Seafood Safety (1991) / Chapter Skim
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5. Occurence of Chemical Contaminants in Seafood and Variability of Contaminant Levels
5. Occurence of Chemical Contaminants in Seafood and Variability of Contaminant Levels
Pages 111-171
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From page 111... ...
The variability of contaminant concentrations among geographic areas is important because it indicates the potential for reduction of exposure through restrictions on the harvesting of aquatic organisms from specific sites. Based on analyses of data for inshore marine waters, for the most variable contaminants/sets of species, it would be possible theoretically to reduce the population dosage delivered by more than 50% by restricting harvesting/marketing from only the 5% most intensely contaminated sites.
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From page 112... ...
Both this chapter and the next deal with aspects of chemical residues in aquatic organisms. In this chapter the committee focuses on the tasks that are usually thought of as part of the hazard identification portion of a quantitative chemical health risk assessment.
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From page 113... ...
Then, a focused examination is provided of available Food and Drug Administration (FDA) risk assessment and risk management analyses for two types of residues-one a set of organic carcinogens, polychlorinated biphenyls (PCBs)
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From page 114... ...
Antimony has been recognized as both an occupational and an iatrogenic toxicant (Anonymous, 1988a,b; Groth et al., 1986~. Recent seafood residue studies, however, either have failed to sample for this metal or indicate concentrations above detectable levels in few contaminated sites (Lowe et al., 1985; NOAA, 1987~.
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From page 115... ...
Its ability to stimulate metallothioneine production in aquatic animals, however, does much to decrease its toxicity (Viarengo, 1985~. Cadmium has been responsible for major human poisoning incidents as a contaminant of wastewater used for irrigation in Japan where the illness is known as itai-itai (ouch-ouch)
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From page 116... ...
Sources of lead found in the environment are multiple, and the metal is truly ubiquitous, being commonly found in food, water, and air. Evidence exists that lead in the environment has increased during the past 200 years, and it is not surprising that it can be found as a contaminant of aquatic animals (Shukla and Leland, 1973~.
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From page 117... ...
Selenium levels in water from seleniferous areas are often quite high so it is not surprising that selenium has been found as a contaminant of fresh and marine aquatic animals. Its source however is not solely natural.
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From page 118... ...
The carboxylic acid herbicide 2,4(dichlorophenoxy~acetic acid (2,4-D) has been found in oysters from the northern Chesapeake Bay and Alaskan bivalves (NOAA, 1988~.
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From page 119... ...
The selection for relatively persistent congeners in aquatic organisms might tend to increase human risk relative to that expected from a naive extrapolation; other factors might have the opposite effect. In any event, the numbers of cases that could be expected seem large enough to warrant exploration of further options for risk reduction.
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From page 120... ...
lipophilic substances of uncertain health significance in humans, and are among the most widespread and frequently sampled of the chlorinated hydrocarbons. They are also persistent in ecosystems and bioaccumulate at higher levels of the food chain, resulting in toxicity to birds and aquatic organisms.
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From page 121... ...
water quality treatments (copper compounds)
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From page 122... ...
Such chemotherapeutic drugs include, but are not limited to, the potentiated sulfonamides, antibiotics, and nitrofurans. Their widespread use, both nationally and especially internationally, may pose a threat to human health if residues persist in the edible portions of fish and shellfish.
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From page 123... ...
Chloramphenicol administered for long periods may cause blood dyscrasias such as aplastic anemia and has recently been incriminated as a carcinogen. It is not approved for use in the United States in food producing animals.
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From page 124... ...
Conclusions 1. Certain drugs with potential toxicity to humans are used to control disease in cultured food producing aquatic animals.
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From page 125... ...
This has been shown to impart a residual sulfite level of less than 100 ppm on the edible portion of penacid shrimp.6 Product treated in this way must be labeled to designate prior use and residuals in excess of 10 ppm. General concern for allergic-like reactions, particularly in some asthmatic people, has given rise to concern about the continued use and appropriate labeling of sulfites (Lecos, 1985~.
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From page 126... ...
to determine toxic contaminants as a basis for the identification of potential geographic differences (Mussel Watch, Tier 1~; 2. to identify areas where environmental quality may be significantly compromised (Mussel Watch)
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From page 127... ...
Most important, the NOAA Quality Assurance Program used by NS&T establishes analytical protocols that ensure reliability of data. It is unfortunate, from the point of view of human exposure assessment, that the NS&T program examines fish liver samples rather than edible portions.
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From page 128... ...
Arsenic (As) National Status and Trends data for shellfish residues are summarized in Table · Mean levels: Descriptive statistics of all NS&T shellfish data are presented in Table 5-1 and Figure 5-1.7 The arithmetic grand mean arsenic levels of all bivalves
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From page 129... ...
129 o c4 ~ o o o tl tl o Vie _.
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From page 130... ...
The arithmetic grand mean level for cadmium of all bivalves from the 25 most contaminated sites reported in the 1986 Mussel Watch Survey is 0.9039 ppm wet weight with a standard deviation of 0.2621 and a range of 0.6276-1.560 ppm (using a dry weight/wet weight conversion factor of 0.12~. Eight of the most
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From page 131... ...
The arithmetic grand mean lead level of all bivalves from the 25 most contaminated sites reported in the 1986 Mussel Watch Survey is 0.8203 ppm wet weight with a standard deviation of 0.5684 and a range of 0.3804-2.799 ppm (using a dry weight/wet weight conversion factor of 0.12~. Eight of the most contaminated sites (0.7356-2.7996 ppm wet weight)
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From page 132... ...
The arithmetic grand mean mercury level of all bivalves from the 25 most contaminated sites reported in the 1986 Mussel Watch Survey is 0.0351 ppm wet weight with a standard deviation of 0.0084 and a range of 0.02760.0576 ppm (using a dry weight/wet weight conversion factor of 0.12~; 7 of the most contaminated sites (0.0372-0.0576 ppm wet weight) exceed the 95th percentile (0.0363~.
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From page 133... ...
· Mean levels: Descriptive statistics of all NS&T shellfish data are presented in Table 5-1 and Figure 5-5. The arithmetic grand mean selenium level of all bivalves from the 25 most contaminated sites reported in the 1986 Mussel Watch Survey is 0.5145 ppm wet weight with a standard deviation of 0.1391 and a range of 0.39960.9800 ppm (using a dry weight/wet weight conversion factor of 0.124; 8 of the most contaminated sites (0.5364-0.9804 ppm)
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From page 134... ...
For bivalve molluscs, the most contaminated sites are located along the Northeast coast and in southern California harbors. The grand national median for PCBs calibrated against the commercial mixture Aroclor 12428 in the 1976 Mussel Watch SuIvey at 86 sites was 0.009 ppm wet weight with a range of 0.0008-2.09 ppm.
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From page 135... ...
The median of the arithmetic grand means of all bivalves from the 25 most contaminated sites reported in the 1986 Mussel Watch Survey is 0.1287 ppm wet weight (range 0.0728-0.8169~. The national grand median for total polychlorinated biphenyls (tPCBs)
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From page 136... ...
Descriptive statistics of all the NS&T shellfish data are presented in Table 51 and Figure 5-7. The arithmetic grand mean of PAH levels of all bivalves from the 25 most contaminated sites reported in the 1986 Mussel Watch Survey is 0.6471 ppm wet weight with a standard deviation of 0.6458 (range 0.2400-2.760 ppm)
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From page 137... ...
The arithmetic grand mean of all bivalves from the 25 most contaminated sites reported in the 1986 Mussel Watch Survey is 0.0365 ppm wet weight with a standard deviation of 0.0353 (range 0.0570-0.1330 ppm) using a dry weight/wet weight conversion factor of 0.12.
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From page 138... ...
Heptachlor and heptachlor epoxide: Heptachlor and heptachlor epoxide did not occur above the O.O1-ppm wet weight detection limit in any of more than 8,000 shellfish samples analyzed between 1965 and 1977 during the NPMP. Endosulfan: Endosulfan may be a problem contaminant in estuaries near agricultural drainage areas (NOAA, 1988~.
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From page 139... ...
The arithmetic median of the grand means of arsenic in marine fish livers from the 10 most contaminated sites reported in the 1986 NOAA NS&T is 4.80 ppm wet weight.
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From page 140... ...
· 3 3 _' s ._ Ha lo: Cal c _ CL .
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From page 141... ...
The arithmetic median of the grand means of cadmium in marine fish livers from the 10 most contaminated sites reported in the 1986 NOAA NS&T is 1.310 ppm wet weight. The 1986 NS&T grand median for fish livers from all sites (45)
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From page 142... ...
The arithmetic median of the grand means of lead in marine fish livers from the 10 most contaminated sites reported in the 1986 NS&T is 0.230 ppm wet weight. The 1986 NS&T grand median for fish livers from all sites (43)
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From page 143... ...
The arithmetic median of the grand means of mercury in marine fish livers from the 10 most contaminated sites reported in the 1986 NS&T is 0.1700 ppm wet weight. The 1986 NS&T grand median for fish livers from all sites (43)
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From page 144... ...
Sites producing the highest mean concentrations were the New York Bight Apex (1.1 ppm wet weight) and East Bay, near Panama City, Florida (0.42 ppm wet weight)
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From page 145... ...
3-2.53 ppm. The arithmetic grand mean level of PCBs in marine fish livers from the 10 most contaminated sites reported in the 1986 NS&T is 1.90 ppm wet weight with a standard deviation of 0.90 and a range of 0.933-3.97 ppm wet weight.
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From page 146... ...
The arithmetic median of the grand means of tDDT in marine fish livers from the 10 most contaminated sites reported in the 1986 NS&T is 0.441 ppm wet weight. The 1986 NS&T grand median for fish livers from all sites (48)
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From page 147... ...
Dieldrin was a common contaminant in the 1984 NS&T Benthic Surveillance fish liver surrey, occurring in fish livers in some sites at concentrations above 0.001 ppm wet weight. The range was less than 0.001 to a high of 0.104 ppm wet weight in liver of winter flounder from a site in Salem Harbor, Massachusetts (NOAA, 1989~.
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From page 148... ...
Lindane was detected in 44% of 64 California Mussel Watch samples in 1980-1981 through 1985-1986 surveys; most of these were from San Francisco Bay and the Los Angeles area, at concentrations slightly exceeding 0.001 ppm wet weight. However, in inland waters, lindane was documented in 16% of the 1980-1981 NPMP fish samples at concentrations exceeding 0.01 ppm wet weight.
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From page 149... ...
It was detected at concentrations above 0.01 ppm wet weight in 24% of the samples of whole fish from the 1980-1981 inland NPMP freshwater fish survey. The highest concentrations of 0.120.13 ppm wet weight occurred in whole fish from the Tombigbee River, Alabama and from the Mississippi River at a site in Louisiana.
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From page 150... ...
Where adequate data are available, it appears that the distribution of contaminant levels is reasonably well described as lognormal in most cases. POTENTIAL OPPORTUNITIES FOR REDUCING EXPOSURES Without prejudging the need for additional controls on specific contaminant residues, it is reasonable to use the observations of contaminant variability derived in the previous sections to draw some preliminary inferences about the potential of different kinds of control measures to reduce seafood contaminant exposures in the United States.
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From page 151... ...
The basic concept is that the more variability there is in contaminant levels associated with geography or size, the greater is the potential for economically reducing population dosage by using those variables to control harvesting and marketing. The advisability of expanded consumer information programs to inform people of the residual risks of different kinds of seafood products, especially people with unusual exposures (e.g., freshwater sport fishers and their families)
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From page 152... ...
For the most variable contaminants/sets of species, it would be theoretically possible to reduce the population dosage delivered by more than 50% through restricting harvesting/marketing from only 5% of the most intensely contaminated sites. For other cases, restrictions on slightly more than 10% of the sites would be required to achieve this goal.
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From page 153... ...
Bivalves Portions Bivalves Bivalves Portions 1 3.3 4.8 11.5 5.4 2.6 1 13.7 14.0 28.4 13.7 28.7 2 20.8 21.1 38.6 20.8 38.9 5 33.7 34.2 54.2 33.8 54.5 10 47.8 48.4 68.1 48.0 68.4 20 65.1 65.6 81.9 65.2 82.1 Site-to-site geometric standard deviation 3.40 3.44 5.75 3.41 5.79 Ratio arithmetic/ geometric mean 2.11 2.14 4.61 2.12 4.67 a Percentage of total population dosage contributed by highest NO if sites of equal contributions to diet are assumed from each site. b Based on concentrations in bivalves, NS&T data (NOAA, 1989~.
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From page 154... ...
An association between fish size and mercury concentration can be seen in Figure 5-11, although there is quite a bit of scatter in the results for individual fish. Unfortunately, when the fish are arranged in size classes to determine the cumulative population dose reduction that could be achieved by restricting ha~vesting/marketing of the biggest fish, the prospects for appreciably reducing population mercury dosage by modest size restrictions appear dim.
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From page 155... ...
/safety factor approach to derive an "acceptable daily intake," based on the cancer findings in the two-year rodent feeding study of Kociba et al.
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From page 156... ...
7. The Z-score in Figure 5-1 is simply the number of standard deviations above or below the midpoint of a standard normal or lognormal distribution, inferred from the rank of a specific individual in a data set.
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From page 157... ...
or organ burden 3. Steady daily intake for toxicity (acute/chronic)
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From page 158... ...
Uncertain for seafood Not reported Steady Daily Intake for Toxicity (mg/ day) Uncertain for seafood 35 Human HalfLife a Blood LOAELb <20 h Cadmium Lead 429 Mercury 0.23 25 Selenium Uncertain for Not reported seafood Uncertain for seafood Three phases Uncertain poor <200 d, +20 d, monitor 10-30 yr Three phases 3-4 weeks, 5-30 yr 70-110 d 1 00-400 Uncertain 0.003 (acute)
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From page 159... ...
Age, Sex, Reproductive Status, and Intenndividual Vanabilitry: No response differences in age, sex, or reproductive status have been reported. Interindividual variability for the effects recorded may be large.
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From page 160... ...
Toxic Body or Organ Burden: No information is available for fish arsenic. Steady Daily Intake for Toxicity: Inorganic arsenic intake in children of 1.3-3.6 mg results in lesions in 33 days (subacute)
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From page 161... ...
Reports concerning dose-response are conflicting for similar effects, and a wide range of interindividual variability is apparent. Half-life: The half-life is 5 years to decades for bones, depending on type and location.
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From page 162... ...
Toxic Body Burden: The body burden that would be toxic to a 70-kg individual is 100400 ma. Steady Daily Intake for Toxicity: The daily intake that would lead to toxicity is uncertain.
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From page 163... ...
Toxic Body Burden: The toxic body burden for a 70-kg individual is calculated to be 25 ma. Steady Daily Intake for Toxicity: The acute daily intake level is 300 jug; the chronic level is uncertain.
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From page 164... ...
Toxic Body Burden: No information is available. Steady Daily Intake for Toxicity: It has been estimated that 1 mg of selenium daily, as the selenite, would be toxic (Yang et al., 1983~.
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From page 165... ...
1982. Risk assessment in a federal regulatory agency: An assessment of risk associated with the human consumption of some species of fish contaminated with polychlorinated biphenyls (PCBs)
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From page 166... ...
1983. Survey of polychlorinated biphenyls in selected finf~sh species from United States coastal waters.
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From page 167... ...
1978. National Marine Fisheries Service Survey of Trace Elements in the Fishery Resource.
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From page 168... ...
1985. National contaminant biomonitoring program: Concentrations of seven elements in freshwater fish, 1978-1981.
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From page 169... ...
of the mussel watch project. Progress Report.
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From page 170... ...
1983. Organochlorine residues in freshwater fish, 1976-1979.
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From page 171... ...
1976. National Marine Fisheries Service preliminary survey of selected seafoods for mercury, lead, cadmium, chromium and arsenic content.
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