TY - JOUR
T1 - Assessment of spatial variation in drinking water iodine and its implications for dietary intake: A new conceptual model for Denmark
AU - Voutchkova, Denitza Dimitrova
AU - Ernstsen, Vibeke
AU - Hansen, Birgitte
AU - Sørensen, Brian Lyngby
AU - Zhang, Chaosheng
AU - Kristiansen, Søren Munch
N1 - Publisher Copyright:
© 2014 Elsevier B.V.
PY - 2014/9/15
Y1 - 2014/9/15
N2 - Iodine is essential for human health. Many countries have therefore introduced universal salt iodising (USI) programmes to ensure adequate intake for the populations. However, little attention has been paid to subnational differences in iodine intake from drinking water caused by naturally occurring spatial variations. To address this issue, we here present the results of a Danish nationwide study of spatial trends of iodine in drinking water and the relevance of these trends for human dietary iodine intake.The data consist of treated drinking water samples from 144 waterworks, representing approx. 45% of the groundwater abstraction for drinking water supply in Denmark. The samples were analysed for iodide, iodate, total iodine (TI) and other major and trace elements. The spatial patterns were investigated with Local Moran's I. TI ranges from <0.2 to 126μgL
-1 (mean 14.4μgL
-1, median 11.9μgL
-1). Six speciation combinations were found. Half of the samples (n=71) contain organic iodine; all species were detected in approx. 27% of all samples. The complex spatial variation is attributed both to the geology and the groundwater treatment. TI >40μgL
-1 originates from postglacial marine and glacial meltwater sand and from Campanian-Maastrichtian chalk aquifers. The estimated drinking water contribution to human intake varies from 0% to >100% of the WHO recommended daily iodine intake for adults and from 0% to approx. 50% for adolescents. The paper presents a new conceptual model based on the observed clustering of high or low drinking-water iodine concentrations, delimiting zones with potentially deficient, excessive or optimal iodine status.Our findings suggest that the present coarse-scale nationwide programme for monitoring the population's iodine status may not offer a sufficiently accurate picture. Local variations in drinking-water iodine should be mapped and incorporated into future adjustment of the monitoring and/or the USI programmes.
AB - Iodine is essential for human health. Many countries have therefore introduced universal salt iodising (USI) programmes to ensure adequate intake for the populations. However, little attention has been paid to subnational differences in iodine intake from drinking water caused by naturally occurring spatial variations. To address this issue, we here present the results of a Danish nationwide study of spatial trends of iodine in drinking water and the relevance of these trends for human dietary iodine intake.The data consist of treated drinking water samples from 144 waterworks, representing approx. 45% of the groundwater abstraction for drinking water supply in Denmark. The samples were analysed for iodide, iodate, total iodine (TI) and other major and trace elements. The spatial patterns were investigated with Local Moran's I. TI ranges from <0.2 to 126μgL
-1 (mean 14.4μgL
-1, median 11.9μgL
-1). Six speciation combinations were found. Half of the samples (n=71) contain organic iodine; all species were detected in approx. 27% of all samples. The complex spatial variation is attributed both to the geology and the groundwater treatment. TI >40μgL
-1 originates from postglacial marine and glacial meltwater sand and from Campanian-Maastrichtian chalk aquifers. The estimated drinking water contribution to human intake varies from 0% to >100% of the WHO recommended daily iodine intake for adults and from 0% to approx. 50% for adolescents. The paper presents a new conceptual model based on the observed clustering of high or low drinking-water iodine concentrations, delimiting zones with potentially deficient, excessive or optimal iodine status.Our findings suggest that the present coarse-scale nationwide programme for monitoring the population's iodine status may not offer a sufficiently accurate picture. Local variations in drinking-water iodine should be mapped and incorporated into future adjustment of the monitoring and/or the USI programmes.
KW - Dietary iodine intake
KW - Iodate
KW - Iodide
KW - Iodine
KW - Local Moran's I
UR - http://www.scopus.com/inward/record.url?scp=84905753918&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2014.06.008
DO - 10.1016/j.scitotenv.2014.06.008
M3 - Article
SN - 0048-9697
VL - 493
SP - 432
EP - 444
JO - Science of the Total Environment
JF - Science of the Total Environment
ER -