title: Iodine environmental availability and human intake in oceanic islands: Azores as a case-study.
abstract: Iodine deficiency is the most common cause of preventable mental impairment. Although several studies have established an association between ocean proximity and iodine environmental availability, recent studies revealed an inadequate iodine intake in the Azorean islands. In this study, we aim to understand the underlying causes of iodine environmental availability in oceanic islands and its association with iodine intake in schoolchildren, using the Azores as case-study. Iodine concentration in soil and grass pasture was measured by INAA and in drinking water by spectrophotometry. Urinary iodine concentration (UIC) in schoolchildren was assessed by ICP-MS in a randomized cross-sectional survey with 315 participants from S. Miguel (study group) and Sta. Maria islands (reference group). A validated diet questionnaire assessing sources of iodine was recorded. The iodine concentration in soils of the reference group was significantly higher than in the study group (58.1ppm vs. 14.5ppm, respectively; p=0.001). The prevalence of schoolchildren with inadequate UIC was significantly higher in the study group than in the reference one (63.0% vs. 37.8%, respectively; p<0.001). Chronic exposure to low iodine environmental availability was significantly associated with the exacerbation in iodine deficiency, with a risk 4.94 times higher in the study group. The differences observed in the studied islands are related with each island geomorphology (soil properties and orography) and climate, which can promote or inhibit iodine environmental availability, contributing distinctively to iodine bioavailability and human intake. These findings draw attention to an urgent need for a full investigation of Azores iodine status to apply evidence-based recommendations for iodine supplementation.
authors: Department of Biology, University of the Azores, 9501-801 Ponta Delgada, Azores, Portugal; CVARG, Center for Volcanology and Geological Risks Assessment, University of the Azores, 9501-801 Ponta Delgada, Azores, Portugal. Electronic address: dlinhares@uac.pt.
authors: Diana Paula Silva
authors: DP
authors: Linhares
authors: Department of Biology, University of the Azores, 9501-801 Ponta Delgada, Azores, Portugal; CE3C, Centre for Ecology, Evolution and Environmental Changes/Azorean Biodiversity Group, University of the Azores, 9501-801 Ponta Delgada, Azores, Portugal. Electronic address: patriciag@uac.pt.
authors: Patrícia Ventura
authors: PV
authors: Garcia
authors: Department of Biology, University of the Azores, 9501-801 Ponta Delgada, Azores, Portugal. Electronic address: alexandra_almada@hotmail.com.
authors: Alexandra
authors: A
authors: Almada
authors: Department of Geosciences, University of the Azores, 9501-801 Ponta Delgada, Azores, Portugal; CVARG, Center for Volcanology and Geological Risks Assessment, University of the Azores, 9501-801 Ponta Delgada, Azores, Portugal. Electronic address: teresa.jl.ferreira@azores.gov.pt.
authors: Teresa
authors: T
authors: Ferreira
authors: Department of Geosciences, University of the Azores, 9501-801 Ponta Delgada, Azores, Portugal; CVARG, Center for Volcanology and Geological Risks Assessment, University of the Azores, 9501-801 Ponta Delgada, Azores, Portugal. Electronic address: maria.gp.queiroz@azores.gov.pt.
authors: Gabriela
authors: G
authors: Queiroz
authors: Department of Geosciences, University of the Azores, 9501-801 Ponta Delgada, Azores, Portugal; CVARG, Center for Volcanology and Geological Risks Assessment, University of the Azores, 9501-801 Ponta Delgada, Azores, Portugal. Electronic address: jvc@uac.pt.
authors: José Virgílio
authors: JV
authors: Cruz
authors: Department of Biology, University of the Azores, 9501-801 Ponta Delgada, Azores, Portugal; CVARG, Center for Volcanology and Geological Risks Assessment, University of the Azores, 9501-801 Ponta Delgada, Azores, Portugal. Electronic address: rodrigues@uac.pt.
authors: Armindo dos Santos
authors: Ados S
authors: Rodrigues
mesh_terms: D000328:Adult; D001394:Azores; D004032:Diet / Q000706:statistics & numerical data; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D004785:Environmental Pollutants / Q000652:urine*; D005260:Female; D006801:Humans; D007455:Iodine / Q000652:urine*; D008297:Male
chemical_list: D004785:Environmental Pollutants; D007455:Iodine
keywords: Bioavailability; Environmental availability; Human intake; Iodine; Oceanic islands