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INTRODUCTION
1.1
History of  the International Joint
with reproductive and teratogenic effects, the Board
Commission Involvement in Detroit-
identified those pollutants which they considered of
Windsor/Port Huron-Sarnia Regions
greatest concern.  With respect to carcinogenic potential,
the Board identified fifteen chemicals having the highest
The 1975 Reference to the Commission from the
level of  concern relative to direct inhalation, including
Governments of  Canada and the United States led to the
1,2-dichloroethane, 1,3 butadiene, 1,4 dichlorobenzene,
creation of  the International Michigan-Ontario Air
arsenic compounds, benzene, benzo(a)pyrene, beryllium,
Pollution Board (the Board).  The Reference requested
cadmium, carbon tetrachloride, chloroform, chromium
the International Joint Commission, through this Board,
compounds, formaldehyde, nickel compounds, perchlo-
report annually on the state of  air quality in the Detroit-
roethylene (tetrachloroethylene) and trichloroethylene.
Windsor and Port Huron-Sarnia areas.  Ambient air
quality trends and emissions of  sulphur dioxide, sus-
The Board determined the calculated risk of  cancer for
pended particulates, and odours were to be the focus of
these two regions resulting from  the presence of  these
these reports.
hazardous pollutants through application of  a  bench-
mark established in the U.S. Clean Air Act for hazardous
In 1983, the Commission noted that domestic regulatory
air pollutants of one in one million lifetime cancer risk.
programs and control strategies in the region(s), com-
The 1990 Board report to the Commission concluded
bined with the decommissioning of some older indus-
that the calculated risk of  cancer associated with several
trial facilities and the upgrading of  pollution control
contaminants in these two regions was significantly
systems at others, had resulted in significant improve-
higher than the Clean Air Act benchmark of  one-in-
ments in levels of  sulphur dioxide, particulates and
one-million over a lifetime.
odours.  While noting these trends, the Commission
informed the Governments that reporting solely on
The Board concluded that the highest priority for any
these three pollutants did not provide an adequate
pollution prevention initiative should be focused on
overview of  the atmospheric environment for the
benzene, formaldehyde and 1,3-butadiene.  Contami-
region.  However,  the objectives of  the Reference
nants of  concern identified by the Board for their
having essentially been met, the Commission informed
association with reproductive and teratogenic potential
the Governments of  the effective completion of  the
include benzene, chloroform, formaldehyde, nickel
Reference and the Commission disbanded the Interna-
compounds, styrene and xylene.
tional Michigan-Ontario Air Pollution Board.
The Commission held public meetings on the findings
In 1988, the Commission was asked by the Govern-
and recommendations of  the Board.  Following a review
ments to report on the hazards posed to human and
of the recommendations of the Board, public com-
environmental health from airborne emissions in the
ments and written submissions, the Commission issued
Detroit-Windsor region.  The Commission formed the
their 1992 Air Quality in the Detroit-Windsor/Port
International Air Pollution Advisory Board for the
Huron-Sarnia Region   Report to the Governments.
Detroit-Windsor/Port Huron-Sarnia Region.  Particular
Among the conclusions in that report were the following
expertise on the impact of  air pollution on human
statements:
health was represented on this Board, to allow analysis
of the impact of  the emissions and concentrations of
sufficient information exists on airborne toxic
selected hazardous air pollutants in the two regions.
chemicals in the region to conclude that there is a
significant health issue which requires immediate
This latter Board identified a list of  125 chemicals for
implementation of additional air emission abate-
consideration and summarized emission and air moni-
ment and preventive measures;
toring data for these pollutants.  Using this information,
ambient concentrations of  the examined airborne
the Board was able to estimate how widespread the
toxics in the two regions were similar to other urban
exposure to specific pollutants could be, while consider-
centers of  comparable size and industrial develop-
ing relevant toxicity.  Combining this information with
ment; and further,
screening techniques for both carcinogens and chemicals
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