Public Health Assessment
NAVAL WEAPONS STATION YORKTOWN, CHEATHAM ANNEX
WILLIAMSBURG, YORK COUNTY, VA
CERCLIS NO. VA3170024605
ATSDR analyzed fish tissue sampling results for fish obtained from a variety of waterways in the vicinity of Norfolk, Virginia. This appendix describes the objectives, methods, and results of the data review.
Fishing and fish consumption are both enjoyable pastimes and an important source of nutrition for many people who vacation or live near waterways. The waterways near Norfolk, Virginia, support a variety of fish and are frequented by recreational and possibly subsistence fishers. Some of these waterways are also bordered by military bases, industrial facilities, agricultural areas, roads, parking lots and other potential point and non-point sources of contaminants that could affect water quality and fish tissue contaminant concentrations. ATSDR has performed, or is performing, public health assessments for many of the military installations in the Norfolk area. Frequently, people who live near these installations ask if locally caught fish are safe to eat.
While some installations may be able to provide results of fish tissue sampling for fish obtained from on-base ponds and streams, few installations sample fish from streams or rivers that border the base. ATSDR evaluated fish sampling data obtained from the Virginia Institute of Marine Sciences (VIMS) to identify if public health concerns exist for either recreational or subsistence fishers.
The purpose of this data review was to identify if recreational or subsistence fishers, utilizing the sampled area, could be exposed to contaminants at levels that could cause health effects. This review was not designed to identify potential sources of contamination, describe the impact of neighboring contaminant sources, or evaluate the fate and transport of chemicals detected in the fish tissue. The result of this review is not a definitive analysis of the potential health effects associated with consuming fish from the Norfolk area, but an estimation of the potential health effects associated with consuming fish represented by the sampling data from the sampled locations.
A variety of contaminants were detected in the fish fillet and blue crab samples. The maximum concentration of polychlorinated biphenyls (PCBs), arsenic, lead and mercury detected in some of the fish fillet or blue crab samples were above ATSDR comparison values. A more detailed evaluation considering the entire body of sampling data was completed for those chemicals. Results indicate the concentrations measured in the blue crab are below levels expected to cause health effects. The concentration of PCBs, arsenic, lead and mercury in some of the fish samples were slightly above ATSDR comparison values. However, for all of these chemicals, the concentrations are within the range normally measured in fish and other food groups. Recreational or subsistence fishers who choose to eat fish from other sources or substitute other foods for fish are not expected to significantly change their potential exposure to these chemicals. These chemicals are commonly found in fish and other foods.
The following figure illustrates the health concerns associated with different fish fillet ingestion rates. For the vast majority of fish fillet consumers, there are no health concerns related to fish fillet consumption. People who consume fish several times a week may be exposed to PCB, arsenic and mercury at levels greater than ATSDR's comparison values, however their exposure is not likely to cause health effects. People who routinely consume 2 or more 8-ounce (oz) fish fillets per day will likely have a PCB exposure that is many times greater than the ATSDR comparison value. While this exposure is still below levels known to cause health effects, it would be prudent for those people to consider reducing their fish fillet consumption.
Regardless of their fish fillet ingestion rate, fish consumers can reduce their PCB exposure by selecting the younger, smaller fish of a species (within legal limits), removing the skin, belly fat, and internal organs prior to cooking, baking or broiling the fish fillet, and not eating the fatty juices or drippings.
Relationship to other Advisories Only one fish advisory currently exists for this sample area. The Virginia Department of Health (VDH) issued an advisory for the James River from the Hampton-Norfolk Bridge Tunnel (I-64) near the mouth of the James River, upstream to Richmond. The advisory includes that section of the James River and its tributaries that were originally closed to fishing after sampling identified Kepone contamination in the water, sediment and fish tissue in 1975. Kepone, an insecticide used for ant and roach traps, was released into the river at Hopewell, Virginia, from 1966 until its ban in 1975.
Annual sampling results indicate fish tissue concentrations of Kepone have been decreasing since 1976. Since 1983 the concentrations have been well below the Food and Drug Administration (FDA) action level (Chesapeake Bay Program 1999). Currently there are no fishing bans in this area; however, the Kepone advisory, placed in July 1988, is still in effect. The advisory applies to daily consumption of fish from the James River and tributaries and states that Kepone may be hazardous to your health. There are no specific recommendations or consumption limits (VDH 2003).
The data set reviewed by ATSDR only included information about the chemicals that were detected in at least one of the samples. The data did not include any information about Kepone. This could indicate that it was not considered during the analyses or that all of the fish tissues sampled did not contain detectable levels. Given that some of the fish samples came from the James River near Norfolk and overlapped the Kepone advisory area, it is likely that Kepone was not considered in our data set. Therefore ATSDR recommends that fishers of the James River and tributaries continue to be aware of the VDH Kepone advisory.
VDH has 11 advisories for PCBs in rivers and lakes across Virginia. Recommendations range from limiting consumption of certain fish to not eating any fish from these waters. The closest PCB advisory for the sample area is for the James River and tributaries from the intersection of the Flowerdew Hundred Creek upstream to Richmond. The Flowerdew Hundred Creek is approximately 10 miles upstream from the most upstream James River sampling location. There are no PCB advisories for any of the rivers included in the sampling area (VDH 2003).
VDH considers issuing fish advisories when sampling results supplied by the Virginia Department of Environmental Quality indicate the concentration of PCB congeners in fish fillets may exceed 600 micrograms/kilogram (µg/kg) (or 600 parts per billion [ppb]). This concentration is expected to be protective of the general population (Tripathi 2003). The general population typically includes the non-fishers, recreational fishers, and subsistence fishers in the area surrounding the water body under consideration. Studies indicate the average daily ingestion rate for the general population is approximately 6 to 21 grams/day (g/d), while studies of recreational and subsistence fishers indicate their ingestion rates vary between 17 and 540 g/d (EPA 2000). ATSDR evaluated the VIMS data set to identify if recreational or subsistence fishers primarily using the surface waters within the sampling area would be exposed to contaminant concentrations that would be expected to cause health effects.
Results of fish tissue analyses for chemical concentrations in fillets were obtained from the Virginia Institute of Marine Science (VIMS). VIMS analyzed a substantial number of fish and shellfish samples provided to them by the Virginia Department of Environmental Quality under a fish tissue monitoring program. VIMS performed the laboratory analysis of the tissue samples and compiled a searchable database. ATSDR obtained results from the database in 2001.
Figure 1 shows the locations of available fish tissue sampling data, by chemical category. Results were provided for two chemical categories, metals and organics. Metals results included arsenic, cadmium, chromium, lead, mercury and selenium. Organics included pesticides, PCBs and polyaromatic hydrocarbons (PAHs).
Wet weight concentrations were measured in the fillet portion of finfish and the edible portion of blue crab, oyster and clam samples. Typically fillets from similarly sized fish of the same species and from the same sampling location were first homogenized and then chemically analyzed. Samples of blue crab, oysters, and clams only included the 'edible portion' of muscle tissue. While there were several results for blue crab there was only one result each for oysters and clams. Following the initial screening, results from the oyster and clam samples were not considered. Results included the sample identification number, sampling location, sampling date, fish species, number of fish included in the homogenate, average size of the fish and chemical concentration. Tables 1 and 2 show the number of result records evaluated by fish species for both the organics and metals and the time periods during which the samples were obtained.
Figure 1 and Tables 2 and 3 illustrate some of the differences between the results for the organics and metal analyses. Approximately 53 locations were sampled for organics and 25 locations were sampled for metals. At all locations where results are available for metals, results are also available for organics. Not all locations where samples were analyzed for organics were sampled for metals. Twenty seven (27) fish species were analyzed for organics, 20 were analyzed for metals. Again all of the species that were analyzed for metals were also analyzed for organics. Results from the organics sampling were gathered over a 4-year period, while the metal results were only available for the two most recent years. Over 11,000 results are available from the organic analyses while 672 are available for metals. In addition, the metals results provided information about non-detects while the organics results did not. Information about method detection limits was not provided for the organics. Therefore ATSDR analyzed the two data sets separately, but used a similar methodology for each dataset.
Both the organics and metals datasets contain results of chemical concentrations measured in blue crabs, and results for one oyster and one clam sample. While it is not truly appropriate to combine finfish and shellfish data, ATSDR did so during the initial screening to identify contaminants present in any of the tissues above comparison values. Contaminants that were present above the comparison values were considered in greater detail.
Methodology The organic and metal results reviewed provide information about the concentration of these chemicals measured in the tissue samples. The goal was to identify if health effects would be expected for people who eat fish fillets and blue crabs represented by the sampled tissues. To accomplish this, ATSDR performed a multi-tiered screening analysis to reduce the total number of records to those that could best reflect the potential public health concerns associated with consumption of local fish within the sampled region.
During the evaluation, ATSDR estimated the amount of each chemical people would ingest while consuming fish. The estimated exposure for each chemical was then compared with screening levels that are known to be protective of human health. Specific information on these 'comparison values' (CVs) exist for a wide variety of chemicals that are commonly found in the environment. However, in the case of PCBs and some other chemicals, direct comparison of the measured chemicals with the CVs was not possible.
|Species||Number of Records; Organics||Number of Records; Metals|
|LARGE MOUTH BASS||339||12|
|Total Number of Fish Species||27||20|
|Total Number of Records||11564||672|
The VIMS data set included results for individual PCB congeners, combinations of two or three PCB congeners, combinations of PCB congeners and other chemicals (typically pesticides, pesticide metabolites, or pesticide by-products), and metabolites and by-products of parent pesticides. Many of these individual chemicals, and most of these chemical groups, do not have specific comparison values. When possible, ATSDR combined individual chemicals into a chemical group, which could then be compared with a CV, by summing the individual concentrations of contaminants within the group. The chemical groups were prepared for each of the following chemicals:
- DDT and related metabolites and byproducts
Approximately 2006 (17%) of the organic records were not compared to individual or group CVs. These records included 35 different chemicals, mostly PAHs. Only 7 of these chemicals were detected in more than 100 of the 197 total sampling events.
When available the ATSDR chronic oral minimal risk levels (MRLs) were used as CVs; if those were not available, the intermediate MRLs were used.
During the first tier of the process, the maximum concentration of the individual or chemical group was used to calculate an estimated exposure dose (ED) for each chemical using the following formula:
ED = C * IR/BW
ED = Exposure Dose [g/kg/d]
C = Concentration [g/kg]; the maximum concentration measured in the tissue
IR = Ingestion Rate [kg/d]; the estimated amount of fish eaten on a daily basis
BW = Body Weight [kg]; the body weight of the individual eating the fish
(assumed to be 70 kg = 155.6 pounds [lbs])
During the initial screening, very high estimates of the daily ingestion rate were used for both the recreational and subsistence fishers. Table 3 shows the range of ingestion rates that have been identified in previous studies and the values used for the initial screening. Recreational fishers were assumed to consume 25 g/d of fish fillets; this is equivalent to one 8-oz fish fillet every 9 days, or about 3 to 4 8-oz fillets every month. Subsistence fishers were assumed to consume 400 g/d of fish fillets, which is approximately 1 to 2 8-oz fish fillets every day.
|Fish Consumer Population||Fish Consumption [g/d]||Fish Consumption [oz/d]||Number of 8-oz Fish Meals|
|Recreational *||17.5||0.6||~ One meal every 12 days|
|Subsistence *||142||5||~ One meal every day or two|
|Native American Subsistence *||390||14||~ Two meals per day|
|Traditional Native American Subsistence *||540||19.4||~ 2 ½ meals per day|
|Recreational Comparison Consumption Rate **||25||0.9||~ One meal every 9 days|
|Subsistence Comparison Consumption Rate **||400||14.4||~ 1.8 meals every day|
| * Information from: EPA 2000, Table 1-3 |
** Values used by ATSDR during the initial screen process
Individual chemicals or chemical groups where the exposure dose calculated from the maximum concentration exceeded the comparison value were included in the second tier of the evaluation. The second tier evaluation attempted to consider the entire body of sampling data by repeating the exposure dose estimations using the average concentration. In addition, the second tier evaluation also considered information about how frequently the chemical was measured in fish from other locations and the range of measured concentrations. This information was used to evaluate how the potential chemical exposure of recreational and subsistence fishers would change if they switched to consuming fish from other locations or to eating other types of food.
Results and Discussion
Considering just the maximum concentration measured for each chemical or chemical group, the following chemicals were included in the second tier analysis: heptachlor epoxide, total chlordane, total DDT, total PCBs, arsenic, cadmium, chromium, lead and mercury. Additional review of the data eliminated heptachlor epoxide, total chlordane, and cadmium from further evaluation because in each case only one of the 197 sampling events resulted in an estimated exposure dose that was above the CV, and all of the other sampling results were well below the comparison values. Total DDT was not considered for further evaluation because only 8 of the 189 samples with detectable DDT concentrations (of the 197 tissue samples) resulted in an estimated exposure dose in excess of the CV assuming an ingestion rate of 400 g/d, and none of the calculated doses exceeded the CV when the ingestion rate was assumed to be 25 g/d. In addition the estimated exposure dose considering the average concentration and an ingestion rate of 400 g/d (ED = 0.00012 milligrams [mg]/kg/d) was over 4 times lower than the CV (CV = 0.0005 mg/kg/d).
PCBs, arsenic, lead and mercury were considered in greater detail. Results of the initial screening indicated the potential exposure to these chemicals in the tissue samples was greater than the ATSDR CV. They do not indicate that health effects are likely or that there are health concerns associated with the fish or the waterways bounded by the sampling locations. The initial screening method was designed to be a highly conservative method in order to identify which chemicals should receive the greatest attention during the evaluation. The following sections describe the evaluation process used for each of these chemicals.
Polychlorinated biphenyls (PCBs) are a mixture of up to 209 individually chlorinated compounds (known as congeners). As a result of their chemical properties, they are highly persistent in the environment and can easily be taken up by fish. PCBs can accumulate in fish so that fish tissue concentrations can be many times greater than that of the water or sediment. In addition to fish, PCBs may be found in other foods such as meat, eggs, milk, bread and cereal. While some people may be exposed to PCBs in occupations dealing with old electrical devices, most people are exposed to PCBs primarily through their diet. The most common health effects documented during occupational exposure include acne and skin rashes. Some studies show occupation exposure led to changes in blood or urine chemistry that may indicate liver damage. The EPA and the International Agency for Research on Cancer (IARC) have classified PCBs as probable carcinogens.
In this dataset, PCBs were detected in fish fillets in almost all of the sampling events. The vast majority of the measured concentrations were within the range of PCB concentrations measured in fish from remote areas (ATSDR 2000). PCB concentrations in fish from lakes and rivers located in Alaska, Wisconsin and the Sierra Nevadas Mountains, taken between 1992 and 1997, ranged between 0.0013 and 0.46 ppm. PCB concentrations in the Norfolk-area sampling locations ranged from 0.0005 to 0.89 ppm; 96% of the Norfolk samples had a concentration less than 0.46 ppm.
As previously mentioned, the data set evaluated by ATSDR contained only information about the chemicals that were above detection limits in the fish fillets. The detection limits for the organic chemicals were not provided. Results for a total of 197 sampling events were included in the data set. There were 181 PCB detections in this data set. The 16 sampling events that did not report PCB concentrations were not included in the calculations for the mean or 95th percentile PCB concentrations because of uncertainty in the PCB detection limit. Therefore the average and 95th percentile PCB concentrations used in this analysis may be slightly over-estimated.
The fish gathering method used by VIMS is believed to have captured the majority of the fish that were in the sampling location at the time the sampling was conducted. It was not designed to gather just the fish that are known to be desired by recreational or subsistence fishers. Some of the samples with reported PCB concentrations were from fish that are not typically eaten by recreational fishers. Table 4 shows all of the species for which at least one PCB result is available and the species that were considered to be most sought after, and therefore eaten, by recreational fishers. Blue crabs and oysters were not included as a species eaten by recreational fishers because shellfish are physiologically different from finfish and not all recreational fishers consume shellfish. To be conservative, subsistence fishers were assumed to consume all of the finfish species. Because there was only one sampling event each for oysters and clams, they were not included in this evaluation.
|All Species||Species Most Targeted by Recreational Fishers|
|BLACK CRAPPIE||BLACK CRAPPIE|
|BLUEGILL SUNFISH||BLUEGILL SUNFISH|
|CHANNEL CAT||CHANNEL CAT|
|COMMON CARP||COMMON CARP|
|CROAKER, ATLANTIC||CROAKER, ATLANTIC|
|GREY TROUT||GREY TROUT|
|LARGE MOUTH BASS||LARGE MOUTH BASS|
|LONGNOSE GAR||LONGNOSE GAR|
|PUMPKINSEED SUNFISH||PUMPKINSEED SUNFISH|
|REDBREAST SUNFISH||REDBREAST SUNFISH|
|SEA BASS||SEA BASS|
|STRIPED BASS||STRIPED BASS|
|SUMMER FLOUNDER||SUMMER FLOUNDER|
|WHITE CATFISH||WHITE CATFISH|
|WHITE PERCH||WHITE PERCH|
|YELLOW PERCH||YELLOW PERCH|
For each of the species, Table 5 shows the number of sampling events with a detectable PCB concentration, as well as the maximum, average and 95th percentile concentrations, standard deviation, and coefficient of variation.
Table 6 shows the maximum, average and 95th percentile concentrations, standard deviation, and coefficient of variation for the species used to evaluate the subsistence and recreational fishers and blue crab consumers.
ATSDR estimated the PCB exposure fish consumers would receive based on the amount of fish they tend to eat on a daily basis. Figures 2 and 3 show how the estimated PCB exposure varies with the PCB concentration and the fish fillet ingestion rate. These graphs indicate that for equivalent ingestion rates, subsistence fishers (people who evenly consume every type of fish available in the river) would be expected to have a higher estimated PCB exposure than recreational fishers (people who preferentially consume the recreational target fish). This is because gizzard shad, a fish species not typically consumed by recreational fishers, had relatively high concentrations of PCBs.
Figures 2 and 3 show the estimated PCB exposure for recreational and subsistence fishers based on their daily ingestions rates and the assumed average concentration of PCB in the fish fillets. The 95th percentile and average concentrations were taken from Table 6. Figure 2 considers daily ingestion rates to 500 g/d while Figure 3 only considers daily ingestion rates of 50 g/d or less. Figure 3 also shows the ATSDR chronic oral MRL for PCBs (0.00002 mg/kg/d). This MRL is for non-cancer health effects. Based on the average PCB concentration measured in the fish fillets, both subsistence and recreational fishers consuming less than a daily average of 10 g of fish fillets per day, would have estimated PCB exposures equal to, or less than, the ATSDR MRL. Subsistence and recreational fishers consuming 100 g/d of fish fillets would have an average estimated PCB exposure approximately 10 times greater than the ATSDR MRL. Individuals consuming 500 g/d of fish fillets would have an average estimated exposure of approximately 50 times the MRL. This indicates that people who consume very large amounts of fish caught from the sampling area will be exposed to PCBs at levels above ATSDR comparison values.
|Species||Number||Maximum [mg/kg]||Average [mg/kg]||95th Percentile [mg/kg]||Standard Deviation [mg/kg]||Coefficient of Variation [%]|
|LARGE MOUTH BASS||6||0.181||0.0667||0.164||0.0712||107|
|Number||Maximum [mg/kg]||Average [mg/kg]||95th Percentile [mg/kg]||Standard Deviation [mg/kg]||Coefficient of Variation [%]|
Figures 4 and 5 show how the estimated PCB cancer risk varies with the ingestion rate. These graphs illustrate that the theoretical cancer risk exceeds 10-4 for ingestion rates greater than approximately 25 g of fish fillets per day for both subsistence and recreational fishers. These graphs also suggest that people who eat large amounts of fish from the sampling area may be exposed to PCB levels above theoretical risk screening values. Information in the PCB Toxicological Profile (ATSDR 2000) was used to identify if these exposures would be expected to cause health effects.
The PCB Toxicological Profile (ATSDR 2000) briefly summarizes the results of 171 studies conducted using animals that ingested PCBs. Results of these studies suggest that the highest estimated exposure (based on an ingestion rate of 500 g/d, approximately 2.2 8-oz fish fillets per day) is about 10 time less than the exposure shown to cause less serious health effects in some animals. Interestingly, several other studies using higher exposures reported no adverse health effects for similar animal models. In total, the available data is inconclusive about type and severity of health effects that are likely to result following long-term (chronic) exposure to PCBs in fish fillets with concentrations similar to those measured in this sampling area. More moderate consumption rates are several orders of magnitude below these levels.
ATSDR expects that people who consume 1 to 2 8-oz fish fillets per month (approximately 10 g/d) will not experience any health concerns. Higher consumption rates, 3 to 4 8-oz fish fillets per week (approximately 100 g/d), are also likely to not cause health concerns. However, people who consume this amount of fish from the sampling area should pay attention to their preparation and cooking methods in order to reduce their PCB exposure. People who consume large amounts of fish from the sampling area, more than 2 8-oz fish fillets per day (approximately 450 g/d), will be exposed to levels of PCBs close to the levels where animal studies first begin to report less serious health effects. While it is uncertain if health effects would be expected in people consuming this amount of PCBs, it would be prudent for these consumers wishing to reduce their PCB exposure to consider supplementing their diet with other protein sources.
However, even if people do not eat the fish from this sampling area, they are still likely to ingest PCBs as a part of their normal diet. The concentration of PCBs measured in the fish from the Norfolk sampling locations is similar to that found in fish from other locations. In addition, the average PCB concentration in these fish is within a factor of 10 of the PCB concentrations measured in other common foods. Table 7 shows the concentration of PCBs measured in other foods. As shown in this table, the major dietary source of PCBs is fish.
The comparison of the fish sampling data from the Norfolk sampling locations with that of fish from other sources (and other foods) suggests that consumption of fish from the Norfolk sampling area is unlikely to cause an increase in PCB exposure for subsistence or recreational fishers, compared to that of other fish consumers around the country. In addition, due to the presence of PCBs in other foods, the exposure of subsistence fishers is expected to be only slightly higher than that of non-fish consumers. Direct health effects of fish consumers due to PCB exposure are unlikely. However people who wish to gain the nutritional value of fish and reduce their PCB exposure may due so by:
- Selecting the younger, smaller fish of the species (within legal limits)
- Removing the skin and fatty tissue in the belly and along the sides
- Baking or broiling the fish
- Throwing away the fatty juices and drippings
- Not eating the liver and other internal organs of the fish
These steps reduce PCB exposure because PCBs tend to accumulate in the fat and some internal organs. PCBs are also poorly metabolized; they tend to remain stored in fatty tissue. The younger (and therefore smaller) fish of a species have had less time to accumulate PCBs in their body. Removing the tissues where PCBs tend to accumulate reduces the amount of PCBs ingested by fish consumers. Baking and broiling tend to allow fatty juices, and their associated PCBs, to separate from the fillet.
ATSDR also evaluated the potential for health effects resulting from a large meal of blue crabs based on the average PCB concentration measured in the blue crabs taken from this sampling area. Results indicate that the PCB exposure following a large meal of blue crab would be thousands of times lower than the exposures that have resulted in less serious health effects for animal models. Even meals consisting of 1 to 2 pounds of blue crab would not be expected to cause health effects.
|Food Items Analyzed||Concentration of Total PCBs [ppm]|
|Maximum of All Fish Samples 1||0.89|
|Average of All Fish Samples 1||0.15|
|Fillets and Deep Fried Fish 2||0.55|
|Standard and Trim Milk 2||0.01|
|Colby and Mild Cheese 2||0.24|
|Ice Cream and Yogurt 2||0.08|
|Cereal, Rice, Spaghetti 2||0.07|
|Potatoes and Hot Chips 2||0.05|
|Snack Foods 2||0.02|
Arsenic was only detected in 5 of the 112 sampling events, 2 of the 89 fish fillets and 3 of the 21 blue crab sampling events. Table 8 shows the maximum, average and 95th percentile concentrations, standard deviation, and coefficient of variation for the species used to evaluate the subsistence and recreational fishers and blue crab consumers. Since the detection limits were used to estimate the arsenic concentrations in the non-detect sampling events, it is likely that the average concentrations are significantly less than those shown in this table.
|Number *||Maximum [mg/kg]||Average [mg/kg]||95th Percentile [mg/kg]||Standard Deviation [mg/kg]||Coefficient of Variation [%]|
|All Fish Species||89||1.9||0.525||0.5||0.170||32|
|* Numbers do not include the results from the one oyster and one clam sampling event|
The measured arsenic concentration reports total arsenic; arsenic in fish is typically rapidly converted to a non-toxic organic form. Therefore, the potential health effects associated with fish consumption are typically much less than that predicted by considering the total arsenic concentration. The MRL comparison values used in this evaluation are for the more toxic inorganic forms of arsenic. Studies indicate that between 0.1 - 41% of the total arsenic measured in fish is actually toxic inorganic form of arsenic (ATSDR 2000b). The following evaluation assumed that 20% of the total reported arsenic concentration was present as the more toxic inorganic form. Figures 6 and 7 show the estimated arsenic exposure of fish and blue crab consumers based on the daily ingestion rate and the assumed arsenic concentration.
These graphs illustrates that people who consume up to 200 g/d of fish fillet or 100 g/d of blue crab from the sampling area would not be exposed to concentrations of arsenic above ATSDR comparison values. Because blue crab is only available certain times of the year and some crab enthusiasts are known to eat large portions of crab in one sitting, ATSDR also evaluated the potential arsenic exposure following a large blue crab meal. The previous graph shows both the chronic and acute MRL for arsenic. It shows that a single large meal of blue crab could exceed the ATSDR chronic MRL, it will not exceed the acute MRL. In other words, no adverse health effects would be expected to occur after a single large fish meal. People who consume fish or blue crabs from the sampling area are not expected to develop health concerns.
Arsenic has been identified in a variety of different foods, frequently at concentrations within the range reported for the Norfolk area. Table 9 shows some of the arsenic concentrations reported in various foods. It is expected that fish consumers who choose other sources of fish or foods to replace what they are currently consuming from the Norfolk area will not significantly change their potential arsenic exposure.
|Food Items Analyzed||Arsenic Concentration 5 [ppm]|
|Maximum of Blue Crab Samples 1||4.3|
|Average of Blue Crab Samples 1||0.7|
|Maximum of Fin Fish Samples 1||1.9|
|Average of Fin Fish Samples 1||0.5|
|Detection Limit for VIMS Fin Fish and Blue Crab Samples 1||0.5|
|Marine Fish 2||3.05|
|Canned Fish 2||1.2|
|Meat and Poultry 2||0.02|
|Wild Rice 3||0.006 to 0.1 (Inorganic)|
|Bakery Goods and Cereal 2, 4||0.02|
Lead was only detected in 2 of the 112 sampling events for metals: once in the fish fillets and once in the clam sample. The detection limit was 0.1 mg/kg, the maximum concentration measured was 0.48 mg/kg (fish fillet), and the average concentration across the 112 sampling events was 0.1 mg/kg. There is no MRL comparison value for lead. However, the FDA has published a provisional tolerable total intake level (PTTIL) for lead based on the lowest level of lead exposures associated with adverse effects (FDA 1993). This guidance was used as the basis for ATSDR's evaluation. The greatest public health concern associated with chronic lead exposure is for young and unborn children; premature births, learning difficulties and reduced growth have been associated with lead exposure by pregnant women, infants or young children (ATSDR 1999b). Because of its low solubility, there is little concern about lead-related health effects resulting from eating a large amount of fish or blue crab at one meal (FDA 1993).
Table 10 shows the PTTIL value for various population groups, the assumed body weight for each group, and the resulting calculated number of daily or weekly fish meals an individual from that population group could consume and remain within FDA recommendations. This table indicates that people who consume fish caught within the bounds of the sampling data are not expected to experience health concerns due to lead exposure.
|Population Group||PTTIL [mg/d]||Assumed Body Weight [kg]||ATSDR Calculated Comparison Value [mg/kg/d]||Calculated Allowable Number of Daily (Weekly)* 8-oz Meals Based on the Average Concentration (0.1 mg/kg)|
|Adults||.075||70 (155 lbs)||0.0011||3.4 (23 - 24)|
|Pregnant Women||.025||50 (113 lbs)||0.0005||1.1 (7 - 8)|
|Older Children (7 years or older)||.015||25 (57 lbs)||0.0006||0.66 (4 - 5)|
|Young Children (6 years or younger)||.006||10 (23 lbs)||0.0006||0.26 (1 - 2)|
|The average concentration of lead measured in fish fillets was 0.1 mg/kg. |
All population groups were assumed to eat meals including 8-oz fish fillets. People who consume smaller fish fillets may consume fish more frequently.
* Values in this column show the number of daily meals with the number of weekly meals shown in parentheses
While reviewing this table, it is important to remember two points. First, these estimates assume that the only lead exposure people have would be from the fish. People who are exposed to lead occupationally or live in older homes (where there might be lead in the water pipes or paint) may want to reduce their total lead exposure by limiting the amount of fish they consume. Second, 110 of the 112 samples had non-detectable lead concentrations; the actual lead concentration was less than 0.1 mg/kg. While it is likely that the lead exposure is less than estimated, it is not possible to know how much less.
Lead has been detected in other foods. Table 11 shows the range of typical concentrations detected in common foods compared to those measured in the fish fillets from the Norfolk area (ATSDR 1999). While the maximum lead concentration measured in the fish fillets is clearly above the typical range, the detection limit is within the range for meat, fish and poultry. So while the detection limit is not low enough to estimate the potential exposure subsistence fishers may have to lead in fish caught in this area, it is expected that people who choose other sources of fish or protein will not significantly change their potential lead exposure.
|Food Group||Lead Concentration [mg/kg]|
|Maximum concentration measured in fish fillet samples 1||0.48|
|Detection limit for fish fillet and blue crab samples 1||0.1|
|Meat, fish and poultry 2||0.002 - 0.159|
|Dairy products 2||0.003 - 0.083|
|Grain and cereal products 2||0.002 - 0.136|
|Vegetables, fruit and fruit juices 2||0.005 - 0.649|
In the environment mercury can exist in several different forms; methyl mercury is the form usually found in fish (ATSDR 1994). Mercury was detected in 40 (36%) of the 112 sampling events for metals; 29 of the 89 (33%) fish fillet samples and 11 of the 21 (52%) blue crab samples. Table 12 shows the maximum and average mercury concentration for the fish fillet and blue crab samples, as well as the concentration of mercury reported in other fish. Mercury is commonly detected in fish. It tends to accumulate in fish tissue so that older fish and fish that feed on other fish have higher mercury concentrations. Mercury concentrations are generally low in other types of food; the average concentrations measured in fruits, vegetables, grains, beef, cow milk, poultry and eggs ranged from 0.001 to 0.05 mg/kg. The following table shows the ranges of mercury measured in fish from a variety of environments. This comparison indicates that the concentration of mercury in the fish fillets from the Norfolk area is within the range measured for other lakes and rivers. People who choose to eat fish from other sources are not expected to significantly change their potential exposure to mercury.
The FDA limits the concentration of methyl mercury in fish commercially sold to the public to 1 mg/kg or less. FDA based that limit on studies of people exposed to high levels of mercury. However, there is still some concern whether that limit will protect unborn children from health effects potentially associated with maternal consumption of methyl mercury (FDA 1994). In all of the 112 sampling events, measured concentrations were significantly less than the FDA limit. Figure 8 shows the estimated mercury exposure for fish fillet and blue crab consumers based on their ingestion rate.
This graph indicates that people can consume approximately 325 g/d of fish fillets and 500 g/d of blue crab and remain within ATSDR comparison values. This is equivalent to about 1.4 8-oz fish fillets per day, or more than 1 lb of blue crab per day.
|Sample Information||Mercury Concentration [mg/kg]|
|Maximum concentration measured in fish fillet samples 1||0.17|
|Average concentration measured in fish fillet samples 1||0.026|
|Maximum concentration measured in blue crab samples 1||0.04|
|Average concentration measured in blue crab samples 1||0.017|
|Detection limit for all samples 1||0.01|
|National Contaminant Biomonitoring Program (1984 - 1985) 2||0.10|
|Lake Ontario Trout 1977 2||0.24|
|Lake Ontario Trout 1988 2||0.12|
|Fish from the Savannah River 2||0.10 - 0.72|
|Canned tuna||0.10 - 0.75|
A variety of contaminants were detected in the fish fillet and blue crab samples. The maximum concentration of PCBs, arsenic, lead and mercury detected in some of the fish fillet or blue crab samples were above available comparison values. A more detailed evaluation considering the entire body of sampling data was completed. Results indicate the concentrations measured in the blue crab are below levels expected to cause health effects. While the concentration of PCBs, arsenic, lead and mercury in some of the fish samples were slightly above ATSDR comparison values, the concentrations are within the range normally measured in fish and other food groups. Recreational or subsistence fishers who choose to eat fish from other sources or substitute other foods for fish, are not expected to significantly change their potential exposure to these potential contaminants, because they are commonly found in fish and other foods.
Figure 9 illustrates the health concerns by the fish fillet ingestion rate. For the vast majority of fish fillet consumers there are no health concerns related to fish fillet consumption. People who consume fish several times a week may be exposed to PCBs, arsenic and mercury at levels greater than ATSDR's comparison values, but the exposure is not likely to cause health effects. People who routinely consume 2 or more 8-oz fish fillets per day will likely be exposed to PCBs as levels many times greater than the ATSDR comparison value. While this exposure is still below levels known to cause health effects, it would be prudent for those people to consider reducing their fish fillet consumption.
Regardless of their fish fillet ingestion rate, fish consumers can reduce their PCB exposure by selecting the younger, smaller fish of a species (within legal limits), removing the skin, belly fat, and internal organs prior to cooking, baking or broiling the fish fillet, and not eating the fatty juices or drippings.
Agency for Toxic Substances and Disease Registry (ATSDR) 1994. Toxicological Profile for Mercury (Update). US Department of Health and Human Services. May 1994.
ATSDR 1999. Toxicological Profile for Lead (Update). US Department of Health and Human Services. July 1999.
ATSDR 1999b. Lead ToxFAQs. US Department of Health and Human Services. June 1999.
Available at: http://www.atsdr.cdc.gov/tfacts13.pdf
Accessed on Nov 24, 2003.
ATSDR 2000. Toxicological Profile for Polychlorinated Biphenyls (Update). US Department of Health and Human Services. November 2000.
ATSDR 2000b. Toxicological Profile for Arsenic (Update). US Department of Health and Human Services. September 2000.
ATSDR 2001. Polychlorinated Biphenyl ToxFAQs. US Department of Health and Human Services. February 2001.
Available at: http://www.atsdr.cdc.gov/tfacts17.pdf
Accessed on Nov 19, 2003.
Chesapeake Bay Program. 1999. Kepone in Fish Tissue on the Decline! September 21, 1999.
Available at: http://www.chesapeakebay.net/status/fish-kepone.cfm?SUBJECTAREA=CROAKER
Accessed on Dec 10, 2003.
Chesapeake Bay Program. 2003. Fish Consumption Advisories within VA Waters of the Chesapeake Bay Watershed.
Available at: http://www.chesapeakebay.net/pubs/subcommittee/nsc/doc-fishadvisoryVA%20.pdf
Accessed on Dec 10, 2003.
US Environmental Protection Agency (EPA). 2000. Guidance for Assessing Chemical Contaminant Data for Use in Fish Advisories. Volume 2 Risk Assessment and Fish Consumption Limits, Third Edition. EPA 823-B-00-008. November 2000.
Available at: http://www.epa.gov/ost/fishadvice/volume2/
Accessed on Nov 18, 2003.
US Food and Drug Administration (FDA). 1993. Guidance Document for Lead in Shellfish. Center for Food Safety and Applied Nutrition. August 1993.
Available at: http://www.cfsan.fda.gov/~frf/guid-pb.html
Accessed on Nov 24, 2003.
FDA 1994. Mercury in Fish: Cause for Concern? FDA Consumer Magazine. September 1994. Available at: http://www.fda.gov/fdac/reprints/mercury.html
Accessed on Nov 24, 2003.
Tripathi. Virginia Department of Health. 2003. Personal Communication. December 16, 2003.
Virginia Department of Health (VDH). 2003. Fishing Advisories. Last Updated October 29, 2003.
Available at: http://www.vdh.state.va.us/hhcontrol/fishing_advisories.htm
Accessed on Dec 10, 2003.