Prevalence of Skeletal Fluorosis in Northern Tanzania: A Follow-Up Study.

OBJECTIVES: Skeletal fluorosis is a metabolic bone disease caused by excessive exposure to fluoride, predominantly through contamination of drinking water. This study aimed to identify all cases of skeletal fluorosis in Tindigani village situated in Northern Tanzania. This was done following changes in drinking water sources after a previous prevalence study in 2009 in this population. METHODS: In a door-to-door cross-sectional study of Tindigani village, a sample of residents was assessed for skeletal fluorosis and dental fluorosis. Diagnosis of skeletal fluorosis was based on pre-defined angles of deformity of the lower limbs. Dental fluorosis was diagnosed and graded using the Thylstrup and Fejerskov Index. Samples from current drinking water sources underwent fluoride analysis. RESULTS: Tindigani village had a population of 1,944 individuals. Of the 1,532 individuals who were screened, 45 had skeletal fluorosis, giving a prevalence of 3.3% (95% CI=2.4, 4.3). Dental fluorosis was present in 82.5% of those examined (95% CI=79.8, 85.3). Dental fluorosis was present in all individuals with skeletal fluorosis and at higher grades than in the rest of the population. Drinking water samples were collected from 28 sources. These included piped, surface, well, and borehole water sources. Fluoride concentrations ranged from 0.45-38.59 mg/L of fluoride. CONCLUSIONS: Skeletal fluorosis is an ongoing but preventable health problem in the current population. The delivery of sustainable low fluoride piped water to this community would be of clear health benefit. This has been addressed at a local level.

A Door-to-Door Prevalence Survey of Dental Fluorosis in Tindigani, a Village in the Hai District of Northern Tanzania.

Fluoride in excess of the World Health Organisation limit of 1.5mg/L in drinking water can cause dental fluorosis (DF) in developing teeth. DF is a significant problem in the Hai District of Northern Tanzania, where there is limited access to safe piped water and groundwater is high in fluoride. A door-to-door prevalence survey of residents of Tindigani village was undertaken to assess current prevalence and severity of DF in the Hai District, and the effectiveness of previous interventions to promote low-fluoride drinking water, following a prevalence survey in 2009. DF was graded by trained assessors, utilising dental photography, and drinking water sources were sampled for chemical analysis. DF was endemic in the 563 people assessed, with a prevalence of 79.4% (CI=76.1-82.7%). Prevalence and severity were found to be higher in permanent teeth than deciduous teeth. Fluoride concentrations in non-piped water sources ranged from 2.5-38.6mg/L. Despite more households reporting the use of low-fluoride, piped water sources, compared to 2009 (82.8% versus 62%), DF remains a significant problem in Tindigani and other such communities where low-fluoride drinking water is not easily and reliably accessible. Policy makers must prioritise reliable access to low-fluoride water, especially for children as their permanent dentition develops.