Substance flow analysis: a case study of fluoride exposure through food and beverages in young children living in Ethiopia

Abstract

Context: Dental and skeletal fluorosis is endemic in the Ethiopian Rift Valley. Children are especially vulnerable to excessive fluoride intake because their permanent teeth are still being formed. Strategies to reduce the total fluoride intake by children are thus warranted.

Case presentation: By combining the results of field studies in Ethiopia, the relevant pathways for fluoride intake have been identified in 28 children 2-5 years of age living in two villages on the Wonji Shoa Sugar Estate in the Ethiopian Rift Valley. The focus of the present study was to simulate the fluoride intake of the children using the methods of material flow analysis (MFA) and substance flow analysis.

Discussion: With a model based on MFA, we quantified the potential reduction in total fluoride intake given different scenarios-for example, by reducing the fluoride intake from drinking water and cooking water. The results show clearly that only by removing fluoride completely from both drinking and cooking water does the probability of remaining below the daily tolerable upper intake level exceed 50%. Both prepared food and food ingredients must be taken into consideration when assessing the total fluoride intake by children living in high-fluoride areas.

Relevance: This knowledge will help health personnel, the government, and the food authorities to give scientifically based advice on strategies for reducing the total fluoride intake by children living in high-fluoride areas in the Ethiopian Rift Valley.

Figure 1

System analysis for fluoride intake in children living on the WSSE in the Ethiopian Rift Valley. The arrows denoted by I₁ to I₁₀ are the food and beverage ingredients used for cooking (input flows). These ingredients are “processed” in the kitchen to make prepared foods and beverages (A₁ to A₆) consumed by the children (consumption flows). Shiro is the Amharic name of pretoasted, crushed beans or peas mixed with spices. When it is prepared with berberre (local spices made of red peppers and various spices), it is called meten shiro.

Figure 2

Daily estimated mean ± SD fluoride (F) intakes contributed by food and beverages, and total intakes: results according to observed fluoride concentrations in water sources for villages A and K and for four scenarios in village K (K1–K4).

Figure 3

Daily estimated mean ± SD fluoride (F) intakes contributed by ingredients used in children’s food and drinks: results according to observed fluoride concentrations in water sources for villages A and K and for four scenarios in village K (K1–K4). Foods such as fish sauce were not consumed during the period observed but are part of the diet.

Figure 4

Daily estimated mean ± SD fluoride (F) intakes contributed by different food and drink items: results according to observed fluoride concentrations in water sources for villages A and K and for four scenarios in village K (K1–K4). Foods such as fish sauce were not consumed during the period observed but are part of the diet.

Figure 5

Relative contributions of prepared foods, beverages, and their ingredients to estimated daily fluoride intake in children from villages A and K.