Shellfish Safety
Acknowledgements
Health Canada, First Nations and Inuit Health,
Environmental Health
Canadian Food Inspection Agency
BC Ministry of Agriculture & Lands
Klaus Schaillie (retired)
Bill Heath
Enrico Buenaventura
Scott Pilcher
Liliana Rodriguez
Environment Canada
Our Goals
• Determine the levels of cadmium, PSP,
organochlorines in our shellfish
• Determine safe shellfish consumption level
• Improve overall knowledge of FN fisheries
staff and community
M
e
t
h
o
d
s
Health Survey
Shellfish Testing
Adult volunteers invited to participate
Part 1. Interview
A) Questions about how much oysters,
butters, manilas, horse clams, cockles
and crab are eaten
B) Questions about smoking
C) Questions about overall health,
diabetes, kidney health and illness due
to eating shellfish
Part 2. Laboratory Tests
Blood test to
measure iron stores
Measure cadmium
in horse clams, butter clams,
mussels, manila clams, crab,
cockles, oysters, littlenecks
Test for PSP at 2 sites
Test water quality
Urine test to measure
whether kidney function
is normal
Together this information will help us understand the benefits and risks of
harvesting shellfish and how we can increase shellfish consumption safely.
Cadmium in shellfish (ug/g)
Common Name
Species
Avg
Min
Max
Cockle
Clinocardium
nuttali
.03
.03
.15
Oyster
Crassotreas gigas
1.40
.89
2.0
Littleneck
Protothaca
Staminea
.36
.22
.50
Butter
Saxidomus
Giganteus
.09
.06
.12
Manila
Tapes
Philippinarum
(Tapes
Japonica)
.34
.21
.56
Horse
Tresus capax
.16
.06
.36
Mussels
Gallo spp.
.69
.52
1.01
Dungeness Crab
Magister
.08
.01
.26
Shellfish Intake (g/day)
Overall
Cowichans eat
about 2 tbsp of
shellfish daily
Penelakut eat
about 1/4 cup
of shellfish daily
Average US intake of shellfish 5-16 g/day
Cadmium intake from shellfish (ug/day)
Concern level from WHO and HC is 55 ug/day
Cadmium in urine of smokers vs nonsmokers
• Smoker (n=24) 0.97+/-0.6
• Non-smoker (n=27) 0.88 +/- 0.76
All were current smokers or had smoked
previously
Iron status of the participants
Serum ferritin less than 30ug/L
Many people who volunteered for this study
have low iron stores.
Cadmium-recommendation
• Levels of cadmium in oysters are lower in
Hul’qumi’num territory than elsewhere in
BC.
• On a weekly basis, it’s safe for adults to
eat 1 cup of shucked oysters harvested
locally (about 4-5 oysters weekly or 200
oysters per year)
Paralytic Shellfish Poison
• For a year we sampled mussels for PSP at
2 sites (Kuper Island, Cherry Point).
• PSP levels at our site at Cherry Point were
similar to the CFIA site for the area
• PSP levels at Kuper were consistently
lower than those at the CFIA site
Organochlorines
We found no significant levels of
organochlorines in clams, oysters
or crabs we sampled from our
harvesting locations.
What do the results tell us?
– Shellfish are rich in iron
– Clams are low in cadmium
– Oysters contain some cadmium. Adults can safely eat
about 1 cup weekly
– Many females have low iron stores. Low iron stores
can cause more cadmium to be taken in by our
bodies. It’s important to eat iron rich foods daily.
– PSP closures appear to be accurate for shellfish
harvesting in Cowichan Bay area. It may be valuable
for Penelakut if CFIA’s site moves closer to Kuper
Island.
– People want more information on harvesting shellfish.
Education materials
• To help educate about shellfish safety, this project
created
– Shellfish Safety Technical Manual for Fisheries and Health staff
– Maps for Fisheries and Community members to identify open/
closed areas
– Poster/Brochures to guide community members about what
kinds of questions to ask about wild clams/oysters
– Poster for youth/adults to promote eating shellfish and Fisheries
Guardians as knowledgeable community members for open/
closed areas information
– Activities for teachers/fisheries/health staff to teach children and
youth about shellfish safety (beach walk, Hul’qumi’num mix/
match, mapping exercise, colouring book)
Poster
Brochure
Poster for Youth