Protocol for the Derivation of Environmental and Human ... - CCME

Appendix F
Appendix F
Multi-media Exposure Assessment
Multi-media exposure assessment can be defined as the quantification of total concurrent exposure from
all known or suspected sources via all known or suspected routes. Sources of exposure can be air,
water, food, soil and consumer products. Routes of exposure can be inhalation, ingestion and dermal
absorption.
The estimated daily intake (EDI) of a particular contaminant by an average Canadian can be obtained
from a multimedia exposure assessment. The concept of estimated daily intake of a chemical for an
individual can be defined as the sum of all exposures from various pathways and is represented by the
following equation:
n
EDI = S ED i [1]
i=1
Pathway specific equations are used in exposure estimates. In comparison to hazard identification and
dose-response assessment, exposure assessment has few components that can be applied to all media.
The specific equations for each exposure pathway (inhalation, water ingestion, soil ingestion, food
ingestion, and dermal skin) follow the generic equation :
ED i is the exposure from pathway i,
ED i = C × CR × BF × EF [2]
BW
where,
ED
C
CR
BF
EF
BW
= exposure dose (mg/kg⋅day)
= contaminant concentration in medium (e.g., mg/L)
= contact rate (e.g., mg/day)
= bioavailability factor (unitless)
= exposure factor which is the product of the exposure frequency (events/year) and
exposure duration (years/lifetime) and is unitless
= body weight (kg)
Total multimedia exposure is simply the sum of the dose estimated from air, water, soil, food (and
consumer products where appropriate).
The four phases to quantifying exposure are:
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