium (0.070 mg/kg), Sodium (7.530 mg/kg), Zinc (0.028 mg/kg), Chromium (0.158 mg/kg), Lead (0.007 mg/kg), Iron (0.100 mg/kg) and Magnesium (0.020 mg/kg). The result of the proximate composition showed  that the moisture, fat, crude protein, crude fibre, ash, carbohydrate and energy value content of the samples were 3.58±0.04%, 6.25±0.09%, 21.79±0.26%, 48.51±2.31%, 13.28±1.86%, 6.60±1.79% and 169.81±8.49  kcal/100 g respectively. The pH value obtained was 5.65±0.09. These indicate that the plant can be effective source for drugs. The elemental and proximate analysis shows that it contained appreciable amount of nutrients which could be included in diets to supplement human daily nutrient needs and animal.

Heavy metal concentration in roadside soil and plants are increasingly becoming of health concern. This work determined the concentration of selected heavy metals (Cd, Pb, Zn, Cr, Fe, Mg, Mn, Co, Ni and Cu) in roadside soils and plants samples from selected sites (Plaifu, Shiwa, Fadama-rake and Damdrai) along major road in Hong. Soil samples were taken 10 m, 20 m and 30 m away from the edge of the road at the  depth of 0-10 cm, 10-20 cm and 20-30 cm. Plant samples were randomly collected within the vicinity where the soil samples were taken and were analysed using Atomic Absorption Spectrophotometer. The result revealed the trend in soil heavy metal concentration was Fe > Mn > Mg > Pb > Zn > Ni > Co > Cu > Cr > Cd and for plant the trend was Fe > Mn > Mg > Zn > Pb > Ni > Cu > Cd > Co > Cr. The concentrations decreased with increasing distance away from the edge of the road as well as with depth at which the soil sample were taken. The transfer factor showed that the concentration of Zn, Mn, Cu and Mg were greater than 1, which shows that plant were enriched by Zn, Mn, Cu and Mg from the soil. Mg and Cd equal to 1 at Plaifu and Damdrai. Most of the values of TF at the study area super pass 0.5, which implies that generally, the ability of bioaccumulation of these heavy metals in examined plants were relatively high.

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