OEPA
United States
Environmental Protection
Agency
Office of Science and
Technology (WH-551)
Washngton, DC 20460
EPA 823-F-92-001
November 1992
Water
What t« the ttudy?
The National Study of Chemical Residues in Fish
(NSCRF, formerly the National Bioaccumulation Study,
or NBS) is a one-time screening investigation to deter-
mine the prevalence and sources of selected
bioaccumulative pollutants in fish. Fish samples were
collected at 388 sites nationwide (Figure 1, below) and
analyzed for 60 pollutants including RGBs, dioxins,
furans, and mercury.
The sites sampled included 314 "targeted" sites
thought to be influenced by various point and nonpoint
pollutant sources. Targeted sites included pulp and
paper mitts (chlorine and non-chlorine), wood preserv-
ing operations, certain refineries, Superfund sites, pub-
licly-owned treatment works (POTWs), sites near
industrial complexes, and sites that could be influenced
by runoff from urban or agricultural areas. Other sites
inducted 35 background locations and 39 USGS sites
to provide national coverage.
Why wmm the study performed?
The study began in 1986 as an outgrowth of EPA's
National Dtoxin Study, a nationwide investigation of
2,3,7,8 tetrachkxodibenzo-p-dioxin (2,3,7,8 TCDD)
contamination of soil, water, sediment air and fish.
Some of the highest concentrations of 2,3,7,8 TCOD
were detected in fish. The Agency initiated the Na-
tional Study of Chemical Residues in Fish to investi-
Figure 1
Location of BioaccumulatJon Study
Sampling Sites
tH> rear,
n
gate whether there may be other toxic pollutants
bioaccumulating in fish. The NSCRF is also part of
r^£s ^a5008* S « Petition from the Environmental
Defense Fund (EOF) and the National Wildlife Feder-
ation (NWF). This petition requests EPA to conduct an
aquatic monitoring survey of the occurrence of dioxins
and furans.
Who performed the study?
EPA Regions and State personnel were involved in the
selection of sites and sample collection. An EPA Work
Group provided continuing review of the study and the
final draft was sent to 62 reviewers and seven experts
outside EPA for a final round of comments. ^^
The samples were analyzed by the EPA laboratory at
Duluth for 60 compounds, including 10 PCBs 15 dwx-
ms/furans, 21 pesticides/herbicides, mercury, biphe-
nyl, and 12 other organic compounds. Chemicals were
selected for analysis based on the potential of the
compound to btoaccumulate in fish, the potential for
human health effects, the persistence of the chemical
in the environment, and existence of analytical meth-
ods for detecting the compound in fish tissue.
When WM the study performed?
The study was initiated in 1986. Fish samples were
collected beginning in 1966 and continuing through
1989. Most of the samples were collected in 1987.
Laboratory analyses were conducted between 1987
and 1990. States received the data as soon as QA/QC
was completed on each sampte.The data analyses and
report preparation were conducted between 1988 and
1990.
What did the study find?
Of the 60 compounds studied, the most frequently
detected pollutant was ODE found at over 98 percent
of all sites sampled (Table 1). This compound is a
metabolic breakdown product of DOT which was a
widely used pesticide and is extremely persistent in the
environment Other compounds detected at more than
90 percent of the sites are mercury, total PCBs and
biphenyi. PCBe were detected at the highest concen-
tration with a maximum value of 124,000 parts per
billion (ppb), and an average concentration of 1,890
PPb.
Seven of the 15 dioxirvYuran compounds and 15 of the
other 46 compounds were detected at over 50 percent
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of the sites . The two most frequently detected dioxm
and furan compounds were both found at 89 percent
of the stes. The dioxm compound considered to be the
most toxic. 2,3,7,8 TCDD, was found at 70 percent of
the sites at a maximum concentration of 204 parts per
trillion (ppt) and an average concentration of 6.8 ppt.
Statistical analyses of various source categories show
that DUID and paper mills using chlorine appear to be
the aoranant (statistically significant) source category
of 2.3.7.8 TCDD and 2.3,7,8 TCDF found in fish tissue.
For the other dioxins/furans, the statistical correlation
tests showed no dominant source category. Based on
a simple comparison of median fish tissue concentra-
tions, however, highest concentrations for penta-
furans occurred near Superfund sites, highest for
hexa-furans occurred near refinery/other industry sites,
and highest for penta-and hexa-dioxins occurred near
paper mills using chlorine. Using the same statistical
correlation tests as for dioxins/furans, no single domi-
nant source category was identified for the other 45
chemicals. However, a number of observations can be
drawn from the data. For example, while the median
PCB concentration was below detection at the 20
background sites where RGBs were sampled. PCB
values ranged from 213 to 525 ppb for industrial urban
sites, paper mills using chlorine, refinery/other industry
sites, non-chlorine paper mills and Superfund sites.
Cancer risks were estimated for 106 targeted and 4
background sites having fillet data. Using EPA as-
sumptions (id-, upper-bound cancer potency factors,
6.5 grams/day consumption rate), PCBs are the only
chemical to exceed a health risk at one in a thousand
(Table 2). The cancer risk exceeded the 10 risk level
(one in ten thousand) at 42 sites for PCBs and at 6 sites
for dieldrin. PCB use was restricted in 1982 and
dieldrin use was banned in 1985. Risks for dioxins
and furans were not estimated because of the ongoing
dioxm risk assessment.
What do the results mean to us?
EPA projects upper bound cancer risks to exceed one
m ten thousand at 46 sites where fish are contaminated
by high levels of PCBs and/or dieldrin. Three of these
sites had risks above this level for more than one of
these compounds. States have adopted fish bans or
advisories at 41 of the 46 sites where consumption of
fish could be a human hearth problem. Additional
monitoring at the remaining 5 sites has not indicated
the need for advisories to date.
General Questions and Answers
• Has EPA provided outside review of the report and
peer review of the site selection process and ana-
lytical methods?
Sites were selected by EPA regional or state staff
based on proximity to point/nonpoint sources. Many of
the sites were targeted because of known dioxin
contamination.
The NSCRF report was sent to 62 agency personnel
and seven experts outside of the Agency for review. We
believe that technical comments have been addressed.
Analytical methods were developed by EPA's Duluth
Lab and reviewed by national experts at Wright State
University and Columbia Research Laboratory and
found to be adequate for purposes of this study.
• Has EPA proposed stringent enough foflow-up ac-
tions?
Steps EPA w« take for PCBs and dieldrin are outlined
below. lnatf
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