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8.4 Fish Consumption Advisories
Fish from contaminated sites may contain high levels of toxic
bioaccumulating contaminants, and may show elevated levels of
abnormalities, including tumours (see Tables 12 through 15 of
this paper, and Dawe et al. 1991). These levels of toxins and
abnormalities, along with a variety of striking abnormalities
that have been observed in fish-eating birds and mammals, have
raised concerns that eating Great Lakes fish may lead to health
effects in people who eat large amounts of such fish. Provincial
governments and state governments in the Great Lakes region have
therefore issued sportfish consumption guidelines such as the
1995-96 Guide to Eating Ontario Sport Fish (Ontario Ministry
of Environment and Energy 1995).
The human health studies that have looked at the levels of exposure
of anglers and other people who eat Great Lakes fish to toxic
bioaccumulating contaminants found in such fish or in game were
reviewed in a recent report (USEPA-GLNPO 1995). This report points
out that populations in the Great Lakes basin rely on the nearshore
waters for numerous residential, commercial, and recreational
uses, and that most of the data available on human exposure to
toxic substances in the Great Lakes come from analyses of contaminant
levels in drinking water and in sport fish. Only very limited
information is available about the health risks associated with
exposure to such contaminants.
There is sufficient evidence that consumption of contaminated
sport fish and wildlife can significantly increase human exposure
to Great Lakes pollutants. A spectrum of major contaminants have
been identified in cooked Great Lakes fish, and methods have been
recommended for reducing the amounts of contaminants by judiciously
preparing and cooking the fish (Skea et al. 1979; Voiland et al.
1991; Zabik and Zabik 1995; Zabik et al. 1995). Investigators
have demonstrated that blood serum levels of these contaminants
are significantly increased in consumers of Great Lakes sport
fish as compared with the levels in non-fisheaters (Humphrey 1983a,
1983b; Jacobson et al. 1989; Kearney et al. 1995). Also, several
investigators have shown that exposure from fish far outweighs
exposure from atmospheric, terrestrial, or water-column sources
(Humphrey 1983b; Swain 1983). The exposure patterns associated
with
the different pathways may vary for different populations, especially
those living in the vicinity of industrial sites, such as refineries
or smelters.
Several epidemiological studies have investigated the association
between water pollutants in the Great Lakes and the health of
residents who live on or near the lakes. The following studies
have demonstrated increased tissue levels of toxic substances
(body burdens) that may be associated with reproductive, developmental,
behavioural, neurological, endocrinological, and immunological
effects:
· Michigan Maternal and Infant Study (Fein et al. 1983)
· Michigan Sports Fisherman Study (Humphrey 1976)
· Minnesota Ecologic Epidemiologic Study (Schuman et al. 1982)
· New York Ecologic Epidemiologic Study (Kagey and Stark 1992)
· Dar's Wisconsin Maternal and Infant Study (Dar et al. 1992)
· Wisconsin Sports Fish-Consumers Study (Fiore et al. 1989; Sonzongni et al. 1991)
· Smith's Wisconsin Maternal and
Infant Study (Smith 1984)
Other epidemiological studies of mothers exposed to toxic substances
similar to those identified in Great Lakes fish showed either
reproductive and developmental or neurobehavioural effects in
their children. These studies include the following:
· Japan and Taiwan PCBs Studies (Hsu et al. 1985)
· The North Carolina Breast Milk and Formula Project (Rogan et al. 1986)
· Occupationally Exposed Female
Capacitor Workers (Taylor et al. 1989)
The limitations of these human health studies have been documented.
They include concerns about laboratory techniques and sensitivity
in some studies; concerns about sample size, non-random sampling
techniques, recall bias, and uncontrolled confounders were noted
in other studies.
Despite such limitations, epidemiological studies of exposed human
populations provide the most convincing evidence of human health
effects.
The most direct evidence for adverse human health effects from
environmental pollution is found in a series of studies linking
PCB exposure to consumption of contaminated fish (Fein et al.
1984; Jacobson and Jacobson 1988; Jacobson et al. 1984a, 1984b,
1984c). Replicating and continuing these types of epidemiological
studies should provide the most relevant and convincing evidence
regarding the status of human health following exposure to Great
Lakes pollutants.
More recent ongoing human health studies in the United States
and Canada were designed to build on and extend these earlier
studies. Further, the later studies were designed to control various
limitations that had hampered the previous health studies in the
Great Lakes. Most of these studies were begun just a few years
ago and are not yet complete. Preliminary findings do support
earlier reports of an association between the consumption of contaminated
Great Lakes fish and body burdens of persistent toxic substances,
including PCBs, other organochlorines, heavy metals such as mercury
and lead, and PAHs. The body burdens for such substances that
have been identified in the fluids and tissues of fish consumers
are three- to fourfold higher than those in the general population.
Additionally, some preliminary data support the earlier observations
of both neurobehavioural and developmental deficits associated
with the consumption of contaminated fish.
Most of these more recent human health studies target populations
that are presumed to be particularly susceptible-that is, Native
North Americans, sport anglers, the urban poor, pregnant women,
and fetuses and nursing infants of mothers who consume contaminated
Great Lakes fish. Focusing our efforts on such at-risk populations
offers the best opportunity to address the important public health
questions that remain unanswered regarding exposure to chemical
contaminants in the basin. Results from the following studies
are not yet available:
· An Assessment of a Human Population at Risk: The Impact of Consuming Contaminated Great Lakes Fish on Native American Communities (University of Wisconsin-Superior & Milwaukee)
· Cognitive and Motor Effects of PCB Exposure in Older People from the Michigan Fisheater Cohort: Emphasis on the Role of Ortho-Substituted Congeners (University of Illinois at Urbana-Champaign)
· Consortium for the Health Assessment of Great Lakes Sport Fish Consumption (Wisconsin Department of Health and Social Services)
· Contribution of Nursing to Behavioral Changes in Children of Mothers Who Consumed Lake Ontario Fish: Two Methodological Approaches (State University of New York at Oswego)
· Great Lakes Fish as a Source of Maternal and Fetal Exposure to Chlorinated Hydrocarbons (University of Illinois at Chicago)
· Health Risks from Consumption of Great Lakes Fish (Michigan State University)
· The New York State Angler Study: Exposure Characterization and Reproductive and Developmental Effects (State University of New York at Buffalo)
· PCB and DDE Exposure among Native
American Men from Contaminated Great Lakes Fish and Wildlife (New
York State Department of Health)
In 1992-93, Health Canada carried out an exposure study on 176
adult men and women from Mississauga, Ontario, and Cornwall, Ontario.
Many of these people had been eating fish from Lake Ontario or
from the St. Lawrence River for many years. They were compared
to 56 men and women who ate no Great Lakes fish (the controls)
(Kearney et al. 1995). Analysis of blood samples showed that most
of the fisheaters had PCB levels in blood plasma that were well
below those seen in other fisheater studies; only four participants
slightly exceeded Health Canada guidance levels of 20 µg/L.
Mean blood plasma levels of organochlorine pesticides were lower
than mean levels seen in other studies of fisheaters. Levels of
chlorinated dibenzofurans and dibenzodioxins were also low, and
appeared to be strongly correlated with age-that is, older people
generally had higher blood plasma levels than did younger people.
Total blood mercury and methylmercury levels were also low and
below Health Canada's guideline value. Blood cadmium levels reflected
mainly tobacco consumption levels. No relationships were found
between fish consumption and liver plasma enzyme levels, thyroid
hormones, urinary porphyrins, or urinary d-glucaric acid levels.
Urinary cotinine was an effective biomarker for tobacco-
smoking status. The small differences between fisheaters and controls
did not warrant further health studies of fisheaters in the study
areas.
Health Canada is currently conducting a pilot dietary and fish
consumption study on Asian immigrants in the Toronto area (a group
thought to have a high level of fish consumption), as well as
a shoreline angler survey in the Toronto-Hamilton, Niagara, and
Windsor areas. These studies may provide further insight into
the fish consumption habits of various population groups and into
the possible benefits and risks of eating fish from the Great
Lakes.
In Canada, the Ontario Ministry of the Environment and Energy's
Sport Fish Contaminant Monitoring Program has measured contaminant
concentrations in fish from the Ontario nearshore waters of the
Great Lakes for more than 20 years. The results have been used
to provide consumption advice to the public.
Most fish are collected by the Ministry of Natural Resources.
When possible, researchers catch 20 fish of each species with
lengths and weights representative of the size range of the species
in the location being tested. The length, weight, and sex of each
fish are recorded and a skinless, boneless fillet of the dorsal
muscle is removed from the fish, packaged, and frozen for shipment
to MOEE laboratories for analysis. This sample portion provides
the most consistent test results and is also the best edible portion
of the sport fish.
All fish are analysed for mercury. Depending on the location being
studied, analyses may also be done for PCBs; pesticides (including
DDT and toxaphene); mirex; dioxins and furans; metals (such as
lead); PAHs; chlorinated phenols; and chlorinated benzenes.
The consumption advice provided to the public in the Guide
to Eating Ontario Sport Fish (Ontario Ministry of Environment
and Energy 1995) is based on the health protection guidelines
developed by Health Canada. The advice is phrased as a maximum
number of recommended meals per month; consumption categories
are eight meals, four meals, two meals, one meal, and no meals
per month. Consumption advice specifies the species of the fish,
the length of the fish, and the location where the fish is caught.
The Guide's advice is designed to apply to anglers who
consume moderate amounts of fish. The consumption advice will
protect individuals who follow the Guide's advice and consume
no more than eight sportfish meals per month. Health Canada guidelines
have been developed to protect the health of the most sensitive
individuals, generally considered to be children and pregnant
women. But as an added precaution, the Guide recommends
that women of childbearing age and children under 15 avoid consuming
any fish that falls into the one-meal-per-month category as well
as any fish in the restricted category.
For the Great Lakes, consumption advice is provided for blocks
or regions of each lake. Contaminant levels for all fish of a
given size and species should be similar throughout a block. The
blocks' boundaries were established in consultation with fisheries
biologists who are familiar with local fish populations and after
comparing contaminant levels in fish from several adjacent locations.
Consumption advice is provided on a wide variety of sport fish
species. For the purposes of this paper, lake trout were chosen
as an indicator species for the coldwater fishery because of their
distribution across all Great Lakes. Additionally, because of
their high fat levels, lake trout are particularly useful as monitors
of organic contaminants such as PCBs, mirex, and toxaphene. Lake
trout in a size class (55-65 cm) that would typically be kept
and consumed by anglers were selected for this assessment.
A summary of the 1995-96 consumption advisories for 55-cm to 65-cm
lake trout in the Canadian waters of the Great Lakes is given
in Figure 24. The consumption categories of four meals, two meals,
and one meal per month are shown as "limited" consumption.
The eight-meal-per-month category is shown as "not restricted."
Table 20 identifies the contaminant or contaminants causing the
consumption restrictions.
In Lake Superior, lake trout in the 55-cm to 65-cm size class
are safe to consume in limited amounts in the western end of the
lake. In the eastern end of the lake, in the open waters from
Sewell Point to Batchawana Bay, as well as in the waters of Thunder
Bay's outer harbour, consumption of 55-cm to 65-cm lake trout
is not advised. The principal contaminant causing these consumption
restrictions is toxaphene. Dioxins are a concern in specific locations,
such as Jackfish Bay, as well (Table 20).
In Lake Huron, 55-cm to 65-cm lake trout are not restricted for
consumption in the North Channel, in the open waters south of
Manitoulin Island, and in Georgian Bay. Where data exist, "limited"
consumption restrictions are in place for lake trout down the
length of the eastern shore of Lake Huron, from Fitzwilliam Island
to north of Grand Bend (blocks H2 and H4 in Figure 24). PCB is
the principal contaminant of concern causing these consumption
restrictions.
In Lake Erie, information on contaminants in lake trout is limited
to the eastern end of the lake. A "limited" consumption
advisory is in place for lake trout from Long Point Bay and in
Lake Erie east of Long Point Bay (Figure 24). Again, PCB is the
contaminant causing the consumption restrictions.
At all locations in Lake Ontario and the Niagara River for which
information is available, a "limited" consumption advisory
is in effect for 55-cm to 65-cm lake trout (Figure 24). PCB is
the principal contaminant of concern causing the consumption advisories,
with levels of mirex and dioxin also of concern in certain locations
(Table 20).
No single species of fish is suitable as an indicator of the warmwater/coolwater
fishery because none are distributed across all locations in the
Great Lakes. Consequently, for the purposes of this paper, smallmouth
bass (30 cm to 35 cm), walleye (35 cm to 45 cm), and yellow perch
(20 cm to 25 cm) were chosen as indicators. Fish from these size
classes were chosen for assessment as being representative of
sizes of fish that would typically be kept and consumed by an
angler.
A summary of the 1995-96 consumption advisories for 30-cm to 35-cm
smallmouth bass, 35-cm to 45-cm walleye, and 20-cm to 25-cm yellow
perch in the Canadian waters of the Great Lakes is given in Figure
25. Where information on more than one of the species is available,
the most restrictive consumption advisory is given. In this figure,
the consumption categories of four meals, two meals, and one meal
per month are shown as "limited" consumption. The eight-meal-per-month
category is shown as "not restricted." Table 20 identifies
the contaminant or contaminants causing the consumption restrictions.
Table 20. Consumption Advisories for Selected Great Lakes Fish
Lake |
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L. Superior | |||||
St. Marys R. |
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L. Huron | |||||
St. Clair R. |
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Lake St. Clair |
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Detroit R. | |||||
L. Erie | |||||
Niagara R. | |||||
L. Ontario | |||||
St. Lawrence R. |
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1Zones refer to Figure 24 and Figure 25.
255-cm to 65-cm lake trout, 30-cm to 35-cm smallmouth bass, 35-cm to 45-cm walleye
320-cm to 25-cm yellow
perch, 35-cm to 45-cm walleye, 30-cm to 35-cm smallmouth bass
Figure 24. Fish Consumption Advisories for Coldwater Species
Figure 25. Fish Consumption Advisories for Warmwater Species
For Lake Superior, information on contaminants in these warmwater/coolwater
indicator species exists for limited sites only. In the waters
around Pie Island, Thunder Bay harbour, Nipigon Bay, and Goulais
Bay, no consumption restrictions are in place for these fish species
at the sizes noted. "Limited" consumption of 35-cm to
45-cm walleye in the waters from Shreiber Point to Sewell Point
is advised. The contaminant of concern causing the consumption
restriction is mercury (Hg).
In Lake Huron, no consumption restrictions on the indicator species
in the sizes noted are in effect for the North Channel, Georgian
Bay, the waters south of Manitoulin Island, or from Grand Bend
to Pt. Edward. Only smallmouth bass in the waters from Stokes
Bay to Point Clark (H3 in Figure 25) have a "limited"
consumption advisory in place. The advisory is due to mercury.
No consumption restrictions are in effect for any of the warmwater/coolwater
indicator fish species/sizes in Lake St. Clair or Lake Erie. A
"limited" consumption advisory is in effect for 20-cm
to 25-cm yellow perch from the upper Detroit River due to PCB.
In Lake Ontario and the St. Lawrence River, there are no consumption
restrictions in effect for any of the warmwater/coolwater indicator
species/sizes, except for 30-cm to 35-cm smallmouth bass caught
in waters east of the Scarborough Bluffs to Colborne (Block 6
in Figure 25). The principal contaminant of concern causing the
consumption restriction is mercury.
Figure 26.Trends in Contaminant Concentrations
Trends in contaminant concentrations vs. time are plotted in Figure
26, focusing in each lake on the contaminants causing the current
consumption restrictions in the coldwater and warmwater indicator
species. Data plotted are mean measured concentrations of a contaminant
for a given species across all size classes collected in a specific
location vs. year of collection.
Trend information on toxaphene in Lake Superior lake trout is
limited, with four observations from 1986 to 1992. No temporal
trend can be identified from this information. No information
is available to identify trends in mercury, the principal contaminant
of concern in the warmwater indicator species.
Concentrations of PCBs in lake trout from southern Lake Huron
declined from 2.6 ppm in 1976 to 0.67 ppm in 1994. Mean mercury
levels in walleye in southern Lake Huron varied from 0.26 to 0.47
ppm over the period 1981 to 1992 but show no trend vs. time.
No trend information is available for the contaminant of concern
(PCB) in either the coldwater or warmwater indicator species for
Lake St. Clair or Lake Erie.
In Lake Ontario, good long-term trend information is available
for both PCB and mirex in rainbow trout at the Ganaraska River.
In both cases, concentrations declined between 1976 and the middle
to late 1980s and have shown no clear trend since then. PCBs declined
from 3.9 ppm in 1976 to 0.65 ppm in 1994, and mirex concentrations
dropped from 0.26 ppm in 1976 to 0.06 ppm in 1994. Mean mercury
concentrations in walleye in eastern Lake Ontario varied between
0.19 ppm and 0.43 ppm over the period 1981 to 1994, with no clear
trend over time.
In the United States, most Great Lakes states have been monitoring
contaminants in fish and issuing fish consumption advisories since
the middle 1970s. At one time, the FDA (Food and Drug Administration)
action levels were the most common criteria by which the advisories
were issued. As programs expanded and risk analysis became more
common, the states began to re-evaluate their advisory criteria
and, at times, to deviate from the FDA-action-level approach.
Because of the differences among states in criteria for issuing
advice (Table 21), the states created a group known as the Great
Lakes Fish Advisory Task Force. This group, which comprised health
and environmental officials from each of the Great Lakes states,
was charged with creating a uniform fish advisory protocol for
the region. The group delivered a proposed protocol to the Council
of Great Lakes Governors in September 1993. The protocol has undergone
considerable debate since that time. Minnesota and Indiana have
adopted the protocol for their Great Lakes waters, and Ohio has
adopted a version of the protocol. The other five states continue
to debate the issue.
Polychlorinated biphenyls (PCBs) are by far the most common reason
for the issuance of advisories for U.S. Great Lakes fish. Several
states have also issued advisories for other contaminants, including
chlordane, dioxin, and mirex.
The advisories have changed with time, so that an exact basinwide
accounting is not available. But more sites and species have probably
been added to the fish advisories over the years than have been
taken off. For example, Wisconsin has not removed any sites from
the advisory; Michigan has removed some but added others-particularly
near harbours or tributaries where contaminant concentrations
are higher than in the associated lake as a whole. Indeed, if
there has been an increase in the listings, it probably reflects
more intensive monitoring over time rather than further degradation
of the environment. The 80 percent decrease in contaminant levels
(primarily PCBs) observed in Great Lakes fish since 1980 supports
this interpretation.
New York |
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Pennsylvania |
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Ohio | |||||||||
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Indiana | |||||||||
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Illinois | |||||||||
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Michigan |
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Wisconsin |
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Minnesota |
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Ontario |
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Table 21 (continued): Summary of Existing Sport Fish Consumption
Advisory Programs and Criteria Related to the Great Lakes Basin,
1989
New York | Pamphlet, fishing guide, news release | Yearly, May-June |
Will issue mid-year advisories if significant conditions are detected; "significant" not defined. Start reviewing data in January for April deadline. | ||
Pennsylvania | News releases |
No specific date | Interagency agreement between DOH, DER, Fishery Commission; no designated budget for fish monitoring. Uses composite samples of skin-on fillets rather than individual fillets. | ||
Ohio | News Releases |
Site-specific, when data available | Interagency fish tissue monitoring group, no ongoing monitoring program for health considerations. Uses composite samples of skin-on fillets rather than individual fillets. | ||
Indiana | Pamphlet, fishing guide | Yearly, March-April | Yearly sampling, but not of all waters. | ||
Illinois | Pamphlet, fishing guide | Yearly | Interagency agreement within Illinois; now coordinating with states to south and southwest. Uses composite samples of skin-on fillets rather than individual fillets. Half of Mississippi River stations collected every year. | ||
Michigan | Fishing guide, news releases | Yearly, late January | Interagency agreement between MDPH, MDA, MDNR; draft policy awaiting Great Lakes Fish Advisory Task Force [[POST: Please double-check my addition of "Fish Advisory" here. Draft had "G.L. Task Force"; I queried, but MNC answered only "I guess-add." Might be best to be sure.]] decisions. | ||
Wisconsin | Pamphlet, news releases, fishing guide | Twice yearly, April and October | Has not released an advisory since April 1994, pending a decision regarding Great Lakes protocol. | ||
Minnesota | Fishing guide, news releases, booklet | Every two years |
Interagency program. Analyses routinely only for Hg, PCB, and TCDD. Uses composite samples of skin-on fillets rather than individual fillets. | ||
Ontario | Large guidebook, news releases, bulletins | Yearly, May | Sample type different from other jurisdictions-uses a skinless dorsal section of the fillet, rather than untrimmed skin-on fillets. |
SOURCES: After Hesse 1990; updated in 1996 by J.
Amrhein, Wisconsin DNR.
a N.A. = Not Applicable
b AL = Action Level
c If several contaminants present just below guideline threshold, list species.
d LOD = Analytical
level of detection (value in parentheses, when specified, applies
to row).
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