7. FEBRUARY 2012 AARHUS UNIVERSITET

IODINE IN GROUNDWATER IN DENMARK

IMPLICATIONS FOR HUMAN HEALTH

DENITZA VOUTCHKOVA PHD FELLOW

AU

AARHUS UNIVERSITET

PROJECT PRESENTATION

› Geo-Center project, financed by GEUS and AU › 2011- 2014 › Project title:

“Iodine in the hydrological cycle in Denmark: implications for human health“

› People involved in the project:

› Søren Munch Kristiansen (AU, Department of Geoscience) › Birgitte Hansen, Vibeke Ernstsen, Brian Sørensen & Kim Esbensen (GEUS) IODINE IN GROUNDWATER IN DENMARK DENITZA VOUTCHKOVA 7. FEBRUARY 2012 2

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WHY IODINE IS INTERESTING?

Medical aspect Geochemical aspect

› ›

essential component of the thyroid hormones low iodine intake:

› variety of IDD – › prevention – mental retardation, goitre, hypothyroidism, etc; fortification of table salt and salt in bread (dk mandatory since 2000/2001) ›

high iodine intake:

› tolerable upper intake level › associated with the correction of iodine deficiency or/and chronically high intake – iodine induced hyperthyroidism, elevated goitre and subclinical hypothyroidism › › ›

iodine in groundwater (= tap water)

› mapping regional/temporal variations › not included in the monitoring programs of the waterworks; › data mainly from GRUMO wells; some studies

understanding the involved processes source/sources of iodine in the groundwater in Denmark

IODINE IN GROUNDWATER IN DENMARK DENITZA VOUTCHKOVA 7. FEBRUARY 2012 3

PREVIOUS STUDIES

Andersen, Petersen, Lauberg “ Iodine in drinking water is bound in humic substances“ 2002 AARHUS UNIVERSITET Rasmussen, Larsen, Ovesen “Iodine content in drinking water and other beverages in Denmark” 2000 Pedersen, Laurberg, Nøhr, Jørgensen, Andersen "Iodine in drinking water varies by more than 100-fold in Denmark. Importance for iodine content of infant formulas" 1999 IODINE IN GROUNDWATER IN DENMARK DENITZA VOUTCHKOVA 7. FEBRUARY 2012 4

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AVAILABLE GROUNDWATER DATA

Status December 2011: 2562 samples

2011 2006 2005 2001 1995 1991 1990 1988 1986 Poster Bari 1975 1959 1958 Data quality assessment • Different methods data • Unit mistakes Statistical analysis of the Picking up interesting areas for case-studies 1941 1940 0 1933 200 400 600 800 Number of Iodine* samples 1000 IODINE IN GROUNDWATER IN DENMARK DENITZA VOUTCHKOVA 7. FEBRUARY 2012 5

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MULTIVARIATE DATA ANALYSIS

Purpose:

1. finding outliers 2. grouping due to date, method, etc.

3. exploring the relations/correlations between the different data LI H2S CH4 O2 AGGCO2 NVOC PO4

Other constituents

I

Hypothesis:

there is correlation between iodine and the other constituents or some of them SO4 NO3 PH LED RED K FE MN BIK CA MG NA

Geology Distance to coastline Distance to major faults

I • • •

Hypotheses:

Iodine originates from the rock/sediment sea water intrusion upward diffusion of old saltwater FL BOR BA BR CL JOD SR 1200 430 417 65 237 667 901 1621 1627 1693 1686 822 1614 1623 1617 1059 1026 1048 987 875 1406 1247 1628 2131 2562 1269 IODINE IN GROUNDWATER IN DENMARK DENITZA VOUTCHKOVA 7. FEBRUARY 2012 6

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IODINE SPECIATION

Important for the geochemical understanding of the Iodine cycle Inorganic iodine Organo-iodine Total iodine 𝐼 − 𝐼𝑂 3 − Lab methods development and testing: 1. Inorganic Iodine – IC 2. Total Iodine – ICP-MS 3. Organo-iodine

Storage experiment:

How the Iodide concentration in groundwater sample is affected by: 1. storage conditions – 5ºC,10ºC, freezer 2. storage period

µg/l

15,00 14,00 13,00 12,00 11,00 10,00 9,00 8,00 7,00 6,00 5,00

Storage experiment

Statistically significant difference 2 days 3 days 6 days 10 days 21 days mean 10ºC mean 5ºC mean freezer Freezer – indications that the composition of the water was different; new experiment needed in order to make conclusions IODINE IN GROUNDWATER IN DENMARK DENITZA VOUTCHKOVA 7. FEBRUARY 2012 7

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CASE STUDIES

Purpose:

1. Source - explanation for the observed concentrations 2. Iodine speciation 3. Geochemical analysis 0 meq/l Na+K Mg Ca HCO3 Cl SO4 Ishøj Hjelmsølille 11 IODINE IN GROUNDWATER IN DENMARK DENITZA VOUTCHKOVA 7. FEBRUARY 2012 8

FUTURE PLANS AND POSSIBLE COLLABORATION

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Medical aspect Possible collaboration Geochemical aspect In progress:

› Case studies › Multivariate analysis of Jupiter data

National study on Iodine in drinking water:

› Sampling from waterworks wells › Reflecting the different geology and the size of the waterworks › Mapping of Iodine concentrations in drinking water › Estimation of the dietary iodine intake in Denmark › Combined study with data from medical registers IODINE IN GROUNDWATER IN DENMARK DENITZA VOUTCHKOVA 7. FEBRUARY 2012 9

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