Unregulated mining of precious metals has led to pollution in the environment and food chain, as well as

outbreaks of poisoning in affected communities. However, there is limited evidence on the effect of heavy

metals on the environment and health of communities in north-central Nigeria. This study investigated the

comparative presence and concentration of some heavy metals, namely, arsenic (As), cadmium (Cd), cobalt

mg/kg, respectively, in Kataeregi; and Cd, 0.023 mg/L; Hg, 0.012; and Hg, 0.315 mg/kg, respectively, in

Kurebe. Heavy metal concentrations in staple food cultivars consumed at both mining sites were found to be

within the permissible levels set by the WHO/FAO, except for As (1.72:1.82 mg/kg), Cd (0.41:0.09 mg/kg), Ni

(0.41 mg/kg) and Hg (0.71 mg/kg) in cereals and vegetables from Kataeregi, and As (1.56 mg/kg), Hg (2.09

mg/kg), in legumes and Cd (0.43 mg/kg) in tubers from Kurebe. Also, significant elevations in the blood Pb,

11.2 µg/L; Hg, 11.1 µg/L; urea, 8.43 mmol/L and creatinine, 1.61 mg/dL and a decreased mean hemoglobin

compromised renal functioning and hematologic impairment to the accumulation of toxic heavy metals, as

evident in the clinical manifestation of inhabitants in both mining sites. Alternative safe drinking water sources,

continuously monitoring, sensitization and assessment on the potential health risks and profiles are highly

abundant mineral deposits which has led to the proliferation of artisanal mining activities in the area (Obaje et

al., 2018). Artisanal and small-scale mining (ASM) is conducted by individual miners or small enterprises with

limited capital investment and production (O’Neill & Telmer, 2017). In Nigeria, ASM has become a persistent

phenomenon due to the rising price of precious metals, coupled with the ever increasing poverty and

unemployment rates (Liman et al., 2021). ASM exposes our water bodies, soils, food chain to deliterious heavy

metals which subsequently affects human metabolomics and the entire ecological function; these which has

remained an issue of public health concern.

Heavy metals are ubiquitous elements with atomic density greater than 5 g/cm

, atomic number greater than 20,

and atomic weight greater than 40 amu (Kaur et al., 2019). The presence of heavy metals in water can be

northeastern and central Nigeria, from Zamfara to Niger, only a paucity of data on the many repercussions of

small-scale artisanal mining has been reported, ranging from environmental and food crop pollution to health

concerns and mitigation (Abdulkareem et al., 2015; Liman et al., 2021; Mallo, 2012). This study therefore

aimed to assess the comparative presence and health impacts of some heavy metals, namely, As, Cd, Co, Cr,

Cu, Fe, Hg, Ni, Pb and Zn in various samples collected from drinking water sources, soils, staple food

cultivars, and blood samples of inhabitants around Kataeregi and Kurebe mining communities in Niger State,

Nigeria. This study is necessary and timely, as the findings may likely constitute a vital planning tool that

could be streamlined into the green economy blueprint of the State government.

The study was conducted in two mining communities located in eastern and southern districts of Niger State.

10°27′46.3"N. Shiroro has a population of 235,404 and a land area of 5,558.0 sq km (NPC, 2006). The

community is split into neighbouring villages of Rafin Kanya, Gidan Zarmai and Dagwachi, with a large

proportion of Hausa and Gbagyi tribes engaged in artisanal small-scale mining operations and local farming of

crops such as sorghum, millet, soybeans, groundnut, cowpeas, yam, and maize (Fashae et al., 2017). The

temperature is highest with an average value of 28.7°C in April and lowest with an average value of 23.9°C

around August annually (Nigerian Meteorological Agency [NMA], 2014).

In both communities, a total of 30 water samples were collected using Grab method from the available drinking

water sources (river, stream, well and borehole) from the mining communities within the period of three

Quintuplet samples of each staple crops, classified as tubers: yam (Discorea rotundata) and cassava (Manihot

esculenta); legumes: beans (Phaseolus vulgaris) and soybean (Glycine max), and leafy vegetables; okra

(Abelmoschus esculentus), Roselle (Hibiscus sabdariffa) and amaranth (Amaranthus retrofleus); cereals: maize

(Zea mays), guinea corn (Sorghum bicolor) and millet (Pennisetum glaucum) were randomly collected at study

sites. Staple crop cultivars were thoroughly washed with deionised water to prevent airborne contaminants and

oven dried at 80 °C until stable weight was obtained (Chiroma et al., 2019). The dried cutivars were then

ground in a mortar, sieved, and kept for heavy metal analysis.

A total of 40 surface and sub-surface (20-30 cm below the surface) soil samples each, were collected randomly

around the mining sites ( Kataeregi and Kurebe) at a distance of not less than 1 km apart, using a plastic spoon

and put in a labeled polyethylene bag. The samples were air dried in the laboratory, ground with mortar and

pestle, and then sieved with a 2mm mesh. The sieved samples were stored in labeled polyethene bags prior to

blood collection and transferred into a refrigerator at 4 °C (Cornelis et al., 2005). Site of the venipuncture were

thoroughly swabbed to avoid external contamination of the blood sample. Renal function parameters were

determined using Rayto RT-9200 Semi-auto Chemistry Analyser. Hematologic parameters of Mean

corpuscular volume (MCV), Hemoglobin (Hb) were analyzed by DIATRON Abacus 380 Hematology

Analyzer (Diatron-A380, Hungary).

All participants were given written copies and verbal explanations of the informed consent to participate in the

study, and ethical approvals were obtained from the Research, Ethics and Publication Committee of General

Hospital Minna (HMB/126/VOL.II/792) and Niger State Ministry of Health Ethical Review Committee

(ERC/PAN/2022/03/21).

acid (HNO

filter paper to 100 mL. The concentrations of the metals in blood and the digested solutions were determined

using Shimadzu AA 500 Atomic Absorption Spectrophotometer (WINPRO-AAS500VGP. Spectrum, USA), at

wavelengths and slits specific to each metal.

Results were expressed as the mean ± standard deviation and values of mean were calculated and two-factor

without replication ANOVA was used to ascertain the relationships between the heavy metals in media

analysed. Microsoft Excel was adopted to compare the graphical distribution of the contaminants in the study

area. The results were discussed and compared with the reference standards with respect to the associated

Table 1: Mean concentration (mg/L) of heavy metals in water samples from Kataeregi and Kurebe (WHO,

2011 & NSDWQ, 2015).

Table 2: Mean concentration (mg/kg) of heavy metals in surface and sub-surface soil samples from Kataeregi

and Kurebe.

Fig. 3: Mean concentration of Cr, Hg & Ni in staple food crops consumed at Kataeregi and Kurebe mining

communites.

To better reflect the heavy metal concentration in staple crops across the two study areas, variety of staple

crops collected were classified into four groups (cereals, legumes, vegetables and tubers). The mean

concentrations of heavy metals in staple crops from Kataeregi and Kurebe were calculated and presented in

Figures 1-3. The mean concentrations of As, Cd, Hg, Ni from staple crops in Kataeregi were 1.72, 0.41, 0.71,

0.41 mg/kg in cereals; 1.10, 0.03, 1.00, 0.04 mg/kg in legumes; 1.82, 0.09, 0.15, 0.61 mg/kg in vegetables,

0.63, 0.09, 0.91, 0.05 mg/kg in tubers, respectively. The results also reveals that the bioaccumulation pattern of

heavy metals in this study indicates the trend Fe>Zn>Cu>As>Hg>Ni>Cd>Cr>Pb in cereals just as revealed in

the findings of Tegegne (2015), and a slightly different order occurred in the case of vegetables:

Fe>Zn>Cu>As>Ni>Cr>Hg>Cd>Pb, irrespective of the study areas; Kataeregi and Kurebe mining sites. The

concentration of Cd in the vegetables varied significantly with the leafy vegetables having higher values. Leafy

vegetables have been linked with high absorption rates because of their large surface area (Latif et al., 2018).

Dubey, (2019), but much higher than the values reported by other researchers (Abiya et al., 2019; Orisakwe et

al., 2017; Ratul et al., 2018).

Table 3. Characteristics of the population

A total of 100 subjects from Kataeregi and Kurebe mining communities were recruited in this study, with their

demographic characteristics depicted as seen in table 3 above. 100 blood samples were collected from local

personal information, employment status, lifestyle and education level.

Table 4. Mean concentrations of heavy metals, urea, creatinine and hematological parameters among human

participants in Kataeregi and Kurebe.

This environmental epidemiologic study on the mining areas, evaluated heavy metals levels and their

correlations with hematologic and renal function indicators for miners and inhabitants of Kataeregi and Kurebe

mining communities.

The mean blood heavy metal levels analysed among Kurebe inhabitants were well within the stipulated

reference values, with a slightly below the hematologic reference for blood hemoglobin (Hb) and mean

corposcular volume (MCV) values. On the other hand, biochemical assays of blood samples from inhabitants

in Kataeregi mining area revealed elevated levels of urea and creatinine, with correspondingly decreased blood