COMPTE-RENDU DU COLLOQUE

Arsenic
Bin am
Cadmium
Chromium
Fluoride
Lead
Substance
RESEARCH RISK ASSESSMENT RISK MANAGEMENT
Laboratory and field
obtervationi of advene
health effects and ex*
poiurei to particular
agents
Information on
extrapolation methods
for high to low dose
and animal to human
Field measurements,
estimated exposures,
characterisation of
populations
Hazard Identification
(Ooes the agent cause
the adverse effect?)
Dose-Response Assessment
(What is the relationship
between dose and inei*
dence in humans?)
Exposure Assessment
(What exposures are
currently experienced
or anticipated under
different conditions?)
Risk Characterization
(What is the estimated
ineidenee of the ad*
verse effect in a
given population?)
FIGURE 1-1 Elements of risk assessment and risk management.
FIGURE 15
TABLE 2
CANADIAN AND U. S. DRINKING WATER STANDARDS: A COMPARISON OP RATIONALES
Canadian
MAC
(mg/1) Canadian rationale
0.05 Human exposure at 0.05 tag/! has not been
associated with adverse effects in limited
epidemiological studies; no attempt has been
made to extrapolate cancer risk from Taiwan
studies
1.0 Hie 2.0 mg daily exposure on water would
contribute about two-thirds of the daily
amount from food; lifetime studies with rats
at 5 mg/1 showed no adverse health effects
0.005 - Drinking water would contribute only 15% of
an estimate FAO/WHC tolerance intake (or
57.71 *ig/day)
0.25 1*25 rag/L for 3 yean caused no in effects in a
family of 4; toxic effects were seen in rats and
rabbits with >5 mg/1 of hexavalent chromium
1.5 Qaim that denial fluorosis may be objectionable
at concentrations greater than M mg/1
0.05 State that at dietary intakes of lead common in
Canada, the Wood lead levels are not likely to
exceed 40 Ml/100 ml, a level associated with
dinical toxicity symptoms in children, when
the drinking water concentration of lead
remains below 0.10 mg/1
FIGURE 16
Development of
regulatory options
Evaluation of public
health; economic,
social, political
consequences of
regulatory options
Agency decisions
and actions
Comparison
vnih U S. U. S. rationale
Different from U. S.
Different from U. S.
Different from U. S.
Comparable to U. S.
Comparable to (J. S.
Different from U. S.
/132
Since arsenic was thought to be a human
carcinogen. EPA wanted to limit the total
exposure to arsenic Consequently, the current
standard was designed to allow no more than
10% of one's total daily exposure to come
from drinking water.
No specific human studies; based on an
industrial air standard
It would take 352 of Cd per day for 50 yean
to reach a critical level in the kidney (200
ppm) based on animal studies; at the current
standard of 0.01 mg/L 20 Mg/day would be
additionally contributed to an average of 75
jig/day from food; thus, a safety factor of 4 is
assumed
Since Pb from other sources was not closely
regulated and since the total daily intake of
Pb that results in progressive retention is leas
than twice the average intake, the standard
was adopted. At the EPA standard, 25-33%
of a I-3-year-old child's daily lead exposure
would be derived from the drinking water