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ANALYSIS OF THE POTENTIAL POPULATIONS AT RISK FROM THE
CONSUMPTION OF FRESHWATER FISH. CAUGHT NEAR PAPER MILLS
Craig McCorrnSck
Office of Policy Planning; and Evaluation
David-Cl'everly
Office of Research and Development
U.S. Environmental Protection Agency
April 23,1990
INTRODUCTION: ' .
OTS, OSW, and OW have conducted a detailed human and ecological risk
assessment of environmental loadings of dioxirt from bleached pulp and paper
mills. In that analysis only maximum lifetime cancer risk and average lifetime
cancer risk to the hypothetically exposed individual was estimated for various
exposure scenarios. No estimation of potential population risk, especially to
sensitive subgroups, was provided in the analysis. Since draft publication of these
results, we have identified populations of Asians, and tribal Native Americans that
reside along the banks of the Columbia River in Oregon. The State government
indicates that there are eight bleached pulp and paper mills that directly discharge to
the Columbia River. The State also indicates that freshwater fish caught from the
Columbia river are the main, source of animal protein for these people. They
consume an. average of 100 to 150 grams of fish flesh each day over the course of the
year. These individuals are much more likely to catch and consume fish that has
been contaminated with dioxin from the effluent discharged from the mills than
other populations in the area. The Native Americans number about 15,000, and the
Asians number about 30,000 people.
In addition to these subpopulations exposed by diet to dioxin, we have
estimated that approximately 610,000 people living in the vicinity of pulp and paper
mills have family incomes at or below the poverty level. These individuals are also
expected to derive a significant portion of animal protein from both subsistence and
sports fishing in rivers near paper mills. Subsistence fishermen consume about 100
grams of fish per day/i, and sports fishermen consume about 69 grams fish per day/2.
For purposes of the assessment of potential cancer risk, we have employed
monitoring data of dioxin contamination in fresh water fish caught in the vicinity
of bleached pulp and paper mills. This was developed by the Environmental
Research Laboratory in Duluth Minnesota as part of the National Bioaccumulation
Study of freshwater fish in the U.S. The range of detected TCDD equivalent
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concentration in the edible fish fillet was from 0.1 ppt - 24 ppt. The weighted
average fillet concentration was 6.5 ppt (6-5 pg/gm). For purposes of estimating
incremental lifetime cancer risk to the most exposed individual, a fillet
concentration of 24 ppt was used. The weighted average dioxin concentration in the
fillet of 6.5 ppt was used to derive the approximate average lifetime risk to
subsistence and sports fishermen. The average exposure and average lifetime risk
was used to estimate the annual cancer incidence in these sensitive subpopulations.
In addition a human body weight of 70 kilograms was assumed to compute
estimates of excess cancer risk.
CONCLUSIONS:
It is currently no.t possible to directly measure the association between the
chronic dietary intake of dioxin contaminated freshwater fish, and the occurrence of
specific forms of cancer in the exposed populations. The epidemiologic studies of
these populations with a high dependency for subsistence fishing as a source of
dietary animal protein have not been conducted. Therefore we have
mathematically estimated lifetime excess cancer risk to the population residing near
the Columbia River, as well as to low-income populations living in the vicinity of
other mills in the U.S. This analysis is not intended to replace any previous risk
assessments involving 'the human consumption of fish that has been contaminated
with dioxin from the effluent discharged from paper mills, but is merely to illustrate
that methodologies can be developed to estimate total populations at risk in the U.S.
The following are the results:
Pop. MIRfal AVG RiskiM Cancer Inc.tel
Native Americans
Asian Americans
Total Risk
15,000 .
30.000
45,000
. . . 8.6X10-3
8.6X102
8.6X10-3
1.5X10-3
1.5X10:2
1.5X 10-3
0.33
0.67
1.0
Low income families 610,000 5.4X 10-3 l.Q X10-* 9.3
(a) MIR is the maximum individual risk, and is associated with the highest fish
consumption rate and the highest dioxin concentration in fish caught near paper
mills.
(b) Average lifetime cancer risk is the excess cancer risk based on the average fish
consumption rate for subsistence and sports fishermen, and the weighted average
dioxin concentration in fish caught near paper mills.
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(c)Cancer incidence is the estimated number of cancer cases per year within the
defined exposed population. This was computed using average lifetime risk,
I/ U.S. Environmental Protection Agency (1988). Risk Assessment for Dioxin
Contamination Midland, Michigan. Region 5. EPA-905/4-88-005.
2/Estimated consumption by the U.S. Food and Drug Administration, assuming
substitution of average U.S. population daily consumption of red meat with fish.
Calculations of Risk
1. Native Americans
Assumptions:
*
a. MEI consumes 150 gms fish/day.
b. Average consumption is 100 grms fish/day.
c. 70 kilogram person.
d. Lifetime exposure.
e. Max. dioxin concentration in fish fillet = 24 pg/gm.
f. Weighted average dioxin in fish fillet = 6.5 pg/gnv
g. Population of 15,000.
h. Risk Specific Dose of Dioxin = lifetime cancer risk of one in a million is:
0.006 pg/kg/day.
Max. Daily Dose= (150 gms/day X 24 pg/gm) / 70 kg person
= 51.43pgdioxm/kg/day
MIR ={( 51.43 pg/kg/day) / (0.006 pg/kg/day)} X1O6
MIR =8.6 XI0-3
Avg. Daily Dose= (100 gms/day X 6.5 pg/gm)/ 70 kg person
= 9.28 pg dioxin /kg/ day
Avg. lifetime risk = {(9.28 pg/day)/(0.006 pg/kg/day)) X10-6
= 1.5 X10-3
j
Annual Cancer Incidence = ( Avg risk * population)/ 70 year lifespan
= (1.5 X10-3 * 15,000V 70 yrs
= 0.33
2. Asian Americans
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Assumptions are the same as with Native Americans. The population size is
30,000.
Max. Daily Dose = 51.43 pg dioxin/kg/day.
MIR = 8.6X10-3
Avg. Daily Dose = 9.28 pg dioxin/kg/day
Avg. lifetime risk = 1.5 X 10-3
Annual Cancer Incidence = ( 1.5 X 10-3 * 30,000)/70 yr lifespan
= 0.67
3. Low income families.
Assumptions:
a. MEI consumes 100 gms fish/day.
b. Average consumption is 69grms fish/day.
c. 70 kilogram person.
d. Lifetime exposure.
e. Max. dioxin concentration -in fish fillet = 24 pg/gm.
f. Weighted average dioxin in fish fillet = 6.5 pg/gm.
g. Population of 610,000.
h. Risk Specific Dose of Dioxin = lifetime cancer risk of one in a million is:
0.006 pg/kg/day.
Max Daily Dose = (100 gms/day) X ( 24 pg dioxin/gm)/ 70 kg person
= 34.28 pg dioxin/kg/day
MIR = {(34.28 pg/kg/dy)/(0.006 pg/kg/dy)} X 10*
= 5.7X10-3
Avg. Daily Dose = (69 gms/day) X (6.5 pg/gm)/70 kg person
= 6.41 pg dioxin/kg/day
Avg. lifetime risk = { ( 6.41 pg/kg/dy)/(0.006 pg/kg/dy)} X 10-6
= 1.0 X
Annual Cancer Incidence ={ (1.0 X 10-3) * (61 0,000)} / 70 year lifespan
=9.3
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The Bottom Line:
» The "Forest through the trees" is that the environmental loadings of
dioxin from the mills may result in high levels of risk to humans.
• The analysis of the regulatory options suggests that this particular
industrial source category fits the mold for a regulatory pollution prevention
initiative through use of the CWA, TSCA, and RCRA.
* could require substantial reduction in the overall use of chlorine
* BACT seems to be oxygen delignification
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