9. october 2014 aarhus universitet natural iodine content in drinking water (& groundwater) in...

9. OCTOBER 2014AARHUSUNIVERSITET

NATURAL IODINE CONTENT IN DRINKING WATER (& GROUNDWATER) IN DENMARK

DENITZA D. VOUTCHKOVAPhD DEFENCE AU

PHD DEFENCEDENITZA D. VOUTCHKOVA

9. OCTOBER 2014AARHUSUNIVERSITETAARHUSUNIVERSITET

PROJECT, FUNDING, PARTICIPANTS

› 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

SLIDE 2

PhD dissertation



PRESENTATION OUTLINE

› Background

› PhD objectives

› Iodine in groundwater – Paper 1, 3 & 4

› Iodine in drinking water – Paper 2 & Technical Note 1

› General conclusion

SLIDE 3



BACKGROUNDPart 1

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Why Iodine?

› 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]

SLIDE 5

[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.

WHO region “Europe”



Iodine Status of Danish Population

› 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]

SLIDE 6

[1]

55 tap water samples

[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.



Iodine Intake

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 150

Pregnancy/lactation 250

SLIDE 7

[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

25%

[2]

?!Temporal and Spatial VariationBioavailabilityGoitrogens and other factors



Drinking Water Supply in Denmark

SLIDE 8

› Treated groundwater

› Simple treatment mainly

› Decentralised structure

[1] Jupiter database , status December 2012

[1]

[1]



Iodine Cycle

SLIDE 10

No data

Total Iodine = Iodide + Iodate + Org. Iodine

50-60 µg/L

~5 µg/L



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

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IODINE IN GROUNDWATERPart 3

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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

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Paper 1: Data & Methodology

SLIDE 14

› 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)



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)

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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)

SLIDE 16



Paper 3SLIDE 17

› 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 4SLIDE 18

› GRUMO – iodine included since 2011

2,5m depthlacustrine gyttja

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

SLIDE 19



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

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Paper 2: Study design

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› 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

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› 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 factorsSLIDE 23

› 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



SLIDE 24Paper 2: Spatial autocorrelation analysis

Local Moran’s I

Threshold distance

dij

[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

[a]



Paper 2: Method of generalisationSLIDE 25



Paper 2: Contribution to dietary intake

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General Conclusion› Main findings

› 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

SLIDE 27

› 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



SLIDE 28

Thank you for listening!Questions?

Denitza Voutchkova

[email protected]

9. october 2014 aarhus universitet natural iodine content in drinking water (& groundwater) in...

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