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 Table of Contents  
Year : 2022  |  Volume : 9  |  Issue : 1  |  Page : 71-75

Prevalence and causes of endemic hydric fluorosis in a village in rural Karnataka, India

1 Department of Community Medicine, MS Ramaiah Medical College and Hospitals, Bengaluru, Karnataka, India
2 Department of Biostatistics, MS Ramaiah Medical College and Hospitals, Bengaluru, Karnataka, India

Date of Submission16-Dec-2020
Date of Decision11-Jan-2021
Date of Acceptance29-Jul-2021
Date of Web Publication18-Oct-2022

Correspondence Address:
Arjunan Isaac
Department of Community Medicine, MS Ramaiah Medical College and Hospitals, Bengaluru - 560 054, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/cjhr.cjhr_174_20

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Background: Fluorosis is caused because of excessive fluoride intake. Karnataka is one among the states that have reported high fluoride content in the groundwater. This study aimed to determine the prevalence of and clinical manifestations suggestive of fluorosis, along with the causes for fluorosis among the population of Kaiwara village. Methodology: The present cross-sectional survey was performed among 3003 permanent residents of Kaiwara village. Demographic details such as age, occupation, education, economic status, and anthropometric details were recorded. Parameters such as predominant diet, genu valgum, and grades of goiter were studied and recorded to determine their association with fluorosis. Dean's index was used to detect dental fluorosis. The levels of fluoride in urine were estimated using the ELICO-LI-126 Fluoride ion analyzer. Results: The most observed age group among study subjects was 10–49 years (males: 813 and females: 1304). Age, diet, genu valgum, and grade of goiter were significantly (P < 0.001) associated with Dean's index. Of the study subjects, about 11.8% were unable to touch their toes indicating fluorosis. 2.075 mg/dl was the mean baseline fluoride level found in all the four samples from the main water tanks supplying water to the village. Out of 100 urine samples randomly taken, all had fluoride levels above the acceptable levels (>0.1 ppm). Conclusion: Hydric fluorosis is endemic among the general population of Kaiwara village in Karnataka. The main leading cause for fluorosis occurrence in this region might be due to high fluoride levels reported in the groundwater.

Keywords: Age groups, dental, genu valgum, goiter, urinalysis

How to cite this article:
Isaac A, Pruthvish S, Radhika K, Murthy N S. Prevalence and causes of endemic hydric fluorosis in a village in rural Karnataka, India. CHRISMED J Health Res 2022;9:71-5

How to cite this URL:
Isaac A, Pruthvish S, Radhika K, Murthy N S. Prevalence and causes of endemic hydric fluorosis in a village in rural Karnataka, India. CHRISMED J Health Res [serial online] 2022 [cited 2023 Apr 1];9:71-5. Available from: https://www.cjhr.org/text.asp?2022/9/1/71/358841

  Introduction Top

Fluorosis, a serious health problem and a systemic disorder, is caused due to excessive ingestion of fluoride. The World Health Organization (WHO) states that fluorosis is endemic in 25 countries globally.[1] In India, it is endemic in ten states and an estimated 25 million people are affected by fluorosis. Out of the ten, five states are known to be hyperendemic, where 50%–100% of the districts are affected, namely Andhra Pradesh, Tamil Nadu, Uttar Pradesh, Gujarat, and Rajasthan. Groundwater passes through the rocks that carry a great amount of fluoride and hence are rich in fluoride content.[2]

Fluoride is an important element that aids in the enamel formation in the teeth.[3] However, prolonged exposure to fluorides in excessive amounts may lead to dental, skeletal, and nonskeletal fluorosis with symptoms of fatigue, muscle weakness, dyspepsia, polydipsia, polyuria, anemia, male infertility, abortions, and repeated stillbirths.[3],[4] Hence, it is obligatory to limit the fluoride concentration to an optimum level.[3] The Bureau of Indian Standards has specified that 1.0 mg/L should be the maximum desirable limit of fluorides in drinking water and 1.5 mg/L should be the permissible limit in the absence of any alternative sources.[3]

Karnataka, one among the South Indian states, has also reported high fluoride concentration in the groundwater.[5],[6] Districts that are endemic for fluorosis here are Raichur, Belgaum, Bijapur Gulbarga, Tumkur, Mandya, Mysore, Mangalore, Chitradurga, Shimoga, Chikmagalur, Bangalore rural, and Kolar. Kaiwara, a rural village, presently comes under Chikkaballapur district in South Karnataka but was previously a part of Kolar district. This village was chosen for our survey to assess the prevalence of endemic hydric fluorosis.[7] The literature on fluorosis among the population of Kaiwara village, Chikkaballapur district, is scarce. The aim of the current study was to assess the prevalence, clinical manifestation suggestive of fluorosis, and the causes for fluorosis among the population of Kaiwara village.

  Methodology Top

The present cross-sectional survey was conducted among the permanent Kaiwara village residents for the period from January 2011 to December 2011. Permission from the Community Development, Grama Panchayat, and Medical Officer was obtained prior to the study commencement. We approached the Institutional Ethical Committee to obtain ethical clearance for the present study.

The pilot study conducted revealed that the prevalence of dental fluorosis among the general population was 35%, with a relative precision of 5%. Keeping the power of study at 80% and an alpha error of 5%, the required sample size was estimated to be 2854. Out of the 4097 residents who stayed permanently at Kaiwara village, 3003 subjects were available for examination during the survey time and the same were included in the study.

A preliminary count and numbering of houses of permanent Kaiwara village residents was done. Trained medical interns posted in Kaiwara recorded the data in a pretested structured protocol. The data collection team of interns, including the investigator, was trained by dental faculty posted in the Community Dentistry unit based in Kaiwara village in using Dean's index for measuring dental fluorosis. During the house-to-house survey, every tenth house was counterchecked by the investigator to maintain integrity and consistency in the data collected and also to minimize observer bias in the study.

Data collection

Demographic details such as age, education, and occupation were collected from the head of the family using a direct interview method. The socioeconomic status was recorded using the updated BG Prasad's classification.[8] Anthropometric measurements were done as per the established standards.

Signs of fluorosis were determined using the illustration chart published by Dr. Susheela.[9] These tests were piloted and used as part of the protocol [Supplementary Material 1]. The information about the predominant diet consumed during the last year was taken considering the staple diet in the region, i.e. either rice or ragi. Dean's index was used to grade the degree of dental fluorosis after examining the subjects for the absence or presence of dental fluorosis.[10] The degree of genu valgum was evaluated with the help of the distance present between the medial malleoli at the ankle calculated using a divider and a plastic scale when the subject would lay down or stand with knees touching each other and graded accordingly as mild (<5 cm), moderate (5–10 cm), or severe (>10 cm). Operationally, those subjects with moderate as well as severe degrees were categorized as having genu valgum.[11] Goiter was detected using the WHO criteria, as fluoride is known to interfere with the activity of the deiodinases and can cause goiter by itself.[12]

From the four main water tanks which supply Kaiwara village, which in turn are supplied by 12 surrounding bore wells, water samples were collected and sent for complete chemical analysis using ion chromatography to the Public Health Institute in Bangalore. Due to the awareness campaign and the good rapport with the community, it was possible to collect 100 urine samples randomly from permanent Kaiwara residents keeping age and sex distribution proportional. Fluoride levels in urine were estimated using the ELICO-LI-126 Fluoride ion analyzer.

Statistical analysis

SPSS v18 (IBM, Bengaluru, India) was used to analyze the data. Categorical data were expressed in number (%) and assessed using Chi-square test. The association between the dental fluorosis and its contributing factors or cofounders such as predominant diet, age, and grade of goiter was assessed using Chi-square test. Statistical significance was considered as P ≤ 0.05.

  Results Top

Most of the study subjects were between the age group of 10 and 49 years (67% in males and 73% in females) with male predominance (19.4%) whereas females in 20–29 years' age group (22.4%). Majority of the subjects studied belonged to social class 3 (37.7%) followed by class 2 (32.7%) and 4 (19%), as shown in [Table 1].
Table 1: Distribution of study subjects by age and gender and per capita income

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The prevalence of very mild-to-mild grades of dental fluorosis was significantly higher in the population who were predominantly rice consumers (30.1%). 10–19 years (34.9%) was the most affected age group by very mild-to-mild grades of dental fluorosis [Table 2]. In subjects with Grade 2 goiter (42.1%) and with intermalleolar distance between 5 and 9.9 cm, the prevalence of very mild-to-mild categories of dental fluorosis was significantly high. Overall, 65.3% of the subjects studied had normal/questionable changes in their teeth, while 25.8% had very mild/mild fluorotic changes and 8.9% showed clear-cut fluorotic changes in the teeth. Age, diet, genu valgum, and grade of goiter were found to be significantly associated with Dean's index (P < 0.001).
Table 2: Association of age, predominant diet, intermalleolar distance, and grade of goiter with Dean's index

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When tested for signs of fluorosis, about 11.8% of the subjects studied were unable to touch their toes and 2.3% of the subjects studied could not touch their chest with their chin [Table 3]. The mean baseline fluoride level in all four untreated water samples was 2.075 mg/dl. None of the water samples showed visible turbidity, and physical appearance was clear in all the water samples [Table 4].
Table 3: Tests for signs of fluorosis in the study population

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Table 4: Complete chemical analysis of baseline water at Kaiwara village before intervention

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All 100 urine samples studied had fluoride levels above the acceptable levels which was 0.1 ppm or more [Table 5]. Of these, 21.0% of people excreted a fluoride concentration of more than 2.0 ppm in the urine and 71.0% excreted a fluoride concentration of 0.5–2.00 ppm in the urine. Although the proportion of subjects in both the genders in the various grades of urine fluoride levels was almost similar, the difference was statistically insignificant (P = 0.148).
Table 5: Urine analysis for fluoride levels in both the gender

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  Discussion Top

Although fluoride is an essential element in the body, its excess ingestion causes fluorosis and sometimes irreversible damage to health and affects an individual's quality of life. It is, therefore, necessary to monitor the fluoride content present in regions where fluorosis is endemic. This survey was conducted to confirm the magnitude of the problem and identify the causes for the same in Kaiwara village.

In the study, 34.7% was the overall prevalence of dental fluorosis among residents. Similar cross-sectional surveys conducted in various parts of India recorded a comparable prevalence, such as Chidambaram taluk, Tamil Nadu (31.4%), Udaipur, Rajasthan (36.3%), and Raichur district, Karnataka (32.6%).[13],[14],[15] A fluoride intake that is higher than the permissible limit could be a possible reason for skeletal and dental fluorosis.

In our study, the prevalence of very mild and mild fluorosis was significantly higher among 10–19 years' age group when compared to adults. This finding is in accordance with the study conducted in Kolar which showed that the prevalence of dental fluorosis was higher among 11–15 years' age group (48.34%), followed by 16–20 years (26.42%). Another study in Solapur district, Maharashtra, also recorded similar findings, where 11–20 years was the most affected age group followed by 1–10 years, with the prevalence decreasing with increase in age, which corresponds well with the present study.[3]

Studies conducted by different authors in different regions have reported that in addition to consumption of fluorinated water, fluoride from other sources such as air (contaminated with industrial waste), food, and excessive use of fluoridated toothpaste may increase the risk of dental fluorosis.[16],[17] It has been reported that developing countries with normal fluoride content in drinking water have a high fluorosis rate due to nutrition and type of diet followed.[17] Similarly, in our study, there was a significant association of dental fluorosis with diet followed.

Genu valgum and dental fluorosis are the two most serious manifestations that occur due to increased fluoride levels in drinking water.[18] A significant association between genu valgum and dental fluorosis was found in a study conducted by Arvind et al., which was consistent with our study.[19] The literature also reports that high intake of fluoridated water is a significant risk factor for and leads to the development of thyroid disorders.[19] A study conducted by Shashi et al. in Bathinda district, Punjab, found a rampant syndrome of low triiodothyronine among study subjects due to chronic fluorosis.[20] A study in Agra also reported that the thyroid dysfunction in the subjects studied was due to excessive ingestion of fluoridated water.[21] In another study, conducted in Delhi, it was reported that excessive fluoride intake led to thyroid hormone imbalance in 90 children aged 7–18 years.[22] Similarly, in our study, we found a significant association between goiter and fluorosis.

After complete chemical analysis, it was found that all the water samples that were collected from different places of Kaiwara village had an excess of fluoride concentration, which indicated that they were unfit for potable purpose. In humans, direct determination of fluoride exposure is difficult as well as expensive, especially in children.[23] The estimation of urine fluoride concentration is considered an alternative and reliable biomarker of fluoride exposure in humans.[23] Moreover, half of the ingested fluoride is excreted through urine, after integration in teeth and bone. Studies have found a significant association between fluoride content excreted and fluoride content in drinking water.[24],[25] Hence, in our study, fluoride content excreted in urine was evaluated.[26] All 100 urine samples excreted more than 0.1 ppm of fluoride in the urine, which is above the acceptable range. This biochemical observation indicates that hydric fluorosis is endemic among the general population of Kaiwara village.

The study has a few potential limitations. First, the groundwater fluoride levels may not be uniform throughout the year. Seasons and seasonal changes such as sunshine, humidity, and rainfall may fluctuate the fluoride concentration in sources of drinking water. Hence, an annual average serves as an ideal indicator of fluoride concentration. Second, to determine the prevalence of fluorosis, only dental fluorosis was assessed using Dean's index and genu valgum was measured in the current study. Investigations for skeletal fluorosis and invasive procedures such as blood fluoride along with urine fluoride levels can be performed in future studies to evaluate the long-term effect of fluoride exposure.

  Conclusion Top

It is evident from our population study that hydric fluorosis is endemic among the general population of Kaiwara village. It is also evident that high fluoride concentration in the groundwater, which is the only source of water available for drinking and cooking proposes in Kaiwara village, may be the main causative factor for fluorosis in this region. Hence, defluoridation must be undertaken in fluoride endemic areas to combat fluorosis and improve the water quality and health of the population.

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Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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