Quantitative Microbial Risk Assessment from surface water to potable water

Jack Schijven, Peter Teunis, Saskia Rutjes, Martijn Bouwknegt, Ana Maria de Roda Husman.
 
QMRAspot: A computational user-friendly interactive tool for quantitative microbial risk assessment from surface water to drinking water.

Water Research, 2011, 45(17):5564-5576.

National Institute for Public Health and the Environment = RIVM
Bilthoven, the Netherlands
www.rivm.nl

What is QMRA

●	Quantitative Microbiological Risk Assessment (QMRA) 
	–	WHO Drinking Water Guidelines: Health based target
	–	The Netherlands: Max infection risk = (10^(-4))/person/year
●	Index pathogens
	–	Enteroviruses (virus), Campylobacter (bacteria),
		Cryptosporidium + Giardia (parasitic protozoa)
●	Indicator organisms
	–	Bacteriophages (virus), E. coli (bacteria),
		SSRC (bacterial spores)
●	QMRA data
	–	Index pathogen levels in surface water
	–	Drinking water treatment (filtration and disinfection)
	–	Consumption of drinking water
	–	Infectivity of pathogen => Infection risk

QMRA from surface water to drinking water

●	Csw	= Pathogen concentration in source water [N/liter]
●	R	= Recovery = fraction of detected pathogens [-]
●	Z	= Fraction of microorganisms passing treatment [-]
●	Cdw	= Pathogen concentration in drinking water [N/liter]
●	V	= Consumption of unboiled drinking water [liter]
●	Pm 	= Infectivity of pathogen [-]
●	Pinf	= Infection risk [per person per day or year]
●	Pinf,day	= Csw x 1/R x Z x V x Pm
●	Pinf,year	=1-(∏_(i=1)^365)(1-Pinf,day)
●	Monte Carlo simulations (variability)

Tool QMRAspot

●	FOR WORLDWIDE USE BY ANY STAKEHOLDER
	(environmental inspector, engineer, employee of drinking water company, student)
●	NO EXTENSIVE KNOWLEDGE NEEDED ABOUT QMRA
●	QUICK-AND-CLEAN
●	FULLY AUTOMATIC
●	RUNS IN MATHEMATICA PLAYER PRO
●	OPTIONS FOR SCENARIOS
●	FREELY AVAILABLE: QMRAspot@RIVM.NL

Tool QMRAspot

Poster

Quality control

●	Quality requirements of risk outcomes from QMRAspot 
	–	Robust tool
	–	Consistent outcomes
●	Reference data set to verify risk outcomes from QMRAspot
	–	Version control of QMRAspot
	–	Models in QMRAspot may change
	–	New versions of Mathematica

Form of QMRAspot

●	Player Pro
	–	Raw data from spreadsheet
	–	Reports (pdf okay; rtf too big)
	–	Player Pro licence
●	WebMathematica
	–	Raw data from spreadsheet
	–	Reports
	–	Central version control (website)
	–	Extra programming code required
●	CDF Player
	–	No raw data from spreadsheet
	–	No reports
	–	Freely available

Discussion: Questions

●	Why no read/write ability of CDFs?
●	Run a CDF on an external website?
●	Mathematica open source?

Thank you for your attention!