Premium
Considering the Risk of Infection by Cryptosporidium via Consumption of Municipally Treated Drinking Water from a Surface Water Source in a Southwestern Ontario Community
Author(s) -
Pintar K. D. M.,
Fazil A.,
Pollari F.,
WaltnerToews D.,
Charron D. F.,
McEwen S. A.,
Walton T.
Publication year - 2012
Publication title -
risk analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.972
H-Index - 130
eISSN - 1539-6924
pISSN - 0272-4332
DOI - 10.1111/j.1539-6924.2011.01742.x
Subject(s) - cryptosporidium , percentile , recreation , environmental health , public health , trihalomethane , transmission (telecommunications) , risk assessment , environmental science , water treatment , medicine , environmental engineering , biology , ecology , mathematics , engineering , statistics , nursing , computer security , computer science , electrical engineering , feces
Through the use of case‐control analyses and quantitative microbial risk assessment (QMRA), relative risks of transmission of cryptosporidiosis have been evaluated (recreational water exposure vs. drinking water consumption) for a Canadian community with higher than national rates of cryptosporidiosis. A QMRA was developed to assess the risk of Cryptosporidium infection through the consumption of municipally treated drinking water. Simulations were based on site‐specific surface water contamination levels and drinking water treatment log 10 reduction capacity for Cryptosporidium . Results suggested that the risk of Cryptosporidium infection via drinking water in the study community, assuming routine operation of the water treatment plant, was negligible (6 infections per 10 13 persons per day—5th percentile: 2 infections per 10 15 persons per day; 95th percentile: 3 infections per 10 12 persons per day). The risk is essentially nonexistent during optimized, routine treatment operations. The study community achieves between 7 and 9 log 10 Cryptosporidium oocyst reduction through routine water treatment processes. Although these results do not preclude the need for constant vigilance by both water treatment and public health professionals in this community, they suggest that the cause of higher rates of cryptosporidiosis are more likely due to recreational water contact, or perhaps direct animal contact. QMRA can be successfully applied at the community level to identify data gaps, rank relative public health risks, and forecast future risk scenarios. It is most useful when performed in a collaborative way with local stakeholders, from beginning to end of the risk analysis paradigm.