Biomaterial Database

Assessing protozoan risks for surface drinking water supplies in Nova Scotia, Canada. 2016

Wendy Krkosek, and Victoria Reed, and Graham A Gagnon

Department of Civil and Resource Engineering, Dalhousie University, Halifax, NS, Canada B3J 1Z1 E-mail: graham.gagnon@dal.ca.

Protozoa, such as Cryptosporidium parvum and Giardia lamblia, pose a human health risk when present in drinking water. To minimize health risks, the Nova Scotia Treatment Standards for surface water and groundwater under the direct influence of surface water require a 3-log reduction for Giardia cysts and Cryptosporidium oocysts. This study determined the protozoan risk of municipal surface source waters in Nova Scotia, through the use of a pre-screening risk analysis of water supplies, followed by subsequent water quality analysis of the seven highest risk supplies. The water supplies were monitored monthly for 1 year to obtain baseline data that could be used for a quantitative microbial risk assessment (QMRA). The QMRA model outcomes were compared to the Health Canada health target of 10(-6) disability-adjusted life years/person/year. QMRA modeling shows that the treatment facilities meet the required log reductions and disability-adjusted life year target standards under current conditions. Furthermore, based on the results of this work, Nova Scotia should maintain the current 3-log reduction standard for Giardia cysts and Cryptosporidium oocysts. The results of this study show that a pre-screening step can help to inform water sources that are particularly vulnerable to protozoan contamination, which can lead to more focused, cost-effective sampling, and monitoring programs.

UI	MeSH Term	Description	Entries
D009674	Nova Scotia	A province of eastern Canada, one of the Maritime Provinces with NEW BRUNSWICK; PRINCE EDWARD ISLAND; and sometimes NEWFOUNDLAND AND LABRADOR. Its capital is Halifax. The territory was granted in 1621 by James I to the Scotsman Sir William Alexander and was called Nova Scotia, the Latin for New Scotland. The territory had earlier belonged to the French, under the name of Acadia. (From Webster's New Geographical Dictionary, 1988, p871 & Room, Brewer's Dictionary of Names, 1992, p384)
D012621	Seasons	Divisions of the year according to some regularly recurrent phenomena usually astronomical or climatic. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Seasonal Variation,Season,Seasonal Variations,Variation, Seasonal,Variations, Seasonal
D016785	Cryptosporidium parvum	A species of parasitic protozoa that infects humans and most domestic mammals. Its oocysts measure five microns in diameter. These organisms exhibit alternating cycles of sexual and asexual reproduction.	Cryptosporidium parvums,parvum, Cryptosporidium
D016829	Giardia lamblia	A species of parasitic EUKARYOTES that attaches itself to the intestinal mucosa and feeds on mucous secretions. The organism is roughly pear-shaped and motility is somewhat erratic, with a slow oscillation about the long axis.	Giardia duodenalis,Giardia intestinalis,Lamblia intestinalis,Giardia lamblias
D060766	Drinking Water	Water that is intended to be ingested.	Bottled Water,Potable Water,Water, Bottled,Water, Drinking,Water, Potable
D018570	Risk Assessment	The qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. (Last, Dictionary of Epidemiology, 1988)	Assessment, Risk,Benefit-Risk Assessment,Risk Analysis,Risk-Benefit Assessment,Health Risk Assessment,Risks and Benefits,Analysis, Risk,Assessment, Benefit-Risk,Assessment, Health Risk,Assessment, Risk-Benefit,Benefit Risk Assessment,Benefit-Risk Assessments,Benefits and Risks,Health Risk Assessments,Risk Analyses,Risk Assessment, Health,Risk Assessments,Risk Benefit Assessment,Risk-Benefit Assessments
D033661	Oocysts	Zygote-containing cysts of sporozoan protozoa. Further development in an oocyst produces small individual infective organisms called SPOROZOITES. Then, depending on the genus, the entire oocyst is called a sporocyst or the oocyst contains multiple sporocysts encapsulating the sporozoites.	Sporocysts,Oocyst,Sporocyst