Towards new estimated daily intakes for the Canadian population

Abstract

Canadians are exposed to background contamination through air, water, soil, food and consumer products. This background exposure is quantified, for a given contaminant, by Estimated Daily Intakes (EDIs). EDIs estimate the typical concurrent background exposure from all known or suspected sources (ambient and indoor air, drinking water, soil, food, breast milk, consumer products) via all known or suspected routes (inhalation, ingestion, dermal contact) for the average Canadian. The total EDI of a chemical - the summation of all these concurrent EDIs - is determined through a multimedia exposure assessment in which a lot of information are required. In risk assessments, RTDI (Residual tolerable daily intake) is considered and corresponds to the dose of a chemical above background to which a person could be exposed without expected adverse effects (i.e., RTDI = TDI - EDI, where TDI is the tolerable daily intake). Additionally, in the derivation of the human health quality guidelines, 20% of the RTDI is allotted to each of the five primary media to which people are potentially exposed (i.e., air, water, soil, food and consumer products). As can be seen, EDIs are an important piece of the human health risk assessment process. For compounds with available EDIs and for compounds still without, there is a need: To assess or re-assess EDIs on a regular basis (data update for example) To evolve towards more accurate EDIs (moving from deterministic to probabilistic EDIs for example) To be transparent in the way EDIs are estimated in order to be easily revisited and updated on a regular basis (every five years for example) This talk will briefly explain the various key aspects of the EDI protocol developed by the HC-CSD in order to assess new Canadian EDIs for several chemicals, notably: Chemicals priorization Data and / or studies selection process Canadian population parameters selection Mediums and routes of exposure Fit of statistical distributions Simulations results Emphasis will be devoted to the current data limitations and their consequences. The urgent need of cooperation between all the federal / provincial / local data generators in order to produce more realistic EDIs will also be highlighted.