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

• Published in: Environmental geochemistry and health 2012-04, Vol.34 (2), p.155-170
• Main Authors: Allibone, Rachel, Cronin, Shane J., Charley, Douglas T., Neall, Vince E., Stewart, Robert B., Oppenheimer, Clive
• Format: Article
• Language: English
• Subjects: Adolescent; Child; Degassing; Drinking water; Drinking Water - chemistry; Earth and Environmental Science; Environment; Environmental Chemistry; Environmental Exposure - analysis; Environmental Health; Fluorides; Fluorides - analysis; Fluorosis, Dental - epidemiology; Fluorosis, Dental - etiology; Gases; Geochemistry; Humans; Islands; Medical research; Original Paper; Prevalence; Public Health; Rain - chemistry; Soil Science & Conservation; Spatial distribution; Terrestrial Pollution; Vanuatu - epidemiology; Volcanic Eruptions; Volcanic islands; Volcanoes; Water analysis; Water demand; Water Resources; Water sampling; Water supply; Wind
• ISSN: 0269-4042; 1573-2983
• DOI: 10.1007/s10653-010-9338-2

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.