Table of Contents
Background
Fluoride (F) is a naturally occurring element found in various forms in different environmental compartments including water, soil, and air. Studies suggest that Fluoride can have both positive and negative impacts on humans depending upon the level of exposure. Fluoride is beneficial for dental health in small amounts and helps prevent tooth decay by strengthening tooth enamel making the teeth resistant to the acids produced by bacteria in the mouth. However, exposure to high Fluoride concentration may lead to dental fluorosis. A medical condition that causes discoloration and damage to bones and teeth. In more severe cases, Fluoride may result in pitting, cracking, and even teeth loss. In addition to its role in dental health, research has highlighted other fluoride health benefits, such as its potential to strengthen skeletal integrity when consumed in appropriate amounts. Furthermore, fluoride can help reduce the incidence of cavities in populations with limited access to dental care, providing a cost-effective public health measure to improve oral hygiene. However, it is crucial to maintain a balance, as excessive fluoride intake can negate these advantages and lead to adverse health effects.
Excessive Fluoride intake can also lead to many other health implications including skeletal fluorosis which is a condition causing bone and joint pain. Further, Fluoride is a known neurotoxicant and has been associated with various neurological disorders. Especially in children, its high exposure has been positively correlated with reduced cognitive functions, stunted growth, and bone deformation. Other adverse health impacts associated with excessive Fluoride exposure include thyroid dysfunction, endocrine disorders, and cancers. Fluoride has been reported to occur in drinking water through various natural and anthropogenic sources. The natural Fluoride levels in drinking water can vary depending on the geology of an area. For example, some regions contain high Fluoride levels naturally that can cause dental fluorosis while others have as low levels that it is necessary to add Fluoride to drinking water to protect against tooth decay.
Moreover, NYC water fluoride can also be impacted by human activities involving industrial pollution (use of F-containing chemicals e. g. Al, steel, and fertilizer industries), and agricultural runoff (Fluoride-containing pesticides and fertilizers). It is also worth mentioning that Fluoride can leach into water sources from certain plumbing materials like lead pipes and old copper pipes to contaminate drinking water. Therefore, it is important to monitor Fluoride levels in drinking water to ensure that they are safe and within the permissible levels. Regular testing and analysis of water sources are vital to safeguard public health and prevent possible adverse effects from excessive fluoride exposure. Additionally, community awareness and education regarding fluoride levels in New York City can empower residents to make informed choices about their drinking water. As such, authorities must prioritize transparency by providing accessible information about water quality and any potential contaminants that may affect the population.
Fluoride is also added to drinking water to prevent tooth decay where its natural levels in water are found in low concentrations. According to CDC, the optimal Fluoride levels in drinking water typically range between 0. 7-1. 2 ppm (mg/L) and Fluoride helps prevent cavities and strengthen the teeth at these levels. Fluoridation is considered safe and effective by many public health organizations including WHO and American Dental Association (ADA). However, the excessive Fluoride levels in drinking water can be of concern due to its established adverse fluoride health effects. Therefore, it is important to monitor drinking water for Fluoride levels to ensure that the supplied water has safe limits of Fluoride. In the US, the Fluoride levels in drinking water are regulated by USEPA under SDWA which has set an MCL of 4 mg/L in drinking water. Importantly, Fluoride is added to the drinking water of many communities in the US as a public health measure to prevent tooth decay. However, some individuals prefer to avoid Fluoride in their drinking water due to concerns about potential health risks. For these individuals, understanding the benefits of nonfluoride water becomes essential, as it allows them to explore alternative sources that may align better with their health preferences. Water filtration methods such as reverse osmosis and activated alumina can effectively reduce Fluoride levels for those who choose to limit their intake.
Further, fluoridation is more common in larger cities and the eastern part of the US and according to CDC, around 74% of the US population on public water systems received fluoridated water in 2020. EPA has also established regulations for Fluoride in bottled water which are enforced by US FDA. According to EPA guidelines, bottled water must meet the same MCL as tap water (4 mg/L). Public water systems in the US are required to test water for Fluoride levels and notify their consumers if the detected levels exceed the MCL. Additionally, the water systems must take action to reduce Fluoride levels if they exceed MCL by treating the drinking water to remove excess Fluoride. It is important to note that populations having high Fluoride levels in their drinking water and using it as their primary drinking water source for extended periods are more prone to Fluoride-associated health risks. Further, people who are already suffering from certain health conditions such as kidney problems and diabetes are more susceptible to the negative effects of Fluoride exposure.
Once ingested, the metabolism of Fluoride in the body involves complex processes. It gets absorbed in the gastrointestinal tract where it gets distributed throughout the body. A major part of absorbed Fluoride is stored in bones and teeth where it helps strengthen and protect them and excess Fluoride is excreted from the urine (Kanduti et al. 2016). Fluoride also affects the pineal gland which is a small endocrine gland located in the brain. Excessive exposure to Fluoride results in its accumulation in the pineal gland which results in the inhibition of melatonin production, a hormone that regulates sleep-wake cycles (Chlubek and Sikora 2020). Toxic responses occur when the body is exposed to excessive levels of Fluoride, which leads to a range of health problems. Several possible mechanisms of Fluoride toxicity have been proposed so far.
One suggests the inhibition of enzymes involved in energy metabolism. Fluoride can bind to enzyme active sites and inactivate the enzyme function leading to decreased energy production in cells (Araujo et al. 2019). Another mechanism suggests the generation of reactive oxygen species (ROS) leading to oxidative stress that eventually causes damage to the cells and DNA (Suzuki et al. 2015). Studies also suggest that Fluoride can show synergistic toxic mechanisms with other contaminants such as Arsenic (As) in drinking water. Co-exposure to Fluoride and As has been shown to cause oxidative stress, cognitive abnormalities, and genetic polymorphisms in exposed children (Saeed et al. 2021). Fluoride can also interfere with the normal Calcium ions functioning in the cell which has high significance for many cellular processes including muscle contractions, nerve impulses, and cell signaling (Chinoy et al. 1994; DenBesten and Li 2011). Further, Fluoride can also disturb the normal functioning of the cell membrane which leads to enzyme dysfunction and disturbances in ion channels and various cellular receptors (Agalakova and Gusev 2012).
Inhibitory functions of thyroid glands have also been related to Fluoride exposure as Fluoride interferes with the production and utilization of thyroid hormones leading to various health problems such as goiter and hypothyroidism (Kheradpisheh et al. 2018). Moreover, high Fluoride levels can also result in negative effects on bones through the inhibition of osteoblasts, which are responsible for bone formation (Qu and Wei 2006). This may result in decreased bone mineral density, making the bones more prone to fractures and other bone abnormalities. It is worth mentioning that Fluoride toxicity can also have a cumulative effect over time, therefore it is necessary to keep Fluoride levels within safe limits to avoid potential health implications. Recently, epigenetic mechanisms of Fluoride toxicity associated with drinking water have also been investigated in population studies. It has been found that excessive Fluoride exposure can adversely impact the genomic DNA methylation patterns in children (Balasubramanian and Perumal 2022; Wang et al. 2021). However, additional research should be conducted to explore molecular mechanisms of Fluoride toxicity under co-exposure conditions with other contaminants such as As since limited evidence is available in this context.
Detection Methods and Removal Strategies
There are many methods available to detect fluoride in drinking water. The most commonly used is the ion-specific electrode method which uses an electrode that is specifically designed to detect Fluoride ions in a sample by placing an electrode in a water sample and passing a current through it. The voltage of the used current is measured which gives information about Fluoride ions present in water (Ruiz-Payan et al. 2005; Solanki et al. 2022). Another used method for Fluoride detection is the SPADNS (sulfo-phenyl-azo-dinitro-benzene) which is based on the reaction of Fluoride ions with SPADNS reagent that produces a colored compound. Additionally, various fluoride testing analytical techniques are employed to ensure the accuracy and reliability of fluoride measurements in water. These techniques include spectrophotometry, which can quantify fluoride concentrations by analyzing the absorbance of the colored compound formed during the reaction with SPADNS reagent. Furthermore, chromatography methods may also be utilized to separate and identify fluoride ions in complex water samples, providing a comprehensive understanding of fluoride levels present.
The detected color intensity is directly proportional to the Fluoride concentration in drinking water (Balan Pillai et al. 2012). Spectrophotometric methods are also capable of detecting Fluoride in drinking water samples which involve the measurement of light quantity absorbed or transmitted by a sample at a specific wavelength (Barghouthi and Amereih 2012). Moreover, Fluoride can also be measured through chromatographic methods in which Fluoride ions are separated from other ions in water and measuring the concentration of Fluoride ions. Each detection method has its own advantages and disadvantages and should be selected based on desired results, cost, sensitivity and accuracy of adopted method.
The detected Fluoride in drinking water can be removed using various developed methods. One method uses bone char made from animal bones that can absorb Fluoride ions from water resulting in their removal (Alkurdi et al. 2019). Porous materials such as activated alumina are also effective in removing Fluoride from drinking water by absorbing Fluoride ions from water (Cheng et al. 2014; Tripathy et al. 2006). Reverse osmosis (RO) systems have a wide application of removing a variety of contaminants from drinking water including Fluoride by passing water with pressure through a semi-permeable membrane (Shen and Schäfer 2014). Other commonly used methods for Fluoride removal from drinking water include ion exchange method and adsorption through the activated carbon.
Public Perspective
Following frequently asked questions (FAQs) try to address some general public concerns in the US, especially the NYC and NJ region.
Excess amounts of F ions in drinking water can cause dental fluorosis, skeletal fluorosis, arthritis, bone damage, osteoporosis, muscular damage, fatigue, and joint-related problems.
Almost all water contains some naturally-occurring fluoride, but usually at levels too low to prevent tooth decay. Many communities adjust the fluoride concentration in the water supply to a level known to reduce tooth decay and promote good oral health.
Bottled water products labeled as de-ionized, purified, demineralized, or distilled have been treated in such a way that they contain no or only trace levels of F unless they specifically list F as an added ingredient.
Different adsorbents are available that are used for F removal from drinking water including activated alumina, carbon, bone charcoal, and synthetic ion exchange resins.
F levels of 2.5 mg/L or higher may increase the risk of skeletal fluorosis. A condition that causes bones to break easily and causes calcium to build up in ligaments and tendons.
Exposure to higher concentrations of F could contribute to kidney damage, ultimately leading to chronic kidney disease.
This mainly includes abdominal pain, Abnormal taste in the mouth (salty or soapy taste), Diarrhea, Drooling, Eye irritation (if it gets in the eyes), Headache, Abnormal levels of calcium and potassium in the blood, and Irregular or slow heartbeat.
F is not considered an essential nutrient for humans but plays an important role in dental and bone health. A deficiency of F can lead to dental caries and potentially bone-related problems.
Absorption of F can be minimized using, calcium gluconate, calcium lactate, or milk of magnesia and aluminum, which form insoluble complexes that decrease the absorption of F. Therefore, calcium-containing compounds are used in acute F toxicity.
When ingested, F is absorbed via the stomach and intestines and passes rapidly around the body in the bloodstream. Peak blood levels appear 30-60 minutes after ingestion.
Yes, fluoride is added to New York City (NYC) water to promote dental health. The NYC water fluoride levels are carefully monitored to ensure they meet established guidelines. This practice aims to enhance oral health without compromising overall water quality.
Questions about the NYC water fluoride content are common, and it’s essential to note that the addition of fluoride is a deliberate measure for dental health benefits. The fluoride in NYC water levels are within recommended standards, and ongoing assessments ensure that the fluoridation process aligns with public health guidelines, addressing any concerns about the NYC water fluoride content.
Conclusion
Fluoride is a well-established drinking water contaminant found in various regions due to natural and anthropogenic sources. It plays role in tooth and bone formation at low concentrations however, high levels in drinking water may contribute to the development of various health abnormalities related to teeth, bones, and neurological disorders. In the US, Fluoride levels in drinking water are regulated by EPA under SDWA and there is an established MCL for its concentration in drinking water. Drinking water supplies must ensure the Fluoride levels under the MCL and if high concentrations are detected, water must be subjected to a suitable treatment strategy before its supplied to the consumers to ensure public health safety.
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- Yasir A. Rehman, Ph.D.
Dr. Rehman was born in Rawalpindi, Pakistan. He completed his MSc from PMAS – Arid Agriculture University Rawalpindi in 2011 where his thesis comprised a health risk assessment of subjects living in the vicinity of wastewater channels in urban settings and its relationship with the incidence of Malaria.
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OTHER RESEARCH ON WATER CONTAMINANTS BY DR. YASIR
