Black Tea Source, Production, and Consumption: Assessment of Health Risks of Fluoride Intake in New Zealand

Abstract

In countries with fluoridation of public water, it is imperative to determine other dietary sources of fluoride intake to reduce the public health risk of chronic exposure. New Zealand has one of the highest per capita consumption rates of black tea internationally and is one of the few countries to artificially fluoridate public water; yet no information is available to consumers on the fluoride levels in tea products. In this study, we determined the contribution of black tea as a source of dietary fluoride intake by measuring the fluoride content in 18 brands of commercially available products in New Zealand. Fluoride concentrations were measured by potentiometric method with a fluoride ion-selective electrode and the contribution of black tea to Adequate Intake (AI) and Tolerable Upper Intake Level (UL) was calculated for a range of consumption scenarios. We examined factors that influence the fluoride content in manufactured tea and tea infusions, as well as temporal changes in fluoride exposure from black tea. We review the international evidence regarding chronic fluoride intake and its association with chronic pain, arthritic disease, and musculoskeletal disorders and provide insights into possible association between fluoride intake and the high prevalence of these disorders in New Zealand.

Mechanisms of Fluoride Toxicity: From Enzymes to Underlying Integrative Networks

“…Aluminum smelter workers and persons living near the factory where fluoride was in high concentration in the atmosphere suffered with psychiatric and neurological disturbances. Endemic fluorosis is caused by persistent fluoride exposure through ingestion or inhalation, and most commonly, as a result of high fluoride levels in drinking water and beverages [90,91]. The WHO's drinking water quality Guideline Value for fluoride is 1.5 mg/L [92].…”

Fluoride Exposure Induces Inhibition of Sodium-and Potassium-Activated Adenosine Triphosphatase (Na+, K+-ATPase) Enzyme Activity: Molecular Mechanisms and Implications for Public Health

“…In countries such as Ireland, the UK, Australia and New Zealand, where habitual tea drinking is commonplace, the major dietary source of F − is tea consumption [151,152,153]. In addition to tea, fluoridated water, and toothpaste other sources of F − exposure include other beverages produced from fluoridated water (powdered infant formula, fruit juices, soft drinks, coffee, beers); pesticide residues in foods, foods processed or cooked in fluoridated water; foods grown in soil containing F − or irrigated with fluoridated water; consumption of foods with elevated F − levels (i.e., seafood and processed chicken); foods cooked in Teflon cookware; tobacco consumption; use of fluoridated mouthwash; use of medical inhalers containing fluoridated gases, and fluoridated medications, in addition to other environmental or occupational exposures to F − [153]. Although the amount of F − ingested in diet can be theoretically measured in dietary intake studies, by measuring the F − content in foods and beverages, the most reliable and accurate method of measuring F − exposure is by measuring the F − content in serum/plasma, bone or urinary F − levels.…”

“…Moreover, the ionic F − levels in blood in infants reported by Warady and associates are within the range known to be associated with skeletal and non-skeletal fluorosis in humans. A review of literature addressing ionic F − levels associated with skeletal and non-skeletal fluorosis in humans has been the subject of an earlier study by Waugh et al [153]. However, it should be also noted that the F − levels reported by Warady and associates for infants aged 4–6 months were two fold higher than those reported for 60-day old non-diabetic weaning Wistar rats fed drinking water with a F − concentration of 50 mg/L, while the plasma F − levels in infants with chronic kidney disease were comparably to diabetic rats fed drinking water with 50 mg/L [172].…”

“…Thus, multiple low dose exposures can result in higher steady state plasma F − levels than single dose exposure to higher doses [177,178,179]. Hence, habitual consumption of tea can result in skeletal fluorosis [153]. Moreover, currently about one-fifth of the currently marketed pharmaceuticals are organofluorine compounds and almost one-third of the top 100 top-selling drugs are organofluorine compounds.…”

Chronic Fluoride Exposure and the Risk of Autism Spectrum Disorder

“…Tea plants ( Camellia sinensis ) are well known for their ability to accumulate high concentrations of both F and Al 3 [80]. A cup of black tea could contain 1.4 mg of F. Evidence suggests that the culture of tea drinking in the US, the UK, and New Zealand, contributes significantly to the total body burden of F [80]. In developed countries a high intake of Al 3+ from food and medicine products is obvious.…”