Tag Archives: Denmark

Status of Small Water Systems in Nordic Countries

Gunnarsdottir MJ, Persson KM, Andradottir HO, Gardarsson SM. Status of small water supplies in the Nordic countries: Characteristics, water quality and challenges. International journal of hygiene and environmental health. 2017 Aug 24. pii: S1438-4639(17)30391-7. doi: 10.1016/j.ijheh.2017.08.006.

Access to safe water is essential for public health and is one of the most important prerequisites for good living and safe food production. Many studies have shown that non-compliance with drinking water quality standards in small water supply systems is much higher than in large systems. Nevertheless, people served by small water supply systems have the right to the same level of health protection. Actions are therefore needed to improve the situation. The objective of the present study was to carry out a baseline analysis of the situation in the Nordic region and provide recommendations for governmental policy and actions. Data were gathered on number of water supplies, population served, compliance with regulations and waterborne disease outbreaks from various sources in the Nordic countries. The collected data showed that there are about 12500 regulated water supplies, 9400 of which serve fewer than 500 persons. The number of unregulated and poorly regulated supplies is unknown, but it can be roughly estimated that these serve 10% of the Nordic population on a permanent basis or 2.6 million people. However, this does not tell the whole story as many of the very small water supplies serve transient populations, summerhouse dwellers and tourist sites, with many more users. Non-compliance regarding microbes is much higher in the small supplies. The population weighted average fecal contamination incidence rate in the Nordic region is eleven times higher in the smaller supplies than in the large ones, 0.76% and 0.07%, respectively. Registered waterborne disease outbreaks were also more frequent in the small supplies than in the large ones.

Monitoring Data Below Detection Limits Lowers Median Pesticide Concentrations

Hansen CT, Ritz C, Gerhard D, Jensen JE, Streibig JC. Re-evaluation of groundwater monitoring data for glyphosate and bentazone by taking detection limits into account. The Science of the total environment. 2015 Jul 17;536:68-71. doi: 10.1016/j.scitotenv.2015.07.047.

Current regulatory assessment of pesticide contamination of Danish groundwater is exclusively based on samples with pesticide concentrations above detection limit. Here we demonstrate that a realistic quantification of pesticide contamination requires the inclusion of “non-detect” samples i.e. samples with concentrations below the detection limit, as left-censored observations. The median calculated pesticide concentrations are shown to be reduced 104 to 105 fold for two representative herbicides (glyphosate and bentazone) relative to the median concentrations based upon observations above detection limits alone.

Drinking Water And Sialolithiasis, Denmark

Schrøder S, Homøe P, Wagner N, Vataire AL, Lundager Madsen HE, Bardow A. Does drinking water influence hospital-admitted sialolithiasis on an epidemiological level in Denmark? BMJ Open. 2015 May 3;5(4):e007385. doi: 10.1136/bmjopen-2014-007385.

OBJECTIVES: Sialolithiasis, or salivary stones, is not a rare disease of the major salivary glands. However, the aetiology and incidence remain largely unknown. Since sialoliths are comprised mainly of calcium phosphate salts, we hypothesise that drinking water calcium levels and other elements in drinking water could play a role in sialolithiasis. Owing to substantial intermunicipality differences in drinking water composition, Denmark constitutes a unique environment for testing such relations.

DESIGN: An epidemiological study based on patient data extracted from the National Patient Registry and drinking water data from the Geological Survey of Denmark and Greenland retrieved as weighted data on all major drinking water constituents for each of the 3364 waterworks in Denmark. All patient cases with International Statistical Classification of Diseases 10th Revision (ICD-10) codes for sialolithiasis registered between the years 2000 and 2010 were included in the study (n=3014) and related to the drinking water composition on a municipality level (n=98).

PRIMARY AND SECONDARY OUTCOME MEASURES: Multiple regression analysis using iterative search and testing among all demographic and drinking water variables with sialolithiasis incidence as the outcome in search of possible relations among the variables tested.

RESULTS: The nationwide incidence of hospital-admitted sialolithiasis was 5.5 cases per 100 000 citizens per year in Denmark. Strong relations were found between the incidence of sialolithiasis and the drinking water concentration of calcium, magnesium and hydrogen carbonate, however, in separate models (p<0.001). Analyses also confirmed correlations between drinking water calcium and magnesium and their concentration in saliva whereas this was not the case for hydrogen carbonate.

CONCLUSIONS: Differences in drinking water calcium and magnesium may play a role in the incidence of sialolithiasis. These findings are of interest because many countries have started large-scale desalination programmes of drinking water.

Danish drinking water fluoride study results are misleading…

These types of studies are used to show the potential benefits of fluoridation of drinking water. However, they are based entirely on an ecologic study design, and do not consider total fluoride exposure, and other factors that confound the results. Such studies are considered hypothesis generating, and not indicative of a causal relationship. In addition, other adverse effects (e.g., fluorosis) were not measured or reported. 

Kirkeskov, L., Kristiansen, E., Boggild, H., von Platen-Hallermund, F., Sckerl, H., Carlsen, A., Larsen, M.J., and S. Poulsen. The association between fluoride in drinking water and dental caries in Danish children. Linking data from health registers, environmental registers and administrative registers. Community Dent Oral Epidemiol. 2010 Feb 10.

Abstract – Objectives: To study the association between fluoride concentration in drinking water and dental caries in Danish children.

Methods: The study linked registry data on fluoride concentration in drinking water over a 10-year period with data on dental caries from the Danish National Board of Health database on child dental health for 5-year-old children born in 1989 and 1999, and for 15-year-old children born in 1979 and 1989. The number of children included in the cohorts varied between 41.000 and 48.000. Logistic regression was used to assess the correlations, adjusting for gender and taxable family income as a proxy variable for socioeconomic status.

Results: Fluoride concentration in drinking water varied considerably within the country from very low (<0.10 mg/l) to more than 1.5 mg/l. Only little variation was found over the 10-year study period. Dental caries in both 5-year-olds and 15-year-olds decreased over the study period. An inverse relation between the risk of dental caries and fluoride concentration in drinking water was found in both primary and permanent teeth. The risk was reduced by approximately 20% already at the lowest level of fluoride exposure (0.125-0.25 mg/l). At the highest level of fluoride exposure (>1 mg/l), a reduction of approximately 50% was found. Similar findings were found if analysis was limited to children residing in the same place during the entire study period.

Conclusions: The study confirmed previous findings of an inverse relation between fluoride concentration in the drinking water and dental caries in children. This correlation was found in spite of the extensive use of fluoridated toothpaste and caries-preventive programs implemented by the municipal dental services in Denmark. Linking Danish health registers with environmental and administrative registers offers an opportunity for obtaining sample sizes large enough to identify health effect, which otherwise could not be identified.

Malaguerra et al 2011: Pesticides in water supply wells in Zealand, Denmark: A statistical analysis

F. Malaguerra, H.J. Albrechtsen, L. Thorling, and P.J. Binning. Pesticides in water supply wells in Zealand, Denmark: A statistical analysis. Science of the Total Environment. 2011 Nov. 14.

Data from the Danish National Borehole Database are used to predict drinking water well vulnerability to contamination by pesticides, and to identify the dominant mechanisms leading to well pollution in Zealand, Denmark. The frequency of detection and concentrations of 4 herbicides and 3 herbicide metabolites are related to factors accounting for geology (thicknesses of sand, clay and chalk layers), geographical location (distance to surface water and distance to contaminated sites), redox conditions and well depth using logistic regression, the binomial test and Spearman correlation techniques. Results show that drinking water wells located in urban areas are more vulnerable to BAM and phenoxy acids contamination, while non-urban area wells are more subject to bentazone contamination. Parameters accounting for the hydraulic connection between the well and the surface (well depth and thickness of the clay confining layer) are often strongly related to well vulnerability. Results also show that wells close to surface water are more vulnerable to contamination, and that sandy layers provide better protection against the leaching of oxidizable pesticides than clay aquitards, because they are more likely to be aerobic. 4-CPP is observed more often at greater well depth, perhaps because of anaerobic dechlorination of dichlorprop. The field data are used to create a set of probabilistic models to predict well vulnerability to contamination by pesticides.

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