Impacts of soil and water fluoride contamination on the safety and productivity of food and feed crops: A systematic review

Although a strong connection between the environmental fluoride contamination and the fluorosis disease is nowadays worldwide well documented, the knowledge on the fluoride contamination levels of cultivated crops at the basis of the human food-chain is limited and fragmented. Adopting a systematic approach, this study reviews the available literature concerning the impacts of soil and water fluoride pollution on the safety and productivity of food and feed crops at a global scale, with the aim to provide a comprehensive overview of the current state of the art. The analyses of literature highlighted that food and feed crops exposed to soil and water fluoride pollution may reach concentrations of fluoride potentially harmful to human health. Nevertheless, despite the efforts already made to assess the crop fluoride accumulation in contaminated areas of India and China, the present study brings to light the lack of knowledge still existing on this issue for some regions strongly affected by environmental fluoride contamination such as the East African Rift Valley. Concerning the impacts of fluoride on cultivated crops, many authors observed that fluoride can produce toxic effects on plants leading to oxidative stress, reduction in chlorophyll content, alterations in the levels of proline, betaine, soluble sugars, nitrogen and macro and micronutrients. However, the appearance of symptoms such as visible injuries, reduced root and shoot length and yield decline was not always observed, also at high levels of fluoride exposure, and in some cases, the biomass production was even stimulated by increasing fluoride doses. (c) 2021 Elsevier B.V. All rights reserved.