Seafood Safety (1991) / Chapter Skim
Currently Skimming:
6. Chemical Health Risk Assessment - Critique of Existing Practices and Suggestions for Improvement
6. Chemical Health Risk Assessment - Critique of Existing Practices and Suggestions for Improvement
Pages 172-266
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 172... ...
Estimates are made of national average daily intakes of various inorganic and organic contaminants via commercially marketed seafood, and for several organic carcinogens, upper-confidence-limit estimates of possible cancer risk are made. However, aside from the methylmercury example, in the absence of better information on the population distribution of the dosage of contaminants to the U.S.
|
From page 173... ...
· Existing FDA and state regulations should be strengthened and enforced to reduce the human consumption of aquatic organisms with relatively high contaminant levels (e.g., certain species from the Great Lakes with high levels of PCBs, swordfish and other species with high methylmercury levels)
|
From page 174... ...
. However, as more is learned about the mechanisms of some other types of toxic effects - particularly reproductive effects and chronic degenerative neurological conditions (NRC, 1989, 1990-concern about potential low-dose effects of other Apes has tended to increase.
|
From page 175... ...
On the other hand, if thousands, millions, or billions of individual irreversible events directly contribute to a particular condition (e.g., very large numbers of individual neurons must die to cause the clinical manifestations of Alzheimer's or Parkinson's disease) , the biological harm should be dealt with under the novel category of chronic cumulative conditions (see below)
|
From page 176... ...
i'safety factor" analysis for arriving at acceptable daily intake (ADI) levels for chemical contaminants.
|
From page 177... ...
4. There is no defined or obvious way to incorporate newer types of relevant data on human interindividual differences in · rates of uptake/absorption for a constant environmental exposure ("exposure variability"; · rates of activating or detoxifying metabolism and excretion, producing differences in the concentration x time of active metabolites per unit of absorbed dose at the site of toxic action ("pharmacokinetic variability"; and differential risk of response ("response variability")
|
From page 178... ...
For example, a key functional intermediate for some reproductive effects of PCBs may well be changes in birth weights (rein et al., 1984; Jacobson et al., 1985; Sunahara et al., 1987; Taylor et al., 1989~. Similarly, blood or tissue concentrations of lead constitute a useful intermediate parameter for lead toxicity.
|
From page 179... ...
Population Weight Births in Birth Weight Birth Weight Change Reduction Category Reduction Reduction White Infants Under 500 0.0006912 0.0007701 1,000 0.6912 0.7701 0.0789 500-999 0.002171 0.002335 673.31 1.4612 1.5720 0.1107 1,000-1,499 0.005249 0.005488 237.85 1.2485 1.3053 0.0568 1,500-1,999 0.009182 0.009575 76.86 0.7057 0.7360 0.0302 2,000-2,499 0.029192 0.032804 26.746 0.7808 0.8774 0.0966 2,500-2,999 0.15164 0.16568 8.3565 1.2672 1.3845 0.1174 3,000-3,499 0.36237 0.37081 4.2566 1.5424 1.5784 0.0359 3,500-3,999 0.31749 0.30337 3.0451 0.9668 0.9238 0.0430 4,000-4,499 0.10100 0.09027 3.0293 0.3060 0.2734 0.0325 4,500+ 0.021021 0.01890 4.941 0.1039 0.0934 0.0105 Total 1 1 9.0736 9.5142 0.4406 Black Infants Under 500 0.0026095 0.0028661 1,000 2.6095 2.8661 0.2566 500-999 0.006279 0.006666 645.90 4.0558 4.3058 0.2500 1,000-1,499 0.012709 0.013154 167.98 2.1348 2.2096 0.0748 1,500-1,999 0.020673 0.02165 57.72 1.1932 1.2495 0.0563 2,000-2,499 0.067052 0.074351 21.482 1.4404 1.5972 0.1568 2,500-2,999 0.24894 0.26444 9.832 2.4476 2.6000 0.1524 3,000-3,499 0.38248 0.37936 6.636 2.5381 2.5174 0.0207 3,501) -3,999 0.20683 0.19100 5.581 1.1543 1.0660 0.0883 4,000-4,499 0.04418 0.04029 5.89 0.2602 0.2373 0.0229 4,500+ 0.008253 0.006226 12.33 0.1018 0.0768 0.0250 Total 1 1 17.9358 18.7257 0.7899 In principle, the use of such intermediate parameters can provide windows on the pathological processes that occur earlier in the development of toxicity, are more sensitive to the action of potential toxicants (compared with attempts to observe actual cases of illness)
|
From page 180... ...
, and if the biological parameter being perturbed is limiting to the performance of that function, then any level of exposure may produce at least some reduction in performance. Addressing the issues of the population distribution of different functional reserve capacities, and the relationship of functional reserve capacities to specific biochemical parameters, is essential to the future research needs of risk assessment for classical chronic toxic agents.
|
From page 181... ...
Clearly, to make real progress in modeling carcinogenic risks, knowledge of the fundamental processes involved must be used to break open the black box between external exposure levels and ultimate production of tumors. The use of pharmacokinetic models and intermediate parameters ("markers")
|
From page 182... ...
. At low doses the number of resident cellular reactant molecules does not change appreciably as a function of the concentration of the input.
|
From page 183... ...
. Changes in the frequency with which initiated cells are effectively removed by terminal differentiation [e.g., effects of early and multiple pregnancies in reducing later breast cancer risk (Kampert et al., 1988; Layde et al., 1989; Moolgavkar et al., 1980~.
|
From page 184... ...
describe the relationships between the numbers, types, and physical distribution of individual damage events and the loss of biological function or clinical illness. Unfortunately, no examples are known in which there has been successful quantitative modeling of any of these three types for any chronic cumulative condition.
|
From page 185... ...
suggested that methylmercury might accelerate the loss of neurons in adult life and contribute to a "chronic cumulative" process that would fall within this category. Recently, an apparently very sound case control epidemiological study among people in Singapore found a strong association
|
From page 186... ...
Perhaps in part because of the difference in cancer potency factors, there is also a great difference in the practical policies of the two agencies in regulating PCBs, with FDA generally taking a far less protective posture toward PCB exposure than EPA.6 Methylmercury is also of special interest because it shows the operation of the old no-effect level/safety factor paradigm in a practical case where, as it happens, an alternative type of quantitative assessment is also possible based on existing data. In this case, therefore, one can examine what levels of risk might implicitly be accepted by using FDA's rule-of-thumb procedure for dealing with noncancer effects.
|
From page 187... ...
consumers, and without a quantitative treatment of the effects of pharmacokinetic differences among people that would tend to make blood levels and risks as a function of dietary intake more variable than blood levels themselves.
|
From page 188... ...
The analysis in the following section indicates that the apparent interindividual variability in susceptibility for fetal effects is much broader than that for adult effects. Consequently, although the tenfold safety factor, as applied, appears to offer a reasonable degree of protection for adult effects, projections based on an additional toxicological assumption of lognormal distribution of threshold for effects (logprobit projections)
|
From page 189... ...
that are the concerns at low doses. Carcinogenic risks are traditionally studied in human populations by case control studies and detailed comparisons of the frequency of specific cancers or cancer deaths in defined cohorts, adjusted for age.
|
From page 190... ...
, it was surprised to find that FDA had actually calculated a series of aggregate estimates of economic costs incurred and cancer cases prevented by going to different standard This analysis appears to have been done in part to satisfy requirements for a balancing analysis of benefits and costs that became a governmentwide requirement for regulatory action in the mid-1970s. For this purpose, however, the calculation of societal aggregate cancer risks from 90th percentile values of consumption for fish consumers is problematic because, of course, the 90th percentile overstates the average.
|
From page 191... ...
5 600,000 2 5,700,000 5,100,000 410,000 1 16,700,000 10,300,000 770,000 a Upper confidence limit. The numbers in this column imply a low-dose cancer potency of about 0.34 cancer case per lifetime average mg/kg/day exposure.
|
From page 192... ...
The numbers in this column are based on a low-dose cancer potency of 0.34 cancer case per lifetime average mg/kg/day exposure.
|
From page 193... ...
of 0.15 m/day (for 45-year, 240-day/year ~ rib -- — r -- r -- ~ -- - - ~ ~ , ~ ~ occupational exposures. This translates into the equivalent of a best-estimate cancer potency factor of 3.9 cases per lifetime mg/kg/day dosage-rather closer to the EPA upper confidence limit estimate of 7.7 than to the FDA estimate of 0.34 case per lifetime mg/kg/day.
|
From page 194... ...
In at least one case, there are measurements of serum PCB levels in the exposed group.] Harold Humphrey of the Michigan Department of Health reportedly has an extensive data set of PCB concentrations in blood in relation to dietary exposure levels.
|
From page 195... ...
.~2 Using such a distribution, if one had an estimate of cancer risk per unit of plasma PCB concentration, an inference could be made not only about the average risk to the population, but about the distribution of risk to various individuals that derives from differences in both dietary habits and PCB elimination rates. Plasma and whole body burden PCB levels could also be productively used as indicators of longterm dosage in epidemiological case control studies of cancer patients (versus other people)
|
From page 196... ...
that the lowest blood mercury level associated with toxic effects was 220 ppb marts per billion] and the lowest hair mercury level associated with toxic effects was 50 ppm (Berglund et al., 1971~.
|
From page 197... ...
Some portion of that human interindividual variability, however, occurs in characteristics that affect individual blood levels-especially individual half-lives for elimination of methylmercury from the body. For those with relatively slow elimination rates, toxicity would be expected to be associated with lower average dietary intakes than for those with average elimination rates.
|
From page 198... ...
198 SEAFOOD SAFETY TABLE 6-10 Biological Half-Lives for Individuals Reported by Al-Shahristani and Shihab (1974) Half-Life (days)
|
From page 199... ...
of one-month diary reports of consumption of different types of fish by 7,662 families, including 25,165 people, and measurements of mercury levels in different species of fish. However, instead of using these data to describe the population distribution of monthly mercury intakes from fish as a whole and the possible effects of different tolerances, Tollefson and Cordle (1986)
|
From page 200... ...
study, i.e. 17 g per day with a mercury residue of 1.5 ppm, the same individual consumed the average daily amounts of tuna, halibut, and salmon at the present average residue levels of mercury for each of the three species, then the total daily intake of mercury from all four species would average 31.7 fig, only 1.7 fig above the ADI.
|
From page 201... ...
. The degree of interindividual variability (the slope of the lines; the shallower the slope, the greater is the variability)
|
From page 202... ...
, . , -0.8 -0.4 0.0 0.4 0.8 1.2 1.6 2.0 z-score FIGURE 6-4 Lognormal plot of whole blood methylmercury levels in South Haven 1.0 _ 0.80.6 0.4 o ~ 0.2,~ Jppo-~r I' IS y = 0.3580 + 0.2958x ~E' R = 0.991 0.0- ., .
|
From page 203... ...
It can be seen that the logo probit slopes for the five different fetal mercury effects range from 0.66 to 1.5 (the logo probit slope is the number of standard deviations of the population distribution of effect thresholds per 10-fold change in dose, smaller numbers indicated a broader lognormal distribution of thresholds)
|
From page 205... ...
1.6 1.8 2.0 2.2 2.4 2.6 2.8 log (ppm Hg Hair) FIGURE 6-9 Logprobit dose-response relationship for "mental symptoms" in children in relation to maternal hair mercury (data of Marsh et al., 1987)
|
From page 206... ...
206 .= o o s ho A: ._ ;^ Ct Ct V)
|
From page 207... ...
1 2 log (ppm Hg Hair) 3 FIGURE 6-11 Logprobit dose-response relationship for adverse neurological scores in children in relation to maternal hair mercury (data of Marsh et al., 1987)
|
From page 209... ...
_ . ~ .= 5.8- hi/ v: 5 6 - / i, 5.2- / ~ ~ y - - 0.8380 + 1.911x 4.6 2.8 3.0 3.2 3.4 3.6 log (ppb Blood Hg)
|
From page 210... ...
x . c~ 3 3.3 3.4 3.5 3.6 3.7 y= -19.88+6.942x R= 0.993 SEAFOOD SAFETY log (ppb Blood Hg)
|
From page 211... ...
procedure suggests somewhat larger probit slopes than the values determined by simple regression analysis of the points. It can also be seen that, in comparison with the fetal effects, the effects in adults tend to have larger probit slopes, indicating less interindividual variability and therefore less risk at low doses.
|
From page 213... ...
. It can be seen in Tables 6-16A and B that although a 10-fold reduction in blood level from the presumed adult LOEL is expected to reduce the incidence of adult effects to quite low rates, the greater interindividual variability associated with fetal effects suggests the possibility that very significant fetal risks may remain.
|
From page 215... ...
215 A: o C~ en V, Ct o ; .
|
From page 217... ...
217 Ct o :s a; s s ~: Ed o Ct s o ~ o o m ~ en _ ~ C)
|
From page 218... ...
(1989) Logit Probit Model Risk Maternal Hair Assumed Blood Model Risk Estimates Estimates (Table 6-16b)
|
From page 219... ...
In particular, to facilitate evaluation of the costs and benefits of measures to achieve quantitative reductions in exposure to carcinogenic inadvertent contaminants, procedures should be developed to supplement current "upper-confidence-limit" cancer potency estimates with estimates representing the central tendency of cancer risks, information on cancer risks from all available species, and comparative information on the pharmacokinetic and pharmacodynamic factors in different species. The FDA is most conspicuously backward in the development of quantitative risk assessment approaches for noncarcinogens.
|
From page 220... ...
220 _` o O test ~ V)
|
From page 221... ...
221 ct A; v' an s ce ct c' _ £ £ =: ~ ._ ~ 0 _ ~ m £ If, s ° ~ m v, .' O In 0 ._ _ 0 c: ~ £ m' ._ ce ~ 3 _% C)
|
From page 222... ...
The principal objective of the Total Diet Study is to develop dietary intake information on industrial chemicals and pesticides and to compare these intakes with acceptable daily intakes (ADIs)
|
From page 223... ...
Data from the Total Diet Study are presented later in this chapter. FDA Pesticide Monitoring Files The committee's use of FDA pesticide monitoring files is discussed at length in exposures from commercial seafood.
|
From page 224... ...
There are basic problems with FDA data. Among them are high detection limits for chemicals of concern, lack of monitoring for industrial pollutants such as PCBs and pesticides in interstate-trafficked bivalves, and lack of monitoring for inorganic contaminants such as arsenic, cadmium, and lead in edible portions of finfish.
|
From page 225... ...
These data, however, were not extensive enough to allow national estimates of exposure to be developed via this route. Exposures from Commercial Seafood Dietary Intake of Seafood of Various Species Perhaps one of the most crucial tasks that the committee faced in determining the efficacy of present programs to protect the public health with regard to industrial chemicals and pesticides was determination of the daily dietary intake of specific commercial seafood species.
|
From page 226... ...
per capita seafood consumption are cod, flounder, tuna, salmon, clams, shrimp, groundfish, and aquatic finfish species from two groupings of miscellaneous fish known as "other marine finfish" and "other freshwater finfish." Inorganic Contaminant Exposures and Suggested Acceptable Intake This section employs some of the best available data for estimating seafoodrelated exposure to inorganic contaminants and compares the indicated national average intakes via commercially marketed seafood with ADIs and related regulatory levels. This comparison provides a very broad indication of potential risk but is potentially misleading because the variability in exposures to different contaminants, and the variability of contaminant exposures from other nonseafood and noncommercial seafood sources, cannot be estimated from the available data.
|
From page 227... ...
a Alewives 20,541 Anchovies 12,857 1 Bluefish 15,226 0.43 0.027 Bonito 11,420 0.43 0.020 Butterfish 10,315 0.38 0.004 Cod 229,711 0.5 0.305 Croaker 11,() 44 0.5 0.023 Cusk 3,064 0.5 0.006 Flounder 199,711 0.45 0.373 Grouper 9,494 0.5 0.002 Hake 56,696 Not given 0.117 Halibut 76,107 0.45 0.116 Herring, sea 207,134b,C 0.59 Jack mackerel 26,671 0.59 0.047 Lingcod 7,027 0.5 0.015 Mackerel 115,103 0.45 0.202 Mullet 30,125 0.5 0.057 Ocean perch 24,184 0.38 0.027 Pollock 597,693 0.5 1.116 Rockfish 117,881 0.5 0.244 Sablefish 102,698 0.5 0.126 Salmon 562,018 0.5 0.510 Scup or porgy 14,295 0.38 0.022 Sea bass 5,083 0.5 0.011 Sea trout 21,871 0.5 0.045 Shark 21,832 0.4 0.036 Snapper 8,908 0.42 0.015 Striped bass 431 0.5 0.001 Swordfish 9,761 0.5 0.016 Tilefish 7,950 0.5 0.016 Tuna 593,444 0.45 1.104 Whiting 34,673 0.45 0.044 Other marine finfish 199,795 0.5 0.376 Other freshwater finfish 117,880 0.5 0.244 Clams 134,357 1.0 0.550 Crabs 386,368 0.183 0.270 Lobsters 51,313 0.22 0.044 Oysters 39,807 1.0 0.164 Scallops 40,773 1 0.165 Shrimp 363,142 0.49 0.657 Squid 82,049 c 0.6 0.151 Other shellfish 89,702 0.4 0.116 Total 4,655,826 7.362 a The numbers in this column are not in all cases equal to the product of the previous two columns because of adjustments for exports and year-to-year inventory changes.
|
From page 228... ...
U.S. Average Annual Per Capita Consumption (lb)
|
From page 229... ...
In contrast to the values quoted in Table 6-22, these suggested levels apply to all foods, not just seafood. Below are a number of comparisons of possible intake rates with these numbers: · The last column of Table 6-23 shows the committee's estimate of what the average daily intake of each element would be if a consumer were to eat 15 pounds of seafood per year at the weighted average concentration observed in a massive (more than 200,000 measurements)
|
From page 230... ...
Daily Intake of Trace Metals Reported by FDA Total Diet Studies (ug/day) Metal FAD/WHO NRC-NAS FDAb Mean Daily Intake from Media ESADDI Mean Daily Intake 15-lbtyr U.S.
|
From page 231... ...
exceeded somewhat the estimated total dietary intake of arsenic from the FDA's market basket survey program. Clearly, seafood is an important source of overall arsenic exposure in the diet, although as mentioned earlier, the organic forms of arsenic that appear to predominate in the seafood species studied in detail are considerably less hazardous than inorganic forms of arsenic.
|
From page 232... ...
Catch Intended for Human Consumption Finfsh, muscle 0.5-0.6 0.55 3.6 0.6-0.7 0.65 17.3 0.7-0.8 0.75 14.9 0.8-0.9 0.85 26 0.9-1.0 0.95 1.7 1.0-2.0 1.5 0.5 All finfish 0.764 64 Molluscs, edible tissues <0.1 0.05 3.4 0.5-0.6 0.55 0.4 0.6-0.7 0.65 0.6 0.7-0.8 0.75 0.1 0.8-0.9 0.85 1.9 0.9-1.0 0.95 1.1 1.0-2.0 1.5 0 All, average 0.469 7.5 Crustaceans, edible tissues 0.2-0.3 0.25 0.1 0.8-0.9 0.85 8.7 0.9-1.0 0.95 1 1.7 1.0-2.0 1.50 7.8 All crustaceans 1.07 28.3 Grand weighted average (ppm) 0.83 99.8a Daily dose for 15 lb/yr (ug/day)
|
From page 233... ...
Average Consumption of Range Percentage of U.S. Catch Intended for Human Consumption Fetish, muscle 0.6-0.7 0.65 0.2 1.0-2.0 1.5 2.6 2.0-3.0 2.5 35 3.0-4.0 3.5 13.8 4.0-5.0 4.5 3 5.0-6.0 5.5 2.8 6.0-7.0 6.5 0.3 7.0-8.0 7.5 5 8.0-9.0 8.5 0.1 9.0-10.0 9.5 0.2 10.0-20.0 15 0.7 20.0-30.0 25 0.2 All finfish 3.54 63.9 Molluscs, edible tissues 2.0-3.0 2.5 4 3.0-4.0 3.5 3.2 4.0-5.0 4.5 0.1 10.0-20.0 15 0.1 All, average 3.13 7.4 Crustaceans, edible tissues 3.0-4.0 3.5 1.8 4.0-5.0 4.5 14.2 5.0-6.0 5.5 2.5 6.0-7.0 6.5 5.8 9.0-10.0 9.5 2 10.0-20.0 15.0 0.5 20.0-30.0 25.0 1.5 All crustaceans 6.56 28.3 Grand weighted average (ppm)
|
From page 234... ...
is a modest, but not completely insignificant (6%) , portion of the overall dietary exposure estimated from the total diet program.
|
From page 235... ...
Average Consumption of Range Percentage of U.S. Catch Intended for Human Consumption Finish, muscle <0.1 0.05 0~3 0.1-0.2 0.15 51 0.2-0.3 0.250 12.5 All finfish 0.169 63.8 Molluscs, edible tissues 0.1-0.2 0.15 0.6 0.2-0.3 0.25 0.7 0.3-0.4 0.35 6.1 All, average 0.324 7.4 Crustaceans, edible tissues 0.1-0.2 0.15 5.4 0.2-0.3 0.25 22.9 All crustaceans 0.23 28.3 Grand weighted average (ppm)
|
From page 236... ...
Average Consumption of Range Percentage of U.S. Catch Intended for Human Consumption Finnish, muscle 0.3-0.4 0.35 9.9 0.4-0.5 0.45 33.8 0.5-0.6 0.55 9.4 0.6-0.7 0.65 10.7 All finfish 0.48 63.8 Molluscs, edible tissues 0.4-0.5 0.45 0.4 0.5-0.6 0.55 3.4 0.6-0.7 0.65 3 0.7-0.8 0.75 0.7 0.8-0.9 0.85 0.1 All, average 0.61 7.6 Crustaceans, edible tissues 0.4-0.5 0.45 0 0.5-0.6 0.55 3.5 0.6-0.7 0.65 18.5 0.7-0.8 0.75 6.2 0.8-0.9 0.85 0.1 All crustacea 0.66 28.3 Grand weighted average (ppm)
|
From page 237... ...
Average Consumption of Range Percentage of U.S. Catch Intended for Human Consumption Finnish, muscle <0.1 0.05 30.7 0.1-0.2 0.15 26.1 0.2-0.3 0.25 3.9 0.3-0.4 0.35 2.2 0.4-0.5 0.45 0 0.5-0.6 0.55 0.7 0.6-0.7 0.65 0 0.7-0.8 0.75 0.1 All finfish (except swordfishes 0.120 63.7 Mollascs, edible tissues <0.1 0.05 7.5 Crustaceans, edible tissues <0.1 0.05 13.7 0.1-0.2 0.15 13.2 0.2-0.3 0.25 1.4 All crustacea 0.107 28.3 Grand weighted average without swordfish (ppm)
|
From page 238... ...
with the highest daily mercury consumption in the FDA Total Diet Study. Aquatic organisms probably make a larger aggregate contribution to the methylated portion of total mercury (total mercury, of course, includes inorganic mercury, which has very different risks)
|
From page 239... ...
Average Consumption of Range Percentage of U.S. Catch Intended for Human Consumption Finfsh, muscle 0.1-0.2 0.15 0.5 0.3-0.4 0.35 2.3 0.4-0.5 0.45 21.2 0.5-0.6 0.55 8.3 0.6-0.7 0.65 4.9 0.7-0.8 0.75 2.1 0.8-0.9 0.85 5.4 0.9-1.0 0.95 1.5 1.0-2.0 1.50 17.7 All finfish 0.819 63.9 Molluscs, edible tissues 0.3-0.4 0.35 3.2 0.4-0.5 0.45 0.8 0.5-0.6 0.55 0.7 0.7-0.8 0.75 2.3 0.8-0.9 0.85 0.5 All, average 0.54 7.5 Crustaceans, edible tissues 0.2-0.3 0.25 0.4 0.3-0.4 0.35 5.1 0.4-0.5 0.45 2.1 0.5-0.6 0.55 1.1 0.6-0.7 0.65 11.9 0.7-0.8 0.75 6.2 0.8-0.9 0.85 1.4 1.0-2.0 1.50 0.1 All crustacea 0.61 28.3 Grand weighted average (ppm)
|
From page 240... ...
The committee believes that because of their frequency in the aquatic food chain and in some areas of the seafood supply, PCBs constitute an important contaminant even at levels below the present regulatory detection limits. Many contaminants probably go undetected by the FDA regulatory monitoring program because the laboratory detection limits used for enforcement of regulations have levels 5-10 times higher than the limits used in the Total Diet Study analyses (Gunderson, 1988, pp.
|
From page 241... ...
The disparity in sampling detection limits between the Total Diet Study and regular FDA seafood monitoring programs raises serious doubts as to whether the FDA sampling program is accurately estimating the actual concentrations of industrial chemicals and pesticides in the seafood supply. Indeed, the FDA laboratories' relatively high detection levels-particularly for PCBs and dieldrin, which can occur in seafood at levels below the current detection limits-lead to so-called nondetected zero values when the PCB concentration might actually be several parts per billion.
|
From page 242... ...
242 ax Ct Cal ._ 2 Cal i_ Ct ._ V]
|
From page 243... ...
Based on the FDA data set, the six U.S. commercially caught seafood products that appear to present the greatest daily per capita aggregate PCB exposures and their upper-confidence-limit cancer risks are other freshwater finfish (5.4 x 10~)
|
From page 244... ...
Yet, only four samples of herring were taken by the FDA monitoring program to be sampled for organic contamination between 1983 and 1987. This lack of data for individual species is disconcerting, especially when there are definite warning signals indicating that more data gathering would be warranted.
|
From page 245... ...
These findings should not be overgeneralized nor, based on present knowledge, can one assume that imported seafood is safer than domestically landed seafood. Exposures from Sport, Subsistence, and Tribal Fishing Noncommercial fishing is a significant source of overall fish for human consumption in the United States-estimated at 3-4 pounds per person on the average.
|
From page 246... ...
to characterize potential human health risks associated with chemical contaminants in Puget Sound seafood (Landolt et al., 1987~. Research focused entirely on recreational harvesters who frequently collect fish, shellfish, or edible seaweed tor use In personal consumption.
|
From page 247... ...
The highest consumption rate for a smaller number of anglers was estimated to be 95.1 g of fish per day from Puget Sound. In this study, upper-confidence-limit cancer risks for cumulative exposure to arsenic and the four organic chemicals of concern ranged from 2 x 104 for average anglers to 4 x 10-3 for those most highly exposed.
|
From page 248... ...
The arithmetic mean concentration of PCBs in medium bluefish was 0.38 ppm in males and 0.37 ppm in females. The arithmetic mean concentration of PCBs in large bluefish was 1.00 ppm in males and 1.58 ppm in females.
|
From page 249... ...
Bonito sampled in the program averaged 0.184 ppm DDT and 0.029 ppm PCBs (Gossett et al., 19824. By using the EPA upper-confidence-limit cancer potency factors for oral administration in conjunction with median consumption rates, the potential cancer risk for consumption of white croakers from Cabrillo pier would be approximately 4 x 104; the cancer risk for DDT would be 1.5 x 10-4.
|
From page 250... ...
For example, it is known that PCBs cross the placenta in women exposed to ordinary dietary levels (rein et al., 1984~. In one study of mothers who ate contaminated lake fish, PCB exposure, determined both in contaminated fish consumption and in cord serum PCB levels, predicted lower birth weight and smaller head circumference.
|
From page 251... ...
Consumer Information and Labeling Programs, and Fishing Advisories Unfortunately, as noted in the discussion of sport fishing, there appears to have been relatively little systematic study of the efficacy of state advisory programs in reducing population exposures to chemical contaminants in seafood from areas known to have higher than usual levels. Consumer information programs do, nevertheless, have features that have attracted the strong support of some members of the committee.
|
From page 252... ...
More generally, markers of modestly impaired status, such as the population distribution of birth weights, should be used to assess the potential effects of other contaminants in people with unusually high in utero exposures to PCBs and related contaminants. Alternative measures of PCB concentration need to be developed that will be better indices of the potential activity of different PCB congeners in producing both reproductive and other effects.
|
From page 253... ...
The fact that some geographic areas (e.g., fresh versus salt water) , some species, and some size classes of aquatic animals have much higher residue levels than others means that important quantitative reductions can be made in individual and societal aggregate health risks with measures that would restrict the overall commercial availability of fresh and marine seafood to only a modest degree.
|
From page 254... ...
Relatively high detection limits have been tolerated for some analytical tests, probably because the agency has focused primarily on determining the incidence of residues over a certain level that would violate current standards, rather than quantifying the overall dose delivered to consumers. Risk Assessment Practices Carcinogenesis risk assessment procedures should be modified to give decision makers additional information about the uncertainties of analysis, as well as both aggregate and individual risk estimates.
|
From page 255... ...
Advances in understanding the likely mechanisms involved in PCB carcinogenesis, the relative potency of different PCB congeners, the findings of subtle noncancer risks at relatively low dose levels (via fetal exposure) , and data on the uneven distribution of residue levels suggest
|
From page 256... ...
Similar blood level population distribution data were also cited in the polychlorinated biphenyl (PCB) case study, although a translation into intake distributions or risks was not possible there because of the incompleteness of information about the pharmacokinetics of different PCB congeners.
|
From page 257... ...
4. Quantifying human interindividual differences in pharmacokinetic or other parameters that are likely to produce different susceptibilities to adverse effects is a key enterprise if risk assessment for traditional categories of toxic effects is to move from the gross no-effect level (NOEL)
|
From page 258... ...
report is statistically sophisticated it appears to be biologically naive, in that is seems to focus on the distribution of daily intake, rather than periods of a month or more to be as comparable as possible to the long biological half-life of methylmercury in humans. The report is unclear enough in its methodology and end product results that the committee is unable to effectively utilize its contents, but it provides at least an illustration of the kind of distributional treatment that, if based on appropriate periods of exposure, could be toxicologically informative.
|
From page 259... ...
For a comparison of best estimates of cancer risk and EPA upper confidence limits in three cases with the aid of physiologically based pharmacokinetic analyses, see Hattis (199Ob)
|
From page 260... ...
1987. Investigation of Cancer Risk Assessment Methods (four volumes)
|
From page 261... ...
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)
|
From page 262... ...
1988. FDA Total Diet Study, April 1982-April 1984, Dietary intakes of pesticides, selected elements and other chemicals.
|
From page 263... ...
1988. Combined effect of childbearing, menstrual events, and body size on age-specific breast cancer risk, Am.
|
From page 264... ...
Seafood Consumers Exceeding the Current Acceptable Daily Intake for Mercury: Recommendations, Regulatory Controls. Seafood Quality and Inspection Division, Office of Fisheries Development, National Marine Fisheries Service.
|
From page 265... ...
1987. Guidance Manual for Assessing Human Health Risks from Chemically Contaminated Fish and Shellfish.
|
From page 266... ...
1989. The relation of polychlorinated biphenyls to birth weight and gestational age in the offspring of occupationally exposed mothers.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.