Applicability of the recreational water quality standard guidelines

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WaL Sci. Tech. Vol. 31. No. 5-6. pp. 27-31. 1995.

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APPLICABILITY OF THE RECREATIONAL WATER QUALITY STANDARD GillDELINES F. J. Marino, E. Martinez-Manzanares, M. A. Morinigo and J.1. Borrego Department of Microbiology, Faculty of Sciences, University ofMalaga, Campus Universitario de Teatinos, 29071 Malaga, Spain ABSTRACT The applicability of WHO/UNEP criteria and the EC bathing water directive as microbial water quality guidelines were examined by means of an epidemiological-microbiological study of two Mediterranean bathing beaches. Neither set of guidelines proved particularly successful for protecting the public from health hazards related to faecal contamination of bathing waten. KEYWORDS Bathing water quality, microbial standards, WHO/UNEP criteria, EC bathing water directive, health effects, epidemiology. faecal contamination

Introduction - The quality of coastal bathing waters is currently assessed according to several criteria, including the WHO/UNEP Guidelines (1977, 1981) and the EC Directive concerning the quality of bathing water (EEC, 1975). The EC Directive must be observed by all community countries, and sets numerical quality standards to be achieved in such waters. A wide variety of physico-chemical, microbiological and aesthetic standards are specified at either "imperative" or "guideline" values which must be attained. Several authors have reviewed such quality criteria (Kay, 1988; Salas, 1989; Morris, 1991; Philipp, 1991), but they have not been based on epidemiological results. In particular, for Mediterranean coastal waters it has not been possible to establish a clear relationship between the microbial quality criteria and the incidence of a detailed symptomatology among the exposed population (Fattal Wi, 1986; Cabelli, 1989). The aim of this study was to test the applicability of two microbial water quality guidelines, the WHO/UNEP criteria and the EC Directive, to coastal zones in the Mediterranean Sea to verify if those criteria really protect the exposed population from the health-hazards associated with the recreational use of sewage-contaminated seawater. Material and Methods - To test the applicability of the recreational water quality standard guidelines proposed by the WHO/UNEP and EC Directive, an epidemiological-microbiological study on two beaches of the Mediterranean littoral (Malaga, Spain) was performed in the bathing seasons from 1988 to 1990. Seawater samples for microbiological analysis were collected in sterile amber glass, maintained in The following isothermic containers, shipped to the laboratory and tested within 611 of collection. microbial parameters were tested: total coliforms (TC), faecal coliforms (FC), Escherichia coli (Ec), faecal streptococci (FS); spores of sulphide-reducer clostridia (SrC), coliphages (Cp), Salmonella spp. (S),

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F. J. MARINo", al.

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Staphylococcus aureus (Sa), Pseudomonas aeruginosa (Pa), Aeromonas hydrophila (Ah), Vibrio sPp. (V) and Candida albicans (Ca). All the microbial parameters were tested using the membrane mtration technique, except for the enumeration of coliphages and Salmonella spp. The media and incubation

conditions used were the following: mEndo agar (36°tlOC, 24h) for TC; mFC agar without rosolic acid (44.5°±0.2°C, 24h) for FC and E. coli (biochemical and fluorogenic confirmations using API 20E and MUG tests, respectively);mEnterococcus agar (36°±1°C, 48·72h) for FS; Tryptose-sulphide-cycloserine and tryptose-sulphide-novobiocine media (36°±IOC, 18h) and ulterior biochemical confirmation for SrC' KRANEP and BFR-O agar (36°±I°C, 48h) for Sa; mPA-E agar (36°±I°C, 48h) for Pa; mA aga; supplemented with ethanol, ampicillin and bile salts (28°±I°C, 24-48h) for Ah; TCBS agar (36°±1°C, 24h) and subsequent biochemical conflIl11ation for Vibrio spp; and mCA agar using 1.2 ~m-pore size membrane filters (36°±I°C, 48h) for Ca. Salmonella spp. and coJiphages were investigated following the methodology described by Borrego M. (1991).

Results.- The distribution of the microbial levels on the beaches selected during the period studied is given in Table 1. Santa Ana beach fulfiled the WHO guidelines during 1988 and 1989, and parrially in 1990, since it fails for FC 90 standard. On the other hand, considering the EC Directive, this beach fails for the FS guidelines value in 1988 and 1989, and in 1990 it does not comply with the TC and FC imperative values and TC, FC and FS guideline values. The other beach selected, the Misericordia beach does not fulfil all the criteria during the studied period.

TABLE 1.- Distribution of the microbial levels· in the beaches selected Microorganisms 1988 Total coliforms Faecal coliforms

NT+

20 17 Escherichia coli 406 Faecal streptococci Sulphide-reducers clostridia NT 29 Coliphages 0 Salmonella spp. 0 Staphylococcus aureus

Pseudomonas aeruginosa 10 11 Aeromonas hydrophila 735 Vibrio spp. 8 Candida albicans

SANTA ANA 1989 1990 34 16 14 125 5 18 0 207 4 38 1765 37

2705 391 309 10414 10 70 0 163 29 405 4054 17

1988

MISERICORDIA 1989

NT 2608 2518 2835

NT

1450 0 0 40 3297 3375 37

24160 18986 9040 19738 2984 36736 12 453 87 5291 60204 5

1990 512078 13296 5738 197373 373251 197385 32

1399

868 40366 42131 801

• Expressed as mean of the microbial concentration per 100 011 of sample

+ No tested

Cumulative In the present study, we have also applied an index of faecal pollution, named Contamination Indexes (e.c.!.) (Borrego llJll., 1991) to evaluate the microbial quality of both beaches of during the period of study. TIle results obtained, shown in Figure I, indicate thut at low levels faecal pollution (Santa Ana beach) the microbial parameters that reflect better the sewage pollution are FC, E. coli and coliphages. On the contrary, at high levels of faecal pollution (Misericordia beach), the most reliable microbial parameters are FS and coliphages. The regression equations obtained using E. coli SO and 90 percentiles as prediction parameters (proposed by the WHO/UNEP) and faecal colifonn 80 and 95 percentiles (proposed by the EEC as imperative and guidelines values) and the perceptive attack rates of skin affections (the symptom most

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Recreational water quality standard guidelines

SANTA ANA VERY BAD

S

4

H

U

BAD

3

ACCEPrABLE

2

GOOD

t>

VERY GOOD

0

1989

1988

1990

• • • TC

~ FS

~

FC

Ec

Ph

Src

E:I

MISERICORDIA VERY BAD

S

4

BAD

H

t> t>

3

ACCEPrABLE

2

GOOD

VERYOOOD

0

1990

1989

1988

• • • TC

~ FC

[:J FS

Ph

Be

8 Src

Figure 1 Cumulative Contamination Indexes (CCI) for six microbial parameters (total colifonns, faecal coliforms, E. coli. faecal streptococci, A. hydrophila. sulphide-reducer clostridia) at two beaches

F. J. MARINOtl aL

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closely and significantly associated with the exposed p"pulation obtained in the epidemiological Study) among the exposed minus those non-exposed of both beaches, indicates there is no significant relationship (p>o.05) between all the microbial parameters specified in the guidelines and the attack rates. On the other hand, only the parameters PaSo and caSo showed a significant relationship with the perceptive attack rates of skin affections in the exposed population. These findings confum the low relationship between the incidence of skin affections and the levels of classical faecal pollution indicators in seawater.

Discussion.- Regarding the applicability of the WHO/UNEP and EEC criteria, two important problems arise. First, the lack of epidemiological data above-mentioned and the subsequent dilemma of applying artificial standards. Second, these criteria are not considered appropriate for determination of the bathing water quality since they do not provide information for the short-term management of a recreational area. In our work, in order to test the applicability of the two directives regarding the microbiological Water quality standards, the current imperative and guideline values were replaced in the regression models obtained with the data of the two beaches studied, and the calculated perceptive attack rates for skin affections were as follows: 4.3-4.8 per 100 persons for the EC50 and FC95 percentiles and 3.7 per 100 persons for the FC80 percentile. As noted by Cabelli ~ (1983), if we suppose for this affection a background illness close to 2% and an acceptable risk of 1%, none of the two directives assess accurately the health-hazard associated With the recreational use of bathing water of the beaches studied. IT we take as an acceptable limit the attack rates lower than 3%, the best indicators to evaluate the health risks associated with bathing in polluted waters are FC80, PaSO, caSo with limits of 75-100, 4-8 and 3-6 CFU per 100 mI. Conclusions- (i) In coastal waters with low faecal pollution level, the best indicators are faecal coliforms E. coli and coliphages. On the other hand, at high faecal pollution level, the best indicators are faecai streptococci and coliphages. (ii) The two directives compared in this study (WHOIUNEP and EEC) adequately classified the bathing zones according to the faecal pollution level. The guideline values proposed by the EEC are the mOSt restrictive limits. (iii) By using the standards established by the EEC (imperative and guideline values) the closest :stimation of the health hazards associated with bathing is obtained. However, if we used the criteria and models obtained with the epidemiological-microbiological data of both beaches, and apply the limits of those directives, the health hazard exceeded the acceptable risk for skin rashes by 2%. Therefore, these directives do not present an optimal applicability for similar zones to those studied. (iv) With the models obtained in the present study, a new quality objective is proposed, which allows us to reduce the acceptable risk to 1%, on the basis of the application of FCBO, PaSo and CaSo percentiles. References Borrego. lJ., Romero, P. and Marino, FJ. (1991) Epidemiological studies related to environmental quality criteria for bathing waters, shellfish-growing waters and edible marine organisms (Activity D). Final report on epidemiological study on bathers from selected beaches in Malaga, Spain (1988-1990). MAP Technical Reports Series No. 53. UNEP, Athens. CabelIi, V.P. (1989) Swimming-associated illness and recreational water quality criteria. Waf. Sci. Teclk, 2,1(2): 13-21.

CabeIIi. V.P., Dufour, A.P., McCabe, L.l. and Levin, M.A. (1983) A marine recreational water quality criterion consistent with indicator concepts and risk analysis. 1. Waf. Polluf. Control fed.. ~: 1306• 1314. EEC (1975) Directive du Conseil concernant la qualite des eaux de baignade du 8 decembre 1975. ImmW Official de Communantes EllT0J2ennes, UlLl.. Fallal, B., Peleg-Olevsky, E.,Yoshpe-Purer, Y. and Shuval, R.I. (1986) The association between morbidity among bathers and microbial quality of seawater. War Sci. Iech ,laO 1): 59-69. Kay, D. (1988) Coastal bathing water quality: the application of water quality standards to Welsh beaches. Appl. GeoWpby, 1\.: 117-134.

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Morris, R. (1991) The EC bathing water virological standard: is it realistic. War Sci Iech.. ~ (2): 49-52. Philipp, R. (1991) Risk assessment and microbiological hazards associated with recreational water spons. Rev. Med. Microbiol.,2: 208-214. Salas, H.J. (1989) Calidad del agua en el medio marino. Historia y aplicaci6n de normas microbiol6gicas. Bot Saint. Panam., lil.1: 226-239. WHO/UNEP (1977) Guidelin~s for health related monitoring of coastal water quality, Copenhagen. WHO/UNEP (1981) Coastal water quality control in the Mediterranean Sea. Copenhagen.