Epidemiology of skeletal fluorosis in Wonji Shoa Sugar Estate, Wonji, Ethiopia: a community based survey.

INTRODUCTION: Endemic skeletal fluorosis is a form of chronic fluoride intoxication resulting from ingestion of excessive quantities of fluoride through drinking water. It is an important public health problem in parts of several developing countries including Ethiopia. OBJECTIVE: The aim of this study is assess the magnitude of the problem at the community level. MATERIALS AND METHODS: This community based, cross-sectional study was undertaken in Wonji-Shoa Sugar Estate. (WSSE). A base line census of the adult population of WSSE was carried out at the beginning of the study. A total of 578 subjects were selected by simple random sampling using a sampling frame which was prepared from the census results. For each study participant, information on socio-demographic characteristics, possible risk factors gathered and X-ray of the forearm PA and Lateral were taken using standard x-ray techniques. RESULTS: The overall prevalence of skeletal fluorosis is 65.7%, with male to female prevalence ratio of 79.3% vs. 53%. The crude analysis of factors associated with skeletal fluorosis shows that, males than females and manual workers than others had significantly higher risk (Crude OR = 3.39, 95% CI = 2.31-4.95 and OR = 3.22, 95% CI = 2.20-4.72 respectively). On logistic regression, only sex, age and camp of residence remained significantly associated with skeletal fluorosis. Adjusted for other factors, males were more likely (about 2.5 times to be at risk than females and older people of age 55 years and above had about 20 times higher risk than young adults of age 15-24. CONCLUSION: The finding of very high prevalence of radiological skeletal fluorosis (SKF) in this study highlights the importance of endemic SKF as a public health problem. Therefore, prompt measures are required to provide the community with safe drinking water to prevent development of crippling skeletal fluorosis.

Lead levels in primary teeth in children from urban and rural areas in Ethiopia.

BACKGROUND: Lead (Pb) is one of the most important and widely distributed pollutants in the environment. Lead concentration in human primary teeth reflects children's exposure to the metal during early life. OBJECTIVE.: In this study we wanted to get preliminary information of the level of lead exposure in Ethiopian children in rural as well as urban areas. METHODS: Primary incisors, exfoliated 1998-2000, were collected from Addis Ababa, the capital, and two rural villages in the Rift Valley. The teeth were analyzed for lead concentrations by graphite furnace atomic absorption Spectrophotometry. RESULTS: Very high lead concentrations were not found. However, teeth from Addis Ababa had statistically significant higher lead concentrations than teeth from the Rift Valley. Teeth from both villages showed very low Pb-concentrations, but one village (Village A) had significantly higher concentrations than the other (Village K). The living conditions of the two villages were similar, the main diference being the fluoride content of the drinking water. The village with the lowest tooth-lead had the highest fluoride concentration. CONCLUSION: Our findings indicate that child lead exposure in Ethiopia is relatively low, especially in the rural populations.

Dental fluorosis in children in areas with fluoride-polluted air, high-fluoride water, and low-fluoride water as well as low-fluoride air: a study of deciduous and permanent teeth in the Shaanxi province, China.

OBJECTIVE: The aim of the study was to assess dental fluorosis (DF) in the deciduous and permanent teeth of children in areas with high-F coal (area A) and high-F water (area C) compared to children from area B, with low-F water and coal. MATERIAL AND METHODS: 596 children were examined. DF was assessed by TF-score. F-content of indoor air, drinking water, coal, tea, rice, and maize was analyzed. RESULTS: F-content of air and coal ranged from 3.2 microg/m(3) and 25.8 mg/kg (area B), 3.8 microg/m(3) and 36.3 mg/kg (area C) to 56.8 microg/m(3) and 713.1 mg/kg (area A). Likewise, mean F-content of water ranged from approximately 0.50 mg/l (areas A and B) to 3.64 mg/l (area C). F-content of tea leaves was similar in all three areas. Maize and rice contained <5 mg F/kg. Prevalence of primary teeth with DF was 49.1%, 2.0%, and 66.8% in areas A, B, and C, respectively. Similarly, DF was found in 96.7% (area A), 19.6% (area B), and 94.4% (area C) of the permanent teeth. Severe fluorosis (TF > or = 5) was found in area A (47.0%) and area C (36.1%) (p<0.01). Early erupting teeth had slightly higher mean TF-scores in area A than in area C. CONCLUSIONS: DF was prevalent in both dentitions in areas A and C. Similarity in percentages of DF may indicate that indoor air with approximately 60 microg F/m(3) and drinking water with 3.6 mg F/L are similarly toxic to developing permanent teeth. The percentage of deciduous teeth with DF was significantly lower in area A compared to area C. Where low-F coal and low-F water were used (area B), approximately 20% of permanent teeth had DF, indicating a relatively low tolerance to fluoride in Chinese children brought up under the present living conditions.

The geographic distribution of fluoride in surface and groundwater in Ethiopia with an emphasis on the Rift Valley.

This paper analyzes the most extensive database on fluoride distribution in Ethiopia. Of the total 1438 water samples tested, 24.2% had fluoride concentrations above the 1.5 mg/l recommended optimum concentration recommended by WHO. Regionally, by far the highest fluoride levels were recorded in the Rift Valley, where 41.2% of all samples exceeded the 1.5 mg/l level. Only 1.0% of the samples from the central and northwestern highlands and 10.0% in the southeastern highlands exceeded 1.5 mg/l. Larger proportions of deep wells (50.0%) and hot springs (90.0%) than shallow wells (27.2%) and cold springs (12.6%) exceeded the 1.5 mg/l level. The highest fluoride concentrations were recorded for Rift Valley lakes Shala (264.0 mg/l) and Abijata (202.4 mg/l) and the lowest in Lake Tana, and rivers, wells and springs in the highlands. The fluoride concentrations of the Awash River, which originates in the highlands and flows through the Rift Valley, increase downstream, giving concern over the current diversion of high-fluoride water from Lake Beseka. Of the various flourosis prevention methods tried in Ethiopia, the treatment of surface water has been shown to be the most feasible and effective for towns and large commercial farms in the Rift Valley, although defluoridation methods should be considered for smaller rural communities.

Tealeaves may release or absorb fluoride, depending on the fluoride content of water.

As the tea plant (Camellia sinensis) is known to accumulate fluoride from the soil, the tealeaves may contain high concentrations of fluoride, which is easily released during infusion. In this study, we have tested the possible effect of original fluoride concentration in the water on the fluoride release from tea. Moreover, we wanted to test the possible capacity of tealeaves (commercially available tea) to absorb fluoride from high-fluoride water. In low-fluoride water, fluoride is easily released from tealeaves. Depending upon the fluoride content of the water, dried tealeaves are able also to absorb fluoride. Thus, if a cup of tea is made from high-fluoride water, the fluoride concentration of the infusion may actually be lower than the original fluoride concentration of the water.

Dental fluorosis and dental caries in permanent teeth: rural schoolchildren in high-fluoride areas in the Shaanxi province, China.

OBJECTIVES: To study the dental fluorosis and caries in the permanent teeth of 12 to 13-year-old children in fluorosis-endemic areas; to assess the relationship between fluorosis and the fluoride content of the drinking water and the relationship between caries and the fluoride content of the water; finally, to analyze the effect of fluoride intake and water stored in clay pots on dental fluorosis. MATERIAL AND METHODS: 477 children were divided into 5 groups (A to E) according to the fluoride concentration of the waters, i.e. by 0.4, 1.0, 1.8, 3.5, and 5.6 mg F/l, respectively. Dental fluorosis was assessed by TF score and caries by the DMF-T index. A questionnaire was used to obtain information about water storage and other information relevant to children's fluoride intake. RESULTS: A positive relationship was found between the mean TF scores and the water fluoride concentration. In groups B and D, the TF score was higher in 13-year-olds than in 12-year-olds. Caries prevalence and mean DMF-T ranged from 2.6% and 0.03 (group E) to 22.1% and 0.38 (group A). Storage of water in clay pots seemed to increase the severity of fluorosis slightly, and to decrease the caries prevalence. CONCLUSIONS: Defluoridation of drinking water, or--alternatively--the provision of low-fluoride water sources, should be given high priority in the examined Shaanxi rural areas. Fluoride concentration of drinking water should be maximum 0.6 mg/l. Storage of water in the local clay pots may increase the severity of dental fluorosis.

The relationship between dental caries and dental fluorosis in areas with moderate- and high-fluoride drinking water in Ethiopia.

OBJECTIVE: The aim of the study is to assess the relationship between caries and dental fluorosis in Ethiopian children living in Rift Valley areas known for endemic fluorosis. METHOD: A total of 306 children (12-15 years old), selected from areas with moderate (0.3-2.2 mg/l), or high (10-14 mg/l) fluoride concentration in the drinking water were interviewed and examined for caries and dental fluorosis. Scorings were recorded according to the DMF system, and the Thylstrup-Fejerskov (TF) Index. RESULTS: Prevalence of dental fluorosis (TF-score > or = 1) was 91.8% (moderate area) and 100% (high-fluoride area). The corresponding caries prevalence and mean DMFT in the areas were 45.3% versus 61.6%, and 1.2 versus 1.8, respectively. Age and severity of dental fluorosis were found to be independent predictors for DMFT > or = 1. When compared with 12-year olds with TF-scores 0-4, odds ratios were 3.0 (95% CI 1.6-5.7) and 2.0 (95% CI 1.2-3.2) if TF-scores were > or = 5 and age 13-15 years, respectively. A positive relationship between caries and fluorosis was observed across tooth types in both areas. The percentage of children with DMFT > or = 1 was highest in groups with TF-score > or = 5 in the second molar, followed by the first molar. CONCLUSION: The present findings indicate that the second molar is the tooth most severely affected by dental fluorosis and dental caries. Dental caries increased with increasing severity of dental fluorosis, both in moderate- and high-fluoride areas. Thus, a positive relationship between dental caries and dental fluorosis was observed across various tooth types, in both areas.

[Effect of drinking water change upon the dental fluorosis].

OBJECTIVE: To assess changes in prevalence and degree of dental fluorosis in individuals born before and after the introduction of water with 1.2 mg/L fluoride instead of water with 2.0-10.0 mg/L fluoride previously used in Da Li County in China. METHODS: The students (n = 291) were divided into 2 groups. The dental fluorosis was scored according to Dean's classification. The statistical analysis was performed by t-test and chi(2) tests. RESULTS: The prevalence of dental fluorosis was significantly lower in the group of the students drinking water from the new well (group 1) as compared to the group of the students drinking the old water (group 2), i.e. 48.8% versus 87.2% (P < 0.01). The percentage of moderate to very severe fluorosis was 13.9% and 0 in group 1 as compared to 32.0% and 8.8% in group 2. The fluorosis community index (FCI), defined by Dean, in group 1 and 2 was medium (1.01) and marked (2.12) respectively. CONCLUSIONS: The results showed that: (1) The prevalence of dental fluorosis was significantly lowered by the new source of drinking water. (2) Drinking water, even with 1.2 mg/L fluoride, may cause dental fluorosis during the period of tooth mineralization.

Perception of dental fluorosis amongst Ethiopian children and their mothers.

This study was conducted in three Ethiopian Rift Valley villages known for endemic fluorosis. Three-hundred-and-six adolescents (12-15 years) and 233 mothers participated. The aim was to study dental fluorosis in the youngsters and to assess the extent of agreement between clinical and self-rated discoloration and pitting of teeth, and also the level at which dental fluorosis is perceived as a problem both by children and their mothers. The children (154 M and 152 F) gave a simple self-assessment of tooth-color and quality of their teeth, and were subsequently examined for dental fluorosis. Finally, four color photographs of teeth with dental fluorosis (TF-scores 2, 3, 5, and 7) were used as references during a structured oral interview of the children, as well as their mothers. At TF score > or = 2, the prevalence of dental fluorosis on maxillary central incisors was 72% and 37% at TF score > or = 4. The mean TF score was significantly higher among boys than among girls of unemployed fathers compared to children of employed fathers. The likelihood of reporting problems with dental appearance increased with increasing individual TF scores. The child/mother pairs found teeth with TF scores 2 and 3 esthetically acceptable, while teeth with TF scores 5 and 7 were considered unacceptable. Mothers were more critical of severe fluorosis than were their children.

Drinking water quality in the Ethiopian section of the East African Rift Valley I--data and health aspects.

Drinking water samples were collected throughout the Ethiopian part of the Rift Valley, separated into water drawn from deep wells (deeper than 60 m), shallow wells (<60 m deep), hot springs (T>36 degrees C), springs (T<32 degrees C) and rivers. A total of 138 samples were analysed for 70 parameters (Ag, Al, As, B, Ba, Be, Bi, Br, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, Dy, Er, Eu, F, Fe, Ga, Gd, Ge, Hf, Hg, Ho, I, In, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, NO(2), NO(3), Pb, Pr, Rb, Sb, Se, Si, Sm, Sn, SO(4), Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn, Zr, temperature, pH, conductivity and alkalinity) with ion chromatography (anions), spectrometry (ICP-OES and ICP-MS, cations) and parameter-specific (e.g. titration) techniques. In terms of European water directives and WHO guidelines, 86% of all wells yield water that fails to pass the quality standards set for drinking water. The most problematic element is fluoride (F), for which 33% of all samples returned values above 1.5 mg/l and up to 11.6 mg/l. The incidence of dental and skeletal fluorosis is well documented in the Rift Valley. Another problematic element may be uranium (U)-47% of all wells yield water with concentrations above the newly suggested WHO maximum acceptable concentration (MAC) of 2 microg/l. Fortunately, only 7% of the collected samples are above the 10 microg/l EU-MAC for As in drinking water.

Perception of dental fluorosis among adolescents living in urban areas of Ethiopia.

The objective of the study was to assess the perception of dental fluorosis among adolescents residing in two urban areas in Ethiopia: Addis Ababa (low-fluoride drinking water) and Nazreth (high-fluoride drinking water). Students aged 12-15 years, enrolled in two junior secondary schools in Addis Ababa (n = 161) and two similar schools in Nazreth (n = 177) responded to evaluative statements concerning the appearance of anterior maxillary teeth. Color photographs depicting dental fluorosis (TF score 2, 3, 5 and 7) in maxillary front teeth were used as reference during structured interviews. A majority of the students from Addis Ababa and Nazreth were dissatisfied with the appearance of teeth having TF scores 2 and above. More than 66% of the students from both areas confirmed a need for dental consultation concerning fluorotic teeth with TF > or = [corrected] 2. As compared to their counterparts in Nazreth, children in Addis Ababa felt more embarrassed with TF score 2 and 3 (p < 0.01). TF scores 5 and 7 were found unacceptable both in Addis Ababa and in Nazreth. Students in Addis Ababa, more frequently than their counterparts in Nazreth, believed (erroneously) that dental fluorosis were related to neglect on the part of the child. The present findings confirm that fluorotic teeth constitute a social problem among junior secondary school children residing in low-fluoride as well as in high-fluoride urban areas in Ethiopia and, thereby, corroborate the public concern for safe drinking water.

High-fluoride drinking water. A health problem in the Ethiopian Rift Valley 1. Assessment of lateritic soils as defluoridating agents.

PURPOSE: High-fluoride drinking water represents a health hazard to millions of people, not least in the East African Rift Valley. The aim of the present project was to establish a simple method for removing excessive fluoride from water. MATERIAL AND METHODS: Based on geological maps and previous experience, 22 soil samples were selected in mountainous areas in central Ethiopia. Two experiments were performed: 1. After sieving and drying, two portions of 50 g were prepared from each soil and subsequently mixed with solutions of NaF (500 mL). Aliquots (5 mL) of the solutions were taken at pre-set intervals of 1 hour to 30 days for fluoride analysis--using an F-selective electrode. 2. After the termination of the 30-days test, liquids were decanted and the two soil samples that had most effectively removed fluoride from the NaF solutions were dried, and subsequently exposed to 500 mL aqua destillata. The possible F-release into the distilled water was assessed regularly. RESULTS: Great variations in fluoride binding patterns were observed in the different soils. The percent change in F-concentration in the solutions, as compared to the original absolute value(F-), varied: at 1 hour from a decrease of 58% to an actual increase of 7.7%, while--at 30 days--all soil samples had caused a decrease in the F-concentration, varying from 0.5% to 98.5%. Only minute amounts of fluoride would leach from the fluoride-enriched soils. CONCLUSION: Lateritic soils may remove excessive fluoride from drinking water. Methods for practical application of this principle should be tested at household level.

Caries experience and caries predictors--a study of Tanzanian children consuming drinking water with different fluoride concentrations.

The aim of this investigation was to assess the role of predictors of caries experience among children in urban and rural areas of northern Tanzania. Children of the different communities had varying dietary habits and consumed water with varying fluoride (F) concentration. Subjects (n=256) aged 9-14 years were examined in high-F areas (3.6 mg F/l, Arusha and Arusha Meru, n=101) and low-F areas (<0.4 mg F/l, Moshi and Kibosho, n=155). Dental caries was assessed under field conditions using the decayed, missing, filled teeth (DMFT) index and the WHO criteria. The prevalence of caries was 14%. The mean DMFT score was 0.22 (n=256), the range between areas 0.07-0.66. Carious lesions were mainly observed in mandibular first molars. Logistic regression analyses indicated that subjects in the high-F and urban Arusha municipality were at a significantly higher risk of dental caries than children in the low-F areas (odds ratio [OR] 2.6). Controlling for ethnicity, children in urban areas were at higher risk for caries (OR 5.4) than children living in low-F rural Kibosho.