dr. andrew papadopoulos

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RETHINKING RECREATIONAL WATER MONITORING: CAN PREDICTIVE MODELLING INCREASE PUBLIC HEALTH OUTCOMES?Dr. Andrew Papadopoulos

Associate Professor and Coordinator, Master of Public HealthDepartment of Population MedicineUniversity of Guelph, Ontario, Canada

NEHA Annual Educational Conference and IFEH World Congress

July 8, 2014

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Outline

1. The public health issue2. The current regulatory state In Ontario,

Canada3. The use of E. coli as a measurement tool4. Geometric means5. Predictive modeling6. Risk communication7. A multi-barrier approach8. Increasing public health outcomes9. Moving forward

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Introduction

Pathogenic microorganisms such as Shigella, enterohaemorrhagic Escherichia coli (EHEC), Giardia, Cryptosporidium, Norovirus, and Leptospira have been linked to disease outbreaks from exposure to recreational waters in North America

Gastrointestinal illness is the most well-studied outcome associated with recreational water quality, but febrile respiratory illness and ear and skin infections are also of concern

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Potential Burden of Illness

•According to Ontario Parks, approximately 9 to10 million persons use their parks per year

•Wasaga Beach – estimated 2 million visitors annually

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The Issue

Timeliness of E. coli test Varying standard of number of E. coli per

100mL of recreational water There is a lack of supporting

epidemiological evidence that supports the current standard or any other standard

Is current method most effective, both in terms of scarce resource consumption and public health?

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Current Ontario Ministry of Health Program

The goal of the Safe Water Program Standard Prevent or reduce the burden of water-borne

illness and injury related to recreational water use Boards of health are required to manage service

delivery to their recreational facilities and water front activities program in accordance with the protocols under this standard

Must undertake assessment and surveillance, develop policies and health promotion strategies, prevent disease, and protect human health

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OPHS: Beach Management and Recreational Water Protocols

Under the protocols, boards of health have the following reporting requirements

Provide Safe Water Program common data elements

Conduct surveillance of public beaches and recreational water facilities

Conduct surveillance of water-related illnesses

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Provide education for owners and operators Implement a recreational water

management program to reduce risks of illness or injury from recreational activities

Provide 24/7 on-call response for issues relating to recreational water activities

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Surveillance and Inspection

a) Pre-season assessmenti. Inventory of public beachesii. Historical and epidemiological dataiii. Environmental survey

b) Routine public beach surveillance Sampling program (as per water sampling

methodology) Special consideration for frequency and

timing of sampling and items as noted above

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OPHS: Population Health Assessment and Surveillance Protocol

Under the protocol, boards of health have the following reporting requirements

BOH must conduct surveillance of water-related illnesses associated with recreational activities

Conduct epidemiological analysis of surveillance data, monitor trends (spatial and temporal), and vulnerable populations

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Use of Fecal Indicator Bacteria

Health Canada distinguishes between three types of fecal indicators1. Primary fecal indicators inform on the level

or the extent of fecal contamination2. Secondary fecal indicators provide clues to

the sources of contamination, for example distinguishing between human and cattle fecal material

3. Pathogen indicators are intended to help estimate the risk from a specific pathogen

There is no single perfect fecal indicator

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An indicator should survive longer than pathogens; however, guidelines point out that, “The density of the indicator should be quantitatively related to swimmer-associated illnesses” Unlikely in cases of intermittent contamination when

the indicator persists in the environment for longer than the pathogen

Turbidity can interfere with the quantification of indicator organisms by allowing multiple bacteria to adhere to a single particle and therefore, create a single colony in assay, and also by interfering with membranes used in filtration

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Current practice emphasizes using information about primary fecal indicators to estimate the level of risk to recreational water users

Two types of bacteria are used as primary fecal indicators: Escherichia coli (fresh water) and enterococci species (marine water)

Meta-analysis of epidemiological data on swimming-associate gastroenteritis supported the use these organisms

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Testing Standards: Canada

Ontario 35 BOHs use 100 E. coli limit Canada’s guideline value of 200

Other Provinces Use the 200/400 E. coli/100 ml value; with

variations Some allow for use of thermo-tolerant coliforms Quebec uses water quality grades (A-D) below

200

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Trigger for Action

Currently Ontario’s boards of health use 100 E.coli per 100 mL (based on a geometric mean of at least 5 samples) as a trigger value for action

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Geometric Mean

The geometric mean is calculated by converting the counts from a minimum of five or six samples to a logarithmic scale, calculating the mean, and converting that mean value back to a base 10 number

The relationship between fecal indicators and illness is on a log scale, so the use of a geometric mean is appropriate

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Daily Geometric Mean and the Persistence Model

Results from cultures can take 18-24 hours Therefore, beach management decisions

based on a previous day’s cultures have been termed a “persistence” model

The temporal variability in indicators coupled with the delay in obtaining culture results often means that beaches are still open at times of peak risk, and closed later, once risk has already begun to fall

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Monthly and Seasonal Geometric Means

Weekly sampling can be appropriate to identify new, but persistent contamination problems

Can be used to estimate risk with samples taken at different times within a defined period

Many regions in Canada and the US use a geometric mean of samples taken over the preceding month as the basis for beach management decisions

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Various Guideline Values

A guidelines of ≤200 E. coli per 100 mL for freshwater has a risk of 10 per 1000 bathers, while 100 E. coli per 100 mL has a risk of 4.5 per 1000 bathers

Some guidelines have a ceiling value of ≤400 E. coli per 100 mL which has shown to discourage more extensive or targeted sampling because such practices are more likely to generate a sample above the ceiling

An alternative approach specifies that the geometric mean (of at least six samples) may not exceed 200 E. coli per 100 mL and a statistical threshold value of 400 E. coli per 100 mL that cannot be exceeded by more than 10% of samples

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Spatial Consideration in Sampling A US EPA (2005) study at five beaches found that sample

depth was the strongest predictor of indicator levels Levels decreased significantly and progressively from ankle

depth, to knee depth, to chest depth Sampling where water reaches a depth of 1.2-1.5 m

(equivalent to adult chest level) best predicts swimming-associated illness

Health Canada suggests sampling from non-representative sites where contamination has the potential to be higher, such as areas under direct influence of storm water, sewage, or river outlets Can be valuable for understanding the sources of

contamination in an area

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Temporal Considerations in Sampling

A study by the US EPA (2005) found that at three of the five beaches studied, levels tended to decline from the early morning to the afternoon

Also found that at least half of the time, the daily geometric mean changed by at least a factor of two from one day to the next

“When sampling, consideration should also be given to the collection of samples for the purposes of characterizing event-driven episodes of pollution that may affect recreational waters – for example, immediately following periods of heavy rainfall or at times of greatest swimmer activity.”

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Predictive Modeling

A means of getting timely estimates of fecal contamination through the use of readily available environmental explanatory variables to “predict” the levels of fecal indicator organisms that would be cultured from water samples taken in the present

Predictive models have focused on modeling fecal indicator bacteria as the best available surrogate for human health risk

The ideal model would estimate infection risks not only from fecal bacteria, but a full range of pathogens

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Risk Communication

A method of reducing exposure when water quality hazards are present Posting warning signs is an accepted means of

communicating that a beach is temporarily unsuitable for swimming

Three elements must be present1. Identification of health or safety risk2. A recommended action to take3. The name and contact info for the authority responsible

the warning Some jurisdictions are incorporating international

icons for safe or unsafe swimming into any warning signs

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Evidence Gaps

Understanding of the risk factors for swimming-related infections

In Canada, there is the added challenge of limited domestic surveillance

Lack of surveillance for illnesses related to recreational water use in order to improve risk assessments

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Risk Management Framework: Applying A Multi-barrier Program

The WHO (2003) also endorses a multi-barrier approach where ideally, water quality hazards are identified and addressed before recreational water users are ever exposed

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Components of a risk management framework

Environmental (sanitary) survey Wave conditions Land use activities Number of bathers Animal/bird activities

Inspection and assessment Risk-based assessment approach Predictive models

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Surveillance and monitoring initiatives Sampling program Epidemiological data

Laboratory testing and diagnostic services Laboratory turnaround time = 24 hours

to report indicator results

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Public Communication and Notification Develop risk communication plan

Evaluation Conduct an evaluation of program

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Increasing Public Health Outcomes

Using predictive modeling to establish a risk management framework It is recognized that relying solely on E. coli results may

not reflect the current state of the recreational water Each public health agency must complete the pre-season

assessment Framed in an epidemiological study, the outcome of

interest is water quality where the independent variables would be items such as surrounding land use, meteorological events, natural landscape, algae growth, and turbidity

The establishment of such a framework could potentially reduce the amount of sampling required thereby reducing costs and provide timelier advice to the public

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Validate the current threshold for action Different jurisdictions use different standards

and different sampling techniques Sufficient research into the appropriate action

levels should be available before changing procedures and a two to five year epidemiological study to establish the most appropriate bacterial threshold level would be helpful in both quantifying the amount of illness and the potential level of illness to the public

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Develop a robust communication plan that is well understood by partners and stakeholders, including the public and the media The exploration of a standard sign that is well

understood by the residents and visitors would be helpful in conveying the potential level of risk

The employment of risk communication experts would be valuable to ensure the message is clear and understandable

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Moving Forward

Research is required to create an evidence-based recreational water use program that can be communicated and shared with partners and stakeholders

The establishment of a risk management framework that could aid BOHs in a predictive model capacity is required

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Moving Forward

It is of paramount importance to analyze the current threshold for action of 100 E. coli per 100 ml

A robust communication plan that is well understood by partners and stakeholders, including the public and the media must be developed

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Acknowledgement

The National Collaborating Centre for Environmental Health

The Ontario Ministry of Health and Long-term Care

Dr. Justine Hutchinson

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Thank you...

Questions or Comments?

Andrew [email protected]

dr. andrew papadopoulos

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