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

Appendix B
P l
P r
BW
= percent produce purchased
= average chemical concentration in retail produce (mg/kg)
= body weight (kg)
For non-carcinogens, the receptor is assumed to be a 13 kg child consuming 125 g of produce (i.e.
vegetables) per day. For carcinogens, the receptor is assumed to be a 70 kg adult consuming 250 g of
produce per day (Health Canada, 1994). For residential land use, 10% of garden produce consumed is
assumed to be locally grown. For agricultural land use, a 50% value is recommended (Table B.1).
3.0 Bioconcentration of Soil Contaminants in Meat and Milk and Estimated
Daily Intakes
For the purposes of this general procedure, only direct ingestion of soils by beef and dairy cattle will be
considered. It is assumed that beef is the major type grazing animal consumed by humans. Grazing
animals directly ingest anywhere from 0.4 to 0.9 kg of soil per day (McKone and Ryan, 1989; Fries
and Paustenbach, 1990). Studies demonstrate that the uptake of lipophilic substances such as PCBs
deposited in or on grazed crops is much less than that taken up through the direct ingestion of soil by
cattle (Fries and Jacobs, 1986). Therefore indirect contamination via ingestion of vegetation is not
considered.
Most dairy and beef cattle are fed from harvested forage in enclosed feed lots or barns (Paustenbach,
1989). Therefore, the opportunity to ingest soils will be somewhat restricted. However, increasing
consumer demand for "organically grown" meat and dairy products from free-range animals increases
the likelihood that animals will spend more of their lifetime grazing. The procedure recommended by the
Subcommitee assumes that an animal is free range for the majority of the year.
3.1 Bioconcentration of Contaminants in Meat
Travois and Arms (1988) have studied the bioaccumulation potential of organic contaminants into beef
and developed the following model:
Where the biotransfer factor for beef (B p ) is defined as:
log B p = - 7.6 + log K ow , n = 36, r = 0.81 [4]
B p = concentration in beef (fresh weight: mg/kg)
daily intake of chemical (mg/day)
Assuming that beef cattle ingest, on average, 0.9 kg of soil per day (Fries and Paustenbach, 1990), and
that chemical intake with vegetation is negligible compared to that with direct soil intake, then the daily
intake of chemical can be defined as:
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