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

2. 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

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

4. Part 1
background

5. 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
[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, (5): p

6. Iodine Status of Danish Population
[1]
55 tap water
samples
The last national survey on iodine status of Danish population [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, (5): p
[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, (2): p

7. 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
[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 , 2010, DTU Fødevareinstituttet. p

8. 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

9. Geology & Groundwater

10. 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

11. 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

12. Part 3
Iodine in Groundwater

13. Paper overview (objectives)
Paper I: Iodine concentrations in Danish groundwater: historical data assessment (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

14. 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)

15. 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: mbt
Dominating setting at depth of extraction (some information about 70% of the samples)

16. 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)

17. Paper 3
Despite the same geology at local scale ( 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

18. 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

19. Iodine in Drinking water
Part 2
Iodine in Drinking water

20. 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

21. 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

22. 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

23. 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

24. 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:

25. Paper 2: Method of generalisation

26. Paper 2: Contribution to dietary intake

27. 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

28. Thank you for listening!
Questions?
Denitza Voutchkova

29. 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 : Hannover, Paris. Via
[2] WHO Protecting Groundwater for Health; Managing the Quality of Drinking-water sources.

30. 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