Health Risk from Consuming
POC-Contaminated Fish:
Part II. Risk Analysis and Prevention
Strategies
Michael H. Dong, MPH, DrPA, PhD
October, 2007
Readings
taken at the Epcot Center, Orlando, Florida, USA
Lecture Objectives
Appreciate the POC residue levels in
fish observed in various countries.
Compare these real-time residue levels
to their respective screening values that
have been adopted as threshold levels.
Revisit the basic strategies used for
preventing health risk from consuming
fish contaminated with POCs.
Performance Objectives
 Students are expected to know that
worldwide levels of some POCs are still
far exceeding their screening values.
 . . to know what the methodological
issues and associated uncertainties are
in the risk analysis conducted here.
 . . to know that the prevention strategies
so discussed can be costly, yet crucial.
Table 2. POC residues in fish from selected localities, as published after the year 2000a
PCDDs/Fs
PCBs
DDT
Aldrin/
Dieldrin
0.03 ppt
2.5 ppb
14.4 ppb
0.3 ppb
-
-
1.5 - 62
-
China (Taihu Lake) (b)
0.5 - 3.8
1.5 - 27.6
-
-
India (River Ganges) (c)
-
-
Korea (coastal waters) (d)
-
3.0 - 96.6
0.8 - 27.0
-
Spain (Atlantic sw coast) (e)
0.04 - 0.19
0.9 - 23.8
-
-
Sweden (Baltic sea) (f)
0.5 - 33.4
-
-
-
Country (Location)b
Screening Valuec
China (Pearl River Delta) (a)
13.6 - 1,666 3.1 - 86.1
USA (salmon worldwide) (g)
65
73
28
6.3
a
all tissue residue concentrations of POCs are in ppb (g/g) wet weight, except for
PCDDs/PCDFs for which the levels are in TEQ-based ppt (g/g) wet weight.
b
from the following studies: (a) Kong et al. (2005); (b) Zhang and Jiang (2005); (c)
Kumari et al. (2001); (d) Yim et al. (2005); (e) Bordajandi et al. (2006); (f) SNFA
(2004); (g) Hites et al. (2004).
c
levels exceeding the screening values (as derived by U.S. EPA, 2000a) are considered
to be of potential public health concern.
Advisory for High Risk Groups
 A considerable number of monitoring
sites were noted to have POC levels >
the screening values by 30-fold+.
 For these areas, no more than 1 or 2 fish
meals/month should be recommended.
 Fish advisories of this kind may not be
all that practical to residents who rely
on fish as their main diet.
Issues Inherent in the Analysis
 Risk analysis of the type conducted here
is far from flawless.
 High consumption observed may not
correlated well with high residue level
detected even in the same vicinity.
 Nor are all fish species in the same
vicinity necessarily contaminated by the
same chemical or to the same extent.
Other Related Issues (I)
 The characteristics, the transport, and
the fate of POCs present in the aquatic
environment all can play a crucial role.
 Current trends may not be indicative of
the POC levels in fish in the future.
 For example, some POCs have been
transported to remote sites where the
chemicals have never been used.
Other Related Issues (II)
 There are also uncertainties with the
empirical data used in the analysis.
 All tolerance limits or screening values
are based on the toxicity data on hand,
which are ever lacking or indirect.
 Residue data are vulnerable to technical
errors inherent in sample collection and
in the analytical procedures used.
Implications of Analysis Data
 While both the tolerance levels and the
POC residue data must be applied with
caution, some level of conservatism
could/should still be exercised to err on
the side of health protection.
 Certain prevention strategies are thus
warranted here for fish contamination
with POCs in many localities.
Concerns with Bioaccumulation
 Bioaccumulation refers to cumulative
and aggregate exposures during the
same time interval.
 Its occurrence in humans can lead to
further alarming health consequences.
 The main concern here is that fish and
shellfish are not a person’s only source
of exposure to the same/a similar POC.
Issues with Bioaccumulation
 Once a lipophilic chemical (e.g., POC)
is inside the human body, it will not go
away any time soon.
 A large enough single dose (exposure)
can induce an acute adverse effect.
 The ADI or RfD used might not have
taken into account the extra amount of a
POC coming from other sources.
A Case of Bioaccumulation
 A pregnant woman was exposed to a
POC daily at a constant dose of 10 units
from fish consumption, and 5 units
through other sources (e.g., milk, water).
 Then on day 10, this woman would
have as her body burden a total of 150
(not 100) units of this chemical, which
would exceed the threshold of 100 units.
Risk Prevention Strategies
 Certain risk prevention strategies hence
should be in place to cope with the
potential hazard from consuming fish
contaminated with POCs.
 These would involve: environmental
health policy; regulatory/research
activities; residue monitoring programs;
and self awareness/prevention.
Environmental Health Policy
 Programs/policies should be developed,
with a focus on better use of POCs and
on better handling of waste removal.
 FQPA-like laws should be adopted to
focus on children’s higher sensitivity.
 Governments should have available
more, as well as more effective, POCrelated illness surveillance programs.
Regulatory/Research Activities
 Activities should be in place to enrich
risk communication resources for fish
contamination with POCs.
 Research is needed to refine the works
done on risk assessment methodology,
on toxicity studies, and on relevant
exposure parameters including fish
consumption pattern.
Residue Monitoring Programs
 More monitoring programs for POCs
in fish need to be developed around the
‘hot spot’ areas (which should be more
aggressively identified).
 These programs should be effective
with a special focus on sampling, on
the analytical technique used, and on
uniform reporting of monitoring data.
Self Awareness/Prevention (I)
 Awareness/prevention at the individual
level is the most effective approach to
minimizing the human health risk from
consumption of POC-contaminated fish.
 This assertion is based upon the notion
that risk prevention at the individual
level is much more tangible, more
controllable, and thus more attainable.
Self Awareness/Prevention (II)
 A fish consumer should make every
effort to choose younger fish to eat.
 The person should remove the fish’s
guts as these are the organs where
some POCs also tend to concentrate in.
 The person should also trim the fish’s
fat, remove the skin, and cut away the
fatty dark meat.
Self Awareness/Prevention (III)
 Lastly, the consumer should cook fish
in a way that would allow the fat to
drip away or drain off.
 This can be accomplished effectively
with most cooking methods.
 Up to 60% or more of the POCs could
be reduced by the way in which the fat
is dripped or drained away.
Self Prevention with a Price
 In closing, it is fair to forewarn that the
type of self risk prevention measures
suggested here is not without a price,
unless fish can swim in or be cultivated
in a cleaner aquatic environment.
 Otherwise, the individual consumers
would end up getting less intake of the
good (i.e., the essential) fats in fish.