Fluoride uptake and translocation in food crops grown in fluoride‐rich soils

Abstract

BACKGROUND: The East African Rift Valley (EARV) area is characterized by an intense volcanic activity, which largely influences the nature of soils, ground and surface waters causing a transfer of fluoride from volcanic emissions to the environment. Field experiments were conducted in fluorine-contaminated areas of Ngarenanyuki (Arumeru district) in north Tanzania. In order to evaluate the potential fluoride exposure from diet and the related health risk for the local population, the content of fluoride in soil and plant tissues was assessed, focusing on the edible portions (leaves, fruits or seeds) of the main cultivated and consumed food crops in the area. RESULTS: Average fluoride contents of 8.0, 11.4, 11.3 and 14.2 mg kg −1 of dry matter were observed respectively for maize (Zea mays L.), tomato (Lycopersicon esculentum Mill.), bean (Phaseolus vulgaris L.) and kale (Brassica sp. pl.) edible parts. The cumulative estimated average daily dose (EADD) ranged from 0.026 to 0.165 mg F d −1 kg −1 among different rural population groups and considering two different hypotheses of absorption fraction (75% or 100%), i.e. the amount of fluoride that is absorbed during the digestion process. The associated hazard index (HI) values varied from 0.43 to 2.75. CONCLUSIONS: Considering the dietary habits of the local population, the outcomes of the present study suggest that the investigated crops can substantially contribute to fluoride related diseases, especially in earlier ages.

Potential fluoride exposure from selected food crops grown in high fluoride soils in the Makueni County, south-eastern Kenya

“…The vulnerability of children to higher dietary F intake than adults was also reported in northern Tanzania (Rizzu et al, 2020), eastern India (Bhattacharya et al, 2017, and southern Pakistan (Kazi et al, 2019). This was associated with a higher intestinal absorption rate and higher energy requirements relative to lower body weight in children compared to adults (Bhattacharya et al, 2017;Kazi et al, 2019;Rizzu et al, 2020;Stellman, 1998).…”

“…F health risk assessment The hazard quotient (HQ) associated with the five analyzed food crops was calculated to determine the individual health risk of food dietary F intake using the following formula (Rizzu et al, 2020), HQ = EADD/RfD. Where; RfD is the reference dose for humans associated with the 'no observable adverse effect level' (NOAEL) for F, which is set as 0.06 mg/kg by USEPA (US-EPA, 2003).…”

“…The reference dose (RfD), in red, indicates the no observable adverse effects level (NOAEL), the level below which F has on humans health effects (ATSDR, 2003). The F intake was considered at the two hypothetical absorption rates of 75% and 100% (Rizzu et al, 2020) in the top and bottom frames, respectively Fig. 5 The EADD due to the consumption of different meals prepared from the three analyzed grain-based food crops at different levels of daily energy intake per Kg of body weight, at the two hypothetical absorption rates of 75% and 100% from Makueni County Environ Geochem Health…”

Endogenous Calcium Mediated The Seedling Growth And Fluoride Stress Tolerance In Four Bean Genotypes

“…The total F content was estimated with an acid digestion method and subsequently quanti ed by F ionselective electrode (Rizzu et al 2020).…”

“…Three salt sources were added to the germination substrate (silica sand): sodium uoride (NaF); potassium uoride (KF) and sodium chloride (NaCl) and for each salt, three levels were evaluated: 0 (Control), 80 mg kg − 1 , and 200 mg kg − 1 ; treatment were reported as salt name and level (i.e. KF 80 mg kg −, is reported as KF80) The choice of salt concentration levels was based according to the range of soil F contents observed in F-rich sites of the East African Rift Valley in Tanzania as reported by Rizzu et al (2020). Control (F0) contain only silica sand.…”