Recreational Water Quality and Health

ENVR 890

Mark D. Sobsey

Spring, 2007

Health Risks from Recreational Water

• What are the health risks from recreational water and how important are microbial risks?

• Health risks:– Microbial or infectious disease risks

• enteric, respiratory, skin, eyes, ears, etc.• AFRs: accidental fecal releases and purposeful

introduction of feces (wash the diaper in the pool!)• Sewage, combined sewer overflows, etc.• Animal fecal wastes: waterfowl, etc.• Bather load and microbial shedding

Health Risks from Recreational Water

• Drownings• Spinal and other related “sports” injuries

– Diving– Falling (slipping)

• Boating accidents• Chemical exposures

WHO Health Risk Based Approach to Recreational Water Quality

• Combined use of sanitary assessment or inspection and measurement of water quality

• Provides data on possible pollution sources in a recreational water area and numerical information on actual level of fecal pollution

• Combine these elements to provide a basis for a robust, graded, classification

• Grade beaches to support informed personal choice• Provide on-site guidance to users on relative safety;• Assist in identifying and promoting effective management interventions• Provide an assessment of regulatory compliance.

Simplified Framework and Decision Tree for Recreational Water Management

WHO Risk Based Framework: Application to Recreational Water

• Two components to management: – (a) qualitative ranking of fecal

loading in recreational water environment (sanitary inspection), and

– (b) direct measurement of fecal indicator

• Provide a system to account for the impact of actions to discourage water use during periods, or in areas, of higher risk (e.g., rainfall or uncontrolled sewage contamination)

WHO Guideline Values For Microbial Quality of Recreational Waters

Epidemiological Studies of Recreational Water Quality: Evidence Base

• Many studies show causal relationships between gastrointestinal symptoms and water quality as measured by indicator bacteria numbers (Prüss,1998)

• Strong and consistent associations reported, with temporal and dose–response relationships

• Studies have biological plausibility and analogy to clinical cases from drinking contaminated water

Epidemiological Studies of Recreational Water Quality: Evidence Base

• Rate of certain symptoms or symptom groups were significantly related to the count of fecal indicator bacteria

• Consistency across various studies• Gastrointestinal symptoms were the most frequent

health outcome for which significant dose-related associations were reported

• Gastrointestinal illness

• Respiratory illness

• Skin diseases

• Ear, nose and throat

Health Effects Associated with Swimming

Risk of illness in swimmers against bacterial counts in marine water – A Prüss, (1998)

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Risks of illness in swimmers against bacterial count in fresh water - A Prüss, (1998)

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Overall findings• Swimmers have higher symptom rates than non-swimmers• Fecal indicators (fecal streptococci and fecal coliforms/ E. coli)

associated with symptom rates• Illness rate is associated with counts of fecal indicator ie, dose-

related increase• Overall, best indicators: fecal streptococci/enterococci for

marine waters; E. coli for freshwater • Risk of gastrointestinal symptoms low at 30+ indicators/100 ml

Additional Observations• Indicator:pathogen ratios vary according to health of

population – Depends on types and magnitude of illnesses present

in study population at time of investigation• Present indicators do not always provide good prediction

of epidemiological health risk• Risk varies with:

– Immunity of population varies • USA, UK, Egypt , Hong Kong and South Africa• Local versus tourists

– Age groups – different severity and other responses

WHO Guidelines: Based on UK Studies - Judged Most Rigorous

WHO Guidelines: Based on UK Studies - Judged Most Rigorous

The Upper 95% Percentile Approach• Criteria for recreational water compliance is typically based on % compliance levels.

Either:– 95% compliance levels (i.e., 95% of sample measurements lie below a specific

value in order to meet the standard) OR– Geometric mean values

• Data are collected in the bathing zone• Both criteria have significant drawbacks T• Geometric mean is statistically more stable

– Because the inherent variability in the distribution of the water quality data is not characterized in the geometric mean

– This is variability that produces the high values at the top end of the statistical distribution that are of greatest public health concern

• 95% compliance reflects much of the top-end variability in the distribution of water quality data and is more easily understood.– affected by greater statistical uncertainty and so a less reliable measure of water

quality,• thus requires careful application to regulation

Example of a Classification Matrix for Fecal Pollution of Recreational Water Environments

Indicator Advantages Disadvantages Fecal Streptococci /Enterococci

· Marine and fresh water human health indicator. · More persistent in water & sediment than coliforms.

May not be valid for some waters, due to potential growth in soils and on vegetation. Multiple species, not all of fecal origin

Thermotolerant ("fecal") coliforms

· Indicator of recent fecal contamination. · Not suitable for some waters; growth in soils and water

· Confounded by non-sewage/non-fecal sources (e.g. Klebsiella spp. in pulp and paper wastes)

E. coli

· A fresh water human health indicator. · Indicator of recent fecal contamination. · Typing E. coli to track source of fecal contamination. · Rapid identification if based on Beta-glucuronidase activity

· Sometimes not suitable for tropical and some other waters due to growth in soils and water. - Poor survival in sea water; low concentrations may give poor predictability of health risks

Sulphite-reducing clostridia / Clostridium perfringens

· Always in sewage impacted waters. · Possibly correlated with enteric viruses and parasitic protozoa. · Inexpensive assay with H2S production for detection

· May be from animal feces, too · Very conservative indicator; old fecal contamination · Enumeration requires anaerobic culture or reduced medium

Candidate Fecal Indicators:

Bacteria

Somatic coliphages

· Standard methods · Similar behavior to human enteric viruses - Commonly present in feces and sewage

· Sewage specificity uncertain · Heterogeneous; different groups Persistence of some may differ from human enteric viruses · May grow in some environments (uncertain)

F-specific coliphages

· Standard methods · More persistent than some other coliphages · Host does not grow in environmental waters below 30°C - Potential use for microbial source tracking

· Present in sewage but not always in feces of individuals - Specific to sewage · Some are not as persistent in marine or warm waters as some enteric viruses

Bacteroides fragilis phages

· May be sewage-specific in some regions · Methods available; molecular better than cuilture methods · More resistant than most other phages in the environment; similar to human enteric viruses

· Need anaerobic culture. · Numbers in sewage are lower than other phages; most humans do not excrete (hence no value for small populations - Must use molecular detection

Sanitary plastics

· Immediate assessment possible each bathing day. · Can be categorized · Need Little staff training

· May reflect old sewage contamination and be of little health significance · Subjective and prone to variable description.

Preceeding rainfall (12, 24, 48 or 72 hours)

· Simple regressions may account for 30-60% of variability in microbial indicators for particular beaches

· Each beach area may need to assess its rainfall response/risk · Response may depend on conditions before an event

Candidate Fecal Indicators:

Viruses and Physical Parameters

Fecal sterols

· Coprostanol is sewage-specific · Coprostanol degradation similar to die-off of thermotolerant coliforms · Ratio of 5b/5a stanols > 0.5 is indicative of faecal contamination. i.e. coprostanol/5a-cholestanol > 0.5 indicates human fecal contamination; while C29 5b (24 ethylcoprostanol) / 5a stanol ratio >0.5 indicates herbivore feces. · Ratio of coprostanol:24-ethylcoprostanol can be used to indicate the proportion of human fecal contamination

· Requires gas chromatographic analysis and is expensive (about $100/sample). · Requires up to 10 L of sample to be filtered through a glass fibre filter (Whatman) to concentrate particulate stanols

Caffeine

· May be sewage-specific, but unproven · Could be developed into a dip-stick assay.

· Yet to be proven as a reliable method

Detergents

· Relatively routine methods available. · May not be related to sewage (e.g. industrial pollution)

Turbidity

· Simple, direct and inexpensive assay available in the field.

· May not be related to sewage; correlation needed for each site type

Candidate Fecal Indicators – Chemical and Physical

Many Chemical Indicators are Available to Detect in Water

• Optical brighteners• Fecal sterols• Caffeine• Antibiotic residues• Other pharmaceuticals and personal care products

– analgesics and anti-inflammatories– lipid regulators– antiepileptics– beta blockers (antihypertensives)

Some Problems with Current Bacteria Indicators: Misclassification of Fecal Contamination and Human Health Risks

• E. coli and enterococci not always from fecal contamination• E. coli proliferates in the environment at some conditions

Enterococci not specific to fecal contamination or to only human fecal contamination– Approved medium detects many enterococci, not just E. faecium

and E. faecalis; – Animal and environmental enterococci are detected– Some states use alternative media having unknown or poorly

characterized performance to detect enterococci• E. coli and enterococci are inadequate predictors of viral and

possibly parasite risks from waterborne exposures• No proven microbial indicators for viruses and parasites

US EPA Recreational Water Quality Criteria - Freshwater

• From a statistically sufficient number of samples (generally 5+ samples equally spaced over a 30-day period)

• Geometric mean bacterial densities not to exceed either:– E. coli 126/100 ml; or– enterococci 33/100 ml;

• no sample should exceed a one-sided confidence limit (C.L.) calculated using the following as guidance:– designated bathing beach 75% C.L.– moderate use for bathing 82% C.L– light use for bathing 90% C.L.– infrequent use for bathing 95% C.L.– based on a site-specific log standard deviation, or if site data are insufficient

to establish a log standard deviation, then using 0.4 as the log standard deviation for both indicators.

US EPA Recreational Water Quality Criteria - Marine Water

• From a statistically sufficient number of samples (generally 5+ samples equally spaced over a 30-day period)

• geom. mean enterococci densities not to exceed 35/100 ml;• no sample exceed a one-sided CL using the following guidance:

– designated bathing beach 75% C.L.– moderate use for bathing 82% C.L.– light use for bathing 90% C. L.– infrequent use for bathing 95% C. L.– based on a site-specific log standard deviation, or if site data are

insufficient to establish a log standard deviation, then using 0.7 as the log standard deviation.

US EPA CRITERIA FOR INDICATOR BACTERIOLOGICAL DENSITIES

EPA BEACHES Program http://www.epa.gov/OST/beaches

• Congress passed legislation in 2000 to address the need for improved protection of public health at beaches

• Beaches Environmental Assessment and Coastal Health (BEACH) Act.

• Stronger beach monitoring programs• EPA to work partnership with state and local governments• Must make significant progress in improving public health at our

nation’s beaches• Issues about the situation in some states and territories

– Still relying on the 1968 200 FC/100 mL water standard as their primary indicator for recreational waters

– Fecal and/or total coliform standards more stringent than the US PHS 200 FC/ 100 mL and/or 1000 TC/100 mL

– Provisions in which the numeric criteria for bacteria standards do not apply where CSOs and storm water discharges are likely to result in violations

Progress in Implementing the BEACHES Act

Progress in Implementing the BEACHES Act, Cont’d.

Progress in Implementing the BEACHES Act, Cont’d.

New Zealand Recreational Water Quality Guidelines

New Zealand Recreational Water Quality Guidelines

Issues for Current Management: Classification of Fecal Contamination and Human Health Risks by USA vs. WHO

• USA beaches are classified as safe or unsafe: – OK to swim or no swimming

• Actually, there is a gradient of increasing risk– Increased severity, variety and frequency of health effects with

increasing sewage/fecal pollution• Desirable to promote incremental improvements by identifying and

prioritizing ‘worst failures’ to move towards an improved category of water quality

• WHO approach of risk gradations based on sanitary conditions and water quality, with communication of risks, is more rational– Recognizes differences in local and regional conditions and

encourages incremental improvement

Current Recreational Water Quality Management - Problems

• Management actions (e.g., beach closures/postings) are retrospective– Occur only AFTER human exposure to the hazard– It takes too long to get test results

• Risks to health are primarily from human and secondarily from animal excreta– But, traditional bacterial indicators may also derive from other non-fecal

sources (vegetation, soil, etc.)• Poor inter-laboratory and international comparability of

microbiological analytical data• Climate and geographic differences are a challenge in setting

universal criteria and standards– Temperature and water quality differs, as does disease burdens