Volume II Chapter 4.0 Pages 2 of 4 page next page 3

4.4.3. Sediment Summary 4-13

4.5. CONCENTRATIONS IN FISH AND SHELLFISH 4-13

4.5.1. North American Data 4-14

4.5.2. European Data 4-18

4.5.3. Fish Summary 4-20

4.6. CONCENTRATIONS IN FOOD PRODUCTS 4-22

4.6.1. Migration of CDD/CDF from Paper Packaging Into Food 4-23

4.4.3. Sediment Summary

Some general observations for CDD and CDF levels are possible from the data presented in the various sediment studies above:

. The CDD and CDF congener distribution patterns in sediment generally follow those exhibited by the contaminant source.

. The concentration of hexa- to octa-chlorinated CDD and CDF congeners in sediment is usually the result of industrial processes and generally increases with the degree of chlorination, but decreases uniformly with distance from the source.

Based on the above studies, seven samples were selected as representing background conditions in the United States. The mean TEQ level was computed as 3.9 ppt assuming that nondetects equal half the detection limit. Similarly, 20 background samples were selected from the European data with a mean of 34.9.

4.5. CONCENTRATIONS IN FISH AND SHELLFISH

Tables B-8 B-9 B-10 (Appendix B) contain summaries of data from the numerous studies in the published literature regarding concentrations of CDDs, CDFs, and coplanar PCB congeners in fish and shellfish. PCB congener data were found only for North American species.

It should be noted that some studies reported fish concentrations on a whole weight basis and others reported concentrations for fish fillets. Whole weight concentrations were converted to fillet concentrations assuming that the fillet contained one-half the concentration of the whole fish (USEPA 1990; Branson et al. 1985). This was necessary for estimating human exposures because it is assumed that fish fillets, and not whole fish, are ingested by humans.

4.5.1. North American Data

A large quantity of fish data were collected as part of EPA's National Study of Chemical Residues of Fish (NSCRF), more commonly referred to as the National Bioaccumulation Study, during the period of 1986 to 1989 (U.S. EPA, 1992).

Based on these data, several summaries were prepared and are presented here. Tables B-8 and B-9 include the dioxin and furan data collected as part of the National Bioaccumulation Study. Samples were collected from a wide variety of sites across the United States, including 314 sites thought to be influenced by point or nonpoint sources and 35 sites identified as relatively free of influence from point and nonpoint sources. This latter group of sites can be characterized as background per the definition used in this document.

Background data are presented in Table 4-1. Table B-10 includes similar data for the various PCB congener groups from 362 National Bioaccumulation Study sites. Because the specific PCB congeners could not be identified, it is not known what percentage of these concentrations represent the PCBs identified as dioxin-like. Twenty of these sites were identified as background sites.

The total PCB, all 209 congeners, mean concentration for these background sites was 46,900 ppt. Because the dioxin-like PCBs consist of only 11 of the 209 possible PCB congeners, it may be that they are a small percentage of the total. However, only congener specific analysis can ultimately confirm this. As discussed at the end of this section (in 4.5.3), this study was selected as the best basis for estimating background fish levels in the United States.

table Table 4-1 Background Data from the National Bioaccumulation Study.
Samples of striped bass, blue crabs, and lobsters collected from Newark Bay and the New York Bight all contained high levels (up to 6,200 ppt) of 2,3,7,8-chlorine substituted tetra- and penta-CDDs and CDFs (Rappe et al., 1991). The levels of 2,3,7,8-TCDD were higher than any other New Jersey samples, and the highest sample in this study may be the highest level of 2,3,7,8-TCDD ever reported for aquatic animals.

The crustaceans resembled one another in congener pattern. Specifically, they all contained both a large number and large amounts of CDD and CDF congeners in addition to the 2,3,7,8-chlorine substituted compounds. The striped bass samples, on the other hand, contained primarily the 2,3,7,8-chlorine substituted congeners.
expand table Table V2 4-1

Carp, catfish, striped bass, large mouth bass, and lake trout were collected from sites in the Hudson River and the Great Lakes Basin that were contaminated with industrial chemicals or contained known or suspected levels of PCBs (Gardner and White, 1990). The congener 2,3,7,8-TCDF was detected in 12 fish at levels that ranged from 3 to 93 ppt. A 2,3,7,8-chlorine substituted PeCDF was detected in 14 fish at levels ranging from 4 to 113 ppt.

An interesting observation in this study was that 2,4,6-chlorine substituted CDFs were detected in four fish samples, suggesting that those fish may have been exposed to chlorinated phenols. The study indicated that the 2,4,6-chlorine substituted CDFs occurred in the fish at levels similar to those of the 2,3,7,8-chlorine substituted CDFs, but with less frequency.

Samples of lake trout or walleye collected from each of the Great Lakes and Lake St. Clair were analyzed for CDDs and CDFs (De Vault et al., 1989). CDF and CDD concentrations in lake trout were substantially different for each lake and between sites in Lake Michigan, probably reflecting differences in types and amounts of loadings to the lakes.

In all of the sampling sites except Lake Ontario, 2,3,7,8-TCDF was the dominant CDF congener in lake trout and ranged from 14.8 ppt in Lake Superior to 42.3 ppt in Lake Michigan. In Lake Ontario, the dominant congener in lake trout was a 2,3,7,8-chlorine substituted PeCDF.

The distribution of CDF congeners in the Lake Erie walleye was very similar to that of the lake trout from Lake Superior. With regard to CDDs, the concentrations of 2,3,7,8-TCDD ranged from 1 ppt in Lake Superior to 48.9 ppt in Lake Ontario.

With the exception of Lake Ontario, the dominant CDD congener was a 2,3,7,8-chlorine substituted PeCDD. A 2,3,7,8-chlorine substituted HxCDD also contributed significantly to the total CDD concentrations. As with CDFs, the distribution of CDD congeners in the Lake Erie walleye was very similar to that of the lake trout from Lake Superior.

In another study, CDDs and CDFs were measured in four species of salmonids (lake trout, coho salmon, rainbow trout, and brown trout) collected from Lake Ontario (Niimi and Oliver, 1989a). Levels of 2,3,7,8-TCDD in whole fish ranged from 6 to 20 ppt, and the HxCDD congener group was most dominant in all fish.

High levels of OCDD also were detected in lake trout and coho salmon, but not in rainbow trout or brown trout. Although the total CDF levels were about 25 percent lower than the total CDD concentrations, the levels of 2,3,7,8-TCDF (which was the dominant component of the TCDF congener group) were the same range as 2,3,7,8-TCDD (6 to 20 ppt).

However, the study suggested that, although collection sites can influence chemical levels and congener composition, comparisons of chemical levels and congener frequencies may not be suitable because of differences resulting from localized factors.

The study also indicated that the importance of the various CDD and CDF congeners can differ with location (i.e., the same species of fish collected at different locations in a study area may reveal that the most common congener is different at each site).

Travis and Hattemer-Frey (1991) evaluated data generated as part of the National Dioxin Study regarding 2,3,7,8-TCDD concentrations in fish. The fish were collected from 304 urban sites in the vicinity of population centers or areas with known commercial fishing activity, including sites from the Great Lakes Region. Data from that study indicated that concentrations of 2,3,7,8-TCDD in whole fish from urban sites ranged from nondetectable to 85 ppt.

In addition, only 29 percent of the fillets from urban sites had detectable levels of 2,3,7,8-TCDD, with a geometric mean concentration of 0.3 ppt. Whole fish samples from the Great Lakes Region had higher 2,3,7,8-TCDD levels than fish from urban areas (e.g., 80 percent vs 35 percent detectable levels). In the Great Lakes Region, 2,3,7,8-TCDD concentrations in whole fish samples ranged from nondetectable to 24 ppt, with a geometric mean of 3.8 ppt.

These levels were 10 times higher than the concentration in whole fish from urban areas. Likewise, the mean concentration of 2,3,7,8-TCDD in Great Lakes Region fish fillets (2.3 ppt) was about seven times higher than the levels in the fillets from urban areas (0.3 ppt). As with the whole fish samples, fish fillet samples from the Great Lakes Region had higher 2,3,7,8-TCDD levels than fillets from background urban areas (e.g., 67 percent vs 29 percent detectable levels). Comparable levels of 2,3,7,8-TCDD were detected in whole bottom feeders and predators from the Great Lakes Region.

Samples from all trophic levels in the Lake Ontario ecosystem were analyzed for PCB congeners (Oliver and Niimi, 1988). Analysis revealed that the PCB concentration increased from water to lower organisms to small fish to salmonids, demonstrating the classical biomagnification process. In addition, the chlorine content of the PCBs increased at the higher trophic levels.

PCBs with the highest chlorine content (57 percent) were found in sculpin, small bottom-living fish that feed on benthic invertebrates. The TrCBs and TCBs comprised a much higher percentage of the PCBs in the lower trophic levels than in salmonids and small fish. The percentage of PeCBs and OCPB in all samples was fairly uniform, but the HxCBs and HpCBs comprised a much larger fraction of the PCBs in the small fish and salmonids than in the lower trophic levels.

A study regarding the distribution of PCBs in Lake Ontario salmonids (brown trout, lake trout, rainbow trout, and coho salmon) showed that the PeCBs and HxCBs were dominant in all species (Niimi and Oliver, 1989b). The 10 most common PCB congeners represented about 52 percent of the total content and did not appear to be influenced by species or total concentration.

The homologues observed averaged approximately 56 percent chlorine by weight in whole fish and muscle. The analysis of the chlorine content suggested that the more persistent congeners tend to behave as a homogeneous mixture instead of as individual congeners.

4.5.2. European Data

Evaluation of fish in the Baltic Sea (Gulf of Bothnia) and northern Atlantic Ocean in the vicinity of Sweden revealed that concentrations of CDDs and CDFs in herring from the Atlantic Ocean were lower than those in the Gulf of Bothnia (Rappe et al., 1989b). Detectable levels of 2,3,7,8-TCDD in salmon were found in both wild homing (4.6 to 19 ppt) and hatchery-reared (0.2 to 0.3 ppt) varieties in the Gulf of Bothnia.

In addition, concentrations of the same representative congeners of the Cl5 to Cl8 CDD and CDF congener groups found in herring were found in both varieties of salmon. Levels of those congeners in the wild salmon, however, were five to ten times higher than the herring levels, while the levels in the hatched salmon essentially were the same as in the herring samples.

Perch collected at a distance of 1-6 km from a pulp mill in the southern part of the Gulf of Bothnia contained 2,3,7,8-TCDD and 2,3,7,8-TCDF; the levels were higher in the samples collected closer to the pulp mill. These two compounds have been identified in bleaching effluents from pulp mills as well as in bleached pulp. Arctic char collected from Lake Vattern, a popular fishing lake in southern Sweden, contained levels of 2,3,7,8-TCDD (6.5 to 25 ppt), 2,3,7,8-TCDF (21 to 75 ppt), and representative congeners of the PeCDD and PeCDF homologues. There was a good correlation between the weight of the fish and the levels of CDDs and CDFs. The main general pollution sources of the long, deep, narrow lake are two pulp mills.

Fish (cod, haddock, pole flounder, plaice, flounder, and eel), mussels, and edible shrimps from a fjord area contaminated by wastewater from a magnesium factory in Norway were analyzed for CDDs and CDFs (Oehme et al., 1989). Certain magnesium production processes can result in the formation of substantial amounts of CDDs and CDFs as byproducts.

The congener pattern of Cl4 and Cl5 CDDs and CDFs released in wastewater during the magnesium production process is very characteristic and is dominated by congeners with chlorine in the positions 1,2,3,7 and/or 8. Fish and shellfish differ in their ability to bioconcentrate CDD and CDF congeners.

For example, fish generally only concentrate the most toxic 2,3,7,8-substituted congeners, whereas shellfish can usually concentrate most of the congeners. Nearly all congeners were present in the shrimp and mussel samples.

Although these organisms displayed the very characteristic PeCDF congener pattern of the magnesium production process, some deviations were found in the TCDF congener distribution within those species. For fish, the concentrations of CDDs and CDFs are dependent on the exposure level, fat content, living habit, and the species degree of movement. The highest CDD and CDF levels were found in comparatively high fat-content bottom fish collected close to the source. Cod and haddock, lower fat-content nonstationary fish, had much lower concentrations, even in the vicinity of the magnesium production factory.

An interesting note is that the main stream of the fjord follows the west coast; subsequently, cod and eel samples collected along the west coast of the fjord had considerably higher levels of CDDs and CDFs than those collected from the eastern fjord entrance. Similarly, the level of 2,3,7,8-TCDD in mussels decreased by one order of magnitude from the vicinity of the magnesium production factory to the outer region of the fjord system.

Brown trout, grayling, barbel, carp, and chub collected in the Neckar River in southwest Germany contained much higher levels of 2,3,7,8-TCDF than in eels collected from the same river and the Rhine River (Frommberger, 1991).

In addition, eels from both rivers showed very similar patterns for CDD and CDF congener distribution, whereas the patterns of CDD and CDF distribution generally showed some degree of difference among the other fish collected from the Neckar River. Perch and bream collected from various locations in the vicinity of Hamburg Harbor, however, showed similar patterns in the distribution of the Cl4 to Cl8 CDD and CDF congener groups (Gotz et al., 1990).

In general, the levels of CDFs were higher than the level of CDDs in these fish, especially with regard to the TCDFs to HxCDFs. Pooled samples of eels collected at six different localities in the Netherlands contained low levels of CDDs and CDFs, the major congeners of which were 2,3,7,8-chlorine substituted (Van den Berg et al., 1987).

The concentrations of the various congeners identified in the eel samples ranged from 0.1 to 9.1 ppt. The sample with the highest concentration of 2,3,7,8-TCDD (9.1 ppt) was collected from Broekervaart in a location that was not far from a chemical waste dump that contained high concentrations of the same congener.

4.5.3. Fish Summary

Some general observations for CDD and CDF levels are possible from the data presented in the various fish and shellfish studies above:

. Fish and shellfish differ in their ability to bioconcentrate CDD and CDF congeners. Fish generally concentrate the most toxic 2,3,7,8-substituted congeners, but shellfish can usually concentrate most congeners.

. For fish, the concentrations of CDDs and CDFs are dependent on the exposure level, fat content, living habits, and the degree of movement of the species. Comparatively high fat-content bottom fish collected close to the contaminant source generally have the highest CDD/CDF levels, whereas lower fat content, nonstationary fish have much lower concentrations, even in the vicinity of the contaminant source.

. The National Dioxin Study indicated that the levels of 2,3,7,8-TCDD in fish from the Great Lakes Region were higher than those from urban areas. Comparable levels were detected in whole bottom feeders and predators from the Great Lakes Region.

. With regard to PCBs, concentrations increase from water to lower organisms to small fish to salmonids, and the chlorine content of the PCBs increase at the higher trophic levels.

The background fish data collected as part of EPA's National Bioaccumulation Study (EPA, 1992) were selected as the best basis for identifying background levels in U.S. fish. Sixty fish samples were collected from fresh and estuarine water at a total of 34 sites where no obvious industrial sources were present.

The average TEQ (assuming zero for the nondetects) was 0.59 ppt, and 1.2 ppt (assuming half the detection limit for the nondetects). In the original study, some of the samples were analyzed on a whole body basis and others on a fillet basis. However, for purposes of this document, whole body data were converted to a fillet basis. All concentrations were expressed on a wet weight basis.

This information is based on the report and clarifications provided via a personal communication from Annette Huber, Office of Water, to John Schaum, Office of Research and Development, May 17, 1993. Several points should be considered in using these estimates to assess human exposure:

. The National Bioaccumulation Study data were derived from fresh and estuarine water fish and, therefore, are not representative of open ocean fish. Some types of open ocean fish such as tuna and sword fish are commonly eaten. The cod and haddock data from Schecter et al. (1993) could be representative of these species. (See discussion in Section 4.6.2.) These data showed a range of 0.023 to 0.13 ppt. Presumably, the contaminant levels in open ocean fish are lower than fresh water and estuarine fish because they live in waters farther from dioxin sources.

. Whole fish contaminant levels are normally twice as high as fillets, which is generally considered the edible portion. However, some small fish and shell fish, such as clams, are typically eaten whole.

. These "background" samples may not be representative of what many individuals consume. EPA (1992) found an average of 11 ppt of TEQ across all 314 locations sampled. Even though these other locations were near industrial point sources, recreational or subsistence fishermen from local populations may consume fish from these waters.

. Market basket surveys would probably provide the best information on dioxin levels in fish commonly consumed by the general population. Data of this type were provided by Schecter et al. (1993). As discussed in Section 4.6.2., this study analyzed five fish collected from a supermarket and found an average of 0.05 ppt of TEQ.

These data may mean that fish exposure levels are lower than the value selected here as representative of background levels (i.e., 1.2 ppt). However, only a limited number of samples were analyzed. Also the fish samples represent ocean species, whereas the National Bioaccumulation Study sampled freshwater and estuarine fish.

4.6. CONCENTRATIONS IN FOOD PRODUCTS

Dietary intake is generally recognized as the primary source of human exposure to CDD/Fs (Rappe, 1992). Several studies have estimated that over 90 percent of the average daily exposure to CDD/Fs are derived from foods (Rappe, 1992; Henry et al., 1992; Fürst et al., 1991). CDD/Fs in fatty foods such as dairy, fish, and meat products are believed to be the major contributors to dietary exposures (Rappe, 1992; Henry et al., 1992). Travis and Hattemer-Frey (1991), using a fugacity model, estimated that the food chain, especially meat and dairy products, accounts for 99 percent of human exposure to 2,3,7,8-TCDD.

Analysis of trace levels of CDD and CDF congeners in food has in the past been hindered by lack of sensitive analytical detection methods, extraction difficulties from the high-lipid content food products in which these chemicals are most often found, and the presence of other potentially interfering organochlorine compounds. As the analytical difficulties associated with detecting CDD and CDF congeners at ppt levels or lower are overcome (Firestone, 1991), more food data should be generated.

Tables B-11 and B-12 (Appendix B) contain summaries of data from the recent published literature regarding concentrations of CDDs and CDFs in food products. Most of the selected studies investigated "background" levels of CDDs and CDFs rather than studies targeted at areas of known contamination. Table B-13 contains a summary of PCB congener concentrations in food products.

The studies summarized in Tables B-11 and B-12 primarily examined CDD and CDF levels in products of animal origin (i.e., fish, meat, eggs, and dairy products). Because of their lipophilic nature, CDDs and CDFs are expected to accumulate in these food groups.

The data in the tables indicate that CDDs and CDFs are found at levels ranging from the intermediate ppq up to the low ppt range. As expected, the highest levels reported are those measured in foods with high animal fat content.

The highest reported congener concentrations are for the HpCDDs and OCDD. In general, for the less-chlorinated congener groups (i.e., Cl4 - Cl6), the CDF levels measured were larger than the CDD levels but were still within an order of magnitude. The situation is reversed for the Cl7 and Cl8 congener groups.

4.6.1. Migration of CDD/CDF from Paper Packaging Into Food

In the past, low levels of CDDs and CDFs have been detected in bleached paper. (See discussion in Chapter 3.) Because bleached paper is sometimes used for food packaging, concern has been expressed that CDD/Fs may migrate from the paper into the food.

Using refined and highly sensitive analytical methods, LaFleur et al. (1990) observed the migration of 2,3,7,8-TCDD; 2,3,7,8-TCDF; and 1,2,7,8-TCDF from bleached paper milk cartons into whole milk. After 12 days of exposure, 6.7 percent of the 2,3,7,8-TCDD; 18 percent of the 2,3,7,8-TCDF; and 13 percent of the 1,2,7,8-TCDF in the milk carton leached into the milk. The concentrations of the three congeners in milk were 8.5, 110, and 49 pg/kg for 2,3,7,8-TCDD; 2,3,7,8-TCDF; and 1,2,7,8-TCDF, respectively. [Note: These data are not reported in Appendix B; only data for raw milk are reported.]

The study results reported by LaFleur et al. (1990) were performed by the National Council of the Paper Industry for Air and Stream Improvement (NCASI) at the request of the U.S. Food and Drug Administration (FDA) as part of a cooperative Federal agency effort to assess the risks posed by dioxin contamination of paper products (i.e., the Federal Interagency Working Group on Dioxin-in-Paper).

In addition to assessing the migration of CDDs and CDFs from milk cartons, studies were also conducted to assess the extent of CDD/CDF migration into food from coffee filters, cream cartons, orange juice cartons, paper cups for hot beverages, paper cups for soup, paper plates for hot foods, dual ovenable trays, and microwave popcorn bags. Migration of CDD/Fs from the paper into food was observed in all studies.

The FDA report presented data on direct measurements in these paper articles, showing TCDD and TCDF levels in the 1 - 13 ppt range. These levels were similar to the levels measured in bleached wood pulp which averaged about 8 ppt at the time of the study. As discussed in Section 3.2, the paper industry has made process changes that they expect have generally reduced dioxin levels in bleached paper pulp to less than 2 ppt of TEQ. Similar or lower levels could be expected in final paper products. NCASI reports that essentially no detectable migration of dioxin to milk occurs from cartons at these levels.

The results of these migration studies and an assessment of the risks to the general population posed by migration from paper are addressed in detail in U.S. EPA (1990a). The CDD/CDF levels currently found in food due to any leaching of dioxin-like compounds from paperboard containers are expected to be significantly lower than those reported in U.S. EPA (1990a) because of process changes implemented by the pulp and paper industry to reduce formation of CDDs and CDFs.