In Canada and other industrialized nations, a combination of guidelines, regulations and
good management practices help ensure that the risk of contracting infectious disease
from drinking water is very low. Despite this, outbreaks of waterborne gastroenteritis
have occurred, even in the absence of bacteriological indicators. Quantitative microbial
risk assessment (QMRA) tools applied to drinking water offer a risk-based approach to
understanding how drinking water treatment barriers, and interactions between them, may
impact human health risk from pathogens.
Health Canada and Decisionalysis Risk Consultants Inc. have developed a probabilistic
model that estimates the level of risk to human health from exposure to index pathogens
in treated drinking water. The model explores the impact of water treatment upon the
burden of disease associated with pathogens found in drinking water, namely
Cryptosporidium parvum, Giardia lamblia, Rotavirus, and pathogenic Escherichia coli.
The primary estimates produced by the model include: the reduction in pathogen levels as
a result of treatment barriers; the expected number of illnesses per year from the
reference pathogens in treated drinking water; and, the disease burden attributable to
the treated drinking water. To illustrate the use of the tool, data from the City of Ottawa
is used to estimate the impact of a number of current and future treatment scenarios on
the risk of waterborne disease. Results are used to compare the relative importance of
multiple treatment barriers during optimal and non-optimal operating conditions. Results
are also used to determine optimum treatment targets for primary disinfection. The
QMRA model provides a framework for understanding the nature of microbial risk in a
drinking water supply system, and can be used to evaluate the impact of changes in water
treatment on population health risk. Includes 29 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 340 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 15 |
| Published : | 11/01/2007 |
