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

Appendix B
Appendix B
Checking Protocol for Contaminated Ingestion Resulting
from Produce, Meat, and Milk Produced at Remediated
Residential and Agricultural Sites
1.0 Background and Application
Humans can be indirectly exposed to contaminants in soils through food-chain contamination of
produce, meat, and milk. For agricultural land use, it is likely that some meat, produce (i.e.,
vegetables), and milk will be produced and consumed on-site. In the residential setting, it is also
possible that a backyard garden may provide a significant portion of the produce consumed by a family.
To ensure that soil remediation guidelines do not result in an unacceptable contribution to total daily
intake of contaminants via homegrown produce, meat, and milk, it is necessary to compare the
expected intake of contaminants from these sources with the total intake.
The concentration estimated to occur in food from soils contaminated at the preliminary soil guideline
concentration must be less than the maximum residue limit (MRL) published under the Food and Drug
Act. If no MRL exists for the chemical under study, then the total daily intake estimated by the
procedure outlined in this appendix must not exceed total background exposure from food (i.e.,
estimated daily intake) by more than 20% of the difference between the TDI and the EDI, for noncarcinogens.
For carcinogens, total contaminant intake must not exceed the risk specific dose (RSD)
for a cancer risk of 10 -6 .
The procedure and assumptions for estimating the concentration of a contaminant in food and daily
intake is described in Section 1.1. The protocol provides an estimate of bioconcentration of
contaminants into, and consumption of, these foods, in relation to the assumptions outlined in Section
1.1. This procedure applies only to non-polar organic contaminants. Methods for the assessment of
the bioconcentration of metals, or other chemicals not typically known to bioaccumulate, should be
considered on a chemical-by- chemical basis.
No detailed data about the proportion of food Canadians consumed from local origin are available.
However, it is believed to be a substantial contribution to total daily intake, especially in an agricultural
setting. For example, a 1985 survey in Quebec indicates that 42% of urban residents, and 58% of rural
residents consume vegetables from their own gardens (MAPAQ, 1985). The proportion may vary
considerably from one location to another. Generally however, it should reflect the variations relating to
the type of environment considered (i.e.,urban, rural or suburban) and it is also unlikely that these foods
will be consumed over the entire year.
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