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State of Environment Reporting
 Trends
in Dioxins and Furans in
Dungeness Crabs Near Pulp Mills
Average
dioxin and furan levels in the digestive gland
of Dungeness Crab
SOURCE:
Pollution Prevention and Assessment Division, Environment Canada,
Pacific and Yukon Region, 2001. NOTES: To approximate total risk
from the most toxic chemical forms of dioxin and furans (17 of which
are assessed in this analysis), all are assessed by comparing their
toxicity to that of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD),
the most toxic of this group using an internationally accepted procedure.
Concentrations derived in this manner are referred to as toxic equivalents
(TEQs).
Trends
in dioxins and furans in Dungeness crabs near
pulp mills
- Between
1989 and 1998, average concentration of
dioxin and furans in the digestive gland
of Dungeness crab most highly exposed
to pulp mill effluent decreased by 97%.
Dungeness crabs are a good indicator of
contaminant levels in sediment because
they are bottom dwelling foragers that
generally stay in the same area throughout
their lifetime.
- In
British Columbia, dioxins and furans were
produced as a by-product of the chlorine
bleaching process by pulp and paper mills.
In the late 1980s, industries adopted
technologies that minimize the release
of dioxins and furans. The government
introduced regulations in 1992 to motivate
further reduction.
- A
newly identified source of atmospheric
dioxins and furans is the burning of wood
that has been soaked in salt water. Government
and industry are currently working together
to find a solution to this issue.
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