Key takeaways:
~ Fluoride may help your teeth resist decay by increasing the resistance to acid produced by bacteria.
~ Too much fluoride is linked to skeletal and dental fluorosis, decreased IQ levels, and problems with thyroid hormone production.
~ Genetic variants impact your resilience to the negative effects of chronic fluoride consumption. Some people are more likely to be affected at lower levels, while others may not notice problems until fluoride exposure reaches higher levels.
~ There are many ways to reduce your exposure to systemic fluoride if you want to concentrate the fluoride on your teeth.
Members will see their genotype report below, plus additional solutions in the Lifehacks section. Consider joining today.
Understanding Fluoride Health Effects: Dental Benefits and Potential Risks
Fluoride is known for its anti-cavity effects, but it is also in the news for studies showing negative effects on other aspects of health.
Like many health questions, whether fluoride is ‘good’ or ‘bad’ is not simple to answer. Instead, you’ll need to understand how fluoride is absorbed in the bones and teeth, how much is required, at what levels it is toxic, and how fluoride is eliminated from the body.
Some areas of the world have a lot more fluoride in the water than others, and diet (especially tea drinking) also plays a big role.
Additionally, genetic variants impact how well you detoxify fluoride.
Thus, the answer to the question – is fluoride good or bad – depends on many different elements.
Let’s dive into the science so that you can make informed decisions for yourself.
What is fluoride? Where does it come from?
Fluorine (chemical symbol F) is an element commonly found in minerals in the Earth’s crust. It is strongly reactive, so elemental fluorine is rarely found in nature. Instead, fluorine is incorporated into minerals or other compounds.
Fluoride (F−) is an ionic form of fluorine, and the name can commonly refer to several compounds that contain fluoride. For example, sodium fluoride, an ingredient in many kinds of toothpaste, is often referred to simply as fluoride.
How Does Fluoride Stop Tooth Decay?
According to the CDC: “Fluoride works by stopping or even reversing the tooth decay process—it keeps tooth enamel strong and solid. Certain bacteria in the mouth cause tooth decay. When a person eats sugar and other refined carbohydrates, these bacteria produce acid that removes minerals from the tooth’s surface. Fluoride helps to remineralize tooth surfaces and prevents cavities from forming.”[ref]
No offense to the CDC, but that didn’t really explain how fluoride stops tooth decay. Let’s dig into it further…
Fluoride ions are taken up by bone tissue and other supporting tissue, including the teeth, skin, and hair.[ref]
In tooth enamel, fluoride can do an ion exchange with hydroxyapatite, a calcium-containing compound that makes up part of your bones and tooth enamel.[ref]
Fluoride is incorporated into the hydroxyapatite, forming fluorapatite, which is more resistant to the acidic pH caused by certain bacteria in the mouth. This facilitates enamel remineralization, preventing cavities from forming when acidity is high.
Toxicity of Fluoride: Health Effects and Concerns
Fluoride is toxic in higher amounts. The saying “the dose makes the poison” definitely applies to fluoride. The question is: At what level is fluoride OK, and at what level does it cause harm?
While sources on this vary just a little bit, the symptoms of acute fluoride poisoning may appear with as little as 1mg/kg of body weight. Thus, fluoride can be a problem for infants and small children at much lower levels than for adults.
According to Mt. Sinai Hospital, symptoms of acute fluoride toxicity include:
- Abdominal pain, diarrhea, nausea and vomiting
- Abnormal taste in the mouth (salty or soapy taste), drooling
- Headache
- Irregular or slow heartbeat, heart attack (severe cases)
- Shallow breathing
- Tremors
Acute fluoride poisoning is fairly uncommon. One notorious case back in the 1940s was at the Oregon State Hospital. A patient at the mental hospital mistakenly brought cockroach poison made of sodium fluoride for the cooks to use in the kitchen instead of powdered milk. This caused acute fluoride poisoning in the Oregon State Hospital patients who ate the fluoride-laced food, with 47 resulting fatalities.[ref]
High fluoride in groundwater supplies:
Fluoride levels in the soil and water vary quite a bit. Most areas have natural fluoride levels in the water in the 10s to 100s of PPM (parts per million). However, in some areas of the world, fluorine concentrations in the water are high enough to cause health problems. This can be due to agricultural runoff (fertilizers), often combined with higher natural mineral levels in the water.[ref]
Average fluoride intake in the US:
Fluoride is now classified as a micronutrient, and the US has determined an adequate intake of 3 mg/day for women and 4 mg/day for men. The upper daily limit is set at 10 mg/day.
Long-term fluoride consumption:
Skeletal fluorosis is caused by long-term fluoride consumption at higher than tolerable levels. Skeletal fluorosis causes pain and damage to bones and joints due to the incorporation of fluoride into the bones and connective tissue.
The sources of fluoride people are commonly exposed to include drinking water (especially in some regions of the world with high natural fluoride), fluoride inhalation from burning coal, and fluoride from drinking a lot of tea. The largest source is tea consumption, especially in areas where the water also contains fluoride.[ref]
Researchers studied the causes of toxicity in fluorosis due to high fluoride water in a region in India. They found a reduction in PON1, acetylcholine esterase, and ATPase. Both the heart and liver also showed altered lactate dehydrogenase. The researchers concluded that higher fluoride levels in the water had a collective effect on cellular energy production in fluorosis patients.[ref]
Dental fluorosis:
While a little bit of fluoride may benefit enamel, too much fluoride can damage teeth. Excess fluoride, whether chronic or acute, can cause dental fluorosis, especially if it happens when the permanent teeth are developing (ages 0-3).
Enamel fluorosis initially causes whitish areas on the teeth. More severe enamel fluorosis causes pits and brown spots on the teeth.[ref]
Here’s what dental fluorosis can look like:
Permanent teeth are mineralized during the first three years of childhood, well before they come in. Amoxicillin, a commonly used antibiotic, can increase the risk of mild fluorosis in teeth when exposed during a certain window of development. A study on kids with fluorosis found that exposure to amoxicillin between 20 and 24 months increased the risk of fluorosis by 3-fold. A previous study had also identified amoxicillin use between 3 and 6 months as slightly increasing the risk of fluorosis. The study does note that what is called fluorosis in these cases may be due to hypomineralization and not necessarily excessive fluoride exposure. [ref]
Intestinal Absorption and Excretion:
Fluoride is readily absorbed in the body. About 1% is absorbed in the mouth, with the rest absorbed in the stomach and small intestines. After absorption, the fluoride is transported throughout the body via the bloodstream. Concentrations in the bloodstream peak 20-60 minutes after consumption.
Approximately 50% of absorbed fluoride is excreted – mainly through urine. Adults retain a little less fluoride, and children retain a little more fluoride.
About 99% of the remaining fluoride is concentrated in the calcified tissues (e.g., bones, teeth), with 1% entering the soft tissues (e.g., brain, lungs, kidneys).[ref]
Pregnant women pass about 60% of the concentration of fluoride in their bloodstream to the placenta at lower levels. At high concentrations, the placenta acts as more of a barrier to protect the fetus from high fluoride levels. Fluoride also passes through breast milk at low concentrations.[ref]
How did fluoride get added to drinking water?
In many towns and cities in the US and Canada, low levels of fluoride are added to municipal water supplies.
The history of using fluoride for preventing cavities dates back a century or more. It was observed that people with mottled stains on their tooth enamel (fluorosis) were exposed to high natural fluoride levels in their drinking water. An epidemiological study showed that people averaged fewer cavities in areas with more prevalent dental fluorosis. In 1945, four US cities added 1mg/L of fluoride to their municipal water supplies, and they subsequently noted a decrease in cavities. This kicked off decades of research on fluoride for cavity prevention, including whether the fluoride was more effective if given topically on the teeth or systemically.[ref]
The CDC currently recommends 0.7 mg/L of fluoride in drinking water.[ref] Approximately 73% of municipal water systems in the US follow the CDC recommendations and have added fluoride to the water.[ref]
Vitamin D, fluoride, and bones:
I mentioned above that excess, chronic fluoride from drinking lots of tea or water high in fluoride could impact bone health.
Vitamin D is involved in how bones absorb minerals such as calcium – and fluoride. Genetic variants in the vitamin D receptor are linked to an increased risk of skeletal fluorosis in people exposed to a lot of fluoride. (More in the genotype section)[ref]
Related article: Vitamin D Genes
Sodium fluoride was tried as a medication in the 80s and 90s as a way of preventing osteoporosis. However, long-term studies showed that not only did fluoride not prevent osteoporosis, but it may actually make bone density slightly worse.[ref][ref]
Fluoride health effects on thyroid function
Your thyroid needs iodine to synthesize thyroid hormones. Fluorine can impact how well the thyroid functions, which is exacerbated when low iodine intake.[ref]
TSH, a thyroid-stimulating hormone, is often measured to determine whether someone has hypothyroidism or underactive thyroid gland activity. TSH levels above 4.5 mIU/L with normal thyroid (T3, T4) hormone levels usually indicate hypothyroidism. Some researchers consider TSH levels above 2.5 mIU/L as increasing the risk of subclinical hypothyroidism, which affects 5-10% of the population.[ref]
A recent study in Canada found that higher fluoride exposure is linked to thyroid dysfunction only in people who were also iodine deficient. There was no link between fluoride levels and higher TSH levels with adequate iodine. About 18% of the study participants were iodine deficient.[ref]
Related article: Genes related to thyroid hormone production
Sperm count and reproductive effects:
Animal studies show that high fluoride levels can impact sperm motility, and a study in the 1990s in India showed that higher fluoride exposure correlated with slightly decreased testosterone levels.
A recent study looked at men grouped by lower fluoride exposure (2-13mg/day) and higher fluoride exposure (up to 27mg/day). A decrease was seen in the sensitivity of FSH response to inhibin-B in the high fluoride group. However, none of the semen parameters were altered in the high fluoride group. The study concluded: “The results obtained indicate that a fluoride exposure of 3–27 mg/day induces a subclinical reproductive effect that can be explained by a fluoride-induced toxic effect in both Sertoli cells and gonadotrophs.”[ref]
Related article: Male Infertility and Genetics
Soft tissue calcification:
Fluoride can be incorporated into various tissues in the body, causing calcification. The question, in my mind, is whether this is relevant at levels that humans are chronically exposed to. Only about 1% of absorbed fluoride is stored in soft tissue.[ref]
In animal studies, higher chronic fluoride exposure increased calcification in the aorta (heart).[ref]
For people living in an area with high fluoride in the water, an X-ray study found that 89% showed “calcification and/or ossification of the attachments of ligaments, tendons, muscles, and interosseous membranes.”[ref]
Whether fluoride causes soft tissue calcification isn’t clear-cut and likely involves several variables. For example, in an animal study with a higher ratio of phosphorus to calcium than normal, the addition of fluoride reduced calcification in the kidneys.[ref]
Fluoride and calcification of the pineal gland:
The pineal gland is an endocrine gland in the middle of the brain that primarily excretes melatonin at night. Melatonin not only is important in circadian rhythm and sleep, but it also is a potent antioxidant with many health benefits.
Calcification of the pineal gland in aging causes lower levels of melatonin to be produced at night. Fluoride is also taken up in the pineal gland and it is likely the most fluoride-saturated organ in the body. Researchers believe that the negative effects of fluoride, whether before or secondary to calcification, are negatively affecting the function of the pineal gland. Higher intake of fluoridated water is associated with sleep apnea and daytime sleepiness. Another study also found that a higher intake of fluoride in drinking was “was associated with 34% higher relative risk of reporting sleeping less than the recommended duration for age”. [ref][ref]
Intelligence and Neurobehavioral Problems:
Higher fluoride levels in the water are a problem for developing children, especially in countries with both agricultural runoff and naturally higher fluoride mineral levels. China is one country that has studied the effects of higher water fluoride levels fairly extensively.
On average, children exposed to higher fluoride in their water have slightly lower IQs. This is a problem of serious concern in areas of China and India with higher groundwater fluoride concentrations.[ref]
Fluoride causes neurotoxicity in the brain by interfering with the activity of several metabolic enzymes. It can inhibit brain glucose utilization and affect mitochondrial function in the neurons. Additionally, animal studies clearly show that higher fluoride levels cause neurotoxicity.[ref]
A study of ~1,000 children in China divided the participants into two groups called high intelligence (>120) and non-high intelligence (70-120). The average fluoride exposure of the high-intelligence group was 0.7 mg/l of water, while the non-high-intelligence group had an average of 1 mg/l of fluoride in their water.[ref] To be clear: the fluoride in the water for the ‘non-high intelligence’ group is above the range of what is added to fluoridated municipal supplies in the US and Canada.
Genetics plays a role in whether high fluoride in the water is more likely to cause decreased IQ levels. Genetic variants in the dopamine receptors and enzymes related to dopamine breakdown are linked to decreased IQ with high fluoride exposure.[ref] (More in the genotype report)
Related article: Genetics and IQ
What about fluoride from regular drinking water?
A 2024 study showed that maternal fluoride exposure increased the risk of neurobehavioral problems in their children at age 3. This study was conducted on women in LA who were drinking fluoridated water. Higher urinary levels of fluoride in the mothers during pregnancy resulted in an increased risk of neurobehavioral problems. [ref]
Degenerative Eye Diseases:
Fluoride exposure also contributes to degenerative eye diseases like cataracts and macular degeneration.
A 2019 study found that fluoride exposure is a risk factor for cataracts and macular degeneration, and it also elucidated the mechanism of action. The researchers found that fluoride impacts enzymes and genes related to mitochondrial energy as well as reactive oxygen species and oxidative stress (e.g., Nrf2, glutathione, NF-kB, heat shock proteins).[ref]
Mast cell activation from fluoride:
An older study in animals states: “Calcium triggers the secretion of histamine from mast cells after previous exposure to sodium fluoride.”[ref] Other animal studies back up the link between mast cell degranulation, histamine release, and fluoride exposure[ref][ref], especially in the presence of N-acetylcysteine.[ref]
However, I’m not finding any studies that elaborate on the amount of fluoride needed to cause mast cell degranulation in humans.
Fluoride Genotype Report:
Lifehacks: Natural Ways to Decrease Fluoride
You’ll need to weigh the pros and cons of fluoride for yourself, considering the benefits of cavity prevention and the long-term effects of higher fluoride exposure.
The solutions below are geared towards reducing systemic fluoride exposure and facilitating detoxification. We will look at:
- Determining if there is fluoride in your water
- Alternatives for toothpaste to help prevent cavities
- The fluoride in tea brands
- Supplements to help reduce fluoride in the body
Is fluoride in your municipal water supply?
The first question to answer if you want to decrease your systemic fluoride exposure is whether it is even added to your tap water.
The CDC has an interactive map that lets you drill down by county to determine if your water is fluoridated. Not all states participate in the program, so you may need to call your water supplier.
4 Supplements that decrease fluoride’s negative impacts:
Related Articles and Topics:
Gingivitis: The Genetic Connection between Gum Disease, Inflammation, and Overall Health
References:
About Fluoride | FAQs | Community Water Fluoridation | Division of Oral Health | CDC. 19 Feb. 2020, https://www.cdc.gov/fluoridation/faqs/about-fluoride.html.
Arulkumar, Mani, et al. “Alteration of Paraoxonase, Arylesterase and Lactonase Activities in People around Fluoride Endemic Area of Tamil Nadu, India.” Clinica Chimica Acta; International Journal of Clinical Chemistry, vol. 471, Aug. 2017, pp. 206–15. PubMed, https://doi.org/10.1016/j.cca.2017.05.036.
CDC – MWF – About My Water’s Fluoride. https://nccd.cdc.gov/doh_mwf/default/AboutMWF.aspx. Accessed 28 Mar. 2023.
CDC – MWF – My Water’s Fluoride Home. https://nccd.cdc.gov/doh_mwf/default/default.aspx. Accessed 28 Mar. 2023.
Cocco, Fabio, et al. “The Caries Preventive Effect of 1-Year Use of Low-Dose Xylitol Chewing Gum. A Randomized Placebo-Controlled Clinical Trial in High-Caries-Risk Adults.” Clinical Oral Investigations, vol. 21, no. 9, 2017, pp. 2733–40. PubMed Central, https://doi.org/10.1007/s00784-017-2075-5.
Cui, Yushan, et al. “Dopamine Receptor D2 Gene Polymorphism, Urine Fluoride, and Intelligence Impairment of Children in China: A School-Based Cross-Sectional Study.” Ecotoxicology and Environmental Safety, vol. 165, Dec. 2018, pp. 270–77. ScienceDirect, https://doi.org/10.1016/j.ecoenv.2018.09.018.
Dey, S., et al. “In Vivo Efficacy of Tamarind (Tamarindus Indica) Fruit Extract on Experimental Fluoride Exposure in Rats.” Research in Veterinary Science, vol. 91, no. 3, Dec. 2011, pp. 422–25. PubMed, https://doi.org/10.1016/j.rvsc.2010.09.013.
Du, Yuhui, et al. “Iodine Modifies the Susceptibility of Thyroid to Fluoride Exposure in School-Age Children: A Cross-Sectional Study in Yellow River Basin, Henan, China.” Biological Trace Element Research, vol. 199, no. 10, Oct. 2021, pp. 3658–66. PubMed, https://doi.org/10.1007/s12011-020-02519-8.
“Fluoride Overdose Information | Mount Sinai – New York.” Mount Sinai Health System, https://www.mountsinai.org/health-library/poison/fluoride-overdose. Accessed 28 Mar. 2023.
Gaffney-Stomberg, Erin, et al. “Association Between Single Gene Polymorphisms and Bone Biomarkers and Response to Calcium and Vitamin D Supplementation in Young Adults Undergoing Military Training.” Journal of Bone and Mineral Research: The Official Journal of the American Society for Bone and Mineral Research, vol. 32, no. 3, Mar. 2017, pp. 498–507. PubMed, https://doi.org/10.1002/jbmr.3008.
Harrison, J. E., et al. “The Effect of Fluoride on Nephrocalcinosis in Rats.” Clinical Biochemistry, vol. 18, no. 2, Apr. 1985, pp. 109–13. PubMed, https://doi.org/10.1016/s0009-9120(85)80091-6.
Kanduti, Domen, et al. “FLUORIDE: A REVIEW OF USE AND EFFECTS ON HEALTH.” Materia Socio-Medica, vol. 28, no. 2, Apr. 2016, pp. 133–37. PubMed Central, https://doi.org/10.5455/msm.2016.28.133-137.
Khandare, A. L., et al. “Effect of Tamarind Ingestion on Fluoride Excretion in Humans.” European Journal of Clinical Nutrition, vol. 56, no. 1, Jan. 2002, pp. 82–85. PubMed, https://doi.org/10.1038/sj.ejcn.1601287.
Kumar, Nagapuri Kiran, et al. “Protective Effect of Curcumin on Hippocampal and Behavior Changes in Rats Exposed to Fluoride During Pre- and Post-Natal Period.” Basic and Clinical Neuroscience, vol. 11, no. 3, 2020, pp. 289–99. PubMed, https://doi.org/10.32598/bcn.11.2.1189.1.
Lubojanski, Adam, et al. “The Safety of Fluoride Compounds and Their Effect on the Human Body—A Narrative Review.” Materials, vol. 16, no. 3, Jan. 2023, p. 1242. PubMed Central, https://doi.org/10.3390/ma16031242.
Mishra, Sumita, et al. “Probiotics-A Complete Oral Healthcare Package.” Journal of Integrative Medicine, vol. 18, no. 6, Nov. 2020, pp. 462–69. PubMed, https://doi.org/10.1016/j.joim.2020.08.005.
Munir, Muhammad Usman, et al. “Synthesis, Characterization, Functionalization and Bio-Applications of Hydroxyapatite Nanomaterials: An Overview.” International Journal of Nanomedicine, vol. 17, May 2022, pp. 1903–25. PubMed Central, https://doi.org/10.2147/IJN.S360670.
Regelson, Spencer, et al. “Evaluation of Fluoride Levels in Commercially Available Tea in the United States.” General Dentistry, vol. 69, no. 1, 2021, pp. 17–20.
Rezaee, Taraneh, et al. “Increasing Fluoride Content Deteriorates Rat Bone Mechanical Properties.” Bone, vol. 136, July 2020, p. 115369. PubMed, https://doi.org/10.1016/j.bone.2020.115369.
Sadat-Ali, Mir, et al. “Genetic Influence on Circulating Vitamin D among Saudi Arabians.” Saudi Medical Journal, vol. 37, no. 9, Sept. 2016, pp. 996–1001. PubMed, https://doi.org/10.15537/smj.2016.9.14700.
Savchenkov, M. F., et al. “[Thyroid gland pathology in children population exposed to the combination of iodine deficiency and fluoride pollution of environment].” Gigiena I Sanitariia, vol. 95, no. 12, 2016, pp. 1201–05.
Sharma, Chhavi, et al. “Curcumin and Resveratrol Rescue Cortical-Hippocampal System from Chronic Fluoride-Induced Neurodegeneration and Enhance Memory Retrieval.” The International Journal of Neuroscience, vol. 128, no. 11, Nov. 2018, pp. 1007–21. PubMed, https://doi.org/10.1080/00207454.2018.1458727.
Søgaard, C. H., et al. “Marked Decrease in Trabecular Bone Quality after Five Years of Sodium Fluoride Therapy–Assessed by Biomechanical Testing of Iliac Crest Bone Biopsies in Osteoporotic Patients.” Bone, vol. 15, no. 4, 1994, pp. 393–99. PubMed, https://doi.org/10.1016/8756-3282(94)90815-x.
Susheela, A. K., and P. Kharb. “Aortic Calcification in Chronic Fluoride Poisoning: Biochemical and Electronmicroscopic Evidence.” Experimental and Molecular Pathology, vol. 53, no. 1, Aug. 1990, pp. 72–80. PubMed, https://doi.org/10.1016/0014-4800(90)90025-9.
Upi. “Unsuspecting Poisoner of 47 At a Hospital in 1942 Is Dead.” The New York Times, 4 Oct. 1983. NYTimes.com, https://www.nytimes.com/1983/10/04/obituaries/unsuspecting-poisoner-of-47-at-a-hospital-in-1942-is-dead.html.
Vano, Michele, et al. “Effectiveness of Nano-Hydroxyapatite Toothpaste in Reducing Dentin Hypersensitivity: A Double-Blind Randomized Controlled Trial.” Quintessence International (Berlin, Germany: 1985), vol. 45, no. 8, Sept. 2014, pp. 703–11. PubMed, https://doi.org/10.3290/j.qi.a32240.
Vitamin D Receptor Gene FokI Polymorphism Contributes to Increasing the Risk of Tuberculosis: Evidence from a Meta-Analysis. 12 Aug. 2021, https://doi.org/10.21203/rs.3.rs-774522/v1.
Wang, Y., et al. “Endemic Fluorosis of the Skeleton: Radiographic Features in 127 Patients.” AJR. American Journal of Roentgenology, vol. 162, no. 1, Jan. 1994, pp. 93–98. PubMed, https://doi.org/10.2214/ajr.162.1.8273699.
Waugh, Declan T., et al. “Black Tea Source, Production, and Consumption: Assessment of Health Risks of Fluoride Intake in New Zealand.” Journal of Environmental and Public Health, vol. 2017, 2017, p. 5120504. PubMed Central, https://doi.org/10.1155/2017/5120504.
Waugh, Declan Timothy. “The Contribution of Fluoride to the Pathogenesis of Eye Diseases: Molecular Mechanisms and Implications for Public Health.” International Journal of Environmental Research and Public Health, vol. 16, no. 5, Mar. 2019, p. 856. PubMed, https://doi.org/10.3390/ijerph16050856.
Wu, Junhua, et al. “Modifying Role of GSTP1 Polymorphism on the Association between Tea Fluoride Exposure and the Brick-Tea Type Fluorosis.” PLoS ONE, vol. 10, no. 6, June 2015, p. e0128280. PubMed Central, https://doi.org/10.1371/journal.pone.0128280.
Xu, Kaihong, et al. “Interaction of Fluoride Exposure and CREB1 Gene Polymorphisms on Thyroid Function in School-Age Children.” Chemosphere, vol. 303, no. Pt 2, Sept. 2022, p. 135156. PubMed, https://doi.org/10.1016/j.chemosphere.2022.135156.
Yang, Dan, et al. “Association between Vitamin D Receptor Gene FokI Polymorphism and Skeletal Fluorosis of the Brick-Tea Type Fluorosis: A Cross Sectional, Case Control Study.” BMJ Open, vol. 6, no. 11, Nov. 2016, p. e011980. PubMed Central, https://doi.org/10.1136/bmjopen-2016-011980.
Zhou, Yue, et al. “Particle Size Distribution and Inhalation Dose of Shower Water Under Selected Operating Conditions.” Inhalation Toxicology, vol. 19, no. 4, Apr. 2007, pp. 333–42. PubMed Central, https://doi.org/10.1080/08958370601144241.
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