Due to the semi-arid nature of Makueni County in South-Eastern Kenya, there is a high dependence on groundwater resources for domestic use. Reliance on this source of potable water may have health implications for the population, given the presence of several naturally occurring and potentially harmful elements reported from aquifer source rocks, soil, and water in the area. A survey involving questionnaires and focus group discussions (FGDs) was conducted with 115 individuals to determine the local population’s knowledge, attitude, and perceptions of their drinking water quality and its health impacts. The results show that most respondents (67%) preferred piped water because it was pre-treated and not saline. Only 29% of the respondents were very satisfied with the taste of their drinking water, while the rest complained about varying salinity levels, ranging from slightly salty to very salty. This low satisfaction might have influenced the low daily drinking water consumption (1–2 L) by most respondents. Health issues reported by many (43%) respondents in the area include diarrhoea and gastrointestinal upsets, which may be associated with the saline nature of the drinking water. Elevated fluoride (F⁻) in the local groundwater was reported, and the health effects remain a concern. Although 91% knew someone with dental fluorosis, 53% did not know the deleterious effects of high F⁻ in drinking water. Most respondents (59%) associated the salty nature of the water with dental fluorosis, and as a result, 48% avoided drinking the salty water to prevent the condition. Despite the high prevalence and known psycho-social effects, most people did not perceive dental fluorosis as a severe health threat. The increased health risks associated with high salinity and high F⁻ in drinking water in Makueni County are poorly understood by most residents, regardless of their education, gender, or age. This warrants an immediate public health education programme and detailed epidemiological studies to determine all the health effects associated with naturally occurring, potentially harmful elements in groundwater in the area.

Makueni County, located in south-eastern Kenya, faces challenges such as limited potable water and restricted food supplies as the result of semi-aridity. High fluoride (F) concentrations have been reported in drinking water with resultant dental fluorosis affecting the local population. To determine the potential F exposure through the consumption of food crops grown in the area, F concentration was assessed in the main five locally grown and consumed crops. Additionally, the water-soluble F fraction was determined from 30 soil samples with mineralogical determination of 20 samples. Mean F concentration in the food crops was in the order; 700, 288, 71.2, 36.6, and 29 mg/kg in kale, cowpeas leaves, green grams, cowpeas (legume portion), and maize, respectively. The F concentration in farm soils ranged from 0 to 3.47 mg/kg (mean of 0.87 mg/kg) and showed a significant strong positive correlation (p = 0.03, r = 0.89) with F values in the crops. Apatite, muscovite, and biotite were identified as the F-rich minerals present. While considering two hypothetical F absorption fractions (75 and 100%), the estimated average daily dose (EADD) of F from consuming the crops ranged between 0.004 and 65.17 mg/kg/day where the highest values were from the vegetables. Most of these values were higher than the F reference dose (RfD) of 0.06 mg/kg. The estimated EADD values of several hypothetical meals prepared from the analyzed crops revealed that steamed kale and maize porridge pose the highest health risk of F associated diseases to the local population, whereas boiled cowpeas pose no health risk. Children, due to their higher daily energy requirement and low body weight, were the most vulnerable group at risk of high daily F intake relative to the RfD. These results suggest that consumption of the analyzed food crops in Makueni County may significantly contribute to F related diseases in the local population. This creates a food security issue for the area because of the potential health risks associated with these crops which are highly relied upon in the semi-arid area with a limited selection of food crops available and viable to grow.

This study investigates the pathways by which potentially toxic elements (PTEs) enter the environment during coal mining activities in Moatize, Mozambique. Using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Ion Chromatography (IC), samples of coal (n = 11), soil (n = 18), sediment (n = 4), and food crops (n = 15) were analysed. Results confirm significant accumulation of PTEs in coal. Environmental contamination is evident, as mean concentrations of Al, Co, Fe, and Mn in soil and sediments surpass the standards established by the Food and Agriculture Organization/World Health Organization (FAO/WHO). In crops, Cr (0.92–4.16 mg/kg) and Ni (0.47–1.18 mg/kg) exceeded the permissible limit (0.1 mg/kg) in 60% of samples. Enrichment factors (EF > 2) for As, Co, and Ni indicate an attribution to anthropogenic activity, whereas an extreme ecological risk (Er > 320) for As and Co suggests that mining activities are the predominant sources. The Toxicity Risk Index (TRI) indicates higher ecological stress in soils (65% high TRI) than sediments, primarily due to As and Cr toxicity. Human health assessments confirmed non-carcinogenic risks, with Hazard quotients (HQ > 1.0) for Al, Mn, and Fe in adults and Al and Fe in children. Bioaccumulation factors were higher in Cowpea than Zea mays , posing a greater risk to consumers of local food crops. Although the cumulative hazard index (HI) for Cr, Cu, Ni, and Zn remained low, Cr posed the highest carcinogenic risk, especially for adults. These findings emphasise the importance of regular monitoring and sustainable land-use practices to reduce ecological and human health risks and safeguard the Moatize ecosystem.