THE CAUSE OF MOTTLED ENAMEL

Spatial variation and health risk assessment of fluoride in drinking water in the Chongqing urban areas, China

Fluoride is an essential trace element for humans, and its deficiency or excess in the environment could lead to disease. To investigate the spatial distribution and health risk assessment of fluoride (F^-) in drinking water, 302 tap water samples from Chongqing urban areas, China, were collected to analyze F^- using an ion chromatograph. The results showed that (1) F^- concentration in drinking water ranged from 0.100 to 0.503 mg/L, with an average of 0.238 ± 0.045 mg/L. (2) The spatial autocorrelation analysis showed that high-low clusters were mostly located in Dadukou District and Beibei District, while low-low clusters were mainly in southern Banan District. (3) The fluoride average daily doses of children, teens and adults were 0.030, 0.029 and 0.031 mg/(kg day). (4) Hazard quotients of excessive fluoride (HQ_e) of children, teens and adults were 0.51 ± 09, 0.49 ± 0.09 and 0.52 ± 0.10, respectively (inferior to 1.00), whereas hazard quotients of inadequate fluoride (HQ_i) of those groups were 1.21 ± 0.26, 1.23 ± 0.26 and 1.15 ± 0.25, respectively (superior to 1.00). Therefore, average daily fluoride intake of residents with drinking water was inadequate. This could pose dental caries and osteoporosis threats for residents from Chongqing urban areas.

Evidence of Economically Sustainable Village-Scale Microenterprises for Arsenic Remediation in Developing Countries

Although unknown 25 years ago, natural arsenic contamination of groundwater affects over 50 countries and up to 200 million people. The economic viability was analyzed and modeled of eighty-eight community-based arsenic mitigation systems existing for up to 20 years in India and Bangladesh. The performances of three community-based arsenic mitigation systems that are ethnically different and separated across two different countries were monitored closely for 24 months of self-sustainable, long-term operation at WHO standards through local, paid caretakers. Based on data from the use of hybrid ion exchange materials (HIX-Nano) and the broad set of field operations, Monte Carlo simulations were used to explore the conditions required for self-sustainable operation and job creation in low-income communities (<$2/day/capita). The results from field data and cost modeling provided clear evidence of economic growth and job creation for systems managed by villagers' committee through collection of monthly tariffs. Ethnicity and religion did not have perceptible impacts on day-to-day operations or cumulative long-term revenue. The cost of the treatment technology (i.e., HIX-Nano) had minimal impact on the operational profitability, while number of customers and water delivery significantly affected profitability. Local employment generation with income significantly higher than poverty level was the most enduring outcome and led to enhanced sustainability.

Aesthetic treatment of dental fluorosis in a 9-year-old girl: Case report

Background/Aim: Dental fluorosis is a specific disturbance of tooth formation caused by excessive intake of fluoride. The discoloration of teeth is the most common reason for parents to seek treatment. The purpose of this paper is to describe the therapeutic management performed in a 9-year-old girl with fluorosis. Case report: A clinical case of a 9-year-old girl diagnosed with fluorosis is reported. The treatment of this clinical case was achieved using microabrasion, which is a minimally invasive method. This technique improves the aesthetics of the teeth without causing significant loss of dental tissue; a characteristic making microabrasion applicable to children as well. Its implementation involved the combined use of 18% hydrochloric acid and pumice on the enamel surface of upper incisors. The improved appearance of the teeth was aesthetically pleasing and, consequently, the patient gained in self-confidence. Conclusions: In the literature, several treatment choices are proposed, depending on the severity of the fluorosis. In our case, microabrasion was applied and the aesthetic outcome satisfied both the patient and the dentist.

Debating Water Fluoridation Before Dr. Strangelove

In the 1930s, scientists learned that small amounts of fluoride naturally occurring in water could protect teeth from decay, and the idea of artificially adding fluoride to public water supplies to achieve the same effect arose. In the 1940s and early 1950s, a number of studies were completed to determine whether fluoride could have harmful effects. The research suggested that the possibility of harm was small. In the early 1950s, Canadian and US medical, dental, and public health bodies all endorsed water fluoridation. I argue in this article that some early concerns about the toxicity of fluoride were put aside as evidence regarding the effectiveness and safety of water fluoridation mounted and as the opposition was taken over by people with little standing in the scientific, medical, and dental communities. The sense of optimism that infused postwar science and the desire of dentists to have a magic bullet that could wipe out tooth decay also affected the scientific debate.

Dental fluorosis linked to degassing of Ambrym volcano, Vanuatu: a novel exposure pathway

Ambrym in Vanuatu is a persistently degassing island volcano whose inhabitants harvest rainwater for their potable water needs. The findings from this study indicate that dental fluorosis is prevalent in the population due to fluoride contamination of rainwater by the volcanic plume. A dental survey was undertaken of 835 children aged 6-18 years using the Dean's Index of Fluorosis. Prevalence of dental fluorosis was found to be 96% in the target area of West Ambrym, 71% in North Ambrym, and 61% in Southeast Ambrym. This spatial distribution appears to reflect the prevailing winds and rainfall patterns on the island. Severe cases were predominantly in West Ambrym, the most arid part of the island, and the most commonly affected by the volcanic plume. Over 50 km downwind, on a portion of Malakula Island, the dental fluorosis prevalence was 85%, with 36% prevalence on Tongoa Island, an area rarely affected by volcanic emissions. Drinking water samples from West Ambrym contained fluoride levels from 0.7 to 9.5 ppm F (average 4.2 ppm F, n = 158) with 99% exceeding the recommended concentration of 1.0 ppm F. The pathway of fluoride-enriched rainwater impacting upon human health as identified in this study has not previously been recognised in the aetiology of fluorosis. This is an important consideration for populations in the vicinity of degassing volcanoes, particularly where rainwater comprises the primary potable water supply for humans or animals.

A health risk assessment for fluoride in Central Europe

Like many elements, fluorine (which generally occurs in nature as fluoride) is beneficial to human health in trace amounts, but can be toxic in excess. The links between low intakes of fluoride and dental protection are well known; however, fluoride is a powerful calcium-seeking element and can interfere with the calcified structure of bones and teeth in the human body at higher concentrations causing dental or skeletal fluorosis. One of the main exposure routes is via drinking water and the World Health Organisation currently sets water quality guidelines for the element. In Central Europe, groundwater resources that exceed the guideline value of 1.5 mg l-1 are widespread and effects on health of high fluoride in water have been reported. The aim of the current project was to develop a geographic information system (GIS) to aid the identification of areas where high-fluoride waters and fluorosis may be a problem; hence, where water treatment technologies should be targeted. The development of the GIS was based upon the collation and digitisation of existing information relevant to fluoride risk in Ukraine, Moldova, Hungary and Slovakia assembled for the first time in a readily accessible form. In addition, geochemistry and health studies to examine in more detail the relationships between high-fluoride drinking waters and health effects in the population were carried out in Moldova and Ukraine demonstrating dental fluorosis prevalence rates of 60-90% in adolescents consuming water containing 2-7 mg l-1 fluoride.

Fluoride and fluoridation

To date, many of the ways of controlling tooth decay involve the use of fluorides. Either systemically via fluoridated water and tablets, or, topically, with fluoride-containing toothpaste and mouthrinses. There is now evidence that the prevalence of dental caries is declining in communities with unfluoridated water, as well as in those with fluoridated water. This phenomenon may be related to an increase of fluoride in the food chain; the unintentional ingestion of fluoride-containing dental health products; and the increasing contamination of the total environment with fluoride emissions and solid wastes from many industries. The apparent usefulness of fluoride as a preventive against dental caries does not mean that unnecessary exposure to the element should be tolerated. Fluoride at very low concentrations is phytotoxic and harmful to livestock; and in man, excessive intakes of fluoride over many years may lead to a well-defined disorder--skeletal fluorosis. In addition, a number of recent studies have suggested that fluoride may be genotoxic.

Fluoride and bone: an unusual hypothesis

Given the total body weight, the weight of the skeleton and the proportion of minerals in the skeleton, a simple formula can be used to estimate the accumulation of fluoride in the skeleton over periods of years. It would appear that daily intakes of fluoride considered beneficial to developing teeth may, if ingested throughout adult life, lead to skeletal fluorosis of varying degrees in a significant proportion of the population. To date, the accumulation of fluoride in the skeleton seems to have been ignored as a possible aetiological factor in certain metabolic bone disorders now common in the middle-aged and elderly. The unusual hypothesis put forward in this paper suggests that a daily intake of fluoride derived from a multiplicity of sources, and which is now generally considered as 'safe', may in fact be potentially harmful over long periods of time.