Health impact of supplying safe drinking water containing fluoride below permissible level on flourosis patients in a fluoride-endemic rural area of West Bengal

BACKGROUND: The problem of high fluoride concentration in groundwater resources has become one of the most important toxicological and geo-environmental issues in India. Excessive fluoride in drinking water causes dental and skeletal fluorosis, which is encountered in endemic proportions in several parts of the world. World Health Organization (WHO) guideline value and the permissible limit of fluoride as per Bureau of Indian Standard (BIS) is 1.5 mg/L. About 20 states of India, including 43 blocks of seven districts of West Bengal, were identified as endemic for fluorosis and about 66 million people in these regions are at risk of fluoride contamination. Studies showed that withdrawal of sources identified for fluoride often leads reduction of fluoride in the body fluids (re-testing urine and serum after a week or 10 days) and results in the disappearance of non-skeletal fluorosis within a short duration of 10-15 days. OBJECTIVE: To determine the prevalence of signs and symptoms of suspected dental, skeletal, and non-skeletal fluorosis, along with food habits, addictions, and use of fluoride containing toothpaste among participants taking water with fluoride concentration above the permissible limit, and to assess the changes in clinical manifestations of the above participants after they started consuming safe drinking water. MATERIALS AND METHODS: A longitudinal intervention study was conducted in three villages in Rampurhat Block I of Birbhum district of West Bengal to assess the occurrence of various dental, skeletal, and non-skeletal manifestations of fluorosis, along with food habits, addictions, and use of fluoride containing toothpaste among the study population and the impact of taking safe water from the supplied domestic and community filters on these clinical manifestations. The impact was studied by follow-up examination of the participants for 5 months to determine the changes in clinical manifestations of the above participants after they started consuming safe drinking water from supplied domestic filters and community filter with fluoride concentration below the permissible limit. The data obtained were compared with the collected data from the baseline survey. RESULTS: The prevalence of signs of dental, skeletal, and non-skeletal fluorosis was 66.7%, 4.8-23.8%, and 9.5-38.1%, respectively, among the study population. Withdrawal of source(s) identified for fluoride by providing domestic and community filters supplying safe water led to 9.6% decrease in manifestation of dental fluorosis, 2.4-14.3% decrease in various manifestations of skeletal fluorosis, and 7.1-21.5% decrease in various non-skeletal manifestations within 5 months. Following repeated motivation of participants during visit, there was also 9.7-38.1% decrease in the usage of fluoride containing toothpaste, and 9.8-45.3% and 7.3-11.9% decrease in the consumption of black lemon tea and tobacco, respectively, which are known sources of fluoride ingestion in our body and have an effect on the occurrence of various manifestations of fluorosis following drinking of safe water from domestic and community filters. CONCLUSION: Increased prevalence of dental, skeletal, and non-skeletal fluorosis was found among the study population. Withdrawal of source(s) identified for fluoride by supplying domestic and community filters, dietary restriction, and other nutritional interventions led to decrease in manifestation of the three types of fluorosis within 5 months.