NATURAL IODINE CONTENT IN DRINKING WATER (& GROUNDWATER) IN DENMARK DENITZA D. VOUTCHKOVA PhD DEFENCE AU

PROJECT, FUNDING, PARTICIPANTS PhD dissertation Part of GEOCENTER project “Iodine in the hydrological cycle in Denmark: implications for human health” Funded by the Geological Survey of Denmark and Greenland (GEUS) and Aarhus University (AU) Financial support also from the International Medical Geology Association (IMGA) and the International Registry of Pathology (IRP) – Gardner Research Grant Project participants and collaborators: Søren M. Kristiansen Birgitte Hansen, Vibeke Ernstsen, Brian L. Sørensen, Kim H. Esbensen, Chaosheng Zhang

PRESENTATION OUTLINE Background PhD objectives Iodine in groundwater – Paper 1, 3 & 4 Iodine in drinking water – Paper 2 & Technical Note 1 General conclusion

Part 1 background

Why Iodine? WHO region “Europe” Iodine plays an essential role in human metabolism and the early development [1] Iodine deficiency is the single most important preventable cause of brain damage” [2] Insufficient iodine intake  43.9% (30.5million) of 6–12 years old children AND 44.2% (393.1 millions) of the general population in WHO Europe region [3] [1] WHO, Iodine Deficiency in Europe: A continuing public health problem, M. Andersson, et al., Editors. 2007, World Health Organization, UNICEF: France. p. 1-86. [2] WHO, Assessment of iodine deficiency disorders and monitoring their elimination: a guide for programme managers. – 3rd ed., 2007, World Health Organization: Switzerland p. 97. [3] Zimmermann, M.B. and Andersson, M., Update on iodine status worldwide. Current Opinion in Endocrinology, Diabetes and Obesity, 2012. 19(5): p. 382-387.

Iodine Status of Danish Population [1] 55 tap water samples The last national survey on iodine status of Danish population - 1969 [2] Correlation between tap water collected 1999 and the UI data from 1969 (r=0.68, p<0.01) [1] USI programme  1996: decision, 1998: voluntary, 2000: mandatory DanThyr  2 cohorts covering the main difference in levels of iodine intake in Denmark caused by different levels of iodine in groundwater [3] [1] Pedersen, K.M., Laurberg, P., Nøhr, S., Jørgensen, A., and Andersen, S., Iodine in drinking water varies by more than 100-fold in Denmark. Importance for iodine content of infant formulas. European Journal of Endocrinology, 1999. 140(5): p. 400-403. [2] Munkner T. Urinary excretion of 127-iodine in the Danish population. Scand J Clin Lab Invest 1969;110:134. [3] Laurberg, P., Jørgensen, T., Perrild, H., Ovesen, L., Knudsen, N., Pedersen, I.B., Rasmussen, L.B., Carlé, A., and Vejbjerg, P., The Danish investigation on iodine intake and thyroid disease, DanThyr: Status and perspectives. European Journal of Endocrinology, 2006. 155(2): p. 219-228.

Recommended daily nutrient intake (RNI) for iodine [1] Iodine Intake 25% [2] Recommended daily nutrient intake (RNI) for iodine [1]   Age group RNI (µg/day) 0-59 months 90 6-12 years 120 12-17 years 150 Adults Pregnancy/lactation 250 ?! Temporal and Spatial Variation Bioavailability Goitrogens and other factors [1] WHO, Iodine Deficiency in Europe: A continuing public health problem, M. Andersson, et al., Editors. 2007, World Health Organization, UNICEF: France. p. 1-86. [2] Pedersen, A.N., Fagt, S., Groth, M.V., Christensen, T., Biltoft-Jensen, A., Matthiessen, J., Andersen, N.L., Kørup, K., Hartkopp, H., Ygil, K.H., Hinsch, H.J., Saxholt, E., and Trolle, E., Danskernes kostvaner 2003 - 2008, 2010, DTU Fødevareinstituttet. p. 1-200

Drinking Water Supply in Denmark Treated groundwater Simple treatment mainly Decentralised structure [1] [1] Treatment -> by 2012 there are 74 active waterworks which have a permit for advanced water treatment (about 50 mio m3) Advanced treatment types -> Inorganic trace elements (n=31), Major components (29), Organic micropolutants (8), microbiology (6) Total GW abstraction is about 400 mio m3 / year [1] Jupiter database , status December 2012

Geology & Groundwater

Iodine Cycle Total Iodine = Iodide + Iodate + Org. Iodine No data ~5 µg/L 50-60 µg/L Total Iodine = Iodide + Iodate + Org. Iodine No data

PHD OBJECTIVES To map iodine concentration and speciation in DW and GW To study the spatial patterns and to elucidate the governing factors To evaluate the importance of the spatial variation of DW iodine to the population’s nutrition

Part 3 Iodine in Groundwater

Paper overview (objectives) Paper I: Iodine concentrations in Danish groundwater: historical data assessment 1933-2011 (published in “Environmental Geochemistry and Health”) To give overview on the existing gw iodine data with focus on: spatial variation, geological setting, depth of extraction To identify geochemical associations between iodine and other variables in order to elucidate the governing factors for the spatial variation Paper 3: Hydrogeochemical characterisation of Danish groundwater in relation to iodine Paper 4: High resolution depth profiles of iodine concentrations in groundwater at fours multiscreen wells in Denmark: possibilities for future research

Paper 1: Data & Methodology Source: Jupiter database (November 2011) Master dataset (MDS): 2562 x 28 MDS is characterised by: missing values diversity in the data quality – different lab methods Preparation and pre-treatment: Detection limits Excluding variables and samples Missing values Centred log-ratio transformation (clr) Reduced MDS (r-MDS): 506 x 20 Principle Component Analysis Iodine 1933 – 2011 (n=2562) Jupiter is the Danish public nationwide geologic and hydrological database (GEUS)

Paper 1: Univariate data analysis Iodine concentrations <d.l. to 1220 µg/L 90% of the samples <20 µg/L 11 samples >200 µg/L Mean: 13.83µg/L; Median: 5.4 µg/L Spatial variation Large scale trend-> Capital Region vs. Central Denmark (26.81 vs. 7.6 µg/L) Small scale heterogeneity Depth: 40-80 mbt Dominating setting at depth of extraction (some information about 70% of the samples)

Paper 1: Multivariate analysis Iodine, Li, B, Ba, Br are exhibiting similar variability, suggesting common source Saline water influence, further studies needed in order to specify Based on the PC1-PC2 score plot -> high iodine is associated mainly with reduced and alkaline groundwater (Ca-HCO3 dominated gw)

Paper 3 Despite the same geology at local scale (0.1-0.2 km and 5-10 km) TI varied Speciation -> reflects the prevailing reduced conditions The processes governing iodine concentration are site and depth specific TI at different concentration levels governed by different processes

Paper 4 GRUMO – iodine included since 2011 2,2-7,1µg/L 1-4,2 µg/L 2,5m depth lacustrine gyttja GRUMO – iodine included since 2011 2,2-7,1µg/L 1-4,2 µg/L 2,2-25 µg/L 2-48 µg/L Glacial melt-water aquifers

Iodine in Drinking water Part 2 Iodine in Drinking water

Paper overview (objectives) Paper 2: Assessment of spatial variation in drinking water iodine and its implications for dietary intake: A new conceptual model (published in “Science of the Total Environment”) To identify spatial trends, clusters and/or outliers for iodine concentration and speciation and factors governing it; To propose a new conceptual model, while illustrating the importance of the chosen generalisation for future studies To estimate the contribution of drinking water to the dietary iodine intake Technical Note 1: Design of a nationwide drinking-water sampling campaign for assessment of dietary iodine intake and human health outcomes

Paper 2: Study design Criteria for choosing around 180 sampling locations Jupiter data on gw abstraction & location Largest in each municipality Largest in each grid cell

Paper 2: Iodine concentration & speciation The waterworks were involved in the sampling From the updated list (n=189) Positive 80% (n=152) Negative 2% (n=4) No answer n=33 Samples received at the lab (n=144) 175 mio m3/year

Paper 2: Governing factors Limitations Mixing of different water types Pumping strategies Groundwater treatment Treatment Advanced treatment n=14 Only aeration n=2 Aeration + sand filter(s) – the rest Possible effects from the treatment Organic ↔ inorganic iodine Iodine lost to the atmosphere (I2) Iodine removal in the treatment against ferrous iron

Paper 2: Spatial autocorrelation analysis Local Moran’s I Threshold distance dij [a] [a] Zhang C, Luo L, Xu W, Ledwith V. Use of local Moran's I and GIS to identify pollution hotspots of Pb in urban soils of Galway, Ireland. Science of the Total Environment 2008; 398: 212-221

Paper 2: Method of generalisation

Paper 2: Contribution to dietary intake

General Conclusion Main findings Project Goals Iodine concentration GW – from < d.l. up to 14,5 mg/L DW – from <d.l. up to 126 µg/L (could be even higher) Iodine speciation GW – mainly iodide and DOI (reduced gw) DW – 6 different combinations Spatial pattern GW – both large scale trends and small (local) scale heterogeneity DW – complex; multiple governing factors Importance to population’s nutrition Estimated contribution to dietary intake from 0% to >100% of RNI in different parts of the country Jutland – the biggest variation Project Goals To map iodine concentration and speciation in DW and GW To study the spatial patterns and to elucidate the governing factors To evaluate the importance of the spatial variation of DW iodine to the population’s nutrition

Thank you for listening! Questions? Denitza Voutchkova ddv@geo.au.dk

How special is Denmark? Iodine intake from drinking water Groundwater vs. surface water vs. bottled water Registers [1] [2] [1]  Map created by P.Engstrom &K.Brauman. Data: BGR & UNESCO (2008): Groundwater Resources of the World 1 : 25 000 000. Hannover, Paris. Via http://ensia.com/features/groundwater-wake-up/ [2] WHO 2006 Protecting Groundwater for Health; Managing the Quality of Drinking-water sources. http://www.who.int/water_sanitation_health/publications/PGWsection1.pdf?ua=1

Is there really a connection between drinking water iodine and the iodine status of the population? China, Denmark Bioavailability? How to do it Supply area map  Drinking water data Exposure from drinking water Correlation between IDD distribution and exposure