Fluoride distribution in selected foodstuffs from Nakuru County, Kenya, and the risk factors for its human overexposure

Abstract

Critical data on the impacts of fluoride (F) in food systems along the Eastern Africa Rift Valley System (EARS) is needed for public health risk assessment and for the development of strategies for ameliorating its deleterious effects among the affected communities. Long-term F overexposure causes dental and skeletal fluorosis, and leads to neurotoxicity, which impacts several important body functions. Investigating F exposure pathways is of essence to inform and safeguard public health of the affected communities. The current study assessed the F levels in potatoes (Solanum tuberosum L.), beans (Phaseolus vulgaris L.) and garden peas (Possum sativa) from Nakuru County, Kenya, by potentiometric analysis using F ion-selective electrodes. It then evaluated the risk factors for excessive human exposure to F through contaminated foodstuffs. The mean F levels in the potatoes (8.50 ± 4.70 mg/kg), beans (8.02 ± 4.12 mg/kg) and peas (4.99 ± 1.25 mg/kg) exceeded recommended dietary allowances (RDA) level of 4 mg/kg endorsed by US Institute of Medicine for the different categories of people. The F distribution trends in beans and potatoes reflected the environmental patterns of F contamination of the study area but the spatial extent Fin the peas indicated existence of partial resistance of the pea plants to environmental F uptake. The results indicated that both the beans and the potatoes were more liable to accumulating greater amounts of F from the environment than garden peas and that all the three foodstuffs contained high F levels that posed greater risk of F overexposure and its deleterious impacts among the young children, male populations, and in people of greater body weight and high physical activity levels.

Figure 1

Map of the study area in Nakuru County relative to the map of Kenya and map of Africa.

Figure 2

Amounts of dietary F exposure through food for boys and girls aged 1–18 years.

Figure 3

Representative plots of estimated daily F dosage (EADD) for different categories of BW and PAL by gender and by different age groups for: (a) 50 kg BW, (b) 70 kg BW, and (c) 90 kg BW males (NB: TEE is the total energy expenditure in 24 h and BMR is the basal metabolic rate).