Epibathe Accessible Report FP6 Reference 022618 

 

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ACCESSIBLE REPORT 

TO COMMISSION STAFF RESPONSIBLE FOR REPORTING TO THE 

PARLIAMENT AND TO THE COUNCIL UNDER ARTICLE 14 OF THE 

BATHING WATER DIRECTIVE OF 15TH FEBRUARY 2006 

EU FRAMEWORK 6 

SPECIFIC TARGETTED RESEARCH PROJECT 

EPIBATHE 

PROJECT REFERENCE 022618 

MAY 2009 

This Activity Report covers the period 

1st June 2007 to 31st March 2009 

All correspondence to:- 

Epibathe Coordinator 

Professor David Kay 

University of Wales Aberystwyth 

dvk@aber.ac.uk

+44 1570 423565 (Tel and Fax) 
Epibathe Accessible Report FP6 Reference 022618 

 

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Contents 

1 Context of this report 1 

2 Report structure 1 

3 Project rationale 1 

4 Project partners 1 

5 Methodology 2 

 5.1 Fieldwork 2 

 5.2 Data available for analysis 3 

6 Results 3 

 6.1 Summary of principal findings 3 

 6.2 Field sites 4 

 6.3 Results of epidemiological data analysis 5 

 6.4 Risk assessment for marine waters 9 

7 Conclusions 11 

8 Access to the full data analysis 12 
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1 Context of this report 

This Supplement1 to the Epibathe project final report (see Workpackage 9 of the 

Description of Work) is designed to distil the central lessons of the Epibathe project to 

inform Commission Officers in drafting their report to the Parliament and the Council 

as required under Article 14 of Directive 2006/7/EC2

. 

A concise report, accessible to the interested ‘lay’ reader, has been requested. To this 

end, we highlight and illustrate the main findings of the Epibathe project in this 

report. Readers wishing to explore the detailed scientific findings, and statistical 

analyses undertaken to derive the conclusions, can access reports, presentations and 

meeting minutes at 

http://www.epibathe.eu/ 

2 Structure of this report 

This report provides a brief description of the Epibathe project (Sections 3-5) and 

outlines the main findings (Sections 6-7) as well as guiding the reader to the principal 

data which underpins this assessment. 

3 Project rationale 

Epibathe was funded under EU Framework programme 6 to produce ‘science support 

for policy’. It was commenced in December 2005 and was completed in March 2009. 

The imperative for this research effort was the relative paucity of EU data describing 

the health effects of bathing in EU freshwaters and Mediterranean marine waters. 

Both environments provide important recreational resources throughout the 

Community. In formulating the water quality criteria, defined in the 2006 Bathing 

Water Directive2, it was felt prudent that the Commission should seek to initiate 

research into this aspect of bathing water regulation and this aim was drafted into 

Article 14 of the Directive. 

4 Project Partners 

The consortium which undertook the Epibathe project is outlined in Table 1. The 

coordinating institution was UWA. Field investigations in Hungary and Spain were 

undertaken by NIEH and URV respectively. The principal responsibility for 

epidemiological data analysis was with NPHS. UEA provided training materials and 

advice on ethical clearance and WHO undertook literature evaluations and ensured the 

Epibathe outcomes were effectively assimilated within WHO policy developments 

 

1

 See Project Reporting in FP6 (2004), Section 6.9, Page 17 

2

 Anon (2006) Directive 2006/7/EC of the European Parliament and of the Council of 15 February 

2006 concerning the management of bathing water quality and repealing Directive 76/160/EEC. 

Official Journal of the European Union L 64, 37-51. 
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and updating of the WHO Guidelines for Safe Recreational Water Environments 

(2003)3 which was undertaken in 2009. 

Participant name Short 

name 

Country Leader 

University of Wales, Aberystwyth. UWA UK David Kay 

Fodor Joszef Orszagos Kozegeszsegugyi 

Kozpont. (Now named the ‘National Institute 

for Environmental Health’), Budapest. 

FJOKK 

(NIEH) 

Hungary Kádár Mihály 

University of Rovira and Virgili, Reus. URV Spain Maria Figueras 

National Public Health Service, Cardiff. NPHS UK Roland Salmon 

University of East Anglia, Norwich. UEA UK Paul Hunter 

World Health Organisation, Geneva. WHO (UN) Switzerland Jamie Bartram 

Table 1 Partners in the Epibathe project team 

5 Methodology 

5.1 Fieldwork 

A randomised controlled trial (RCT) protocol, as developed during earlier UK4

 and 

German5 investigations, was implemented which mirrors the approach used in 

developing the scientific basis of current WHO (2003)6 ‘Guideline’ values. This 

protocol required a volunteer group which was taken to a bathing water, randomised 

into bather and non-bathers, then exposed through ‘normal’ bathing activity, during 

which time, water quality was closely monitored through detailed spatial and temporal 

measurement of a suite of faecal indicator organisms used to regulate bathing waters. 

Before, during and after the exposure period, the volunteers were interviewed and the 

resultant data analysed to investigate any relationships between water quality and 

health outcomes reported by the volunteers. The experimental protocol required 

approval by appropriate local ethics panels. Eight separate trials were completed, four 

 

3

 WHO (2003) Guidelines for safe recreational water environments Volume I. WHO, Geneva. 219p 

available from http://www.euro.who.int/watsan/Publications/20031021_1. 

4

 Kay, D., Fleisher, J.M., Salmon, R.L., Jones, F., Wyer, M.D., Godfree, A.F., Zelenauch-Jacquotte, Z. 

and Shore, R. (1994) Predicting the likelihood of gastroenteritis from sea bathing - Results from 

randomized exposure. The Lancet 344(8927), 905-909. 

5

 Wiedenmann, A., Krüger, P., Dietz, K., López-Pila, J., Regine Szewzyk and Botzenhart, K. (2006) A 

randomized controlled trial assessing infectious disease risks from bathing in fresh recreational waters 

in relation to the concentration of Escherichia coli, intestinal enterococci, Clostridium perfringens and 

somatic coliphages. Environmental Health Perspectives 8115, 1-41. 

6

 Kay, D., Bartram, J., Pruss, A., Ashbolt, N., Wyer, M.D., Fleisher, J.M., Fewtrell, L., Rogers, A. and 

Rees, G. (2004) Derivation of numerical values for the World Health Organization guidelines for 

recreational waters. Water Research 38(5), 1296-1304. 
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in Hungary and four in Spain. Volunteer numbers exceeded targets in all field 

campaigns which were completed successfully in 2006 and 2007. 

5.2 Data available for analysis 

The new information generated by the Epibathe research: i.e. on EU fresh and 

Mediterranean waters, has been analysed separately and also combined with existing 

data acquired using the same research methods in Germany and the United Kingdom. 

This meta-analysis of the larger data set includes data on over 7,000 volunteers who 

participated in these randomised controlled trials between 1989 and 2007. 

6 Results 

6.1 Summary of principal findings

Water quality encountered during the new Hungarian and Spanish investigations was 

relatively ‘clean’ as would be expected from the choice of sites which were in 

compliance with the Imperative standard of the EU bathing Water Directive (1976). 

However, elevations in symptom reporting in the bather group(s), i.e. when compared 

to the non-bather group(s), were observed. It was also notable that the background 

rates of most symptoms, principally gastrointestinal (GI) symptoms, was lower in the 

Epibathe studies than in previous studies in the UK and Germany. These temporal 

differences could be due to improvements in effluent treatment and the general health 

status of the European population over the 20 year period spanned by these 

investigations. 

The analysis of the combined data set, specifically that component focused on GI 

symptoms, suggests that enterococci are best predictor of illness in bathers using 

marine waters and Escherichia coli is a better index of GI symptoms in bathers using 

freshwater. The evidence-base created by this analysis suggests that exposure to 

marine recreational waters presents approximately twice the risk associated with fresh 

waters containing similar faecal indicator organism densities. Furthermore, the new 

combined analysis suggests similar risk levels to those assumed in derivation of the 

original Guidelines for Safe Recreational Water Environments by WHO in 2003 and 

the revised Bathing Water Directive in 2006. Thus, the Epibathe empirical field 

studies and combined data analysis does not suggest that a change in the water quality 

standards suggested by either the WHO or the European Union are in need of 

revision. 

However, the Epibathe project has produced data suggesting significant limitations in 

the microbiological methods defined in the revised Bathing Water Directive (2006). 

For example, the ‘most probable number’ (MPN) method for E. coli (ISO 9308-3) 

produced false positive results which could have classified a Mediterranean bathing 

area as having ‘poor’ quality when the same site would be characterised as of 

‘excellent’ water quality if measured by the ‘membrane filtration’ (MF) method (ISO 

9308-1). However, the MF method also produced significant problematical results 

generally attributable to its poor selectivity when applied at both the Hungarian 

freshwater bathing sites and at one Mediterranean bathing site influenced by 

freshwater contamination. 
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6.2 Field sites 

Figure 1 shows the 4 Hungarian sites examined and Figure 2 shows the sites in Spain. 

Figure 1 Hungarian sites examined in 2006 and 2007

Figure 2 Spanish sites examined in 2006 and 2007

Water quality, at each field site, was measured in each of six marked swim zones at 

20 minute intervals. Bathers were asked to remain in the water for a minimum of ten 
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minutes and the water quality experienced at the time and place of bathing was 

attributed to each bather. This provided a range of ‘exposures’, i.e. over time and 

space, both between sites and within each three hour exposure period. Figure 3 shows 

the range in water quality as measured by enterococci concentrations for all sites 

examined. (For a full analysis see Appendix 6 Epibathe Final Activity Report). 

Figure 3 Enterococci concentration measured at each of the Epibathe trial sites 

in 2006 and 2007 

6.3 Results of the Epidemiological data analysis relating 

water quality to health outcomes 

Five separate analyses have been completed to examine the following relationships 

and associations: 

i. risk of gastroenteritis from recreational bathing water: analysis of Epibathe 

data from Hungary and Spain; 

ii. risk of gastroenteritis from recreational bathing water: a meta-analysis of 

randomised exposure trials in four European countries; 

iii. estimating the risk of gastroenteritis in European fresh bathing waters using E. 

coli as indicator organism; 

iv. risks of non-enteric diseases from European recreational bathing water; and 

v. the effects of non-water related risk factors on gastroenteritis. 
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For a full analysis, see Appendix 2 of the Epibathe Final Activity Report. A total of 

17 randomised controlled trial experiments were available for this analysis, eight of 

which were funded under the Epibathe project. The populations of bathing and nonbathing volunteers who participated in these trials and provided usable data are 

outlined in Table 2 below. 

Classification GI AFRI Ear Eye Skin

Non-bathers (n) 3,780 3,953 3,943 3,939 3,590 

Bathers (n) 3,432 3,580 3,563 3,557 3,246 

Table 2 Population numbers available for the epidemiological analyses using the 

combined EU data set. 

For EU marine waters (Spain and the UK), the clearest trend in increasing risk of 

illness with decreasing water quality was evident using enterococci as indicator of 

water quality. Table 3 shows a meta-analysis used to calculate the Odds Ratio (OR) of 

gastroenteritis associated with ascending quartile exposures to enterococci. 

Subjects Meta-analysis Quartile cut-points

(enterococci/100ml) N % ill Adjusted 

OR 95% CI

Non-bathers 1,598 6.7 1.00 N/A 

0-8 340 7.1 1.35 0.75-2.45

9-27 360 9.7 1.44 0.87-2.36

28-88 357 13.2 1.47 0.94-2.31

≥89 357 6.7 2.06 0.84-5.04

Overall 3,012 7.9 1.39 1.03-1.87

Table 3 Meta-analysis used to explore the relationship between reported 

gastroenteritis in the bather cohort and enterococci concentration in EU 

marine bathing waters. 

The meta-analysis forest plot for all marine sites is presented in Figure 4 below. 
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Figure 4 Forest plots representing the OR (ES (95%CI)) of gastroenteritis in 

each marine water site (i.e. bather vs non-bather) at different 

enterococci concentrations. The dotted line is the mean OR for all sites.

For fresh waters (German and Hungary), the clearest dose-response relationship 

between gastrointestinal symptoms and water quality was seen with E. coli 

concentration. Table 4 shows the freshwater analysis. 

NOTE: Weights are from random effects analysis

Overall (I-squared = 0.0%, p = 0.885)

Spain II

UK I

Spain I

UK IV

Study

Spain III

UK III

UK II

Spain IV

ID

1.38 (1.03, 1.87)

0.84 (0.38, 1.88)

1.49 (0.69, 3.20)

2.01 (0.79, 5.16)

1.72 (0.71, 4.15)

1.19 (0.51, 2.75)

1.25 (0.59, 2.62)

1.95 (0.72, 5.31)

1.39 (0.58, 3.36)

ES (95% CI)

100.00

13.86

15.32

10.11

11.51

%

12.60

16.14

8.96

11.51

Weight

1.38 (1.03, 1.87)

0.84 (0.38, 1.88)

1.49 (0.69, 3.20)

2.01 (0.79, 5.16)

1.72 (0.71, 4.15)

1.19 (0.51, 2.75)

1.25 (0.59, 2.62)

1.95 (0.72, 5.31)

1.39 (0.58, 3.36)

ES (95% CI)

100.00

13.86

15.32

10.11

11.51

%

12.60

16.14

8.96

11.51

Weight

 .1 1 10
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50 unit cutpoints Subjects Meta-analysis

(E. coli /100ml) N % ill Adjusted 

OR 95% CI

Non-bathers 2,182 4.7 1.00 N/A 

0-49 451 3.3 0.70 0.35-1.39 

50-99 565 5.0 1.39 0.82-2.35 

100-49 239 5.0 1.23 0.56-2.69 

150-199 116 6.0 1.59 0.52-4.88 

200-249 65 10.8 1.77 0.65-4.86 

≥250 582 8.1 1.67 1.04-2.67 

Overall 4,200 5.2 1.20 0.88-1.62

Table 4 Meta-analysis used to explore the relationship between reported 

gastroenteritis in the bather cohort and E. coli concentration in EU 

fresh bathing waters. 

The meta-analysis forest plot for all freshwater sites is presented in Figure 5 below. 

Both analyses (i.e. of fresh and marine waters) suggest elevations in illness in the 

bather cohorts. However, results from fresh water studies do not display a consistent 

incremental elevation in odds ratio (OR) as the exposure increase. 

It should be noted also that the values presented in Tables 3 and 4 are of single 

exposure concentrations and they are, therefore, not directly related to a calculated 

percentile compliance concentration as is specified in the Bathing Water Directive 

(2006) and the WHO Guidelines for Safe Recreational Water Environments (2003). 
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Figure 5 Forest plots representing the OR (ES (95%CI)) of gastroenteritis in 

each fresh water site (i.e. bather vs non-bather) at different E. coli

concentrations. The dotted line is the mean OR for all sites. 

6.4 Risk assessment 

The original risk assessment which underpinned the WHO Guidelines7

 was derived 

from the UK studies. This assumed a simple linear relationship between enterococci 

concentration in marine waters and rates of gastroenteritis in bathers. However, the 

assumption of a single linear relationship becomes questionable where several 

individual studies are combined spanning different regions and time periods. This 

may result in the rates of illness in the non-bather groups exhibiting variability 

between sites and times, which is normal for gastroenteritis in the community. It was 

for this reason that the epidemiological analysis summarised above adopted a ‘metaanalysis’ approach, rather than reporting a linear modelling analysis. Furthermore, 

 

7 Kay, D., Bartram, J., Pruss, A., Ashbolt, N., Wyer, M.D., Fleisher, J.M., Fewtrell, L., Rogers, A. and 

Rees, G. (2004) Derivation of numerical values for the World Health Organization guidelines for 

recreational waters. Water Research 38(5), 1296-1304. 

NOTE: Weights are from random effects analysis

Overall (I-squared = 0.0%, p = 0.483)

Germany II

Germany III

Hungary III

Hungary II

Study

Germany V

Germany IV

ID

Hungary I

Germany I

Hungary IV

1.19 (0.88, 1.62)

1.28 (0.53, 3.10)

1.60 (0.57, 4.52)

1.03 (0.32, 3.28)

0.53 (0.17, 1.66)

0.93 (0.47, 1.85)

2.05 (1.01, 4.16)

ES (95% CI)

1.11 (0.49, 2.47)

0.58 (0.17, 1.98)

2.32 (0.65, 8.28)

100.00

12.03

8.67

7.00

7.24

%

19.88

18.79

Weight

14.49

6.14

5.76

1.19 (0.88, 1.62)

1.28 (0.53, 3.10)

1.60 (0.57, 4.52)

1.03 (0.32, 3.28)

0.53 (0.17, 1.66)

0.93 (0.47, 1.85)

2.05 (1.01, 4.16)

ES (95% CI)

1.11 (0.49, 2.47)

0.58 (0.17, 1.98)

2.32 (0.65, 8.28)

100.00

12.03

8.67

7.00

7.24

%

19.88

18.79

Weight

14.49

6.14

5.76

 .1 1 10
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risk assessment in the period since the WHO analysis was completed as advanced. In 

particular, assumptions of simple linear relationships have been replaced by 

approaches which assume that the ‘drivers’ (e.g. enterococci in marine waters) of an 

outcome (e.g. gastroenteritis rates in a bather group) are better described as statistical 

distributions, rather than individual values. Expressed in risk assessment terminology, 

linear modelling has been replaced by stochastic modelling in many areas of health 

risk assessment. 

The concluding International Workshop of the Epibathe project was conducted at the 

WHO head quarters in Geneva in January 2009 and the choice of risk assessment 

approaches was addressed. The participating expert group agreed that a stochastic 

approach to risk assessment was most appropriate and this was applied to the Epibathe 

data by Professor Paul Hunter (Epibathe partner UEA). The advantages of this 

approach are that the modelling of risk can be accomplished without the need to make 

certain, potentially over-simplistic, assumptions in the underlying data8. Instead, the 

input ‘drivers’ can be expressed as statistical distributions, which is generally a more 

realistic representation of reality. 

Using this approach, the risk of gastroenteritis attributable to bathing in EU marine 

waters (i.e. using the UK and Spanish data sets combined; see Figure 4) which have a 

95th percentile water quality of 200 enterococci per 100ml was calculated at 4.5% (see 

Figure 6). 

Figure 6 Stochastic model of the attributable risk of gastroenteritis experienced 

by bathers in marine waters with a 95th percentile value of 200 

enterococci per 100ml9. 

 

8

 For example, the original WHO assessment made the assumption that all beaches world-wide had the 

same standard deviation for enterococci sampled in the bathing zone, i.e. a log10 value of 0.8103. 

9

 This analysis was completed using Monte Carlo simulation within @RISK software of Palisade Corp. 

2.5% 95.0% 2.5%

-2.0 21.1

-20

0

20406080

100120

0.00

0.02

0.04

0.06

0.08

0.10

0.12

Attributable disease incidence

A ttributable disease 

incidence

Minimum -5.5842

Maximum 100.8291

Mean 4.4952

Std Dev 6.1587

V alues 10000
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This value is comparable with an attributable illness probability of 5%, calculated 

using the original WHO analysis which underpins the WHO10 ‘Level B’ and EU11

‘Good’ criteria for this parameter. 

This broad correspondence between the risks derived from the new information for 

marine waters, generated through the Epibathe project analysed using contemporary 

approaches, and the risks assumed by the designers of the existing standards, led the 

WHO expert group to conclude that there was no evidence-base to suggest that the 

original criteria should be amended in response to any more recent epidemiological 

information. This recommendation is encapsulated within an addendum to the 2003 

WHO Guidelines which will shortly be published by WHO. 

For EU freshwaters, the increase in illness rates attributable to incremental elevations 

of faecal indicator bacterial concentrations was less marked, as seen in Table 4 above. 

The attributable risks were best characterised by Escherichia coli, rather than 

enterococci, bacteria which is in broad agreement with parallel research in the USA. 

The Epibathe analysis would suggest that the risks of bathing in freshwaters is lower 

than attributable to marine water exposures and that the 2:1 risks differential, implied 

by the stricter standards for marine waters, outlined in Annex 1 of the 2006 Bathing 

Water Directive, is in broad agreement with the finding of the Epibathe project. 

7 Conclusions 

1. The Epibathe project has provided new information to supplement the original 

UK data used to underpin the WHO Guidelines for recreational waters 

published in 2003. 

2. This information, together with new data for the USA, has been evaluated by 

WHO in January 2009 during an expert consultation to consider revision of 

the WHO Guidelines in this area from which elements of the EU Bathing 

Water Directive (2006) criteria derive. 

3. A new approach to assessing the risks attributable to bathing in environmental 

waters was applied to the Epibathe data and reported to the WHO expert 

meeting in January 2009. 

4. This analysis suggested that there was broad correspondence between the 

attributable risks assumed in deriving the current WHO and EU standards with 

that calculated using the new information derived from the Epibathe project. 

5. The new research has not, therefore, produced a clear evidence-base which 

would suggest that a revision of the water quality criteria outlined in Annex 1 

of the 2006 Bathing Water Directive should be undertaken. 

6. The risks attributable to bathing in freshwaters were less marked than in 

marine water environments. This suggests that a differential in standards 

applied to both environments, as is evident in the 2006 Bathing Water 

Directive, is supported by the available and newly derived evidence. 

 

10 See Tale 4.7: WHO (2003) Guidelines for safe recreational water environments Volume I. WHO, 

Geneva. 219p available from http://www.euro.who.int/watsan/Publications/20031021_1. 

11 See Annex 1: Anon (2006) Directive 2006/7/EC of the European Parliament and of the Council of 15 

February 2006 concerning the management of bathing water quality and repealing Directive 

76/160/EEC. Official Journal of the European Union L 64, 37-51. 
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8 Access to the full data analysis 

The full data analysis in the form of the five reports noted in Section 6.3 above can be 

obtained as separate .pdf downloads from the web site below: 

http://www.epibathe.eu/