In Brief: Multimedia Health Risk Assesment

6 Pages·2001·0.11 MB·English

by  Ontario Ministry of the Environment

J7V
@
March
Ontario 2001
Ministry ofthe Environmentprograms and initialivcs
Multimedia health risk
assessment
Amultimedia health risk assessment is Hazard identification provides a prelimi-
conducted to gather information in nary identification of potential harmful health
order to understand whether or not environ- effects resulting from exposure to a contami-
mental health risk is present in a community nant. Scientific literature is examined to
A multimedia health and, if so, how much The purpose is to identify any known, undesirable health
risk assessment is predict, as much as scientifically possible, effects associated with a substance.
conducted when the health implications of exposure to In dose-response assessment, informa-
chemical contami- certain contaminants over time. For exam- tion is gathered from various agencies to
nants are foundat ple, a study might be conducted to assess determine the existing acceptable intake
levels thatraise con- a community's risk from exposure to lead or known health guidelines for a substance.
cern aboutpotential or arsenic. These include the World Health Organiza-
risk in the communi- The Ministry of the Environment has tion, Health Canada, the International
ty. The multimedia conducted these studies in Port Hope, Agency for Research on Cancer and the
approach to health Cornwall, Port Colborne, Windsor and U.S. Environmental Protection Agency.
risk assessment Hamilton. The purpose is to predict the relationship
examines total expo- An assessment examines the various between exposure to a contaminant and
sure to contaminants means of exposure, as well as the levels the likelihood of negative effects. That is,
through a number of exposure, to a contaminant. It not only at what dose (or intake level) are harmful
ofpossiblepathways, predicts the likelihood of a health risk, but effects likely to occur?
such as air. soil, also helps identify actions needed to reduce Human exposure assessment involves
drinking waterand that risk. It does not, however, provide a collection of environmental samples from a
food. diagnosis of the present health status of particular site or community. Depending on
people living in the community. the nature of the study, the human exposure
There is always some uncertainty in health assessment may involve collecting air, water,
risk assessment. Science cannot explain dust, soil or other samples from the area
everything about the effects of every chemi- suspected of contamination. It could also
cal and how it acts in the environment. For include sampling body fluids {like urine or
many substances there are no known, or blood) or tissues. Questionnaires are some-
established, acceptable exposure limits. times included to help assess individual and
Actual risks cannot be precisely determined. community exposure factors. That is to
Because of the uncertainties, health nsk determine what activities or behaviours may
assessments are based on careful assumptions. expose an individual to contamination.
Where conditions do not allow for direct
The health risk assessment collection of data, scientists will use comput-
approach er modelling to fill in gaps in available infor-
There are four steps in the process of health mation. Models can be used to estimate the
risk assessment: hazard identification, dose- levels of contamination in air or soil or to
response assessment, human exposure look at how those levels might change over
assessment and risk characterization. time under different conditions.
Ministry of the Environment
FactSheet
Information gathered in a human For more information please contact:
exposure assessment identifies the major Public Information Centre
pathways of exposure (e.g., air, water, food), 135 St. Clair Ave. W.
the levels of exposure from each pathway, Toronto, ON M4V 1P5
and the total exposure from all pathways Tel: [phone]
that contribute to the health risk of concern. Fax: [phone]
That information is then used to predict Toll-free number: 1-800-565-4923
exposure levels for the typical adult and Internet: www.ene.gov.on.ca
child, as welt as for those involved in
activities such as gardening.
Young children are assessed as a special
group because they may be more sensitive
to the effects of certain contaminants. They
may also have more contact with soil and
dust than adults do, and so are at greater
risk of taking in contaminants. Their level
of risk may therefore be higher.
Risk characterization, the final step in the
process, assesses the likelihood of health risk
based on the information gathered in the
first three steps. The risk assessment does
not provide the actual risk for a specific
person but rather the predicted range of
risk to residents in a general area.
Levels of exposure found in a health
risk assessment are compared with known
acceptable guidelines for contaminants.
The comparison helps determine whether
the level of exposure is higher or lower
than the acceptable limits.
The findings of a health risk assessment
also help determine what actions, if any, are
needed to reduce health risk in the commu-
nity and which actions would be the most
effective in reducing risks.
Ministry of the Environment ©
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