Coastal bathing
The University of Salford, School of Environment and Life Sciences and the Telford Institute of Environmental Systems,
Salford, UK
Keywords Sewage, Water quality, Health, Risk
Abstract Over 300 million gallons of sewage are discharged into the sea around the coastline of Britain each year. Raw or partially treated sewage contains a mixture of micro-biological species, some of which are pathogens linked to many diseases. The most common gastro-intestinal infections occur via the faecal-oral route. A bather or water sports enthusiast could ingest enough pathogenic micro-organisms from sewage contaminated sea water to cause illness. Legislation has been passed requiring the quality of bathing water to be tested so as to assess the risks to human health. Standards within the EC Bathing Water Directive remain above the level found to cause risks to human health, despite the existence of economically viable and environmentally sustainable technologies which would ensure safe levels in waste water discharges. Therefore even beaches which meet the standards of the Directive may not be as safe as they appear. This paper attempts to address the issue of Bathing Water Standards. It raises the questions of why standards are so low and looks at what is being done to improve coastal bathing water quality in the UK.
Introduction
Over 300 million gallons of sewage are discharged into the sea around the coastline of Britain each year. Raw or partially treated sewage contains a mixture of micro-biological species, some of which are pathogens linked to many diseases (SAS, 1997).
The most common gastro-intestinal infections occur via the faecal-oral route. A bather or water sports enthusiast could ingest enough pathogenic micro-organisms from sewage contaminated sea water to cause illness, but the quantity of water that the individual would need to consume for this to occur depends on the concentration of pathogens within the water swallowed and the minimal effective dose of viable cells required to infect the individual (SAS, 1998).
Health risks associated with bathing waters
Epidemiological research over the last 50 years in different parts of the world has linked the incidence of disease to the quality of recreational and bathing water, however, no single connection between the two has ever been universally accepted. Legislation has been passed requiring the quality of bathing water to be tested so as to assess the risks to human health (SAS, 1998). Illnesses associated with viruses and bacteria potentially present in domestic wastewater are shown in Table I.
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Historical research into health risks
Bathing waters continue to pose a risk to human health, despite the legislation that has been designed and implemented to prevent it (SAS, 1997).
The first detailed research into the health risks associated with water used for bathing and water sports was done in the USA by Stephenson in 1953. His research included the risks associated with fresh water and bathing pools as well as tidal marine water. Families were provided with diaries to record any symptoms they experienced during the bathing/summer season. The water was assessed in terms of the total coliform concentration and the results were used as a basis for the standards proposed by the National Technical Advisory Committee (NTAC) in 1968. The introduction of the US Environmental Protection Agency (USEPA) standard followed with 200 faecal coliform per 100 ml as the acceptable limit. This was widely accepted and adopted by many other agencies, except the EC Bathing Water Directive with a standard of 2,000 faecal coliforms per 100ml and a guideline standard of 100 faecal coliforms per 100ml (Stephenson, 1953).
Various criticisms of the US standard related to the small amount of detail available on appropriate indicators such as faecal streptococci. Illness incidence was dependent on familial reporting by members of the public.
The UK Public Health Laboratory Service (PHLS) conducted extensive retrospective case and controlled studies of poliomyelitis and enteric fever at coastal resorts where records of exposure to bathing water were available. There was no link between sea bathing and poliomyelitis, though four cases of enteric fever were related to bathing water that was so badly polluted with faecal solids that they were disgusting to look at. Poliomyelitis could not be scientifically or medically linked to coastal bathing and the PHLS committee
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noted that bathing in sewage polluted sea water carries only a negligible risk tohealth, even on beaches that are aesthetically unsatisfactory (SAS, 1998). Only small numbers of two notifiable diseases were used. The data therefore do not relate to other cases of serious disease. It is also not justified to use the data on two serious diseases to suggest that there is no serious risk to bathers or other water users acquiring less serious diseases such as gastro-enteritis, that had previously been reported by Stephenson in 1953.
Despite the vague nature of the PHLS findings they were used to support the view that there was no risk to public health of bathing in sewage contaminated waters, unless they were visually repulsive. Consequently, little was done in the UK to improve the quality of bathing water for two decades. It was not until the introduction of the EC Bathing Water Directive that attention was paid to the matter. Also, the standards laid down by the directive were lower than those already criticised in the USA (i.e. 2,000 faecal coliforms per 100ml). The Directive set a recommended standard for member states and also a guideline standard of 100 faecal coliforms per 100ml. Unfortunately, it was not enforceable through any legislation and so held little weight with those not wishing to invest in a coastal clean up.
The UK government complied with the bathing water directives by meeting the bare legal minimum imperative standards and the water authorities were not required to meet the standards of the directive. So, although some of the standards in the directive were being met, they were the lowest required. Despite the implementation of low standards, limited improvements were made where there were previously no standards at all (SAS, 1997).
The weakness of the USEPA standards, based on Stephenson's earlier research, were recognised in the USA, which introduced a new methodology, devised by Cabelli, with significant improvements. The main factors included trials that were completed on Saturdays and Sundays only. Demographic data was collected during an initial beach interview followed up by subsequent telephone interviews. Wet hair was defined as the indicator for head immersion. Targeted families included bathers and non-bathers. Only gastrointestinal symptoms (e.g. vomiting and diarrhoea) were considered. These were swimming associated and pollution related. The symptoms were related to selected water quality indicators. Water quality during the times of maximum swimming activity was assessed from three to four samples being collected at chest depth (10cm below the surface) each test day. Bivariate log linear regression was used to define the relationship between the swimming associated gastrointestinal symptoms and water quality for these points. A significant relationship was shown to exist between the enterococcus density and swimming associated gastro-intestinal illness. Other relationships between pathogen densities and health risks were not identified (Cabelli, 1989).
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The main reason for coliforms being a poor indicator is that they have a rapid die off rate in cold saline waters when compared to other pathogens such as viruses (SAS, 1997). Beaches that complied with the mandatory EC standards laid down in the Bathing Water Directive were continuing to pose a significant health risk in Britain.
A randomised controlled exposure study followed a suggestion by the World Health Organisation. Groups of healthy adults were randomly selected and invited to bathe or not bathe at UK resorts which met the mandatory EC standard. The levels of indicator organisms to which each individual was exposed were measured. The results showed a strong correlation between faecal streptococci concentration measured at chest height and gastro-enteritis. No other microbiological indicator at any sampling depth displayed a significant trend which related concentration to gastro-enteritis rate. This suggests that the government tests for coliforms 30cm below the surface in 1m depth of water would not be an indicator of the potential occurrence of illness
(Kay et al., 1990). There was no suggestion that faecal streptococci was the
etiological agent, but it appears that whatever causes gastro-enteritis co-exists in sea water with faecal streptococci. It appears that the EC standards provided little protection to coastal bathing waters (Table II).
Table II.
Mineral oils mg/litre < 0.3 No film visible on the
surface of the water
Phenols mg/litre C6H5 OH < 0.005 No specific odour
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Surfers Against Sewage (SAS) is a non-profit making, apolitical organisationcampaigning for the reduction of sewage disposal and toxic dumping at sea. SAS is a high profile, media-oriented campaign. It uses the media to get its message across to millions of people with the aim of changing public opinion and gaining recognition from the controlling bodies involved. SAS campaigns to the DETR, the House of Commons and House of Lords as well as to the European Parliament.
SAS runs the only sewage related medical database in the UK. It contains over 800 cases of illness that may be linked to bathing in UK water. The database provides evidence of real cases of the effects on human health of allowing bathing in UK designated or undesignated bathing areas. This reiterates the question of whether EC standards are high enough to prevent risks to human health (Table III).
Policy developments in relation to bathing water quality
There have been recent investigations regarding the incidence of health risks related to the quality of bathing water (SAS, 1998). Scientific advances indicate the need to change the methods used for testing bathing water quality. Legislation needs to be constantly updated to ensure that the public are at minimal risk. The absence of reliable epidemiological information has had major policy implications for bathing water quality. The 1950s PHLS study caused UK authorities to imply that there were no health risks unless bathing waters were aesthetically revolting due to gross contamination. As a result, bathing water quality was given very little attention, yet in 1973 over half the UK's coastal outfalls did not even reach the low water mark (Department of the Environment, 1973).
The 1976 Bathing Water Directive made significant changes to the legal requirements to designate all bathing waters for water quality monitoring and to clean up UK bathing waters. Non-designated beaches were exempt and polluting discharges could legally continue in these areas. A total of 27 coastal bathing waters were officially designated by 1970. However, some popular holiday resorts, such as Blackpool and Brighton, had not been included (Environment Agency, 1997). Non-specific viral nine including ME type symptoms); and Other
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The link between sewage contamination of sea water and the health risks to bathers encouraged the Royal Commission on Environmental Pollution (1984) to question the government's restricted implementation of the EC Water Directive as well as the undesirable level of sewage contamination in coastal waters. It was not until 1997 that ministers announced the designation of a further 350 bathing waters. No further tests of bathing water quality were done and no attempt was made to increase the standards (SAS, 1997). Government approved beaches may continue to pose a health risk along with many of the undesignated but commonly used beaches. People entering water to paddle, i.e. without immersing their heads, were 25 per cent more at risk from infection than those staying on the beach. For those taking part in water sports the risks were significantly higher. Swimmers were found to be 31 per cent more at risk, and surfers 80 per cent more at risk of becoming ill (SAS, 1997). The exposure of recreational water users to the astrovirus in sewage contaminated waters showed that 93 per cent of surfers showed exposure by the presence of antibodies.
Government-approved beaches therefore continue to pose a health risk. Difficulties exist in advising the public and guidance for managers and designers of sewage discharge systems is also problematic. Faecal streptococci were the only pathogen that showed a relationship between their increased concentration and increased health risk. The most appropriate pathogen indicator tests of bathing water quality are faecal streptococci when measured at chest depth. This test would therefore enable the health risk associated with bathing to be determined (SAS, 1998).
Revision of the EC Bathing Water Directive
In late 1996, EC member states agreed on a revised bathing water directive to be ratified in 1997. The new standard was to address the real issue of protecting the health of those engaged in water-based activities. The water quality tests use faecal streptococci, faecal coliforms and enteroviruses as the indicator micro-organisms. Where a beach fails to meet these standards action should be taken to control the pathogenic loading of waters. In other words, in areas where pathogenic loading exceeds the new standards, disinfection should be applied to the effluents causing the failure (Environment Agency, 1998).
However, the standards within the revised directive for faecal streptococci of 100 per 100ml remain above the level that were found to cause an increased health risk (35 per 100ml) (SAS, 1998). It is therefore apparent that bathing waters may still continue to pose a threat to human health even after the new legislation has been implemented, despite the existence of economically viable and environmentally sustainable technologies which would ensure safe levels in waste water discharges (SAS, 1998).
Conclusion
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problem was not realised initially. It may also be possible that general attitudeshave changed. If problems were not imminent and did not affect people directly at the time, they were ignored. If a solution to the problem was going to cost large sums of money and legislation was not in place to enforce improvements then it may have been the policy to wait until something had to be done.
The improvements in research techniques, improved technology, increased public awareness and a tightening of legislative standards highlight the problem. The issue has been brought to the attention of the government and the public in the UK partly by organisations like SAS and is now being addressed and improvements are being made all the time. However, the changes required to clean up the coastline cannot happen overnight and although in an ideal world more stringent measures are needed, they take time, money and resources to implement. However, the risks to human health of bathing in water of unsatisfactory quality must be eliminated. The need for continuous and methodical research, more stringent sampling and monitoring are all of paramount importance if current legislation is to be changed.
One concern which appears to have been overlooked by the authorities is that of undesignating and bathing areas. Beaches designated under the EC Bathing Water Directive are assessed, but undesignated bathing areas are neglected. Does this mean that no-one uses these beaches? Evidence from local action groups suggests that these beaches are often just along the coast from the designated beaches. In some cases raw/partially treated sewage is being redirected from the designated areas along the coast to these locations (Austin, 1998). This highlights the need to monitor all sewage outfalls, including the ones which legislation neglects.
The best way forward is to provide full treatment, including UV treatment, to all sewage before discharging it to the sea. No side effects of UV treatment have been discovered to date. Alternative methods of dealing with sewage need to be considered rather than discharge to the sea (SAS, 1998).
As we move towards the twenty-first century it becomes increasingly apparent that we need to take notice of research and take precautionary measures rather than acting after a problem has occurred. The issue must be dealt with though. Provision is needed for stringent research, monitoring, legislation, management plans, upgraded procedures, education and public awareness to provide a long-term strategy which looks well beyond the year 2005.
References
Austin, S. (1998), ``Falmouth locals untreated sewage help (FLUSH)'', personal letter.
Cabelli, V.J. (1989), ``Swimming-associated illness and recreational water quality criteria'',Water Science and Technology, pp. 13-21.
Department of the Environment (1973),Annual Report.
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Environment Agency (EA) (1998),An Environmental Strategy for the Millennium and Beyond, pp. 1, 6-7, 14.
Kay, D., Wyer, M., McDonald, A. and Woods, N. (1990), ``The application of water-quality standards to UK bathing waters'',Journal of the Institution of Water and Environmental Management, pp. 436-41.
Stephenson, K. (1953), ``Sewage treatment and disposal'', Memorandum by Surfers Against Sewage.
Surfers Against Sewage (SAS) (1997), ``Sewage treatment and disposal'', Memorandum by Surfers Against Sewage.
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