Supplemental Information 

to Support the 

Fish Consumption Rates 

Technical Support Document 

July 20, 2012 

Toxics Cleanup Program 

Washington State Department of Ecology 

Olympia, Washington 

Contents 

Estimating Annual Fish Consumption Rates Using Data from Short-Term Surveys 

Recreational Fish Consumption Rates 

Health Benefits and Risks of Consuming Fish and Shellfish 

Chemical Contaminants in Dietary Protein Sources 

Salmon Life History and Contaminant Body Burdens 

 

Technical Issue Paper 

Estimating Annual Fish Consumption 

Rates Using Data from Short-Term 

Surveys 

 

Technical Issue Paper 

Estimating Annual Fish Consumption 

Rates Using Data from Short-Term 

Surveys

July 20, 2012 

Toxics Cleanup Program 

Washington State Department of Ecology 

Olympia, Washington 

 

Technical Issue Paper July 20, 2012 Page i 

Table of Contents 

Page

List of Tables .................................................................................................................................. ii

Introduction ......................................................................................................................................1

Limitations of short-term dietary studies .........................................................................................3

I. AMEC summary of short-term study limitations ..............................................................3

II. Comparison of short-term and longer-term survey data ....................................................4

III. Consumption frequency vs. consumption rate estimates ..............................................6

Quantitative methods for adjusting short-term dietary recall data ...................................................7

I. Adjustment of consumption frequency estimates ..............................................................7

II. Adjustment of consumption rate estimates ........................................................................8

III. Statistical reanalysis of national fish consumption data .............................................10

Summary ........................................................................................................................................12

References ......................................................................................................................................13

 
Page ii July 20, 2012 Technical Issue Paper 

List of Tables 

Page

Table 1. Mean population intake, consumer-only intake, and percent consumers of fish 

after 1, 3, 5, 7, 10, and 14 days of data collection ..........................................................8

Table 2. Adjustment of short-term (3-day) to long-term estimates and comparison to 

longer-term (14-day) fish consumption rates (Lambe et al. 2000b) ...............................9

Table 3. Adjustment of short-term (24-hour recall) to long-term estimates and comparison 

to long-term fish consumption rates - Suquamish Tribe study .......................................9

Table 4. Adjustment of short-term (2-day recall) to long-term estimates and comparison to 

long-term fish consumption rates – General Population (CSFII Data) ........................10

Table 5. Adult U.S. National Fish Consumption Rates, Consumers Only (From NHANES 

2003–2006) ...................................................................................................................11

 
Technical Issue Paper July 20, 2012 Page 1 

Introduction 

Ecology received comments on the draft Fish Consumption Rate Technical Support Document

(TSD) expressing concern with the way short-term fish consumption surveys were used to 

extrapolate consumption habits over the long term. 

In some populations, fish are consumed frequently and in large quantities (USEPA 2011). 

Estimating the rate of fish consumption for high-fish consuming groups is important; these 

groups may be at greater health risk if the fish they consume are from contaminated water 

bodies. 

Studies to estimate fish consumption rates for specific target populations are generally one of 

two types: creel surveys and interviews/mail surveys.1

 In a creel survey, fishermen are asked, 

among other things, how many fish they have caught and the number of family members with 

which they will share their catch. Creel survey data do not represent usual behavior because a 

fisherman may not have the same fishing success over time. As a result, results from creel 

studies have often been misinterpreted (USEPA 2011). 

Mail surveys, personal interviews, or telephone interviews ask participants to recall how much 

each family member ate over a certain period of time. The recall period determines whether the 

survey characterizes long-term (i.e., usual) intake or short-term consumption. For risk 

assessment, estimates of long-term consumption are needed, but long recall periods are 

associated with generally higher reporting errors (i.e., it is harder for people to remember what 

and how much they ate over a longer period of time). Short-term studies, on the other hand, may 

underestimate the number of people who consume fish and may overestimate long-term 

consumption. This is particularly true for high end consumers, because short-term studies tend to 

underestimate the number of days when respondents do not consume fish. 

Ebert et al. (1994) describe the problem as follows: 

Although an individual may consume at a rate in the upper 5th percentile of the 

distribution during a specific two-week period, it is not necessarily true that the 

same angler will be an upper 5th percentile consumer throughout the season. Rather, 

that individual may fish only occasionally, may only be interested in consuming 

certain species when they are available, and is not likely to be equally successful on 

every trip. The same uncertainty exists for anglers who have had no activity or 

success during a single two-week period but may, in fact, have different behavior at 

other times. It is likely that activity and consumption by individual anglers are highly 

variable through the season due to weather, fishing regulations, differences in 

species availability, and fluctuations in success rates for the individual angler. 

Although, much of this variability tends to be averaged out in longer-term estimates, 

extrapolation from single-day or short-term measurements can result in an over- or 

 

1 Additional information on fish consumption survey methodology is provided in Consumption Surveys for Fish and Shellfish: A 

Review and Analysis of Survey Methods (USEPA 1992) and Guidance for Conducting Fish and Wildlife Consumption Surveys 

(USEPA 1998). 
Page 2 July 20, 2012 Technical Issue Paper 

underestimation in the inter-individual variation of annual intake. Thus, short-term 

surveys may be useful for characterizing the central tendency in consumption rates 

but not the variance within the population. 

Attempts to account for the variance and uncertainty associated with the use of short-term 

consumption studies have generally included qualitative evaluation of data from a range of 

sources, coupled with consideration of the intended use of the data. 

In the draft Fish Consumption Rate TSD, Ecology identified four fish consumption surveys as 

appropriate for use in establishing a technically defensible default fish consumption rate for 

Washington: 

 Fish Consumption Survey of the Umatilla, Nez Perce, Yakama, and Warm Springs Tribe 

of the Columbia River Basin (Columbia River Inter-Tribal Fish Commission [CRITFC] 

1994). 

 Fish Consumption Survey of the Tulalip and Squaxin Island Tribes of the Puget Sound 

Region (Toy et al. 1996). 

 Fish Consumption Survey of the Suquamish Indian Tribe of the Port Madison Indian 

Reservation, Puget Sound Region (The Suquamish Tribe 2000). 

 Asian and Pacific Islander Seafood Consumption Study, King County (Sechena et al. 

1999). 

These four studies relied on personal interviews and food frequency surveys to obtain dietary 

recall information. The Suquamish survey quantified consumption rates using both a 24-hour 

recall and a food frequency survey. 

The draft TSD also included information on estimated United States per capita fish consumption. 

These national fish consumption rates were based on participant responses to 24-hour dietary 

recall surveys conducted on two nonconsecutive days. 

Public review comments on the draft TSD identified several issues of concern. Many reviewers 

noted correctly that the length of the survey period can have a significant effect on the resulting 

fish consumption rates. Some reviewers suggested that estimates of annual fish consumption 

rates be adjusted to account for lifetime consumption. One reviewer was concerned about the 

difference in mean consumption rates measured in the 24-hour recall portion of the Suquamish 

survey compared to the food frequency survey. 

This Technical Issue Paper discusses the limitations of using short-term studies to estimate longterm consumption, and presents options for adjusting short-term results to better characterize 

long-term consumption habits. It is a targeted examination of the issues raised by review 

comments received on the draft Fish Consumption Rates TSD, and was prepared within a limited 

time frame. Therefore, it may not include all available information on this subject. 

 
Technical Issue Paper July 20, 2012 Page 3 

Limitations of short-term dietary studies 

USEPA (2011) has acknowledged that short-term dietary records present problems when 

estimating long-term consumption rates. AMEC (2003), in a paper prepared for the Northwest 

Pulp and Paper Association, summarized the limitations of short-term dietary studies. Key 

elements of this summary are presented below. 

I. AMEC summary of short-term study limitations 

The length of the recall period in dietary studies can significantly affect the estimate of long-term 

fish consumption. For example, dietary data compiled by the U.S. Department of Agriculture 

(USDA) were collected from survey participants during two non-consecutive 24-hour periods 

(USEPA 2000). Because of the way in which sampling was conducted, the actual fish 

consumption behaviors reported are strongly biased toward those respondents who consume fish 

with a high frequency. 

All of the individuals included as fish consumers in the USDA estimate consumed fish at least 

once during the 2-day sampling period. To use these data to estimate long-term consumption 

rates, it is necessary to assume that the consumption behavior that occurred during the 2-day 

period is the same as the consumption behavior that occurs throughout every other 2-day period 

during the year. Thus, if an individual reported eating one fish meal during the sampling period, 

the extrapolation necessary to estimate long-term consumption requires the assumption that the 

individual continues to eat fish with a frequency of once every two days, or as many as 183 

meals per year. If an individual eats one-half pound (227 grams) of fish per meal, this results in a 

consumption rate of 114 grams/day. 

However, the individual who consumed fish during that sampling period may not actually be a 

regular fish consumer. In fact, that fish meal may have been the only fish meal that the individual 

consumed in an entire year. Thus, that person’s fish consumption rate would be substantially 

overestimated. Unfortunately, because of the way that the USDA data are collected, there is no 

way to determine if the behaviors reported by survey respondents during the sampling period 

were representative of their long-term behaviors. Thus, for the “consumers” in the population 

who were reported in these data, the reported consumption rates must have a minimum of one 

meal every two days. 

Conversely, individuals who did not consume fish during the 2-day sampling period were 

assumed to be non-consumers of fish when instead, those individuals may have been fish 

consumers who coincidentally did not consume fish during the 2-day sampling period. Because 

there are no data on which to base consumption estimates for these individuals, they must be 

assumed to consume 0 gram/day. However, they may in fact consume fish with a frequency 

ranging from as little as 0 meals per year to as much as one meal per day (or even more than one 

meal per day) on all days except the two that USDA conducted the survey. As with the high 

consumers identified in the USDA database, there is no way to determine whether 0 gram/day 

consumers are actually non-consumers or just individuals who consume with less frequency than 

once every two days. 
Page 4 July 20, 2012 Technical Issue Paper 

To demonstrate the effect that the length of the sampling period can have on resulting fish 

consumption rates, the findings of other short-term dietary studies can be compared to long-term 

studies. For example, a USDA survey reported by Mertz and Kelsay (1984) asked 29 people to 

track the types and amounts of food they ate for a one-year period. Because the daily dietary 

records kept by the study subjects could be condensed into 52 discrete one-week periods, it was 

possible to investigate the relationship between annual and weekly average fish consumption 

rates. The mean annual fish consumption rate from the Mertz and Kelsay (1984) survey data was 

estimated by summing the entire quantity of fish consumed by each survey respondent during the 

year and dividing by 365 days. The mean per capita “365-day” fish consumption rate developed 

using this approach was 26 grams/day. In addition, the mean daily fish consumption rate 

averaged over a one-week period, the “7-day” fish consumption rate, was estimated to be 26 

grams/day. Thus, the mean per capita consumption rate did not appear to be affected 

substantially by the recall period. Although this study included only 29 participants, results 

suggest that the mean is a fairly robust and meaningful measure of the average consumption rate, 

regardless of the survey period. 

The same cannot be said, however, of the upper percentiles of the fish consumption rate 

distribution. When comparing the 7-day intake rates collected by Mertz and Kelsay (1984) with 

the 365-day intake rates, the upper percentiles were very different. For example, when looking at 

the 7-day intake rates, the maximum value reported is 228 grams/day. However, when the 365-

day averages are developed, by combining all of the 7-day periods throughout the year, the 

maximum consumption rate is 78 grams/day. Thus, the short-term estimate overstates the actual 

long-term maximum by a factor of three. Similarly, when comparing the 95th percentiles reported 

for these two periods, the 7-day daily average (87.7 grams/day) substantially overestimated the 

365-day average (51.1 grams/day) by 72 percent, again demonstrating that the 7-day recall 

period did not provide a reliable surrogate for long-term consumption behavior at the upper end 

of the distribution. It is very likely that extrapolating from a 2-day sampling period would further 

overestimate long-term behavior. 

This problem has also been demonstrated and discussed by Ebert et al. (1994), who compared 

reported rates of self-caught fish consumption based on the duration of the recall period. Ebert et 

al. reported that when a one-day recall period was used by Pierce et al. (1981) and Puffer et al. 

(1981), “high-end” (95th percentile) intakes ranged up to 339 grams/day for consumers. When 

Pao et al. (1982) used a 3-day recall period, the 95th percentile intake for consumers was reported 

to be 128 grams/day. Using a 30-day recall period, Javitz (1980) reported a 95th percentile intake 

of 42 grams/day, and when a recall period of one year (365 days) was used (Fiore et al., 1989; 

Ebert et al. 1993), the 95th percentile estimates for sport-caught fish consumers ranged from 26 to 

37 grams/day. 

II. Comparison of short-term and longer-term survey 

data 

USEPA has acknowledged that short-term dietary records are problematic when attempting to 

estimate long-term rates of consumption. In its Exposure Factors Handbook (USEPA 2011), 

USEPA stated that “percentiles of the distribution of average daily intake reflective of long-term 

consumption patterns cannot in general be estimated using short-term (e.g., one week) data. Such 
Technical Issue Paper July 20, 2012 Page 5 

data can be used to adequately estimate mean average daily intake rates (reflective of short- or 

long-term consumption); in addition, short-term data can serve to validate estimates of usual 

intake based on longer recall.” 

As part of its compilation of fish consumption survey data for the 2011 Exposure Factors 

Handbook, USEPA obtained the raw data from a study of Michigan sport anglers that included 

both a long-term and short-term component (the West et al. 1989 study). The long-term 

component asked respondents about the frequency of fish meals during each of the four seasons, 

among other questions. The short-term component was a recall survey of fish meals consumed 

by all household members during the past 7 days. USEPA used the short-term data to validate 

the results of the longer recall part of the survey. The results of the analysis showed that there 

was general agreement between mean consumption estimates made using the 1-year recall and 

estimates made using the 7-day recall (14.4 grams/day and 14.0 grams/day for consumption of 

sport-caught fish, respectively), although there was some tendency for infrequent fish consumers 

to underestimate their usual frequency of fish consumption. 

A follow-up survey of Michigan sport anglers was conducted in 1993 (West et al. 1993); this 

survey used a one-week recall period. The mean consumption rate for sport-caught fish was 16.7 

grams/day, similar to the 1989 study. In addition, USEPA (1995) calculated an overall 95th

percentile fish consumption rate based on the 1993 7-day recall data; this value, 77.9 grams/day, 

was about double the 95th percentile estimated using the yearlong consumption data from the 

1989 Michigan survey (38.7 grams/day). USEPA states that “because this survey only measured 

fish consumption over a short (1 week) interval, the resulting distribution will not be indicative 

of the long-term fish consumption distribution, and the upper percentiles reported form the 

[1995] U.S. EPA analysis will likely considerably overestimate the corresponding long-term 

percentiles” (USEPA 2011). 

In the Suquamish Tribal fish consumption survey, one of the four studies selected as appropriate 

for use in developing a Washington State default fish consumption rate in the draft TSD, 

respondents provided information about fish consumption frequency during the period when 

specific fish and shellfish were “in season” and “during the rest of the year.” In addition, 

respondents were asked about fish or shellfish they had consumed in the previous 24 hours. All 

respondents indicated that they are consumers of seafood; however, 55 percent of respondents 

indicated that they had not consumed fish or shellfish in the previous 24 hours. Correspondingly, 

the mean consumption rate measured in the 24-hour recall portion of the study (1.5 g/kg-day) 

was nearly half the consumption rate estimated in the food frequency and portion size survey 

(2.7 g/kg-day). The authors concluded that “lower mean consumption rate for dietary recall 

suggests that a brief set of questions does not uncover all forms of consumption.” 

This conclusion is not consistent with the West et al. (1989) study described above, or with other 

literature on dietary surveys, which show that while a 24-hour recall does not capture day-to-day 

variability, on a population level it may provide a more accurate account of the consumption rate 

than the food frequency survey (Exponent 2012). Some studies indicate that longer-term diet 

history surveys, such as the Suquamish food frequency survey which looked back over a year, 

may be more likely to overestimate usual consumption than a 24-hour recall (Rasanen 1979). 

Others indicate that the upper percentile estimates of fish and shellfish intakes based on a 30-day 

daily average are lower than those based on two- or three-day daily averages (Tran et al. 2004). 
Page 6 July 20, 2012 Technical Issue Paper 

III. Consumption frequency vs. consumption rate 

estimates 

Dietary studies may be conducted for two purposes: (1) to determine the proportion of 

individuals in a population who are at risk, or (2) to evaluate long-term intake rates of a specific 

food or food group. 

To determine the proportion of individuals in a population who are at risk, habitual intake must 

be estimated (Rutishauser 2005). In this case, a single 24-hour recall survey is not adequate. 

Instead, at least two, preferably non-consecutive, days of dietary recall data are needed. Thus, a 

survey such as the USDA 1994–1996 and 1998 Continuing Survey of Food Intakes by 

Individuals (CSFII) may be appropriate for evaluating the proportion of individuals in the U.S. 

population who consume fish; however, this will not provide reliable estimates of individual 

consumption rates. This limitation is recognized by the authors of the USEPA (2002) Estimated 

Per Capita Fish Consumption in the United States (which used the CSFII data), who note that 

the limited time period for collecting information on dietary intake does not produce habitual 

intake estimates. Because short-term studies do not reflect habitual intake, the results of the 24-

hour recall portion of the four principle studies used by Ecology were used to qualitatively

evaluate the habitual intakes reported in the results of the longer-term food consumption surveys, 

rather than to develop a proposed fish consumption rate. 

To evaluate long-term (habitual) intake of a specific food or food group, a food frequency survey 

is preferable to short-term dietary recall data (Rutishauser 2005). One disadvantage of selfadministered surveys (such as mail surveys) is often the lack of detail that is provided. Using 

trained interviewers to collect diet histories rather than relying on self-administered 

questionnaires can overcome this problem. The surveys used in the four principle studies used by 

Ecology were all conducted by personal interview. 

Another disadvantage of food frequency surveys for general nutrition studies is the inability to 

accurately track ingestion of a large range of food types. Rutishauser (2005) recommends 

restricting the use of food frequency surveys to estimating long-term intake for a limited number 

of foods. The surveys used in the four principle studies used by Ecology included only questions 

regarding patterns of habitual seafood consumption. 

Basiotis et al. (1987) conducted a statistical analysis on data collected in the year-long USDA 

Beltsville Human Nutrition Research Center study. The analysis determined the average number 

of days of dietary intake data needed in order to estimate a “true” average of intakes for a group 

or for an individual. (In this case, the parameters of interest were energy and various nutrients.) 

An estimate was determined to be “precise” if it fell within + 10% of the average from the 365-

day dietary study for that individual or group, 95% of the time. The number of days required 

varied significantly by the numbers of individuals in the group, as well as by the nutrient of 

interest. For estimating “true” average daily energy intakes, the average number of days of intake 

data required ranged from 27 to 35 for individuals, with only three days of data required for a 

group. 

 
Technical Issue Paper July 20, 2012 Page 7 

Quantitative methods for adjusting shortterm dietary recall data 

I. Adjustment of consumption frequency estimates 

Carrington and Bolger (2001, 2002) developed a mathematical model to estimate the number of 

annual servings from short-term dietary surveys. Their model is based on the hypothesis that 

using results from short-term surveys to project food consumption over longer periods of time 

may overestimate the amount of food individuals consume and underestimate the number of 

individuals who consume the food. 

First, the algorithm decreases the number of seafood consumption events and increases the 

number of consumers using a Long-Term to Short-Term Consumer Ratio (LTSTCR). Second, 

the algorithm adjusts the LTSTCR for frequent seafood consumers using an exponential function 

that reduces the LTSTCR as the number of servings increases. An example of this function for 

adjusting daily serving data to projected annual servings is provided as: 

LTS = STS x 365 

LTSTCR(α/DS)β

Where 

LTS = projected annual servings (long-term estimate) 

STS = daily servings from short-term survey 

LTSTCR = long-term to short-term consumer ratio 

DS = daily serving 

α = adjustable parameter inversely related to consumption frequency to keep 

average consumption frequency constant 

β = adjustable parameter to determine the shape of the function and keep the low 

end of the curve consistent with short-term estimates 

Estimates based on this model were validated using the resulting seafood consumption rates in an 

exposure model to relate seafood consumption to levels of mercury in blood and hair. Using data 

from the 1989–1991 CSFII (USDA 1998), which recorded consumption over a 3-day period, the 

projected annual seafood servings were estimated as: 

LTS = D3S x 122 

LTSTCR(x/D3S)

Where 

D3S = 3-day servings from short-term survey 

LTSTCR = long-term to short-term consumer ratio = projected % consumers in the total 

population ÷ % consumers recorded in short-term survey = 70 to 90% ÷ 

33.5% = 2.1 to 2.7 

x = exponential slope set to maintain the mean per capita consumption near the 

value measured in the short-term survey 
Page 8 July 20, 2012 Technical Issue Paper 

In this assessment, a value of 1.5 was used for x to result in a mean per capita seafood 

consumption that was within 3% of the value reported in the 3-day survey. As an example, for 

individuals who report consuming 3 servings of seafood over the course of the 3-day survey, the 

projected annual consumption was calculated as: 

LTS = 3 servings/day x 122 = 227 to 257 servings/year 2.1 to 2.7(1.5/3)

Use of the consumption rates projected in this manner along with Monte Carlo simulation of 

species distribution and mercury concentration resulted in a close approximation (within a factor 

of 2 up to the 90th percentile) to mercury biomarker (blood and hair) survey data.

II. Adjustment of consumption rate estimates 

Lambe et al. (2000a) evaluated the influence of survey duration on estimates of food intakes 

using consumption rate data for 32 different foods (including fish) collected for 14 consecutive 

days from 948 teenagers. This evaluation supported the conclusion that shorter-term surveys 

used to predict long-term food consumption may overestimate the amount of food individuals 

consume; however, estimates of group mean intakes are reasonably independent of the survey 

duration once the sample size is sufficient. The results for fish ingestion are representative of 

most of the other 31 foods evaluated. Table 1 shows the survey results for fish consumption rates 

reported after 1, 3, 5, 7, 10, and 14 days. 

Table 1. Mean population intake, consumer-only intake, and percent consumers 

of fish after 1, 3, 5, 7, 10, and 14 days of data collection 

Study Length 

Mean Population Intake 

(g/day) 

Consumer-only Intake 

(g/day) Percent Consumers 

1-Day Diarya 13 112 12% 

3-Day Diarya 14 46 30% 

5-Day Diarya 13 31 41% 

7-Day Diarya 12 24 49% 

10-Day Diarya 12 21 56% 

14-Day Diary 12 18 63% 

Source: Lambe et al. 2000a 

a Data reported for the first 1, 3, 5, 7, and 10 days of a 14-day diary survey. 

While the the mean population intakes showed little difference between the various survey 

durations, food chemical exposure assessments generally require consumption rates for 

consumers rather than the total population (Renwick 1996), and the consumer-only rates were 

strongly influenced by survey duration. 

Using these data, Lambe et al. (2000b) investigated whether combining the data from a shortterm (e.g., 3-day) dietary survey with a long-term food frequency questionnaire could produce 

consumer-only consumption rate estimates comparable to those calculated from a 14-day food 

diary based on the premise that consumer-only intakes are really the mean total population 
Technical Issue Paper July 20, 2012 Page 9 

intakes adjusted for % consumers. As shown in Table 2 for fish ingestion, Lambe et al. 

demonstrated that the mean total population intakes, based on a 3-day food diary, can be divided 

by total % consumers, based on a food frequency questionnaire, to provide values comparable to 

the mean consumer-only intakes from a 14-day food diary. 

The adjusted mean consumer-only fish intake calculated as the total (consumers and nonconsumers) fish intake from the 3-day diary (14 g/day) divided by the total % consumers from 

the food frequency questionnaire (57%) is 25 g/day and is similar to the consumer-only intake 

reported from the 14-day diary survey of 18 g/day. 

This approach has been applied to the results of the short-term study data reported by The 

Suquamish Tribe (2000) in Table 3 and to the national (CSFII) data reported by USEPA (2002) 

in Table 4. 

Table 2. Adjustment of short-term (3-day) to long-term estimates and 

comparison to longer-term (14-day) fish consumption rates (Lambe et al. 2000b) 

Parameter 3-Day Diarya 14-Day Diary 

Long-Term % 

Consumersb

Mean Population Intake 14 g/day 12 g/day -- 

Consumer-only Intake 46 g/day 18 g/day -- 

Percent Consumers 30% 63% 57% 

Consumer-only 3-day 

recall adjusted for longterm exposure 

14 g/day = 25 g/day 57% consumers 

Source: Lambe et al. 2000b

a Data reported for the first 3 days of a 14-day diary survey. 

b From food frequency survey. 

-- = intake rates not calculated from food frequency questionnaire 

Table 3. Adjustment of short-term (24-hour recall) to long-term estimates and 

comparison to long-term fish consumption rates - Suquamish Tribe study 

Parameter 24-hour Recall Long-Term Recall 

Long-Term % 

Consumersb

Mean Population Intake 119 g/day 214 g/day -- 

Consumer-only Intake 263a g/day 214 g/day -- 

Percent Consumers 45% 100% 97% 

Consumer-only 1-day 

intake adjusted for longterm exposure 

119 g/day = 123 g/day 97% consumers 

Source: The Suquamish Tribe 2000 

a Calculated as 119 g/day/45% 

b Upper-bound of non-consumers reported as 3% (The Suquamish Tribe 2000) 

-- = intake rates not calculated from food frequency survey 
Page 10 July 20, 2012 Technical Issue Paper 

Table 4. Adjustment of short-term (2-day recall) to long-term estimates and 

comparison to long-term fish consumption rates – General Population (CSFII 

Data) 

Parameter 2-day Recall Long-Term Recall 

Long-Term % 

Consumersb

Mean Population Intake 19.9 g/day -- -- 

Consumer-only Intake 74.3a g/day -- -- 

Percent Consumers 27% -- 85.4% 

Consumer-only 2-day 

recall adjusted for longterm exposure 

19.9 g/day = 23.3 g/day 85.4% consumers 

Source: USEPA 2002 

a Calculated as 74.3 g/day/27%. 

b Percent of people who never eat meat reported as 14.6 (+ 3%) in (Stahler 2006) 

-- = not reported 

Applying this approach results in minor upward adjustments of the Suquamish 24-hour recall 

(from 119 g/day to 123 g/day) and United States 2-day recall (from 19.9 g/day to 23.3 g/day) 

survey data. The relatively small impact of the adjustment is due to the assumption that a large 

percentage of the population eats fish (97% for the Suquamish population and 85.4% for the U.S. 

population). 

III. Statistical reanalysis of national fish consumption 

data 

Ecology conducted a statistical reanalysis of national and regional-specific fish consumption data 

to derive consumption estimates for different fish species groups (e.g., shellfish, anadromous, 

non-anadromous), estimates of fish consumed based on harvest patterns, and long-term national 

fish consumption estimates statistically derived from short-term episodic2 dietary data. Detailed 

descriptions of the statistical methods used to reevaluate the national and regional-specific data 

are presented in Draft Statistical Analysis of National and Washington State Fish Consumption 

Data (Polissar et al. 2012), a companion document to the Fish Consumption Rate TSD. 

The methodology developed by Tooze et al. (2006), which estimates the usual intake of 

episodically consumed foods such as fish, was used to reassess data from individual responses to 

the 2003–2006 National Health and Nutrition Examination Survey (NHANES). 

These methods were not applied to the regional-specific fish consumption data due to differences 

in data collection methods: the national data were based on two 24-hour recall surveys, while the 

regional data were based on food frequency questionnaires. 

Detailed descriptions of the methodology are provided in the following technical literature: 

 

2 “Episodic” refers to consumption that is intermittent or occasional. 
Technical Issue Paper July 20, 2012 Page 11 

 Tooze et al. 2006. A New Statistical Method for Estimating the Usual Intake of 

Episodically Consumed Foods with Application to Their Distribution. Journal of the 

American Dietetic Association, October 2006, 106: 1575-1587 

 Kipnis et al. 2009. Modeling Data with Excess Zeros and Measurement Error: 

Application to Evaluating Relationships between Episodically Consumed Foods and 

Health Outcomes. Biometrics, December 2009, 65: 1003-1010. 

 Subar et al. 2006. The Food Propensity Questionnaire: Concept, Development, and 

Validation for Use as a Covariate in a Model to Estimate Usual Food Intake. Journal of 

the American Dietetic Association, October 2006, 106: 1556-1563. 

 Keogh and White, 2011. Allowing for never and episodic consumers when correcting for 

error in food record measurements of dietary intake. Biostatistics (2011), 12, 4, PP. 624-

636. 

 Dodd et al. 2006. Statistical Methods for Estimating Usual Intake of Nutrients and Foods: 

A Review of the Theory. Journal of the American Dietetic Association, October 2006, 

106: 1640-1650. 

The fish consumption estimates resulting from this reanalysis are presented below. For 

comparison, national estimates were also derived based on standard statistical methods that did 

not account for estimating the usual, or long-term, fish dietary consumption from episodically 

consumed foods. These estimates are also presented below. 

Table 5. Adult U.S. National Fish Consumption Rates, Consumers Only (From 

NHANES 2003–2006) 

Usual Intake Based on Tooze et al. Methodology (Data from NHANES 2003-2006) 

Population 

National Species Group Descriptive Statistics (grams/day) 

50th Percentile 90th Percentile 95th Percentile 

National U.S. 

Population 

all 12.7 42.5 56.6 

finfish 9.0 31.8 43.3 

shellfish 2.4 13.2 20.5 

Adapted from Table 4, Polissar et al., 2012 

Observed Consumption on Two Days (Data from NHANES 2003-2006) 

Population 

National Species Group Descriptive Statistics (g/day) 

50th Percentile 90th Percentile 95th Percentile 

National U.S. 

Population 

all 37.9 127.9 168.3 

finfish 34.6 115.3 149.8 

shellfish 25.7 100.5 146.6 

Adapted from Table 3, Polissar et al., 2012 

 
Page 12 July 20, 2012 Technical Issue Paper 

Summary 

Because food intake rates from short-term surveys are highly variable and result in a wide range 

of fish consumption patterns, these surveys tend to overestimate the prevalence of low and high 

intake rates. This variation is particularly relevant for assessments of food chemical exposure 

where the parameters of interest are at the extremes of the exposure distribution rather than at the 

center (Lambe 2002). 

Attempts to account for the variance and uncertainty associated with the use of short-term 

consumption studies have generally included qualitative evaluation of data from a range of 

sources, coupled with consideration of the intended use of the data. To evaluate long-term 

(habitual) seafood intake, longer-term survey data are preferable to short-term dietary survey 

data. 

While there are mathematical approaches that attempt to adjust short-term recall data for longerterm consumption estimates, such adjustments are complex, do not provide a clear improvement 

in the fish consumption rate estimate, and are themselves subject to uncertainty. If the percentage 

of fish consumers is high in the population being considered, these adjustments result in a 

relatively minor change in the estimated fish consumption rate. 

Ecology conducted a statistical reanalysis of short-term national fish consumption data to 

estimate long-term (usual) national fish consumption rates, using the methodology of Tooze 

et al. (2006). National fish consumption rate estimates based on this reanalysis are significantly 

lower than estimates based on simple extrapolation of the short-term fish consumption data. 

Additional information is provided in Polissar et al. (2012). 

 
Technical Issue Paper July 20, 2012 Page 13 

References 

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the Umatilla, Nez Perce, Yakima, and Warm Springs Tribes of the Columbia Basin. 

Technical Report 94-3. October 1994. 

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consumption of freshwater fish among Maine anglers. N. Am. J. Fish. Mgt. 13:737-745. 

Ebert, E.S., Price, P.S., and Keenan, R.E. 1994. Selection of Fish Consumption Estimates for 

Use in the Regulatory Process. J. Expos. Anal. Environ. Epidemiol. 4(3):373-393. 

Exponent. 2012. Letter from Mark W. Johns and Michael R. Garry, Exponent, to Washington 

State Department of Ecology, Re: Comments on Publication No. 11-09-050, Fish 

Consumption Rates Technical Support Document, A Review of Data and Information 

about Fish Consumption in Washington. January 17, 2012. 

Fiore, B.J., Anderson, H.A., Hanrahan, L.P., Olson, L.J., and Sonzogni, W.C. 1989. Sport fish 

consumption and body burden levels of chlorinated hydrocarbons: A study of Wisconsin 

anglers. Archives of Environmental Health 44(2):82-88. As cited in AMEC 2003. 

Javitz, H. 1980. Seafood Consumption Data Analysis: Final Report. Prepared by SRI 

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Keogh and White. 2011. Allowing for never and episodic consumers when correcting for error in 

food record measurements of dietary intake. Biostatistics (2011), 12, 4, PP. 624-636. 

 
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Kipnis, V., Midthune, D., Buckman, D.W., Dodd, K.W., Guenther, P.M., Krebs-Smith, S.M., 

Subar, A.F., Tooze, J.A., Carroll, R.J., and Freedman, L.S. 2009. Modeling Data with 

Excess Zeros and Measurement Error: Application to Evaluating Relationships between 

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1003-1010. 

Lambe, J., Kearney, J., Leclercq, C., Zunft, H., De Henauw, S., Lamberg-Allardt, C., Dunne, A., 

and Gibney, M. 2000a. The Influence of Survey Duration on Estimates of Food Intakes 

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Lambe, J., Kearney, J., Leclercq, C., Berardi, D., Zunft, H., Sulzer, S., De Henauw, S., De 

Volder, M., Lamberg-Allardt, Karkkainen, M., C., Dunne, A., and Gibney, M. 2000b. 

Enhancing the Capacity of Food Consumption Surveys of Short Duration to Estimate 

Long Term Consumer-Only Intakes by Combination with a Qualitative Food Frequency 

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Lambe, J. 2002. The Use of Food Consumption Data in Assessments of Exposure to Food 

Chemicals Including the Application of Probabilistic Modeling. 

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study. Am. J. Clin. Nutr. 40(Suppl. 6):1323-1326. 

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individuals: amount per day and per eating occasion. Home Economic Report No. 44. 

U.S. Department of Agriculture, Washington, DC. As cited in USEPA 2011. 

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Study: Preliminary Report. Tacoma-Pierce County Health Department, Seattle, WA. 

December 1981. As cited in AMEC 2003. 

Polissar, N.L., Neradilek, M., Aravkin, A.Y., Danaher, P., and Kalat, J. Draft Statistical Analysis 

of National and Washington State Fish Consumption Data. Prepared for Washington 

State Department of Ecology by The Mountain-Whisper-Light Statistics, Seattle, 

Washington. June 2012. 

Puffer, J.W., Azen, S.P., Duda, M.J., and Young, D.R. 1982. Consumption rates of potentially 

hazardous marine fish cuaght in the metropolitan Los Angeles area. Grant R 807 120010. 

University of Southern California School of Medicine for Environmental Research 

Laboratory. As cited in AMEC 2003. 

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24-hour recall and the dietary history interview. Am. J. Clin. Nutr. 32:2560-2567. 

December 1979. 

Renwick, A. G., 1996. Needs and Methods for Priority Setting for Estimating the Intake of Food 

Additives. Food Additives and Contaminants, 13, 467-475. 

Rutishauser, I. 2005. Dietary Intake Measurements. Public Health Nutrition: 8(7A), 1100-1107. 
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Sechena, R., Nakano, C., Liao, S., Polissar, N., Lorenzana, R., Truong, S., and Fenske, R. Asian 

and Pacific Islander Seafood Consumption Study (EPA 910/R-99-003). May 27, 1999. 

Stahler, C. 2006. How Many Adults Are Vegetarian? Results of a survey conducted by Harris 

Interactive® on behalf of The Vegetarian Resource Group. Vegetarian Journal 2006 

Issue 4. http://www.vrg.org/journal/vj2006issue4/vj2006issue4poll.htm

Subar, A.F., Dodd, K.W., Guenther, P.M., Kipnis, V., Midthune, D., McDowell, M. Tooze, J.A., 

Freedman, L.S., Krebs-Smith, S.M. 2006. The Food Propensity Questionnaire: Concept, 

Development, and Validation for Use as a Covariate in a Model to Estimate Usual Food 

Intake. Journal of the American Dietetic Association, October 2006, 106: 1556-1563. 

The Suquamish Tribe 2000. Fish Consumption Survey of the Suquamish Indian Tribe of the Port 

Madison Indian Reservation. 

Dodd, K.W., Guenther, P.M., Freedman, L.S., Subar, A.F., Kipnis, V., Midthune, D., Tooze, 

J.A., Krebs-Smith, S.M. 2006. Statistical Methods for Estimating Usual Intake of 

Nutrients and Foods: A Review of the Theory. Journal of the American Dietetic 

Association, October 2006, 106: 1640-1650. 

Tooze, J.A., Midthune, D., Dodd, K.W., Freedman, L.S., Krebs-Smith, S.M., Subar, A.F., 

Guenther, P.M., Carroll, R.J., Kipnis, V. 2006. A New Statistical Method for Estimating 

the Usual Intake of Episodically Consumed Foods with Application to Their Distribution. 

Journal of the American Dietetic Association, October 2006, 106: 1575-1587 

Toy, K.A., Polissar, N.L., Liao, S., Mittelstaedt, G.D. 1996. A fish consumption survey of the 

Tulalip and Squaxin Island Tribes of the Puget Sound Region. Tulalip Tribes, 

Department of the Environment, Marysville, Washington. 

Tran, N.L., Barraj, L., Smith, K., Javier, A., and Burke, T.A. 2004. Combining Food Frequency 

and Survey Data to Quantify Long-Term Dietary Exposure: A Methyl Mercury Case 

Study. Risk Analysis, Vol. 24, Issue 1, pp 19-30. February 2004. 

USEPA (U.S. Environmental Protection Agency). 1992. Consumption Surveys for Fish and 

Shellfish: A Review and Analysis of Survey Methods. U.S. Environmental Protection 

Agency, Office of Water. EPA 822/R-92-001. February 1992. 

USEPA. 1995. Fish consumption estimates based on the 1991-1992 Michigan sport anglers fish 

consumption study. Final Report. Prepared by SAIC for the Office of Science and 

Technology, Washington, DC. As cited in USEPA 2011. 

USEPA. 1998. Guidance for Conducting Fish and Wildlife Consumption Surveys. U.S. 

Environmental Protection Agency, Office of Water. EPA-823-B-98-007. November 

1998. 

USEPA. 2000. Methodology for deriving ambient water quality criteria for the protection of 

human health. U.S. Environmental Protection Agency, Office of Water, Office of Science 

and Technology. EPA-822-B-00-004. October 2000. 

USEPA 2002. Estimated Per Capita Fish Consumption in the United States. EPA-821-C-02-003. 
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USEPA. 2011. Exposure Factors Handbook: 2011 Edition. EPA/600/R-090/052F. U.S. 

Environmental Protection Agency Office of Research and Development, Washington, 

DC. September 2011. 

West, P.C., M.J. Fly, R. Marans, and F. Larkin. 1989. Michigan sport anglers fish consumption 

survey. A report to the Michigan Toxic Substance Control Commission. Michigan 

Department of Management and Budget, Contract No. 87-20141. As cited in AMEC 

2003. 

West, P.C., Fly, J.M., Marans, R., Larkin, F., and Rosenblatt, D. 1993. 1991-92 Michigan Sport 

Anglers Fish Consumption Study. Prepared by the University of Michigan, School of 

Natural Resources, for the Michigan Department of Natural Resources. Technical Report 

No. 6. May 1993. As cited in AMEC 2003. 
Technical Issue Paper 

Recreational Fish Consumption Rates 

 

Technical Issue Paper 

Recreational Fish Consumption Rates 

July 20, 2012 

Toxics Cleanup Program 

Washington State Department of Ecology 

Olympia, Washington 

 

Technical Issue Paper July 20, 2012 Page i 

Table of Contents 

Page

List of Tables ................................................................................................................................... i

Introduction ......................................................................................................................................1

Marine Recreational Studies ............................................................................................................2

I. Commencement Bay Seafood Consumption Study (Pierce et al. 1981) .............................3

II. Seafood Catch and Consumption in Urban Bays of Puget Sound (McCallum 

1985) ....................................................................................................................................4

III. 1983-1984 Puget Sound Survey (Landolt et al. 1985, 1987) ...............................................5

IV. Survey of Fish Consumption Patterns of King County Recreational Anglers 

(Mayfield et al. 2007) ..........................................................................................................6

Freshwater Recreational Studies ......................................................................................................8

I. Consumption Patterns of Anglers Who Frequently Fish Lake Roosevelt (WDOH 

1997) ....................................................................................................................................8

II. Lake Whatcom Residential and Angler Fish Consumption Survey (WDOH 2001) ...........9

III. Survey of Fish Consumption Patterns of King County Recreational Anglers 

(Parametrix 2003) ................................................................................................................9

Summary ........................................................................................................................................11

References ......................................................................................................................................13

Appendices 

Appendix A. Recreational Fish Consumption Rates 

List of Tables 

Tables 

Page

Table 1. Fish and Shellfish Consumption Rates (g/day) for Marine Recreational Fishers in 

King County, WA ...........................................................................................................7

Table 2. Fish Consumption Rates (g/day) for Freshwater Recreational Anglers in King 

County, WA ..................................................................................................................10

Table 3. Summary of Recreational Fish Consumption Rates .....................................................11
Page ii July 20, 2012 Technical Issue Paper 

This page purposely left blank for duplicate printing. 
Technical Issue Paper July 20, 2012 Page 1 

Introduction 

The draft Fish Consumption Rates Technical Support Document (TSD) identified four 

fish/shellfish dietary surveys as appropriate for use in establishing a technically defensible 

default fish consumption rate for Washington. These surveys included two Native American 

fish/shellfish dietary surveys for three tribal populations in Puget Sound, one Native American 

finfish dietary survey for four tribal populations in and around the Columbia River basin, and 

one Asian and Pacific Islander fish/shellfish dietary survey from King County. In addition, the 

draft TSD provided information on United States per capita fish consumption, based on the U.S. 

Department of Agriculture’s 1994–1996 and 1998 food intake surveys. 

The draft TSD did not provide specific information about consumption of fish and shellfish by 

recreational fishers.1

 Ecology received review comments requesting the inclusion of additional 

fish consumption information for this receptor group. This issue paper summarizes regionalspecific and selected national fish dietary information for recreational fishers. It is a targeted 

examination of the issues raised by review comments received on the draft Fish Consumption 

Rates TSD, and was prepared within a limited time frame. Therefore, it may not include all 

available information on this subject. 

Although data for the general population is useful for evaluating fish consumption rates, data on 

recreational fishing are needed to assess exposure to individuals with potentially higher fish 

consumption levels. Recreational fishers may consume fish more frequently, and may consume 

larger portions at each meal, than the general population. In addition, they may frequently fish 

from a single contaminated source. These factors may put recreational fishers at higher risk of 

exposure to contaminants in fish and shellfish. 

 

 

1 In this issue paper, the term “fisher” denotes a person who fishes for any type of seafood by any method, including finfish and shellfish. The 

term “angler” refers to a person who fishes with hook and line. Some fish consumption surveys reviewed during preparation of this issue paper 

use the terms “fisher”, “fisherman”, and “angler” interchangeably. 
Page 2 July 20, 2012 Technical Issue Paper 

Marine Recreational Studies 

This section describes fish consumption rate studies for marine and estuarine finfish and 

shellfish. Four recreational fish consumption studies have been conducted in marine/estuarine 

areas of Washington State. Three of these were conducted in the early to mid-1980s, over 25 

years ago (Pierce et al. 1981; McCallum 1985; Landolt et al. 1985, 1987), and the fourth was 

conducted in 2007. All four studies were creel surveys, in which anglers were interviewed while 

fishing. They were asked questions about how much fish they had caught on the day of the 

survey, and the number of family members with which they intended to share the catch. These 

data do not represent usual behavior because an angler does not catch the same number of fish on 

each fishing occasion. 

In a creel study, the target population is typically anyone who fishes at the location being 

studied. Creel studies may not provide data representative of the target population, because the 

probability of being sampled is not the same for all members of the target population (USEPA 

2011). The Environmental Protection Agency’s (EPA) Exposure Factors Handbook (2011) 

describes the problem as follows: 

“For instance, if the survey is conducted for 1 day at a site, then it will include all 

persons who fish there daily, but only about 1/7 of the people who fish there 

weekly, 1/30 of the people who fish there monthly, etc. In this example, the 

probability of being sampled (or inverse weight) is seen to be proportional to the 

frequency of fishing. However, if the survey involves interviewers revisiting the 

same site on multiple days, and persons are only interviewed once for the survey, 

then the probability of being in the survey is not proportional to frequency; in 

fact, it increases less than proportionally with frequency.” 

In most creel studies, there is no mention of sampling weights; by default, all weights are set to 

one, implying equal probability of sampling. Because the sampling probabilities in a creel 

survey, even with repeated interviewing at a site, are highly dependent on fishing frequency, the 

fish intake distributions reported for these surveys may overestimate intake rates of the total 

fishing population that uses the sampled water body (USEPA 2011). 

Price et al. (1994) proposed using the inverse frequency of fishing to adjust data derived from 

creel surveys to statistically “correct” for the increased probability of encountering frequent 

fishers (relative to infrequent fishers). Price’s reanalysis of the Commencement Bay Seafood 

Consumption Study data is described below (Section I). 

Keill and Kissinger (1997, pp. 21-22) noted that multiplying the number of infrequent anglers by 

the inverse of the number of days that they fish per year results in greater weight being given to 

the infrequent angler. For example, an individual who fishes once a year would be assigned a 

weight 365 times an individual who fishes daily. Keill and Kissinger (1997) maintained that this 

adjustment obscures and negates the importance of the subpopulation most likely to incur 

exposure to contaminated fish. They noted that some researchers have specifically excluded 

infrequent anglers from surveys, and/or nonconsumers from analyses, in order to avoid 

characterizing consumption for a population that is not at risk. 
Technical Issue Paper July 20, 2012 Page 3 

CalEPA (2001) stated that many factors can affect the relationship between fishing frequency 

and the probability of sampling, including the actual timing and frequency of sampling, the 

methods for selecting respondents, and whether repeat interviews occur. In addition, a fisher’s 

frequency of fishing may be correlated with the time of day, day of week, climate and seasonal 

factors, and other parameters that may not be equivalent across sampling days. These factors are 

not accounted for in the basic weighting adjustment used by Price et al. (1994). 

Other limitations associated with creel studies were described in the draft Fish Consumption 

Rate TSD, as well as by CalEPA (2001) and Kissinger (2010). These include: 

 Difficulties in eliciting year-round consumption information; 

 Difficulties in using visual aids or other materials to assist in quantifying consumption; 

 Inability to obtain a random, unbiased sample of the study population; 

 Willingness (or unwillingness) of the interviewee to provide information in a field 

situation when the interviewee would rather be fishing; 

 Concerns about accurate transmission of fishing information due to trust issues; 

 Language and communication issues if anglers do not speak English; 

 Inadequate measurement of fish consumption over the geographic area of concern; 

 Inadequate assessment of fishing activity at all times when fishing might occur; 

 Underestimation of catch associated with measuring catch prior to the end of the fishing 

activity; and 

 Problems in relating an angler’s catch to consumption rates of the angler’s family and 

community. 

The Washington State studies are discussed below. Additional studies of marine/estuarine fish 

consumption rates are summarized in Table A-1 (Appendix A of this Technical Issue Paper). 

These include other studies on the West Coast, particularly along the California coast, as well as 

studies from New York/New Jersey, Texas, and Delaware. 

I. Commencement Bay Seafood Consumption Study 

(Pierce et al. 1981) 

Pierce et al. (1981) conducted a creel survey in 1980 for the Tacoma-Pierce County Health 

Department to study seafood consumption patterns and demographics of sport fishermen in 

Commencement Bay, near Tacoma. The objectives of the survey were to: determine the extent to 

which local species of fish and shellfish were used as food; determine which species were most 

commonly consumed; and assess methods of preparation of the catch. Only successful anglers 

were interviewed, and salmon were excluded from the study because they were considered to 

have minimal contact with Commencement Bay pollutants. 

Surveys of shore and boat anglers were conducted in the mornings and evenings, and each 

subarea was sampled five times during the summer and four times during the fall, except for one 
Page 4 July 20, 2012 Technical Issue Paper 

area that was sampled only twice during the fall. The boat fishing area was sampled four times 

during the fall only. Interviews were conducted only with anglers who had successfully caught 

fish, and each angler was interviewed only once during the survey period. The following data 

were recorded: species, wet weight, size of the family, place of residence, fishing frequency, 

planned uses of the fish, age, sex, and race. Sampling periods lasted as late as 1:00 a.m.; 

however, the study authors noted that a considerable portion of the total catch was suspected to 

have been obtained during all-night fishing (CalEPA 2001). 

A total of 304 interviews of shore anglers were conducted during the summer of 1980 (July to 

September), and 204 interviews of shore and boat anglers were conducted in the fall (September 

to November). About 60 percent of the anglers interviewed were white, 20 percent were black, 

19 percent were Asian, and the remainder was Hispanic or Native American (USEPA 2011). The 

dominant species caught were Pacific hake and walleye pollock. Pierce et al. (1981) did not 

present a distribution of fish intake or a mean fish intake rate. 

In 1994, Price et al. obtained the raw data from this survey and re-analyzed it using sampling 

weights proportional to inverse fishing frequency. Price et al. (1994) calculated a median intake 

rate of 1.0 g/day and a 90th percentile rate of 13 g/day. When equal weights were applied, the 

median intake rate was 19 g/day and the 90th percentile was 155 g/day. According to USEPA, all 

of these values are probably underestimates, because the sampling probabilities are less than 

proportional to fishing frequency; thus, the true median for the target population is probably 

somewhat above 1.0 g/day, and the true 50th percentile of the resource utilization distribution is 

probably higher than 19 g/day (USEPA 2011). 

Limitations to this study included the following (CalEPA 2001): 

 Local seafood contamination in this area may have suppressed the reported fish 

consumption rate; 

 Salmon were excluded from the fish consumption rate; 

 Anglers who had not caught any fish at the time of the interview were not included; and 

 Sampling was conducted in summer and fall only; no samples were collected in winter or 

spring. 

II. Seafood Catch and Consumption in Urban Bays of 

Puget Sound (McCallum 1985) 

McCallum (1985) studied shore-based recreational fishers in Elliott Bay, Everett Harbor (Port 

Gardner), and Sinclair Inlet. The objective of the study was to collect information on the species 

consumed, the amount consumed, the frequency of fish or shellfish consumption, and the 

location of collection. Of particular concern was whether Southeast Asian immigrants or other 

low income groups were frequent users of urban fishing sites and whether they consumed the 

more contaminated species (e.g., sole) or the more contaminated parts (e.g., fish liver, crab 

hepatopancreas). 
Technical Issue Paper July 20, 2012 Page 5 

Shore-based fishing, crabbing, or clamming sites within contaminated bays were sampled. Onsite interviews were conducted between July 1983 and June 1984. Initial survey attempts were 

conducted on different days of the week and at different hours of the day. Subsequently, survey 

effort was adjusted to high use days/times. The survey schedule was also modified to reflect 

seasonal changes in fishing, crabbing, or clamming. Only those fishers seeking bottomfish, 

crabs, or clams were fully interviewed. Anglers fishing for salmon or squid were excluded, as 

these species are highly migratory and were not expected to be impacted by contaminants in the 

urban bays. 

Tetra Tech (1988) calculated a 95th percentile consumption rate of 24.3 g/day based on the data 

collected during this study. 

Limitations to this study included (Kissinger 2010): 

 Language barrier problems in conducting interviews; 

 Many individuals refused to be interviewed; and 

 Interviews were not conducted at night (midnight to 6 a.m.), a time period when fishing 

may have occurred. 

III. 1983-1984 Puget Sound Survey (Landolt et al. 1985, 

1987) 

Landolt et al. (1985, 1987) conducted a two-year study of recreational fish and shellfish catch 

and consumption from four urban embayments of Puget Sound: Commencement Bay, Elliott 

Bay, Sinclair Inlet, and Edmonds. The objectives of the study were to: identify the most 

commonly consumed species; assess the demographic characteristics of the fishing population; 

describe patterns of consumption; and estimate the quantity of selected chemicals consumed by 

anglers and their families. 

Personal interviews were used to obtain species-specific catch and consumption information. 

Over 4,000 shore fishers were interviewed during the first year (November 1983 through 

November 1984). Sampling times were initially selected at random, and interviews were 

conducted during all times of the day. After the preferred fishing times were identified, sampling 

focused on those times when the largest number of fishers were expected (CalEPA 2001). The 

second year of the study focused primarily on chemical analysis of tissue samples, but catch and 

consumption patterns for 437 boat anglers at two of the four embayments (Elliott Bay, 

Commencement Bay) were also evaluated during February to October 1985. 

Calculations of consumption rates were based on estimates of the weight of the catch (fish in 

hand) divided by the number of consumers in the household, and by the number of days since 

fish caught at the same site were last eaten. This value was multiplied by a cleaning factor of 0.3 

for fish and 0.49 for squid and crab, to derive the mean daily grams of available edible portion 

per person. Geometric means were then calculated for each embayment and ethnic group. An 

overall geometric mean daily fish consumption rate of 11 g/day for all ethnic groups and species 

was calculated. 
Page 6 July 20, 2012 Technical Issue Paper 

Geometric means ranged from 8 to 14 g/day per person. Consumption rates for the most common 

species were significantly higher than the average. The most common species, squid, was 

consumed at a geometric mean rate of 39 g/day, but only during the fall. Landolt et al. (1987) 

noted that boaters fished primarily for salmon, and consumed 51.7 g/day of King salmon from 

the two bays where boat anglers were surveyed (CalEPA 2001). Correlations were made between 

ethnicity and fishing mode, time of fishing, household size, parts of fish consumed, and 

seasonality of fishing. 

Limitations to this study included: 

 Shore anglers were not interviewed at the end of their fishing trips, potentially 

underestimating consumption; and 

 Measurement of shellfish intake was limited to crab. 

IV. Survey of Fish Consumption Patterns of King 

County Recreational Anglers (Mayfield et al. 2007) 

Mayfield et al. (2007) summarized results of two fish consumption surveys conducted among 

recreational anglers at marine and estuarine sites in King County.2 

The first survey was conducted during a 10-week period from June 1997 to August 1997 at 

marine and estuarine public parks and boat launches throughout Elliott Bay and the Duwamish 

River. Simmonds et al. (1998) originally summarized the results of the survey but did not 

perform a detailed analysis of fish and shellfish consumption rates. Surveys were conducted on 

weekends and 10 randomly selected weekdays, over a period of 10 weeks. Locations were 

visited at least twice a day (morning and afternoon) between the hours of 5:00 am and 10:00 pm. 

A total of 807 and 152 anglers were surveyed in Elliott Bay and the Duwamish River, 

respectively. 

The second survey was conducted between March 2001 and March 2002 at marine locations in 

North King County and Snohomish County. This study followed a random stratified design and 

was conducted on both weekdays and weekends, typically between 7:00 am and 8:00 pm. 

Locations were visited randomly, and surveyors attempted to interview as many anglers as 

possible within a 1-hour site visit. The interviews typically were 5 to 10 minutes each. A total of 

228 anglers were surveyed in North King and Snohomish Counties. 

Data were collected on fishing location preferences, fishing frequency, consumption amounts, 

species preferences, cooking methods, and whether family members would also consume the 

catch. Respondent demographic data were also collected. Consumption rates were estimated 

using information on fishing frequency, weight of the catch, a cleaning factor, and the number of 

individuals consuming the catch. The majority of anglers surveyed were over male, 15 years and 

older, and were either Caucasian or Asian/Pacific Islander. 

 

2 Mayfield eta l. (2007) also summarized results of a fish consumption survey among recreational anglers at freshwater locations; these results 

are discussed in the Freshwater Recreational Studies section of this issue paper. 
Technical Issue Paper July 20, 2012 Page 7 

Mayfield et al. (2007) used the harvest method to calculate fish consumption rates; this method 

estimates consumption by combining information on fishing frequency and the weight of fish 

caught during the time of the interview. Due to the limited number of fish actually measured 

during the time of the interviews, a mean value for total fish weight was used to calculate 

consumption. The mean weights for uncleaned fish and shellfish caught by anglers were 1,574 

and 1,053 g/catch at Elliott Bay, 544 and 821 g/catch at Duwamish River sites, and 1,035 and 

683 g/catch in North King and Snohomish Counties. The North King County survey did not 

query for the number of fish consumers in the family; an average family size of 2.5 was used. 

Mean recreational marine fish and shellfish consumption rates were 53 g/day and 25 g/day, 

respectively (Table 1). Mayfield et al. (2007) also reported differences in intake according to 

ethnicity. Mean marine fish intake rates were 73, 60, 50, 43, and 35 g/day for Native American, 

Caucasian, Asian and Pacific Islander, African American, and Hispanic/Latino respondents, 

respectively. 

Table 1. Fish and Shellfish Consumption Rates (g/day) for Marine Recreational 

Fishers in King County, WA 

Location Sample Size Mean SD SE 

50th

Percentile 

90th

Percentile 

95th

Percentile

Marine Fish Consumption 

Duwamish River 50 8 13 2 2 23 42 

Elliott Bay 377 63 91 5 31 145 221 

North King County 67 32 40 5 17 85 102 

All Locations 494 53 83 4 21 121 181 

Shellfish Consumption 

Duwamish River 16 20 33 8 3 77 123 

Elliott Bay 49 28 33 5 14 74 119 

North King County 31 22 33 6 12 62 132 

All Locations 96 25 33 3 11 60 119 

Source: Mayfield et al. (2007) 

SD = Standard deviation; SE = Standard error 

Limitations to this study included: 

 The Elliott Bay survey was conducted over 10 weeks during peak summer fishing 

activity; 

 A substantial number of individuals refused to have their catch weighed, and/or refused 

to be interviewed; 

 Surveys were very brief (5 to 10 minutes); and 

 The study does not address how language issues were dealt with in administering the 

survey to non-English speakers. 
Page 8 July 20, 2012 Technical Issue Paper 

Freshwater Recreational Studies 

This section describes fish consumption rate studies for freshwater fish and shellfish. Three 

recreational fish consumption studies have been conducted in the freshwater areas of Washington 

State: Lake Roosevelt (WDOH 1997), Lake Whatcom (WDOH 2001), and King County lakes 

(Mayfield et al. 2007, Parametrix 2003). 

Additional studies of freshwater fish and shellfish consumption rates are summarized in Table A2. These include studies in Oregon, California, South Carolina, Tennessee, Minnesota, North 

Dakota, Indiana, Georgia, Connecticut, Alabama, Michigan, New York, Maine, and Wisconsin. 

I. Consumption Patterns of Anglers Who Frequently 

Fish Lake Roosevelt (WDOH 1997) 

A fish consumption survey was conducted at Lake Roosevelt during August through November 

1994 and May through September 1995. The purpose of the survey was to evaluate the 

consumption patterns of anglers who repeatedly fished from the lake, in order to assess the 

public health impacts associated with ingestion of chemically-contaminated fish (WDOH 1997). 

The study included a creel survey (trip length information, fish species, length, and weight) and 

shoreside interviews of boat anglers upon return from their fishing trips. The consumption survey 

form (used during the shoreside interviews) was separate from the creel survey. Lake Roosevelt 

was divided into three sections (upper, middle, and lower); morning and afternoon survey 

locations were randomly selected from a total of 48 possible locations. Anglers who did not 

consume Lake Roosevelt fish and anglers who were previously surveyed were excluded during 

data analysis. A total of 348 survey responses were used to estimate fish consumption rates. 

Surveyed individuals were primarily older adult Caucasian males that are part of two-adult 

households in which both individuals consume fish. Results indicate that surveyed anglers 

consume an average of 42 meals per year, with over 90 percent consuming 103.2 meals or less 

per year (2 meals per week). Fish are consumed primarily as fillets, and rainbow trout and 

walleye are preferred above kokanee and bass. No sturgeon, sucker, or whitefish were reported 

caught and consumed. Consumption rates were estimated based on an assumed 8-ounce meal 

size (Table A-2). 

Limitations of this study include: 

 Reported consumption rates may have been depressed due to the presence of chemical 

contamination in Lake Roosevelt; 

 The survey questions were not adequate for determining fish meal size; 

 Combining the consumption interviews with the creel survey resulted in a survey that 

was too lengthy; 

 Some anglers were anxious to depart the boat launch facilities at the completion of their 

fishing trip, and may have provided responses in haste. 
Technical Issue Paper July 20, 2012 Page 9 

II. Lake Whatcom Residential and Angler Fish 

Consumption Survey (WDOH 2001) 

WDOH conducted a survey of Lake Whatcom residents and anglers in July 2000, to gather 

information on consumption of fish caught in Lake Whatcom and perceptions related to fish 

advisories (WDOH 2001). A retrospective on-site study design with a four-week recall period 

was selected for this survey. Three populations were surveyed: residents who live on or near the 

lake or in developments with direct access to the lake; boat anglers accessing the lake at public 

boat launch facilities; and shore anglers at public access points. Surveys were conducted through 

door-to-door interviews, at frequently used boat launch facilities, and at popular shore-fishing 

locations. A total of 220 surveys were completed, however only 10 shore anglers and 16 boat 

anglers were surveyed; 40 percent and 6 percent of these, respectively, reported eating fish in the 

previous four weeks. Of the 194 residents that were surveyed, 22 percent identified themselves 

as fishers, and only 2 percent reported eating fish in the previous four weeks. 

The primary species caught and consumed were cutthroat trout and smallmouth bass. All anglers 

reported consuming Lake Whatcom caught fish three or fewer months per year. Average meal 

size for shore and boat anglers was 256 grams (9 ounces). The mean fish consumption rate for 

consumers was estimated at 6.0 g/day (ODEQ 2008). 

Limitations of this survey include the following (ODEQ 2008): 

 Small sample size and low number of people who reported consuming fish during the 

previous four weeks; 

 Reports of mercury in Lake Whatcom fish may have affected consumption rates; 

 Accurate frequency of meals per week or month was not clearly presented; 

 The calculated fish consumption rate was based on a number of assumptions, including 

average fillet weight for each species. 

III. Survey of Fish Consumption Patterns of King 

County Recreational Anglers (Parametrix 2003) 

Parametrix (2003) conducted a series of freshwater surveys between 2002 and 2003 at locations 

around Lake Sammamish, Lake Washington, and Lake Union. Mayfield et al. (2007) included 

this study in their survey of fish consumption patterns of King County recreational fishers. 

This study followed a random stratified design and was conducted on both weekdays and 

weekends, typically between 7:00 am and 8:00 pm. Locations were visited randomly, and 

surveyors attempted to interview as many anglers as possible within a 1-hour site visit. The 

interviews typically were 5 to 10 minutes each (Mayfield et al. 2007). 

A total of 212 individuals were interviewed at these locations. The majority of participants were 

male, 18 years and older, and were either Caucasian or Asian and Pacific Islander. Data were 

collected on fishing location preferences, fishing frequency, consumption amounts, species 

preferences, cooking methods, and whether family members would also consume the catch. A 
Page 10 July 20, 2012 Technical Issue Paper 

visual representation of typical serving sizes was used to estimate portion sizes, and respondents 

estimated how many times they had eaten self-caught fish during the previous 30 days. 

Respondent demographic data were also collected. 

Approximately 98 percent of anglers interviewed sought finfish rather than other types of aquatic 

organisms, and over 50 percent reported that they fished only from the location where they were 

interviewed. This indicates that a majority of anglers consistently fish from a single unique 

location (Parametrix 2003). Reported fishing frequencies were 6, 16, and 20 days/year at Lake 

Union, Lake Sammamish, and Lake Washington, respectively. 

Consumption rates were estimated using responses on fish meal frequency and meal size. Mean 

fishing frequency in the King County lakes was 19 days/year, with a 95th percentile value of 74 

days/year. Most anglers (94 percent) reported eating fillets without skin. Meal sizes were 

generally in the 6- to 8-ounce range (64 percent of anglers), with over 30 percent of anglers 

reporting an average meal size greater than 8 ounces (Parametrix 2003). The mean reported 

family size (including respondents) sharing the anglers’ catch was 4.1. 

The mean recreational freshwater fish consumption rates were 10 g/day for all respondents and 

7 g/day for the children of survey respondents (Table 2). Mayfield et al. (2007) also reported 

differences in intake according to ethnicity. Mean freshwater fish intake rates were 26, 13, 8, and 

6 g/day for African American, Asian and Pacific Islander, Caucasian, and Hispanic/Latino 

respondents, respectively. 

Table 2. Fish Consumption Rates (g/day) for Freshwater Recreational Anglers in 

King County, WA 

Location 

Sample 

Size Mean SD SE 

50th

Percentile

90th

Percentile 

95th

Percentile 

Lake Washington 93 11 26 2.7 5.7 NA 30 

Lake Sammamish 35 9.1 18 3.1 0 NA 57 

King County Lakes 

(all respondents) 128 10 24 2.2 0 23 42 

King County Lakes 

(children of respondents) 81 7.2 20 2.2 0 17 29 

Source: Parametrix (2003); Mayfield et al. (2007) 

SD = Standard deviation; SE = Standard error 

Limitations to this study included: 

 A substantial number of individuals refused to have their catch weighed, and/or refused 

to be interviewed; 

 Surveys were very brief (5 to 10 minutes); and 

 The study does not address how language issues were dealt with in administering the 

survey to non-English speakers. 
Technical Issue Paper July 20, 2012 Page 11 

Summary 

Results of recreational fish consumption surveys are presented in Tables A-1 and A-2. It should 

be noted that the fish consumption surveys identified in these appendices were conducted for a 

variety of purposes, used different methods of estimating fish and shellfish consumption, and had 

different target populations. The fish consumption rates listed in Tables A-1 and A-2 typically 

include both finfish and shellfish, although several studies reported separate finfish and shellfish 

consumption rates. Some studies estimated consumption rates for fish consumers only, while 

others included nonconsumers. These differences are noted in the tables, as appropriate. 

A summary of the recreational fish consumption rates listed in Appendix A is provided in Table 

3 below. 

Table 3. Summary of Recreational Fish Consumption Rates

Mean 

(g/day) 

Median 

(g/day) 

Upper (90th to 95th) 

Percentile 

(g/day) 

Marine Fish/Shellfish Consumption Rates

Washington State 11 – 53 1.0 – 21 13 – 246 

Other West Coast Studies 1.2 – 50 2.9 – 37 6.8 – 225 

Studies in Other Regions 12 – 48 9.1 5.1 – 68 

Freshwater Fish Consumption Rates 

Washington State 6.0 – 22 NA 42 – 67 

Other West Coast Studies 27 3.8 – 24 5.7 – 127 

Studies in Other Regions 4.9 – 55 1.1 – 24 18 – 235 

Mean estimated marine/estuarine consumption rates for recreational fishers ranged from 1.2 to 

53 g/day, with similar results reported in Washington State and other regions. Upper percentile 

(90 to 95th percentile) marine fish/shellfish consumption rates ranged from 5.1 to 246 g/day for 

all studies reviewed; consumption rates were somewhat higher in studies conducted along the 

West Coast (Washington, Oregon, and California) than in studies conducted in other regions. 

For freshwater fish, mean consumption rates ranged from 4.9 to 55 g/day. Results from 

Washington and other West Coast states were somewhat lower (6.0 to 27 g/day), however 

studies along the West Coast were very limited (three studies in Washington, and one each in 

Oregon and California). The fish consumption dataset from studies of freshwater fish 

consumption in other regions is more robust (16 studies), and the upper end of the range of mean 

consumption rates is very similar to that estimated for marine fish/shellfish (50 to 60 g/day). 

Upper percentile freshwater fish consumption rates ranged from 5.7 to 235 g/day in all studies 

reviewed, and from 42 to 67 g/day in studies conducted in Washington State. The highest 

reported freshwater fish consumption rates were from a study conducted by Burger (2002b); this 

study, which included both freshwater and marine sport-caught fish and was based on a one-year 

recall survey at a sportsman’s event in South Carolina, likely overestimates freshwater fish 
Page 12 July 20, 2012 Technical Issue Paper 

consumption rates by recreational anglers. The next highest upper percentile result is 136 g/day, 

which is based on a 3-month recall survey of minority recreational anglers in Indiana. With the 

exception of the Burger (2002b) study, results of freshwater fish consumption rates in other 

regions are similar to those observed along the West Coast. 

In conclusion, fish consumption surveys reviewed during preparation of this issue paper can be 

used to provide a conservative estimate of mean and upper (90th to 95th) percentile 

marine/estuarine and freshwater fish consumption rates for recreational fishers in Washington 

State, as follows: 

 Mean consumption rates for both freshwater and marine/estuarine fish and shellfish are in 

the range of 20 to 60 g/day;

 Upper percentile consumption rates are in the range of 200 to 250 g/day for 

marine/estuarine fish and shellfish, and in the range of 100 to 150 g/day for freshwater 

fish.

Based on these studies, recreational fish consumption rates developed in Washington State and 

elsewhere are consistent with the preliminary default fish consumption rate of 157 to 267 g/day 

presented in the draft TSD. In other words, a default fish consumption rate in this range would be 

protective of marine and freshwater recreational fishers. 
Technical Issue Paper July 20, 2012 Page 13 

References 

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fisherfolk along an East Coast estuary. Environ Res 77:25-35. As cited in USEPA 2011. 

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advisory changes on fishing habits and fish consumption in New York sport fisheries. 

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consumption and body burden levels of chlorinated hydrocarbons: A study of Wisconsin 

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KCA Research Division. 1994. Fish consumption of Delaware recreational fishermen and their 

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Keill, L. and Kissinger, L. 1997. Analysis and Selection of Fish Consumption Rates for 

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Potential Toxicant Exposure Among Consumers of Recreationally Caught Fish from 

Urban Embayments of Puget Sound. NOAA Technical Memorandum NOS OMA 23. 

November 1985. 

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Environmental Epidemiology, 17:604-612. 
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McCallum, M. 1985. Recreational and Subsistence Catch and Consumption of Seafood from 

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U.S. EPA, National Center for Environmental Assessments, Washington, DC. As cited in 

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Program (SWAMP). Prepared for King County Department of Natural Resources. 

September 2003. 

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Washington. December 1981. 

Price, P., Su, S., and Gray, M. 1994. The effects of sampling bias on estimates of angler 

consumption rates in creel surveys. J Expos Anal Environ Epidemiol 4:355-371. As cited 

in USEPA 2011. 

Puffer, H.W., Azen, S.P., Duda, M.J., and Young, D.R. 1981. Consumption rates of potentially 

hazardous marine fish caught in the metropolitan Los Angeles area. As cited in USEPA 

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California’s Central Valley Delta. Environ Res 110(4):334-344. As cited in USEPA 2011. 

Simmonds, J., Munger, S., Strand, J., Homan, C., Robinson, S., Toll, J., Wisdom, C., Seidel, P., 

Greer, H., and Shroy, J. Results of a survey on seafood collection and consumption from 

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sport anglers fish consumption study. Prepared by the University of Michigan, School of 

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consumption by Indiana recreational anglers: An onsite survey. Department of Forestry 

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Technical Issue Paper July 20, 2012 Page A-1 

Appendices 

Appendix A. Fish Consumption Rates for 

Recreational Fishers 

 
Page A-2 July 20, 2012 Technical Issue Paper 

This page purposely left blank for duplicate printing. 
Technical Issue Paper July 20, 2012 

Table A-1. Recreational Marine Fish/Shellfish Consumption Rates

Source Purpose of Study Location Population/Subgroup Type of Fish/Shellfish 

Sample 

Size 

Washington State StudiesSurvey of Fish Consumption Patterns of King County Recreational Anglers (Mayfield et al. 2007)

To support environmental analyses of proposed capital improvement projects.

Elliott Bay, Duwamish River, and north King County

Households with members who fish; consumers and nonconsumers

Marine fish; species include sea perch, salmon, rockfish, sole, herring, flounder. 494 Shellfish, primarily crabs and shrimp. 96 

1983-1984 Puget Sound Survey (Landolt et al. 1985, 1987); reanalysis by Tetra Tech 1988

To identify most commonly consumed species, demographic characteristics of the fishing population, and patterns of consumption.

Commencement Bay, Elliott Bay, Sinclair Inlet, Edmonds

Recreational fishers and their households

Fish and shellfish: market squid, Chinook salmon, Coho salmon, unidentified salmon, Pacific hake, Pacific cod, pile perch 4,437

Recreational fishers (shore anglers) and their households Recreational fishers (boat anglers) and their households 

Seafood Catch and Consumption in Urban Bays of Puget Sound (McCallum 1985); reanalysis by Tetra Tech 1988

To assess the number of people with repeated, long-term exposure to fish and shellfish from contaminated urban bays.

Port Gardner, Elliott Bay, Sinclair Inlet

Shore-based recreational fishers; consumers and nonconsumers

Sablefish, striped perch, pile perch, Pacific cod, Dungeness crab, red rock crab, butter clams, littleneck clams; salmon and squid excluded

702 

Commencement Bay Seafood Consumption Study (Pierce et al. 1981); reanalysis by Price et al. (1994)

To examine seafood consumption patterns and demographics of sport fishermen in Commencement Bay.

Commencement Bay

Shore and boat anglers; surveyed fishers only

Common species included Pacific hake, walleye pollock; salmon excluded 508

Shore and boat anglers; total recreational fisher population 

Other West Coast StudiesSan Francisco Bay Seafood Consumption Report (SFEI 2000)

To conduct a comprehensive study of San Francisco Bay anglers.

San Francisco Bay, California

Recreational fishers; consumers only

Marine finfish, including striped bass, halibut, jacksmelt, sturgeon, and white croaker.

465 

Seafood Consumption Survey of the Laotian Community of West Contra Costa County, CA (Chiang 1998)

To obtain data on fishing and fish consumption activities of the Laotian community.

San Francisco Bay, California

Members of the Laotian community; consumers only

Marine finfish, including catfish and striped bass. 199 

Seafood Consumption Habits of Recreational Anglers in Santa Monica Bay (SMBRP 1994)

To study the seafood consumption habits of recreational anglers in Santa Monica Bay.

Santa Monica Bay, California

Recreational fishers; consumers only

Marine finfish, including barred sand bass, Pacific barracuda, kelp bass, rockfish species, Pacific bonito, and California halibut.

555 
Page A-4 July 20, 2012 

Table A-1. Recreational Marine Fish/Shellfish Consumption Rates

Source Purpose of Study Location Population/Subgroup Type of Fish/Shellfish 

Sample 

Size 

National Marine Fisheries Service (NMFS 1993); USEPA analysis

To estimate the size of the recreational marine finfish catch by location, species, and fishing mode, and to estimate the total number of participants in marine recreational finfishing and the total number of fishing trips. 

Oregon and California (Pacific Region)

Adult recreational fishers; consumers and nonconsumers

Marine finfish

1,827 

Oregon

284 

Intake Rates of Potentially Hazardous Marine Fish Caught in the Metropolitan Los Angeles Area (Puffer et al. 1981); reanalysis by Price et al. (1994)

To evaluate intake rates of potentially hazardous marine fish/shellfish by local, nonprofessional fishermen.

Los Angeles, California

Recreational fishers; surveyed fishers only

Finfish and shellfish

1,059

Total recreational fisher population 

Studies in Other RegionsConsumption Patterns and Why People Eat Fish (Burger 2002a)

To evaluate fishing behavior and consumption patterns

Newark Bay and New York-New Jersey Harbor estuary

Recreational fishers; consumers only

Marine/estuarine fish 111 Marine/estuarine crabs

110 

Analysis of Consumption of Home-Produced Foods (Moya and Phillips 2001)

To estimate consumption of selfcaught fish. United States Households with members who fish Freshwater and saltwater fish 220 

Fishing, Consumption, and Risk Perception in Fisherfolk along an East Coast Estuary (Burger et al. 1998)

To examine fishing behavior, consumption patterns, and risk perceptions of people fishing/ crabbing in Barnegat Bay.

Barnegat Bay, New Jersey

Adult recreational fishers; consumers and nonconsumers

Marine finfish and shellfish, including bluefish, fluke/summer flounder, weakfish, and crabs. 515 

Finfish/Shellfish Consumption Study - Alcoa (Point Comfort)/ Lavaca Bay Superfund Site (Draft) (Alcoa 1998)

To evaluate the quantity and species of finfish and shellfish consumed by individuals who fish at Lavaca Bay.

Lavaca Bay, Texas Adult male recreational fishers; 

consumers and nonconsumers

Saltwater fish , including red drum, speckled sea trout, and flounder. 1,979Shellfish, including oysters, blue crab, and shrimp. 

Fish Consumption of Delaware Recreational Fishermen and Their Households (KCA Research Division 1994)

To obtain information on the number of fishing trips, and the amount of fish caught, kept, and eaten by fishing households.

Delaware Marine recreational fishers and 

their households

Marine finfish; some freshwater fish and crabs 867 
Technical Issue Paper July 20, 2012 

Table A-2. Recreational Freshwater Fish Consumption Rates

Source Purpose of Study Location Population/Subgroup Type of Fish/Shellfish 

Sample 

Size 

Washington State StudiesSurvey of Fish Consumption Patterns of King County Recreational Anglers (Parametrix 2003; Mayfield et al. 2007)

To support environmental analyses of proposed capital improvement projects.

King County: Lake Washington, Lake Sammamish 

Households with members who fish; consumers and nonconsumers

Freshwater fish including yellow perch, trout, salmon, bass, bullhead 128 

Consumption Patterns of Anglers Who Frequently Fish Lake Roosevelt (WDOH 1997)

To determine the consumption patterns of anglers who repeatedly fish this lake.

Lake Roosevelt Recreational fishers; 

consumers only

Rainbow trout, walleye, kokanee, bass 348 

Lake Whatcom Residential and Angler Fish Consumption Survey (WDOH 2001)

To gather exposure information for use in assessing the human health implications associated with the consumption of mercurycontaminated fish from Lake Whatcom.

Lake Whatcom Boat anglers, shore anglers, 

and residents living on or near the lake

Smallmouth bass, cutthroat trout, yellow perch, kokanee

220 

Other West Coast StudiesFish Consumption and Recreational Use Surveys - Columbia Slough (Adolfson Associates 1996)

To provide information on the fishing habits of people angling in the Columbia Slough.

Columbia Slough, Portland, Oregon

Columbia Slough fishermen, consumers only

Resident finfish and shellfish, fresh and estuarine 84 

Sauvie Island, Portland, Oregon

Sauvie Island fishermen, consumers only 35 

Contaminated Fish Consumption in California's Central Valley (Shilling et al. 2010, as cited in USEPA 2011)

To assess consumption of contaminated fish in a region with high subsistence fishing rates.

Sacramento-San Joaquin River Delta, California

Recreational and subsistence anglers

Striped bass, salmon, shad, catfish 373 

Studies in Other RegionsDaily Consumption of Wild Fish and Game (Burger 2002b, as cited in USEPA 2012)

To determine consumption patterns for wild-caught fish and game by high-end recreationists.

South Carolina High-end recreational anglers Sport-caught fish, freshwater 

and marine 458 

High-end recreational anglers, male 308 High-end recreational anglers, female 149 

Fishing Along the Clinch River Arm of Watts Bar Reservoir (Campbell et al. 2002, as cited in USEPA 2011)

To examine consumption habits of anglers fishing along the Clinch River near the USDOE Oak Ridge Reservation.

Clinch River, Tennessee

Recreational anglers, consumers only

Locally-caught freshwater fish, including crappie, striped bass, white bass, sauger, and catfish

202 

Recreational anglers, consumers who eat fish from the study area

77 

Analysis of Consumption of Home-Produced Foods (Moya and Phillips 2001, as cited in USEPA 2011)

Analysis of data from the household component of the USDA's 1987-1988 National Food Consumption Survey.

National Fishers, consumers only Self-caught fish, freshwater and 

saltwater 220 househol

ds
Page A-6 July 20, 2012 

Table A-2. Recreational Freshwater Fish Consumption Rates

Source Purpose of Study Location Population/Subgroup Type of Fish/Shellfish 

Sample 

Size 

Minnesota and North Dakota Fish Consumption Survey (Benson et al. 2001, as cited in USEPA 2011)

To evaluate fish consumption by the general population, licensed anglers, and members of Native American tribes.

Minnesota Licensed anglers Sport-caught fish, freshwater 

and marine 2,020 Fish from all sources 2,020 

North Dakota Licensed anglers Sport-caught fish, freshwater 

and marine 1,101 Fish from all sources 1,101 

Examination of Fish Consumption by Indiana Recreational Anglers (Williams et al. 2000, as cited in USEPA 2011)

To evaluate fish consumption by Indiana recreational anglers as a function of ethnicity and income.

Indiana Caucasian recreational 

anglers

Sport-caught fish 177 

Minority recreational anglers Sport-caught fish 143 

Role of Self-Caught Fish and Wild Game in Meat and Fish Diets (Burger 2000, as cited in USEPA 2011)

To evaluate sex differences in consumption patterns of selfcaught fish and wild game in a meat and fish diet.

South Carolina High-end recreational anglers, 

male

Sport-caught fish, freshwater and marine 457 

High-end recreational anglers, female

Sport-caught fish, freshwater and marine 

Consumption of Indiana SportCaught Fish (Williams et al. 1999, as cited in USEPA 2011)

To estimate consumption of sportcaught fish by licensed Indiana anglers.

Indiana Recreational anglers, 

consumers only

Sport-caught fish

1,045 

Ethnic and Socioeconomic Differences in Fishing and Consumption of Fish Caught Along the Savannah River (Burger et al. 1999, as cited in USEPA 2011)

To examine the differences in fishing rates and fish consumption of people fishing along the Savannah River as a function of demographics.

Savannah River, Georgia

Recreational anglers, consumers and nonconsumers

Sport-caught fish

252 

Quantification of Seafood Consumption Rates for Connecticut (Balcom et al. 1999, as cited in USEPA 2011)

To evaluate seafood consumption rates for Connecticut residents

Connecticut Sport-fishing households, 

consumers and nonconsumers

Sport-caught fish, freshwater and saltwater 502 

Sport-fishing households, consumers only 487 

Sportfish Consumption Patterns of Lake Ontario Anglers and the Relationship to Health Advisories (Connelly et al. 1996, as cited in USEPA 2011)

To provide accurate estimates of fish consumption among Lake Ontario anglers, and to evaluate the effect of health advisory recommendations.

Lake Ontario Licensed anglers in six 

counties bordering Lake Ontario

Sport-caught finfish 366 Fish from all sources

366 

Estimation of Daily Per Capita Freshwater Fish Consumption of Alabama Anglers (ADEM 1994, as cited in USEPA 2011)

To estimate fish consumption for sport-fishing Alabama anglers.

Alabama Recreational anglers, 

consumers only

Sport-caught fish

563 

1,313 
Technical Issue Paper July 20, 2012 

Table A-2. Recreational Freshwater Fish Consumption Rates

Source Purpose of Study Location Population/Subgroup Type of Fish/Shellfish 

Sample 

Size 

Follow-up to Michigan Sport Anglers Fish Consumption Survey (West et al. 1993, as cited in USEPA 2011)

To provide short-term recall data of fish consumption by recreational anglers over a full year.

Michigan Recreational anglers, 

consumers only

Sport-caught fish

2,475 

Effects of Health Advisory and Advisory Changes on Fishing Habits and Fish Consumption in New York Sports Fishers (Connelly et al. 1992, as cited in USEPA 2011)

To assess the awareness and knowledge of New York anglers about fishing advisories and contaminants, and their fishing and fish consuming behaviors.

New York Recreational anglers, 

consumers only

Sport-caught fish

1,030 

Consumption of Freshwater Fish by Maine Anglers (Chemrisk 1992, as cited in USEPA 2011)

To characterize the rates of freshwater fish consumption among Maine residents.

Maine - flowing and standing water bodies

Licensed anglers and their households, consumers only

Salmon, white perch, brook trout 1,053 

Licensed anglers and their households, consumer and nonconsumers

1,369 

Michigan Sport Anglers Fish Consumption Survey (West et al. 1989, as cited in USEPA 2011)

To evaluate sport angler fish consumption by Michigan residents with fishing licenses.

Michigan Licensed anglers and their 

households

Sport-caught fish

738

Fish from all sources

738 

Sport Fish Consumption and Body Burden Levels of Chlorinated Hydrocarbons (Fiore et al. 1989, as cited in USEPA 2011)

To assess sociodemographic factors and sport-fishing habits of anglers, to evaluate anglers' comprehension of fish advisories, and to examine the relationship between body burden levels of PCBs/DDE with consumption of sport-caught fish.

Wisconsin Licensed anglers, consumers 

and nonconsumers

Sport-caught fish

801 

Licensed anglers, consumers only

Sport-caught fish

729 

Technical Issue Paper 

Health Benefits and Risks of 

Consuming Fish and Shellfish 

 

Technical Issue Paper 

Health Benefits and Risks of 

Consuming Fish and Shellfish 

July 20, 2012 

Toxics Cleanup Program 

Washington State Department of Ecology 

Olympia, Washington 

Technical Issue Paper July 20, 2012 Page i 

Table of Contents 

Page

List of Figures and Tables............................................................................................................... ii

Figures....................................................................................................................................... ii

Tables ........................................................................................................................................ ii

Acronyms & Abbreviations ........................................................................................................... iii

Introduction ......................................................................................................................................1

Analysis............................................................................................................................................2

I. Benefits associated with eating fish and shellfish ..........................................................2

A. Seafood as a high quality protein source .......................................................................2

B. Seafood as a source of essential fatty acids ...................................................................2

C. Seafood as a source of nutrients (vitamins and minerals) ..............................................4

D. Seafood consumption and improved health outcomes ...................................................5

II. Risks associated with eating fish and shellfish ............................................................12

A. Brief summary of potential health effects ....................................................................12

B. Adverse health effects associated with primary contaminants of concern ..................14

III. Comparison of health benefits and risks ......................................................................17

A. Metrics for evaluating risks .........................................................................................17

B. Risk/Benefit Comparisons ...........................................................................................17

Conclusions ....................................................................................................................................34

References ......................................................................................................................................35

 
Page ii July 20, 2012 Technical Issue Paper 

List of Figures and Tables 

Figures 

Page

Figure 1. n-3 PFA intake and mercury exposure (hair-mercury) compared to the mercury 

RfD and recommended daily allowance of DHA=EPA ...............................................27

Figure 2. Decision pathway representing the balance between benefits and risks associated 

with seafood consumption ............................................................................................29

Figure 3. EPA+DHA and mercury content in representative seafood portions ...........................30

Tables 

Page

Table 1. Frequency of consumption rank and concentrations of n-3 PFAs ..................................3

Table 2. Classification of the content of EPA plus DHA by total mercury content in 96 

finfish and shellfish species ..........................................................................................18

Table 3. Classification of the content of EPA + DHA by dioxin content in 76 finfish and 

shellfish species ............................................................................................................19

Table 4. Estimated changes in child IQ resulting from maternal consumption of fish with 

different methylmercury and EPA plus DHA contentsa ...............................................20

Table 5. Estimated changes in mortality per million people from consuming fish with 

different dioxin and EPA plus DHA contents a

 ............................................................21

Table 6. Fish Species Most Consumed (>4 percent of total) for Japanese Population ...............25

Table 7. Fish Species with Greatest Mercury Intake (>5 percent of total) for Japanese 

Population .....................................................................................................................25

Table 8. Fish Species Most Consumed (>4 percent of total) for Korean Population .................26

Table 9. Fish Species with Greatest Mercury Intake (>5 percent of total) for Korean 

Population .....................................................................................................................26

Table 10. Estimated mercury intake from fish consumption for Tulalip Tribes, Squaxin 

Island Tribe, and Suquamish Tribes .............................................................................32

 
Technical Issue Paper July 20, 2012 Page iii 

Acronyms & Abbreviations 

AD Alzheimer’s disease 

AHA American Heart Association 

ALA alpha-linoleic acid 

AMD age-related macular degeneration 

BMD bone mineral density 

CHD coronary heart disease 

CKD chronic kidney disease 

CVD cardiovascular disease 

DDT dichloro diphenyl trichloroethane 

DEHP di-ethylhexyl phthalate 

DHA docosahexaenoic acid

DPA docosapentaenoic acid 

Ecology Washington State Department of Ecology 

EPA eicosapentaenoic acid

FAO Food and Agriculture Organization of the United Nations

IOM Institutes of Medicine 

LCP long-chain polyunsaturated fatty acid 

n-3 PFA or PUFA Omega-3 polyunsaturated fatty acid

NSAID nonsteroidal anti-inflammatory drug 

PAH polycyclic aromatic hydrocarbon 

PBT Persistent Bioaccumulative Toxics 

PCB polychlorinated biphenyl

PCDD polychlorinated dibenzo-p-dioxin

PCDF polychlorinated dibenzofuran 

PTMI provisional tolerable monthly intake 

TCDD 2,3,7,8-tetrachlorodiobenzo-p-dioxin

TERA Toxicology Excellence for Risk Assessment 

TEQ toxic equivalent 

TSD Fish Consumption Rates Technical Support Document

USDA U.S. Department of Agriculture 

USEPA U.S. Environmental Protection Agency 

WDOH Washington Department of Health 

WHO World Health Organization 

 

 
Page iv July 20, 2012 Technical Issue Paper 

This page purposely left blank for duplicate printing. 
Technical Issue Paper July 20, 2012 Page 1 

Introduction 

Multiple comments received by the Washington State Department of Ecology (Ecology) on the 

draft Fish Consumption Rates Technical Support Document (TSD) (Ecology 2011) asked why 

the TSD did not include a discussion of the relative benefits of consuming fish and shellfish or 

address the potential public health risks if people consume less fish. Others also suggested that 

the TSD should include some information regarding the contaminant concentrations in 

Washington State fish and shellfish. 

Fish is a good source of protein and, unlike fatty meat products, it is not high in saturated fat. 

Fish is also a good source of omega-3 fatty acids. Omega-3 fatty acids benefit the heart of 

healthy people, and those at high risk of, or who have, cardiovascular disease. While some types 

of fish may contain high levels of mercury, PCBs (polychlorinated biphenyls), dioxins and other 

environmental contaminants, the American Heart Association recommends eating fish 

(particularly fatty fish) at least two times (two servings) per week.1 

According to the Food and Agriculture Organization of the United Nations, worldwide fish 

consumption reached an all-time high in 2011, with an average consumption of 17 kg per 

person.2

 

This Technical Issue Paper summarizes the known health benefits of consuming seafood and the 

risks associated with a set of common contaminants in Washington State seafood, and compares 

these health benefits and risks. It is a targeted examination of the issues raised by review 

comments received on the draft TSD, and was prepared within a limited time frame. Therefore, it 

may not include all available information on this subject. 

Throughout this paper, use of the word “seafood” denotes fish and shellfish. A review of 

Washington State seafood contaminant concentrations and potential human exposures is 

presented in another Technical Issue Paper (Chemical Contaminants in Dietary Protein Sources). 

 

 

1 http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/HealthyDietGoals/Fish-and-Omega-3-FattyAcids_UCM_303248_Article.jsp 

2 http://www.fao.org/news/story/en/item/50260/icode/ 
Page 2 July 20, 2012 Technical Issue Paper 

Analysis 

I. Benefits associated with eating fish and shellfish 

The most recent guidance from the American Heart Association (AHA) recommends eating fish, 

particularly fatty fish (e.g., salmon, anchovy, herring), at least two times per week (AHA 2012). 

The following sections describe why fish and shellfish are recommended as an important part of 

the diet. 

A. Seafood as a high quality protein source 

Fish is a good source of high quality protein that is not high in saturated fat (USDA 2010; AHA 

2012). Saturated fats have a chemical makeup in which the carbon atoms are saturated with 

hydrogen atoms and are typically solid at room temperature. Eating foods that contain saturated 

fats raises the level of cholesterol in the blood. High levels of blood cholesterol increase the risk 

of heart disease and stroke. Many foods high in saturated fats are also high in cholesterol. 

Shellfish contain more cholesterol than most types of fish, but are very low in saturated fat 

(AHA 2012). A significant proportion of dietary fish intake is comprised of protein (Undeland 

et al. 2009). Fish proteins are considered easily digestible and are rich in essential amino acids 

(the building blocks of proteins) (review in Costa 2007). Essential amino acids are those that 

cannot be made by the body and must be supplied in the diet. 

B. Seafood as a source of essential fatty acids 

Omega-3 (n-3 polyunsaturated) fatty acids (n-3 PFAs) are essential fats that the body needs to 

function properly but cannot make on its own. Humans must get n-3 PFAs from foods. The n-3 

PFAs that are particularly important in human nutrition include: alpha-linoleic acid (ALA), 

eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA) 

(review in Mahaffey et al. 2011). EPA and DHA are important for human neurological 

development. These two n-3 PFAs play a role in: (1) cell membrane formation, integrity, and 

functions; (2) functioning of brain, retina, liver, kidney, adrenal glands, and gonads; and (3) local 

hormone production for the regulation of blood pressure and immune and inflammatory 

responses. 

Humans can synthesize some of their requirement for long-chain PFAs from ALA (a short-chain 

PFA), but generally not in the amounts sufficient to meet dietary needs (review in Mahaffey 

et al. 2011). Fish is rich in the very long-chain n-3 PFAs EPA and DHA. Fish and shellfish 

acquire these PFAs by consuming algae (or other fish). Certain fatty fish (e.g., salmon, herring, 

sardines, mackerel) are also high in n-3 PFAs (Table 1). Some that are low in fat (e.g., trout and 

shrimp) are also good sources of n-3 PFAs. 

 
Technical Issue Paper July 20, 2012 Page 3 

Table 1. Frequency of consumption rank and 

concentrations of n-3 PFAs 

Rank Species EPA + DHA 

(mg/100g fish)* 

1 Shrimp 390 

2 Tuna (all, average) 

Tuna canned – light (skipjack) 

Tuna canned – white (albacore) 

Tuna fresh – Bluefin (7 kg) 

Tuna fresh – Skipjack (3 kg) 

Tuna fresh – Yellowfin (5-20 kg) 

630 

128 – 270** 

862 

1,173 – 1,504** 

256 – 328** 

100 – 120** 

3 Breaded fish products 0.26 

4 Salmon 1,590 

5 Crabs 36 

6 Catfish 280 

7 Other fish 54 

8 Scallops 270 

9 Lobster 360 

10 Clams 240 

11 Cod 240 

12 Oysters 350 

13 Other shellfish 310 

14 Flatfish 15 

15 Unknown fish 53 

16 Pollock 260 

17 Mussels 350 

18 Trout 580 

19 Haddock 180 

20 Crayfish 380 

21 Perch 300 

22 Sardines 980 

23 Swordfish 580 

24 Bass (freshwater) 640 

25 Sea bass 490 

26 Pike 140 

27 Mackerel – except King 

King mackerel 

1,790 

401 

28 Shark 220 

29 Walleye 530 

30 Porgy 210 

Source: Adapted from Mahaffey et al. 2011 

*100 grams is equivalent to a 3.5-ounce serving 

** range shown is raw vs. cooked 
Page 4 July 20, 2012 Technical Issue Paper 

C. Seafood as a source of nutrients (vitamins and minerals) 

Many Americans do not eat the variety and amounts of foods necessary to supply needed 

nutrients (USDA 2010). Seafood supplies a number of these essential vitamins and minerals, 

including: vitamins A, B3, B6, and B12, and D, and the minerals calcium, iron, selenium, and 

zinc (summarized from USEPA and TERA 1999; USDA 2010, others). 

a. Vitamins 

Vitamin A (retinol, retinal, retinoic acid) is a fat-soluble vitamin that is critical for vision, 

growth, bone development and maintenance, and immune function, among others. In general, 

fish is a better source of Vitamin A than beef, pork, or chicken, and higher-fat fish species 

contain more of this vitamin than lower-fat species. Some foods, such as milk, are fortified with 

this vitamin. 

Vitamins B3 and B6 are water soluble – they must be supplied daily in the diet because the body 

stores these vitamins only briefly. Vitamin B3 (niacin, nicotinic acid, and nicotinamide) is 

involved in hydrogen transfer reactions and deficiency in the diet causes a condition called 

Pellagra, which is characterized by diarrhea, dermatitis, and dementia. Vitamin B6 exists as 

several different chemical structures that serve as important co-enzymes in various chemical 

reactions in the body that are involved predominantly in metabolism. Deficiency in Vitamin B6 

is very rare in the United States. Vitamin B12 is important in normal functioning of the brain and 

nervous system and for the formation of blood. It is produced by microorganisms in animals and 

does not occur naturally in plant foods. Deficiencies of Vitamin B12 generally occur if 

absorption from food is impaired. Sport-caught fish (salmon, trout, channel catfish) are excellent 

sources of this vitamin. 

Vitamin D is a fat-soluble vitamin that occurs naturally in several forms and can be synthesized 

in the skin when sun exposure is adequate. Vitamin D acts like a steroid hormone, controlling 

blood levels of calcium to affect bone, kidney, and intestinal tissues. Deficiency of Vitamin D 

leads to bone demineralization and a condition called osteomalcia (in children it is called 

rickets). Fish is among the best food sources of this vitamin. Some foods, such as milk and some 

packaged orange juices, are fortified with this vitamin. 

b. Minerals 

Calcium is necessary for bone health as well as nerve transmission, constriction and dilation of 

blood vessels, and muscle contraction. Low calcium intake is associated with low bone mass and 

risk of bone fractures. Dairy products provide about one-half of dietary calcium in the United 

States. Fish with soft bones (walleye, bass, and yellow perch), small fish eaten whole (sardines, 

smelts), and canned fish with bones (salmon) can contribute substantial amounts of calcium to 

the diet. 

Iron is an essential part of many proteins and enzymes, including the proteins involved in oxygen 

transport (hemoglobin, myoglobin). It is also important in many enzyme oxidation/reduction 

reactions. Iron deficiency is the most common nutritional deficiency in the United States The 

heme form of iron, which is the most readily absorbed form, can be found in animal foods (meat 

fish). Seafood is a good source of heme iron. 
Technical Issue Paper July 20, 2012 Page 5 

Selenium, an essential nutrient, is present in the cells of all mammals. When bound to certain 

proteins, selenium acts as an antioxidant by detoxifying free radicals. Selenium must be supplied 

through dietary sources. Seafood and organ meats such as liver are the best sources of dietary 

selenium. 

Zinc is part of many enzymes and deficiencies can cause stunted growth and delayed sexual 

maturation. In general, foods rich in protein are also good sources of zinc. Insufficient zinc levels 

are common in North America, particularly in vegetarians and adult women. 

D. Seafood consumption and improved health outcomes 

Seafood consumption is linked with improvements in health conditions including cardiovascular 

disease, arthritis, and cancer. The following sections summarize reviews of the published 

evidence regarding the various health benefits of seafood consumption. Where the evidence to 

support a link between seafood consumption and a specific health benefit is considered 

preliminary and further research is needed (e.g., with treatment of mood disorders), this is noted 

in the review for that condition. 

There has been a tremendous amount of research into the health benefits of seafood consumption 

in recent years. A Google Scholar® search3 of scientific literature using the keywords seafood 

+benefits +risk +review and limiting the results of the search to the last two years turned up over 

2,700 articles and reports. McManus et al. (2010) provide a recent overview of health benefits 

from seafood consumption, although this is aimed toward benefits in the elderly. For this issue 

paper, the McManus et al. (2010) review was used as the basis for most of the discussions of 

health benefits and was augmented using primary literature and other reviews. 

a. Cardiovascular disease/stroke 

Over 81 million Americans (37 percent of the population) have cardiovascular disease (CVD) 

(AHA 2010). Major risk factors for CVD include high levels of blood cholesterol and other 

lipids, type 2 diabetes, hypertension (high blood pressure), metabolic syndrome, obesity, 

physical inactivity, and tobacco use. Hypertension affects 34 percent of Americans and is a 

major risk factor for heart disease, stroke, congestive heart failure, and kidney disease. 

From McManus et al. 2010: “Strong evidence exists supporting the assertion that fish intake 

significantly contributes to the maintenance of heart health, protecting against cardio-vascular 

diseases, particularly ischemic stroke. Even a small amount of fish can provide a protective 

health effect for seniors. For example, 1 to 2 serves a week of oily fish (sardines, salmon, trout) 

is associated with a reduced rate of hospitalization and mortality, with the highest evidence for 

older women.” 

Consumption of 1 to 2 fish meals per week lowers the relative risk of mortality from coronary 

heart disease (CHD) by 20 to 30 percent (Costa 2007). In fact, moderate evidence indicates that 

consumption of about 8 ounces of seafood per week is associated with reduced cardiac deaths 

among individuals with and without pre-existing CVD (AHA 2010). DHA and EPA in the diet 

likely reduce the risk of fatal CHD by reducing cardiac arrhythmias (Harris et al. 2009). An 

 

3 http://scholar.google.com/ 
Page 6 July 20, 2012 Technical Issue Paper 

arrhythmia is a problem with the rate or rhythm of the heartbeat – too slow, too fast, or with an 

irregular rhythm. A review by Dórea (2008) found two studies indicating that the cardiovascular 

benefits of fish are due not only to the n-3 PFAs but also to the fish proteins. Even short-term 

DHA + EPA consumption (> 1 to 2 g/day) favorably affects many physiological measures of 

cardiovascular risk including blood pressure, resting heart rate, triglyceride levels, and possibly 

heart rate variability (Harris et al. 2009). Other reviews have concluded that n-3 PFAs alone do 

not have a clear effect on total mortality or combined CVD events and that positive effects were 

only seen when taking into account fish-based studies (Undeland et al. 2009). This suggests that 

other, non-n-3 PFA compounds in fish contribute to cardio-protective and neuro-protective value 

of fish consumption. For example, Vitamin D insufficiency has been related to CVD, and 

reduced Vitamin D status has been associated with several CVD risk factors including blood 

pressure and body-mass index. 

Djoussé et al. (in press) conducted a meta-analysis4 of cohort studies that evaluated the 

association between fish consumption or n-3 PFA and heart failure. The authors retained seven 

prospective studies conducted in the United States (four studies) or Europe (three studies) with 

176,441 participants in whom 5,480 incident heart failures occurred. The average duration of 

follow-up in the studies was 13.33 years. The analysis found that higher fish consumption and a 

higher dietary or plasma concentration of EPA/DHA were each associated with about a 15 

percent lower risk of heart failure compared with the lower exposure category (i.e., those who ate 

less fish or had less EPA/DHA in their plasma). The authors noted that their conclusions were 

based on a rather small number of observational studies (albeit with a large number of 

individuals when combined), and stressed that the findings need to be confirmed with a large 

randomized trial. 

Dekelbaum and Calder (2012) discuss reviews and meta-analyses favorable to n-3 PFAs in 

lowering the risk for CHD and myocardial infarction (heart attack), in contrast to some recent 

clinical trials that found no or very little benefit from EPA and DHA. These experts concluded 

that, although the results of recent trials have been mixed, “it seems safe and sensible to follow 

the American Heart Association’s recommendations that all adults eat fish (especially fatty fish) 

at least twice a week...” Eussen et al. (2011) theorized that recent failures of secondary 

prevention trials to demonstrate a beneficial effect of n-3 PFAs on cardiovascular outcomes may 

be due to the growing use of statin drugs since the mid-1990s. When the patients in one of those 

trials (the Alpha Omega Trial) were divided into statin-users and statin non-users, it was found 

that statins modify the effects of n-3 PFAs on major cardiovascular events (fatal cardiovascular 

diseases, non-fatal myocardial infarction, non-fatal cardiac arrest, non-fatal stroke and cardiac 

interventions) after myocardial infarction. In statin users, supplementation with n-3 PFAs had no 

effect. In the statin non-users, n-3 PFA supplementation (EPA-DHA plus ALA) had 54 percent 

fewer major cardiovascular events than those on placebo. 

Evidence for effects on stroke is mixed. Meta-analyses indicate a 30 percent lower risk of 

ischemic stroke with fish intake of ≥ 1 meal/week compared with < 1 meal/month (Harris et al. 

2009). Ischemic stroke involves blockage of the arteries leading to the brain caused by 

 

4 A meta-analysis is a study in which the results of other studies, all published on the same topic, are combined so as to gain 

more information regarding the shared area of inquiry; the larger size of the pooled data lends more evidence to any conclusions 

that are drawn. 
Technical Issue Paper July 20, 2012 Page 7 

artherosclerosis and thrombosis (Undeland et al. 2009). The mechanisms protecting against 

ischemic stroke are believed to be the same as those for CHD. 

b. Arthritis 

Rheumatoid arthritis is a chronic inflammatory autoimmune disease of the joints and bones. The 

n-6 PFA arachidonic acid is the precursor of inflammatory compounds (eicosanoids), which are 

involved in rheumatoid arthritis. The n-3 PFAs EPA and DHA decrease the arachidonic acid 

content of cells involved in autoimmune responses, decreasing the production of the 

inflammatory eicosanoids (summary in Miles and Calder 2012). In a case control study, Rossell 

et al. (2009) found that the risk for developing rheumatoid arthritis was 20 percent lower for 

those who consumed oily fish one to seven times per week compared to those who never or 

seldom consumed oily fish. These researchers found no effect of n-3 PFA supplements on 

incidence of rheumatoid arthritis. 

Studies in Japan and of Eskimos have suggested that consumption of oily fish reduces the risk of 

rheumatoid arthritis (review in Lahiri et al. 2012). Miles and Calder (2012) reviewed the results 

of 23 randomized controlled studies of patients with rheumatoid arthritis and found evidence “for 

a fairly consistent, but modest, benefit of marine n-3 PFAs on joint swelling and pain, duration 

of morning stiffness, global assessments of pain and disease activity, and use of non-steroidal 

anti-inflammatory drugs.” 

Greater intake of Vitamin D is also associated with lower risk for rheumatoid arthritis and 

improvement in rheumatoid arthritis patients (Undeland et al 2009). Vitamin D could have an 

immunosuppressive role in these effects, but more research is needed (Undeland et al. 2009). A 

more recent review by Lahiri et al. (2012) found that the effect of Vitamin D deficiency, with 

respect to rheumatoid arthritis, remains unclear. 

c. Cancer 

McManus et al. (2010) state that “high fish intake has been associated with significantly reduced 

risk of ovarian and colorectal cancer. Furthermore, findings from a recent United Kingdom 

Women’s Cohort Study of 35,372 women supports the assertion that postmenopausal women 

who consumed fish experienced a significantly reduced risk of breast cancer when compared 

with red meat consumers, indicating reduced risk in older women who prefer fish as a primary 

protein source to the exclusion of red meat. High level evidence supports fish consumption as 

protective in reducing the risk of prostate and lung cancers in males. Increased consumption of 

seafood also confers protection against the development of esophageal cancer in males aged 45 

years and older in large population-based studies.” A systematic review by Gerber (2012) found 

that there is increasing evidence suggesting a reduced risk of breast cancer associated with longchain PFAs from fish consumption. In a cohort study of women who had been diagnosed with 

early stage breast cancer, Patterson et al. (2011) found that women with higher intakes of EPA 

and DHA from food had an approximately 25 percent lower risk of additional breast cancer 

events compared to women in the group with the lowest intake. These women also had a dosedependent reduced risk of all-cause mortality. EPA and DHA intake from supplements, however, 

was not associated with breast cancer outcomes in this study. 
Page 8 July 20, 2012 Technical Issue Paper 

Undeland et al. (2009), summarizing the benefits of seafood consumption, stated that 

observational studies5

 on fish consumption have shown protection for risk of digestion tract 

cancers (oral cavity and pharynx, esophagus, stomach, colon, and rectum) and also for ovary, 

pancreas, larynx, and endometrial cancers. Prospective6

 and case-control7 studies, however, 

either do not show an association between fish intake and cancer risk, or only show reduced risk 

at high fish intake levels. Harris et al. (2009) states that the preponderance of evidence for 

anticarcinogenic effects of EPA + DHA is weak despite persuasive data from animal models and 

cultured tumor cell lines. However, a review and meta-analysis of fish consumption and prostate 

cancer risk that found no strong evidence of a protective association between fish consumption 

and prostate cancer risk did show a significant 63 percent reduction in prostate cancer-specific 

mortality (Scymanski et al. 2010). Cockbain et al. (2012) reviewed the research to date on n-3 

PFAs and colorectal cancer and found that there is growing epidemiological, experimental, and 

clinical evidence that n-3 PFAs have anti-colorectal cancer activity and that they may play a role 

in primary prevention as well as treatment of colorectal cancer and advanced metastatic disease. 

A meta-analysis of 22 prospective case studies and 19 case-control studies by Wu et al. (2012) 

found that fish consumption decreased colorectal cancer incidence by 12 percent. However, a 

review by Gerber (2012), indicated that evidence is too limited to draw firm conclusions on the 

effect of long-chain n-3 PFAs and colorectal cancer. 

d. Macular degeneration 

n-3 PFAs are found in photoreceptor outer segment membranes and are a potentially important 

nutrient for eye health (Lim et al. 2012). Depletion of DHA may impair retinal function and 

influence the development of a condition known as age-related macular degeneration (AMD) 

(Souied 2012). AMD is a deterioration or breakdown of the eye’s macula and is a common eye 

condition among people age 50 and older. The macula is the part of the eye that provides sharp, 

central vision needed for seeing objects clearly. AMD is a leading cause of vision loss in older 

adults. Cardiovascular disease is a system risk factor for AMD and cardiovascular risk factors 

such as hypertension have been linked with AMD (Lim et al. 2012). As noted above, intake of 

seafood and n-3 PFAs can improve cardiovascular health. 

In a European study, consumption of oily fish at least once per week reduced the risk of 

neovascular AMD by one-half compared with consumption less than once per week (review in 

Souied 2012). Recently, a cohort study of female medical professionals (over 38,000 with 

average age of 54) found regular consumption of DHA and EPA and fish was associated with 

significantly decreased risk of incident AMD and may be of benefit in primary prevention of 

AMD (Christen et al. 2011). Women who consumed one or more servings of fish per week, 

compared with those who consumed less than one serving per month, had a relative risk of AMD 

of 0.58. According to the review by Souied (2012), the growing body of evidence shows that the 

regular consumption of oily fish or a higher intake of n-3 PFAs is associated with a 30 to 50 

 

5 An observational study draws inferences about the possible effect of a treatment on subjects, where the assignment of subjects

into a treated group versus a control group is outside the control of the investigator. 

6 An analytical study designed to determine the relationship between a condition and a characteristic shared by some members 

of a group. 

7 An analytical study which compares individuals who have a specific disease ("cases") with a group of individuals without the 

disease ("controls"). 
Technical Issue Paper July 20, 2012 Page 9 

percent risk reduction in the occurrence or progression of AMD. However, Souied (2012) also 

noted that the majority of evidence is observational and further research involving cohort studies 

and randomized clinical trials is needed. 

e. Cognitive function 

According to McManus et al. (2010), “omega-3 PUFAs in seafood play an important role in 

neurological structure and function. Docosahexaenoic acid (DHA), a long-chain marine PUFA 

found in seafood, is a catalyst for the slowing of early stage progression of dementia. Further 

study is expected to shed light on how DHA potentially prevents the neurological damage that 

results from dementia.” The review further states that “research from marine and human 

epidemiological studies suggest that ‘higher fish consumption is associated with better cognitive 

function in later life’, enabling resistance to cognitive decline. Recent evidence strongly 

associates a dietary profile in which fish features prominently, with lower risk of developing 

Alzheimer’s disease (AD) and maintaining cognitive function. Evidence increasingly supports 

the assertion that marine source omega-3 PUFAs in fish play a role in delaying onset and 

arresting the progression of AD, though further studies are needed to investigate the mechanism 

involved.” 

The EPA and DHA review by Harris et al. (2009) found that the available evidence for 

protective effects of long-chain PFAs from fish on the risk of dementia is promising but limited. 

Epidemiological evidence is positive for benefits of just one fish meal per week on the risk of 

Alzheimer’s disease, dementia, and cognitive decline. Animal evidence supports a protective 

relationship of n-3 PFAs on neurodegeneration of the brain with aging, and several studies in 

progress in the United States and Europe should shed more light on this relationship. Cunnane 

et al. (2012) note that the negative results of clinical trials with DHA supplements do not agree 

with the largely protective link of fish and DHA that is seen in prospective epidemiological 

studies. In a review that included seven studies of the effects of supplements containing longchain n-3 PFAs (LCP), Dangour et al. (2012) found that only one identified any potential 

benefits on cognitive function. These authors conclude that “Whether this lack of evidence 

results from insufficient thought into designing studies of appropriate size and duration, or 

whether it relates to the selection of study populations who may benefit most from n-3 

supplementation, such as those with low n-3 LCP status at study entry, or finally whether it 

suggests that despite the epidemiological and mechanistic evidence n-3 LCP supplementation 

does not affect cognitive function, remains open to question.” 

f. Hearing loss 

Gopinath et al. (2010) found an inverse association between higher intakes of long-chain n-3 

PFAs and regular weekly consumption of fish and hearing loss. Higher dietary intake of longchain n-3 PFAs was associated with a 24 percent decreased risk of developing incident hearing 

loss. Regular consumption of fish in the diet was negatively associated with the 5-year incidence 

and progression of hearing loss in older adults. These data suggest that n−3 fatty acids and fish 

have a role in maintaining healthy auditory function. 

g. Depression/mood 

According to McManus et al. (2010), “intake of omega-3 PUFA rich seafood is linked to 

increased dispositional optimism in the elderly, and has, in some long term studies, been linked 
Page 10 July 20, 2012 Technical Issue Paper 

to reduced depression, with a recent meta-analytic review of polyunsaturated fatty acid levels in 

patients with depression concluding that ‘n-3 polyunsaturated fatty acids play a role in the 

pathogenesis of depression’. Therefore, omega-3 PUFA rich seafood could benefit individuals 

suffering from depression. Further research on the possible role of seafood consumption in 

moderating depression is required for these findings to be substantiated.” 

Hegarty and Parker (2011) reviewed the evidence implicating marine n-3 PFAs in the etiology 

[causes or origin] of depressive and bipolar disorders and the effect of n-3 PFA supplementation 

in the treatment of those disorders. The authors focused primarily on studies conducted within 

the previous 5 years, and found the following: (1) the evidence suggests a contributory 

etiological role of n-3 PFA deficiency to depressive and bipolar disorders; (2) a growing body of 

evidence implicates inflammatory processes in the etiology and/or progression of depression; (3) 

n-3 PFAs play a role in modulating the n-6 PFA derived pro-inflammatory molecules and are 

able to suppress the expression of a wide variety of inflammatory genes; (4) a recent metaanalysis concluded that levels of EPA, DHA, and total n-3 PFAs are significantly lower in 

depressed patients compared to controls; (5) trials of EPA-rich n-3 PFA supplements were more 

effective in treating depressive symptoms than DHA-rich preparations; and (6) an increasing 

number of trials do not support n-3 PFA supplementation as an effective treatment for major 

depressive disorder or postnatal depression. Hagarty and Parker (2011) concluded that more 

research focusing on EPA-rich supplements is warranted and that, even with many questions 

remaining, two fish servings per week would be recommended with supplementation for those 

with depressive or bipolar disorders. They believe it is possible that n-3 PFA supplementation 

may be of benefit for mood disorders but that research has not yet established the right dose 

and/or the right constituent ratio. A review of the effects of n-3 PFA supplementation on 

behavior and neuropsychiatric disorders by Ortega et al. (2012) found that most of the existing 

studies do not meet the requirements to elucidate the effect of n-3 PFAs, for example, by failing 

to control for dietary intake. 

h. Osteoporosis 

McManus et al. (2010) state that “seafood is a rich source of both calcium and Vitamin D, 

important bone-building micronutrients. Vitamin D rich seafood can play an important role in the 

maintenance of bone mineral density as people age. Potential reduced sun exposure and an 

increased requirement of Vitamin D in older people underpins the need for high quality, 

bioavailable Vitamin D. Seniors also have a reduced capacity to ‘synthesize provitamin D3 in 

skin and to hydroxylate vitamin D3 in kidneys. It is widely recognized that a diet high in oily 

fish prevents vitamin D deficiency; and commonly consumed, affordable sources of seafood 

such as Australian salmon and silver perch contain more than double the recommended daily 

intake of Vitamin D in a 150 g serve. A 150 g serve of Australian Salmon will also deliver more 

than half the recommended daily intake of calcium. Calcium requirements increase with age and 

seafood presents rich serves of calcium combined with optimal amounts of Vitamin D to aid its 

absorption, protecting bone mineral density (BMD). 

Loss of calcium through urinary excretion is of concern to bone health. Evidence is emerging 

showing lower fractures and higher bone mineral density with the consumption of adequate 

levels of calcium rich, high protein seafood. This may be due to increased intestinal absorption, 

which negates the impact of urinary excretion. When calcium and vitamin D intake is adequate, 

dietary protein at moderate levels is beneficial to total body BMD particularly for seniors. 
Technical Issue Paper July 20, 2012 Page 11 

Seafood is a good source of calcium, vitamin D, and protein [and] therefore can favorably 

contribute to BMD.” 

However, according to a review by Orchard et al. (2012), a small number of epidemiological 

studies investigating the relationship of fish consumption or dietary n-3 PFA consumption to 

fracture risk have yielded mixed results. For example, in a study of post-menopausal Chinese 

women, high intake of sea fish was associated with greater bone mass and lower osteoporosis 

risk, especially those consuming more than 250 grams of seafood per week (Chen et al. 2010). 

But in a study of elderly Japanese women, consuming fish 3 to 4 times per week was associated 

with decreased risk of hip fracture but eating more than 4 fish meals per week did not improve 

relative risk (summary in Orchard et al. 2012). Orchard et al. (2012) concluded that “there is a 

need for further large scale investigation of the differential effects of various n-3 PFAs in 

relation to skeletal outcomes, particularly fracture.” 

i. Recent Research 

The following summaries do not represent the results of an exhaustive literature search, which is 

outside the scope of this review, but are articles of interest that were found when searching for 

recent reviews on the benefits of seafood consumption. These articles are too new to have made 

it into the review papers that were published recently. 

Gopinath et al. (2011) investigated the association between dietary intakes of PFA (n-3, n-6 and 

α-linoleic acid), fish and the prevalence of chronic kidney disease (CKD). Due to the antiinflammatory properties of PFA, it has been suggested that they may protect against kidney 

damage in adults. These researchers found that an increased dietary intake of long-chain n-3 PFA 

and fish reduced the prevalence of CKD. Therefore, a diet rich in n-3 PFA and fish could have a 

role in maintaining healthy kidney function. 

In a case-control study of maternal dietary patterns and congenital heart defects, a dietary pattern 

characterized by the high intake of fish and seafood was associated with a reduced risk of 

congenital heart defects in offspring (Obermann-Borst et al. 2011). Based on these findings, the 

researchers suggested further investigation in a randomized intervention trial was warranted. 

Changing human dietary patterns in the last 100–150 years have given rise to an imbalance in the 

dietary ratio of n-6 and n-3 PFAs (review in Candela et al. 2011). This ratio used to be around 1–

2:1 but in Western diets is now as high as 20–30:1. n-3 PFA intake is much lower today due to 

factors such as decreased fish consumption while n-6 PFA intake is higher due to factors such as 

increases in n-6 rich grains and vegetable oils. Although n-6 and n-3 PFAs exert opposing effects 

on inflammatory activity (n-3 PFAs reduce inflammation), high n-6:n-3 ratios have not been 

correlated with high inflammatory marker levels. Some researchers point to the need to decrease 

n-3 PFA intakes while others call for increasing n-3 PFA intakes to mediate the imbalance in the 

ratio. Beneficial effects on asthma (an inflammatory disease) have been seen at ratios of 5:1 with 

adverse effects seen at ratios of 10:1 (review in Candela et al. 2011). With regard to cancers, a 

high n-6:n-3 ratio was associated with increased prostate cancer risk in a recent study (Williams 

et al. 2011). 
Page 12 July 20, 2012 Technical Issue Paper 

II. Risks associated with eating fish and shellfish 

Risks associated with eating fish and shellfish include the risk from chemical contaminants (fish 

and shellfish) and pathogens or biotoxins (generally in shellfish). 

According to the U.S. Environmental Protection Agency (USEPA) 2010 listing of fish 

consumption advisories (USEPA 2011), all 50 states have fish consumption advisories in place 

to protect their residents from the potential health risks of eating contaminated fish caught in 

local waters. As of 2010, 42 percent of the nation’s total lake acreage and 36 percent of the 

nation’s total river miles were under advisories. There were consumption advisories for 33 

different environmental pollutants in the United States in 2010—a total of 4,598 fish 

consumption advisories were in effect. Three pollutants—methylmercury, PCBs, and dioxins—

were responsible for nearly 90 percent of the advisories. These contaminants accumulate in fish 

tissue at concentrations many times higher than concentrations in the water and can persist for 

years in sediments. Fish consumption advisories are designed to “avoid” risks from consuming 

different contaminated fish. For example, the metrics of advice prescribes meal frequency and 

size to reduce exposures to mercury or other fish contaminants. All states, except Nebraska, offer 

meal frequency advice in terms of fish meals to avoid per week, month, year or some 

combination thereof (Scherer et al. 2008). 

Some shellfish species feed by taking in large volumes of water and filtering out the food 

particles (WDOH 2012). These filter-feeding species, such as oysters, clams, and mussels, can 

accumulate natural biotoxins as well as pathogens (e.g., norovirus, fecal coliforms, and vibrio) in 

their edible tissues. The Washington Department of Health (WDOH) Shellfish Program monitors 

for biotoxins such as paralytic shellfish poison and domoic acid in shellfish and closes harvest 

areas when levels pose a threat to public health. The Shellfish Program also classifies shellfish 

growing areas, monitors marine water for pollution, licenses and inspects commercial growers, 

and provides recreational harvesters with information about where, when, and what type of 

shellfish are safe to harvest. Washington State shellfish consumers can minimize their risks of 

becoming ill from shellfish biotoxins and pathogens by avoiding raw shellfish (proper cooking 

kills pathogens although it does not neutralize biotoxins) and complying with shellfish harvesting 

restrictions when the Shellfish Program closes harvest areas. This issue paper focuses on 

chemical contaminants in seafood and so pathogens and biotoxins are not discussed further. 

A. Brief summary of potential health effects 

Toxic contaminants enter Washington’s ecosystems via water (e.g., river or stream inputs, 

industrial discharges, stormwater runoff), the atmosphere, and in the bodies of migrating 

organisms. Some chemicals in the environment pose an immediate health threat. Others 

gradually build up in the environment and, in humans, can cause disease long after exposure. 

Contaminants in sediment and water may accumulate in fish and shellfish through processes 

called bioaccumulation and bioconcentration. Bioaccumulation is the accumulation of chemicals 

in the tissue of fish or shellfish through respiration, ingestion, or direct contact with 

contaminated water, sediment, and pore water in the sediment. Bioconcentration is the process of 

accumulation of water-borne chemicals by fish or shellfish through non-dietary routes. Some 

contaminants are biomagnified up the food chain. This occurs when the tissue concentration 

increases at each trophic level in the food chain when there is efficient uptake of the contaminant 
Technical Issue Paper July 20, 2012 Page 13 

but slow elimination. Hydrophobic chemicals—those that adhere to organic particles in 

sediments—tend to be bioaccumulative. Two types of contaminants that may occur in seafood 

are metals and organics. These are described below. 

a. Metals 

Metals include essential trace elements required for human health, such as zinc and copper, and 

those without any known human dietary need, such as lead and mercury. Many metals, even 

those considered essential in the diet, can be toxic at high enough doses. Some metals are 

widespread in the environment due to natural processes (e.g., arsenic) but have increased locally 

or globally due to human activities (Eisler 2000). Metals contamination occurs throughout the 

state from a variety of sources such as industrial releases, deterioration or wear of roofing and 

other materials, batteries, paints, and dyes. Methylmercury, an organic form of mercury, is 

included in a class of contaminants termed Persistent Bioaccumulative Toxics (PBTs).8

 PBTs are 

of concern because they resist degradation, bioconcentrate from the environment (e.g., water, 

sediments) into organisms, and may biomagnify up food chains (PSAT 2007). 

b. Organics 

Organic contaminants are natural or manmade chemicals that include several PBTs: dioxin and 

dioxin-like compounds (polychlorinated-dibenzo-p-dioxins [PCDDs], polychlorinated-dibenzofurans [PCDFs], and polychlorinated biphenyls [PCBs]), polycyclic aromatic hydrocarbons 

(PAHs), and organochlorine pesticides (e.g., chlordane, DDT). 

PAHs are a group of organic chemicals that have a fused ring structure of two or more benzene 

rings, and are formed during the incomplete combustion of organic materials. PAHs are 

ubiquitous in nature, largely as the result of natural processes such as forest fires and microbial 

synthesis. Anthropogenic sources of PAHs include vehicle exhaust; manufacturing of coal tar 

pitch and asphalt; petroleum refining; and open burning (Eisler 2000 and others). The largest 

sources of PAHs in Washington are wood burning stoves and fireplaces. Other major sources 

include creosote-treated wood, vehicles, leaks and improper disposal of motor oil, and small 

engines (e.g., lawn mowers and garden equipment). PAHs in fish and shellfish are a result of 

contamination of water and sediment while PAHs in livestock (e.g., beef) are from consumption 

of contaminated pasture and vegetation. PAHs may accumulate in shellfish but generally do not 

biomagnify because most are readily metabolized by other species such as fish and humans 

(Eisler 2000). 

Dioxin-like compounds include PCDDs, PCDFs, and certain PCBs. PCDDs and PCDFs have 

natural sources but are also created and are considered unwanted impurities in some industrial 

processes and products such as pesticides (Eisler 2000). Common sources of dioxins in 

Washington State include waste incinerators, pulp mills, industrial processes, and backyard burn 

barrels. PCBs are a group of 209 synthetic organic chemicals that were used as insulating and 

cooling agents in the electricity generating industry, and that had a number of other industrial 

applications (e.g., as additives to caulks and paints to improve durability). The production and 

 

8 Two metals (cadmium and lead) are considered PBT metals of concern in Washington State (Washington Administrative Code 

173-333) but these metals are not always analyzed in seafood tissue samples and do not often appear in articles and reports 

regarding PBTs in seafood in Washington. 
Page 14 July 20, 2012 Technical Issue Paper 

sale of PCBs was banned in the United States in the late 1970s, but these compounds have 

persisted in the environment in soils, sediments, and organisms. Dioxins and PCBs 

bioaccumulate and biomagnify in the food chain. 

c. Primary chemicals of concern in Washington fish and shellfish 

Fish and shellfish in Washington State have been exposed to pollutants discharged into waters 

including sewage, pulp and paper industry wastes, petroleum products, heavy metals, and 

synthetic organic chemicals (e.g., pesticides, PCBs). Accidental spills of dangerous materials and 

past business practices have contaminated land and waters. In 2006, WDOH reviewed Puget 

Sound fish tissue data from the Washington Department of Fish and Wildlife to determine which 

contaminants have the potential to cause public health concern (WDOH 2006). The following 

chemicals were detected in 10 percent or more of the samples: alpha chlordane, arsenic, benzyl 

alcohol, copper, DDT and degradation products, DEHP, mercury, and PCBs. Of these chemicals, 

only PCBs and mercury were detected with sufficient frequency and at high enough levels that 

WDOH believed an assessment of health risk was warranted at that time. WDOH did not include 

shellfish in the risk assessment. Some shellfish are known to accumulate PAHs due to their 

inability to metabolize these compounds. Therefore, because shellfish may be a significant 

source of PAHs for shellfish consumers, PAHs were included in this Technical Issue Paper. Note 

that the Puget Sound Assessment and Monitoring Program did not analyze tissues for PCDDs or 

PCDFs. However, data from the fish and shellfish studies in the Ecology Environmental 

Information Management Database indicate that these chemicals are found in Washington State 

fish and shellfish. This Technical Issue Paper focuses on the health risks associated with 

mercury, PAHs, dioxins/furans, and PCBs. 

B. Adverse health effects associated with primary contaminants of 

concern 

a. Mercury 

Mercury and mercury compounds have no known biological function and their presence in 

biological organisms is undesirable and potentially hazardous (review in Eisler 2000). Most 

atmospheric mercury is in elemental or inorganic forms while the mercury in water, soil, plants, 

and animals is generally in organic forms. Bacteria in the environment convert inorganic mercury 

to organic forms such as methylmercury. Methylmercury is considered the most hazardous 

mercury compound due to its high stability, its lipid solubility, and its ability to penetrate 

membranes in living organisms. Methylmercury can bioconcentrate in organisms and biomagnify 

up food chains. Organic mercury can cross the blood-brain barrier9

 and the placenta. For all 

organisms tested, early developmental stages were the most sensitive to mercury poisoning, and 

organic forms were more toxic than inorganic forms. Mercury is not concentrated in fat but is 

associated with protein and therefore in animal-based foods it is found in the meat/fillet. 

 

9 The blood-brain barrier is a semi-permeable membrane that allows some materials to cross but prevents others from crossing; 

it protects the brain from foreign substances, protects the brain from hormones and neurotransmitters from other parts of the 

body, and maintains a constant environment for the brain. 
Technical Issue Paper July 20, 2012 Page 15 

Mercury is a known teratogen (causing birth defects), mutagen (causing DNA mutations), and 

carcinogen (review in Eisler 2000). Mercury can adversely affect reproduction, growth and 

development, behavior, blood serum chemistry, motor coordination, vision, hearing, histology, 

and metabolism at low concentrations. In several studies, high maternal exposure to mercury 

during pregnancy have been associated with impaired child cognitive development and 

achievement of developmental milestones as measured by various tests including language, 

motor skills, and intelligence (Oken et al. 2008; Cabelli et al. 2009; review in FAO/WHO 2010). 

b. Arsenic 

Arsenic is bioconcentrated but does not biomagnify in food chains (Eisler 2000). Therefore, 

arsenic concentrations are usually low in most organisms. Exposure to inorganic arsenic is 

generally from contaminated drinking water (WDOH 2009). Arsenic in food sources including 

seafood is generally in organic forms, primarily arsenobetaine. Arsenobetaine is very stable; after 

ingestion, it is rapidly excreted unchanged in the urine (summary in Vahter 1994). 

Acute or subacute exposure to arsenic compounds can cause appetite loss, reduced growth, 

hearing loss, dermatitis, blindness, degenerative changes in the kidney and liver, cancer, 

chromosomal damage, birth defects, and death (review in Eisler 2000). Chronic exposure to 

arsenic compounds is associated with liver, kidney, and heart damage, hearing loss, brain-wave 

abnormalities, and impaired resistance to viral infection. However, the probability of chronic 

poisoning from continuous ingestion of small doses is rare due to the body’s ability to detoxify 

and excrete arsenic rapidly. 

In mammals, inorganic arsenic compounds are more toxic than organic arsenic compounds, and 

trivalent species (As+3) are more toxic than pentavalent (As+5) species (review in Eisler 2000). 

Ingestion of inorganic arsenic increases the risk of cancer of the skin, lungs, bladder, and 

kidneys. Early developmental stages are the most sensitive to arsenic. Inorganic arsenic can cross 

the placenta and produce mutagenic, teratogenic, and carcinogenic effects in offspring. However, 

at environmentally relevant levels and routes of exposure, humans are not at risk of birth defects 

from arsenic. 

c. PAHs 

Exposure to PAHs may occur through the lungs, stomach, or skin. Of these pathways, dietary intake 

is a major source of exposure for PAHs (Diggs et al. 2011). Chronic exposure can cause dermatitis 

and hyperkeratosis. Benzo(a)pyrene is considered to be one of the most toxic PAH compounds and is 

the PAH with the most available health effects data. The USEPA classifies benzo[a]pyrene as a 

probable human carcinogen based on multiple studies with rats and mice. According to a Joint Food 

and Agriculture Organization of the United Nations (FAO) / World Health Organization (WHO) 

Expert Committee report (WHO 2006), 13 PAHs are clearly carcinogenic and 15 PAHs are 

genotoxic in experimental animals. Cancer associated with exposures to PAH containing mixtures 

occurs mainly in the lung (inhalational exposure) and skin (dermal exposure). Ingestion of PAHs 

has been associated with esophageal cancer (Diggs et al. 2011). 

d. PCDD/Fs 

Dioxin-like compounds (referred to hereafter as dioxins) include PCDDs, PCDFs, and PCBs. 

Dioxins and furans are discussed here, while PCBs are discussed below. Dioxins affect the 
Page 16 July 20, 2012 Technical Issue Paper 

immune system and cause dermal and hepatic (liver) toxicity, a variety of endocrine (hormone) 

effects, and cancer (summary in Birnbaum and Fenton 2003; others). The embryo and fetal stage 

of development may be especially susceptible to dioxin effects (Birnbaum 2005). Dioxins are 

tumor promoters that cause tumors to grow and enhance the incidence and multiplicity of tumors 

at multiple sites in the body. Dioxins are persistent, accumulating and lasting in the body for 

years. For maternal to offspring exposure to dioxins (e.g., through placenta and breast milk), the 

majority, if not all, of the effects are associated with in utero exposure (Birnbaum 2005). Nursing 

leads to greater infantile exposure through the breast milk, but this does not have long-term 

effects on the adult body burden. 

The mechanism of action for dioxin effects on vertebrate species is through activation of the aryl 

hydrocarbon receptor (Ah-receptor) (White and Birnbaum 2009). The Ah-receptor is believed to 

play key roles in development, aging, hypoxia, and circadian rhythms. Laboratory test animals 

that are missing the Ah-receptor10 are not healthy, which highlights that the receptor and its 

controlled activation are necessary for well-being (summary in Tuomisto and Tuomisto 2012). 

Experiments with animals have shown dioxin to be a multi-site carcinogen, but there is limited 

evidence for the carcinogenicity of dioxin in humans at environmentally relevant concentrations, 

and this issue is extremely controversial. Epidemiological studies of dioxin exposures and effects 

are complicated by the fact that everyone has some exposure to dioxins and to other chemicals, 

and carry body burdens of a suite of chemicals. Recently, Boffetta et al. (2011) conducted a 

critical review of the epidemiologic studies on human exposures to 2,3,7,8-tetrachlorodiobenzo-pdioxin (TCDD) and cancer and concluded that “recent epidemiological evidence falls far short of 

conclusively demonstrating a causal link between TCDD exposure and cancer risk in humans.” 

This finding is mirrored in the review by Tuomisto and Tuomisto (2012) who concluded that 

“Occupational cohorts with the highest exposures imply that there is a small risk of all cancers 

combined, but it is difficult to pinpoint the confounding effect of the main chemicals. Studies 

after major accidents do not unequivocally confirm this risk. The risks to populations at the 

current dioxin levels11 seem trivial if present at all.” 

e. PCBs 

Similar to dioxins, PCBs are lipophilic and move through the placenta and into milk (review in 

Santerre 2008). The USEPA has classified PCBs as a probable human carcinogen (USEPA 

2012). Only a few PCBs are structurally similar to dioxin and therefore are considered to be 

dioxin-like in their toxic effects (i.e., toxicity mediated by induction of the Ah-receptor). The 

non-cancer effects of PCBs may include: immune system suppression, reproductive effects such 

as reduced birth weight, neurological effects such as learning deficits and changes in activity, 

and endocrine effects such as changes in thyroid hormone levels (USEPA 2012). The different 

health effects of PCBs may be interrelated, as alterations in one system may have significant 

implications for the other regulatory systems of the body. PCBs and dioxins are rarely found in 

environmental and biological samples in the absence of one another (White and Birnbaum 2009). 

 

10 Animals that are bred specifically without the receptor to study drug toxicity and the biological function of the receptor. 

11 Emphasis added. 
Technical Issue Paper July 20, 2012 Page 17 

III. Comparison of health benefits and risks 

This section describes the metrics used in evaluating the risks associated with contaminants and 

presents comparisons of health benefits to risks of seafood consumption. The risk assessments 

are presented by date order, with the most recent described first. 

A. Metrics for evaluating risks 

Contaminants can cause a variety of health effects including cancer and non-cancer health 

effects. The metrics used to evaluate risks from contaminants differ depending on if the toxic 

endpoint is cancer or not cancer (e.g., neurotoxicity, immunotoxicity). The following paragraphs, 

modified from USEPA and TERA (1999), describe the most commonly used metrics for these 

two types of endpoints. 

Cancer slope factors are estimates of risk that are derived from dose-response data from 

laboratory animal or human epidemiology studies. Traditionally, a linearized multi-stage model 

has been used to extrapolate from what is observed at high experimental concentrations to lower 

environmental exposure levels. This cancer potency is estimated as the 95 percent upper 

confidence limit of the slope of the dose-response curve in the low dose region. This is an upper 

estimate of risk and the actual risk may be much lower or even approach zero. USEPA proposed 

revised cancer guidelines in 1996 and additional proposed guidance in 1998, which recommend 

that the mode of action be considered. The guidance recommends that a linear extrapolation 

should be used if the chemical is believed to act via a genotoxic mode of action, if the mode of 

action is expected to be linear at low doses, or (as a default) if no mode of action data are 

available. The guidance also recommends that a non-linear approach to extrapolation to low 

doses should be used when sufficient information on mode of action warrants. 

For non-cancer endpoints, a reference dose is identified at which one would not expect to see 

adverse effects in a population (including sensitive subgroups). A single estimate of a “safe” dose 

is identified from animal or human data, using the No Observed Adverse Effect Level (NOAEL). 

This is divided by uncertainty factors to account for extrapolation from animals to humans, 

variability in the human population, and deficiencies in the database of studies on the substance. 

The resulting reference dose (RfD) is defined as “an estimate (with uncertainty perhaps spanning 

an order of magnitude) of a daily exposure to the human population (including sensitive 

subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime.” 

B. Risk/Benefit Comparisons 

a. FAO/WHO (2011) 

In January 2010, the FAO and WHO convened a Joint Expert Consultation on the Risks and 

Benefits of Fish Consumption (FAO/WHO 2011). The tasks of the Expert Consultation were to 

review data on levels of nutrients (long-chain n-3 PFAs) and two chemical contaminants 

(methylmercury and dioxins) in a range of fish species and to compare the health benefits of fish 
Page 18 July 20, 2012 Technical Issue Paper 

consumption and nutrient intake with the health risks associated with contaminants present in 

fish12. 

After reviewing the literature, the Expert Consultation decided to compare the effects of (1) 

prenatal exposure to long-chain n-3 PFAs (EPA and DHA) and methylmercury on child IQ and 

(2) exposure to long-chain n-3 PFAs and dioxins on mortality. The rationale for this choice was 

based on the common health end-points and relatively robust evidence to establish dose–

response relationships from multiple cohort studies. 

Using data on over 75 species of fish and shellfish, the Expert Consultation classified the content 

of n-3 PFAs (as EPA + DHA) by total mercury content and by dioxin content (as total TEQs) 

(Tables 2 and 3). The resulting matrices were produced using those classifications: 

Table 2. Classification of the content of EPA plus DHA by total mercury content 

in 96 finfish and shellfish species 

 EPA + DHA 

 x ≤ 3 mg/g 3 < x ≤ 8 mg/g 8 < x ≤ 15 mg/g x > 15 mg/g 

Mercury 

x ≤ 0.1 μg/g 

Fish: butterfish; catfish; 

cod, Atlantic; cod, 

Pacific; croaker, Atlantic; 

haddock; pike; plaice, 

European; pollock; 

saithe; sole; tilapia 

Shellfish: clams; cockle; 

crawfish; cuttlefish; 

oysters; periwinkle; 

scallops; scampi; sea 

urchin; whelk 

Fish: flatfish; John 

Dory; perch, ocean 

and mullet; 

sweetfish; wolf fish 

Shellfish: mussels; 

squid 

Fish: redfish; 

salmon, Atlantic 

(wild); salmon, 

Pacific (wild); smelt 

Shellfish: crab, 

spider; swimcrab 

Fish: anchovy; 

herring; mackerel; 

rainbow trout; 

salmon, Atlantic 

(farmed); sardines; 

sprat Fish liver: cod, 

Atlantic (liver); saithe 

(liver) 

Shellfish: crab (brown 

meat) 

0.1 < x ≤ 0.5 

μg/g 

Fish: anglerfish; 

catshark; dab; grenadier; 

grouper; gurnard; hake; 

ling; lingcod and 

scorpionfish; Nile perch; 

pout; skate/ray; snapper, 

porgy and sheepshead; 

tuna, yellowfin; tusk; 

whiting 

Shellfish: lobster; 

lobster, American 

Fish: bass, 

freshwater; carp; 

perch, freshwater; 

scorpion fish; tuna; 

tuna, albacore 

Shellfish: crab; 

lobster, Norway; 

lobsters, spiny 

Fish: bass, 

saltwater; bluefish; 

goatfish; halibut, 

Atlantic (farmed); 

halibut, Greenland; 

mackerel, horse; 

mackerel, Spanish; 

seabass; seabream; 

tilefish, Atlantic; 

tuna, skipjack 

Fish: eel; mackerel, 

Pacific; sablefish 

0.5 < x ≤ 1 μg/g Fish: marlin; orange 

roughy; tuna, bigeye 

Fish: mackerel, king; 

shark 

Fish: alfonsino Fish: tuna, Pacific 

bluefin 

x > 1 μg/g Fish: swordfish 

 

12 The U.S. Food and Drug Administration published a draft report on the benefits and risks of food consumption in .January 

2009. The FAO/WHO Expert Consultation reviewed that draft report and incorporated some of the analyses in their assessment. 
Technical Issue Paper July 20, 2012 Page 19 

Table 3. Classification of the content of EPA + DHA by dioxin content in 76 

finfish and shellfish species

 EPA + DHA 

 x ≤ 3 mg/g 3 < x ≤ 8 mg/g 8 < x ≤ 15 mg/g x > 15 mg/g 

Dioxins 

x ≤ 0.5 pg 

TEQ/g 

Fish: anglerfish; 

catshark; cod, Atlantic; 

grenadier; haddock; 

hake; ling; marlin; 

orange roughy; pollock; 

pout; saithe; skate/ray; 

sole; tilapia; tuna, 

bigeye; tuna, yellowfin; 

tusk; whiting 

Shellfish: cockle; clams; 

crawfish; cuttlefish; 

periwinkle; scallops; 

scampi; sea urchin 

Fish: flatfish; John 

Dory; perch, ocean 

and mullet; shark; 

sweetfish; tuna, 

albacore 

Fish: redfish; 

salmon, Pacific 

(wild); tuna, skipjack 

0.5 < x ≤ 4 pg 

TEQ/g 

Fish: catfish; dab; 

gurnard; plaice, 

European 

Shellfish: lobster; 

oysters; scallops; whelk 

Fish: scorpion fish; 

swordfish; tuna 

Shellfish: mussels; 

squid 

Fish: alfonsino; 

goatfish; halibut, 

Atlantic (farmed); 

halibut, Greenland; 

mackerel, horse; 

salmon, Atlantic 

(wild); seabass; 

seabream 

Fish: anchovy; 

herring; mackerel; 

mackerel, Pacific; 

rainbow trout 

(farmed); salmon, 

Atlantic (farmed); 

tuna, Pacific bluefin 

Shellfish: crab (brown 

meat) 

4 < x ≤ 8 pg 

TEQ/g 

 Shellfish: crab, 

spider 

Fish: sardines; sprat 

x > 8 pg TEQ/g 

 Fish: bluefish Fish: eel Fish liver: 

cod, Atlantic (liver); 

saithe (liver) 

For the risk-benefit comparisons, the Expert Consultation created matrices for the calculations of 

(1) the effects on child IQ as a result of the mother consuming one, two, four, or seven servings 

of fish per week with different n-3 PFA and methylmercury concentrations (Table 4), and (2) the 

effects on mortality as a result of consuming one, two, four, or seven servings of fish per week 

with different n-3 PFA and dioxin concentrations (Table 5). The matrices for the effects of 

methylmercury show estimates of changes in IQ. In the calculation, IQ points are lost as a result 

of methylmercury exposure and gained as a result of n-3 PFA. Positive numbers in green show 

where the net effect on IQ is positive—the gain in IQ points (using the upper bound estimate) is 

greater than the loss; negative numbers in red show where the net effect on IQ points is negative. 

Cells where the net effect is negative are shaded. The matrices for the effects of dioxins show the 

net of estimates of lives lost as a result of dioxin exposure and lives saved (due to reduction in 

coronary heart disease) as a result of n-3 PFA exposure. Where the net effect is positive (lives 

gained is greater than lives lost) this is represented by positive, green numbers. Shaded cells with 

negative numbers represent estimates of where the net effect is negative—lives lost are greater 

than lives saved. 
Page 20 July 20, 2012 Technical Issue Paper 

Table 4. Estimated changes in child IQ resulting from maternal consumption of 

fish with different methylmercury and EPA plus DHA contentsa 

(a) One serving per week (3.5 ounces per week, or 14.3 g/day) 

 EPA + DHA 

 x ≤ 3 mg/g 3 < x ≤ 8 mg/g 8 < x ≤ 15 mg/g x > 15 mg/g 

 Median 2 5.5 11.5 20 Methylmercury

x ≤ 0.1 μg/g 0.05 +0.68 +2.0 +4.3 +5.7

0.1 < x ≤ 0.5 μg/g 0.3 +0.3 +1.6 +3.9 +5.3

0.5 < x ≤ 1 μg/g 0.75 –0.43 +0.9 +3.2 +4.6

x > 1 μg/g 1.5 –1.5 –0.2 +2.1 +3.5

(b) Two servings per week (7 ounces per week, or 28.6 g/day) 

 EPA + DHA 

 x ≤ 3 mg/g 3 < x ≤ 8 mg/g 8 < x ≤ 15 mg/g x > 15 mg/g 

 Median 2 5.5 11.5 20 Methylmercury

x ≤ 0.1 μg/g 0.05 +1.3 +4.0 +5.6 +5.6

0.1 < x ≤ 0.5 μg/g 0.3 +0.6 +3.3 +4.9 +4.9

0.5 < x ≤ 1 μg/g 0.75 –0.8 +1.9 +3.5 +3.5

x > 1 μg/g 1.5 –3.2 –0.5 +1.1 +1.1

(c) Four servings per week (14 ounces per week, or 57.1 g/day) 

 EPA + DHA 

 x ≤ 3 mg/g 3 < x ≤ 8 mg/g 8 < x ≤ 15 mg/g x > 15 mg/g 

 Median 2 5.5 11.5 20 Methylmercury

x ≤ 0.1 μg/g 0.05 +2.8 +4.0 +5.5 +5.5

0.1 < x ≤ 0.5 μg/g 0.3 +1.2 +3.9 +3.9 +3.9

0.5 < x ≤ 1 μg/g 0.75 –1.6 +1.1 +1.1 +1.1

x > 1 μg/g 1.5 –6.2 –3.5 –3.5 –3.5

(d) Seven servings per week (25 ounces per week, or 100 g/day) 

 EPA + DHA 

 x ≤ 3 mg/g 3 < x ≤ 8 mg/g 8 < x ≤ 15 mg/g x > 15 mg/g 

 Median 2 5.5 11.5 20 Methylmercury

x ≤ 0.1 μg/g 0.05 +4.9 +5.3 +5.3 +5.3

0.1 < x ≤ 0.5 μg/g 0.3 +2.1 +2.5 +2.5 +2.5

0.5 < x ≤ 1 μg/g 0.75 –2.8 –2.4 –2.4 –2.4

x > 1 μg/g 1.5 –10.9 –10.5 –10.5 –10.5

a Fish serving size was estimated to be 100 g. Ratio of DHA to EPA + DHA was assumed to be 0.67. Maternal body weight was assumed 

to be 60 kg. IQ points gained from DHA exposure was estimated using the coefficient of 4 IQ points for 100 mg of DHA intake. The 

maximum positive effect from DHA was estimated at 5.8 points. Yellow shaded cells represent the estimates where the net effect on child 

IQ, using the upper-bound estimate for methylmercury, is negative. 
Technical Issue Paper July 20, 2012 Page 21 

Table 5. Estimated changes in mortality per million people from consuming fish 

with different dioxin and EPA plus DHA contents a 

(a) One serving per week (3.5 ounces per week, or 14.3 g/day) 

 EPA + DHA 

 x ≤ 3 mg/g 3 < x ≤ 8 mg/g 8 < x ≤ 15 mg/g x > 15 mg/g 

 Median 2 5.5 11.5 20 Dioxins 

x ≤ 1.0 pg/g 0.2 +4,500 +12,450 +26,150 +39,750 

1.0 < x ≤ 4.0 pg/g 2.5 +3,950 +11,900 +25,600 +39,200

4.0 < x ≤ 8.0 pg/g 6.0 +3,150 +12,100 +24,800 +38,400

x > 8.0 pg/g 20.0 –250 +7,700 +21,400 +35,000 

(b) Two servings per week (7 ounces per week, or 28.6 g/day) 

 EPA + DHA 

 x ≤ 3 mg/g 3 < x ≤ 8 mg/g 8 < x ≤ 15 mg/g x > 15 mg/g 

 Median 2 5.5 11.5 20 Dioxins 

x ≤ 1.0 pg/g 0.2 +9,000 +24,900 +39,700 +39,700 

1.0 < x ≤ 4.0 pg/g 2.5 +7,900 +23,800 +38,600 +38,600

4.0 < x ≤ 8.0 pg/g 6.0 +6,200 +22,100 +36,900 +36,900

x > 8.0 pg/g 20.0 –400 +15,500 +30,300 +30,300 

(c) Four servings per week (14 ounces per week, or 57.1 g/day) 

 EPA + DHA 

 x ≤ 3 mg/g 3 < x ≤ 8 mg/g 8 < x ≤ 15 mg/g x > 15 mg/g 

 Median 2 5.5 11.5 20 Dioxins 

x ≤ 1.0 pg/g 0.2 +18,010 +39,610 +39,610 +39,610 

1.0 < x ≤ 4.0 pg/g 2.5 +15,800 +37,400 +37,400 +37,400

4.0 < x ≤ 8.0 pg/g 6.0 +12,500 +34,100 +34,100 +34,100

x > 8.0 pg/g 20.0 –800 +20,800 +20,800 +20,800 

(d) Seven servings per week (25 ounces per week, or 100 g/day) 

 EPA + DHA 

 x ≤ 3 mg/g 3 < x ≤ 8 mg/g 8 < x ≤ 15 mg/g x > 15 mg/g 

 Median 2 5.5 11.5 20 Dioxins 

x ≤ 1.0 pg/g 0.2 +31,570 +39,470 +39,470 +39,470 

1.0 < x ≤ 4.0 pg/g 2.5 +27,700 +35,600 +35,600 +35,600

4.0 < x ≤ 8.0 pg/g 6.0 +21,900 +29,800 +29,800 +29,800

x > 8.0 pg/g 20.0 –1,400 +6,500 +6,500 +6,500 

a Fish serving size was estimated to be 100 g (3.5 ounces). Mean population body weight was assumed to be 60 kg. The numbers of lives 

lost from dioxin exposure was estimated using upper-bound estimates of risk. Estimates of the numbers of lives saved were due to 

reduction in coronary heart disease risk from EPA + DHA intake. The maximum positive effect from EPA + DHA was estimated to occur at 

250 mg/day. Positive green numbers occur where lives saved due to EPA + DHA is greater than lives lost to dioxin. Yellow shaded cells 

with a red number represent the estimates where the net effect is negative; lives lost are greater than lives saved. 

Note that none of the fish species evaluated by FAO/WHO fell into the maximum 

dioxin/minimum n-3 PFA category where risk was greater than benefit (see Table 3), and 
Page 22 July 20, 2012 Technical Issue Paper 

relatively few fish species fell into the mercury range where risk was greater than benefit (see 

Table 2). 

It should be noted that Tables 4 and 5 assume a serving size of 100 grams (3.5 ounces). A study 

by Smiciklas-Wright et al. (2002) estimated mean and 90th percentile fish meal size for general 

population adults using data gathered in the 1994–1996 USDA continuing survey of food intakes 

by individuals. The average amount of finfish (other than tuna) per eating occasion was 

114 grams; males, age 40 to 59, had the highest meal size, with a mean of 130 grams 

(4.6 ounces) and a 90th percentile value of 243 grams (8.6 ounces). Studies of recreational fishers 

have reported average meal sizes up to 376 grams (13.3 ounces; Burger et al. 1999), while 

studies of Native American tribal fish consumers also report meal sizes significantly larger than 

100 grams. 

Concentrations of mercury and dioxins in finfish and shellfish collected in Washington State 

during the last 10 years are summarized in another Technical Issue Paper (Chemical 

Contaminants in Dietary Protein Sources). Average mercury concentrations range from 0.011 to 

0.24 μg/g (11 to 240 μg/kg) in Washington state finfish, and from 0.0074 to 0.067 μg/g (7.4 to 

67 μg/kg) in Washington state shellfish. Mean dioxin TEQs13 range from 0.054 to 1.7 pg/g in 

Washington State finfish; mean concentrations in shellfish range from 0.080 to 6.1 pg/g. These 

concentrations indicate that consumption of seafood results in a net health benefit. 

For example, maternal consumption of 25 ounces per week (or about three 8-ounce servings per 

week) of seafood contaminated with methylmercury at 0.24 μg/g (the high end of the average 

concentration in Washington state finfish) would be expected to result in a net increase in child 

IQ. An estimated 5.4 IQ points would be gained due to DHA exposure, compared to a loss of up 

to 3.3 IQ points due to methylmercury exposure (Table 4). 

Similarly, consumption of 25 ounces per week (or about three 8-ounce servings per week) of 

seafood contaminated with dioxins/furans at a concentration of 1.7 pg/g TEQ (the high end of the 

average dioxin concentration in Washington state finfish) would be expected to result in a net 

increase in health benefits. An estimated 31,900 lives would be saved due to a reduction in 

coronary heart disease, compared to a loss of up to 4,200 lives due to dioxin toxicity, for each 

million people exposed (Table 5). 

The Expert Consultation14 summarized a large body of information available on the health 

benefits and risks associated with fish consumption including: 

 Consumption of fish provides energy, protein, and a range of other important nutrients, 

including the long-chain n-3 polyunsaturated fatty acids (long-chain n-3 PFAs). Optimal 

health benefits can be maximized by consuming fish with higher long-chain n-3 PFA content 

and lower methylmercury content. The risk of coronary heart disease mortality is 

significantly increased by not eating fish. 

 

13 The TEQ calculation is for dioxin and furan compounds only and does not include dioxin-like PCB congener data, which were 

not available for marine fish in the Ecology EIM database. 

14 Some of the statements taken from the Expert Consultation have been edited here for clarity or brevity. 
Technical Issue Paper July 20, 2012 Page 23 

 The benefits of fish consumption, demonstrated in numerous studies across a wide range of 

populations, reflect the sum of benefits and risks from all of the constituents in the fish. 

 Based on observed dose-response relationships and other factors, it is very unlikely that the 

benefits of fish consumption are explained to any large extent by the replacement of less 

“healthy” foods with fish. If this were the case, however, it would still represent a causal 

effect of fish consumption. 

 Among the general adult population, consumption of fish, particularly fatty fish, lowers the 

risk of mortality from coronary heart disease. There is an absence of probable or convincing 

evidence of risk of coronary heart disease associated with methylmercury. While convincing 

evidence that high dioxin exposure increases the risk of cancer, there is currently insufficient 

evidence that typical levels of dietary dioxins (such as seen in fish and other dietary sources) 

increase the risk of cancer. Potential cancer risks associated with dioxins are well below 

established coronary heart disease benefits from fish consumption. 

 When comparing the benefits of long-chain n-3 PFAs with the risks of methylmercury 

among women of childbearing age, maternal fish consumption lowers the risk of suboptimal 

neurodevelopment in their offspring compared with the offspring of women not eating fish in 

most circumstances evaluated. 

 At levels of maternal exposure to dioxins (from fish and other dietary sources) that do not 

exceed the provisional tolerable monthly intake (PTMI) of 70 pg/kg body weight15

established by Joint Expert Council (for PCDDs, PCDFs, and coplanar PCBs), 

neurodevelopmental risk for the fetus is negligible. At levels of maternal exposure to dioxins 

(from fish and other dietary sources) that exceed the PTMI, neurodevelopmental risk for the 

fetus may no longer be negligible. 

 Among infants, young children, and adolescents, the available data are currently insufficient 

to derive a quantitative framework of the health risks and health benefits of eating fish. 

However, healthy dietary patterns that include fish consumption and are established early in 

life influence dietary habits and health during adult life. 

FAO/WHO note that other biological endpoints have been used to measure dioxin risks that are 

more conservative than the gross endpoint of mortality. For example, various studies in human 

populations have examined the association of gestational and/or lactational exposure to dioxins 

and non-dioxin-like PCBs with neurobehavioral development. A problem inherent in these 

studies is that dioxins and PCBs (including dioxin-like and non-dioxin-like PCBs) coexist with 

each other (and with a host of other contaminants) in biological systems. Therefore, the relative 

contribution of the various contaminant components to developmental toxicity cannot be 

delineated. 

For methylmercury, other measures of developmental effects besides IQ have been used in 

various studies, but the Expert Consultation chose to use IQ based on the common health 

endpoint for methylmercury and DHA+EPA exposure and because the dose-response 

relationships from multiple cohort studies had been established by multiple meta-analyses. 

 

15 By comparison, the USEPA RfD for 2,3,7,8-TCDD is 0.7 pg/kg/day, or roughly 210 pg/kg/month assuming a 30-day month. 
Page 24 July 20, 2012 Technical Issue Paper 

b. Tsuchiya et al. (2008–2009) 

Japanese and Korean populations in Washington State consume fish at higher rates than the 

national average. The University of Washington’s Institute for Risk Analysis and Risk 

Communication and the Washington State Department of Health conducted a longitudinal 

study16 examining the mercury exposure in women of childbearing age in these populations 

(Tsuchiya et al. 2008a,b, 2009). The study populations included 106 Japanese and 108 Korean 

women of childbearing age (18 to 45) who resided in the Puget Sound area of Washington for at 

least 6 months. 

The women provided hair samples along with urine, blood, and toenail samples, and completed a 

food-frequency questionnaire that was open ended and spanned fish consumption over the 

previous year. The fish consumption survey was based on surveys previously conducted for 

several other Pacific Northwest fish-consuming populations (tribal surveys and Sechena et al., 

1999). The food frequency questionnaire was a validated dietary tool used and developed by the 

Fred Hutchinson Cancer Research Center and was self administered by the participants of this 

study. As part of the fish dietary survey, participants were provided a pictorial fish booklet 

containing pictures with names of various fish species commonly consumed by Japanese and 

Koreans and seafood commonly found in the Pacific Northwest. Interview questions included 

frequency of consumption and servings sizes (based on fish models of fish steaks, fillets, sushi 

pieces, and shellfish samples). Also, participants were asked if they consumed any other fish not 

listed in the fish booklet. 

The Japanese cohort was interviewed three times and the Korean cohort twice over a 14-month 

period. Participants that returned for second and third visits were administered dietary recall 

surveys spanning the 2-week period prior to the date of the visit. Data were obtained for 106, 90, 

and 85 Japanese individuals on the first, second, and third visits, respectively. The Korean group 

had 108 individuals participate on the first visit with 63 returning a second time. Mercury fish 

tissue concentrations were determined from fish commonly consumed by Japanese and Korean 

communities in the Puget Sound area from local Asian grocery stores. Analysis was conducted 

on skinless edible portions consisting of steaks or fillets. 

Both Japanese and Korean respondents from this survey consume almost the same amounts of 

finfish (mean fish consumption of 60 grams/day for Japanese and 59 grams/day for Korean). 

Also, this similarity in fish consumption for Japanese and Koreans is reflected in the finfish 

consumption distribution with 95th percentiles being 159 grams/day for Japanese and 

147 grams/day for Koreans. Differences in amounts of total fish consumption for these two fishconsuming populations are due to the Koreans consuming nearly 70 percent more shellfish on a 

daily basis (22.7 grams/day/person) compared to the Japanese (13.5 grams/day/person). The 

mean total fish consumption for Japanese (73 grams/day) and Koreans (82 grams/day) is almost 

identical to the 95th percentile estimates from CSFII and NHANES national fish dietary data. 

Table 6 provides the fish species consumed (percent of total fish consumption) for the Japanese 

population. The list of fish species most consumed by the Japanese group did not change much 

over the course of the study. 

 

16 Longitudinal studies make repeated observations or take repeated measurements of the same variable(s) over time. 
Technical Issue Paper July 20, 2012 Page 25 

Table 6. Fish Species Most Consumed (>4 percent of total) for Japanese 

Population 

Species Fish Tissue Mercury 

Concentrations (μg/kg) 

Percent of total consumption 

Visit 1 (n=106) Visit 2 (n=90) Visit 3 (n=85) 

Salmon 72 29.0 28.0 36.3 

Mackerel 40 9.1 18.1 10.6 

Black Cod 97 6.5 4.5 2.6 

Squid 39 5.6 5.5 3.1 

Light Tuna 

(Canned) 

127 5.0 4.8 8.3 

Halibut 216 4.4 0.6 3.3 

Ahi 185 4.2 4.3 6.7 

Cod 115 1.2 8.7 5.5 

Total 65 75 76 

Mean individual fish intake (grams/day 59.5 33.7 31.3 

Adapted from Tsuchiya et al. 2009, Table 1. 

Table 7 provides the mercury intakes (mercury fish tissue concentrations for species consumed) 

for the Japanese population. 

Table 7. Fish Species with Greatest Mercury Intake (>5 percent of total) for 

Japanese Population 

Species Fish Tissue Mercury 

Concentrations (μg/kg) 

Percent of total mercury for species consumed 

Visit 1 (n=106) Visit 2 (n=90) Visit 3 (n=85) 

Salmon 72 17.0 25.0 32.0 

White (Albacore) 

Tuna (Canned) 

361 8.7 5.7 2.8 

Halibut 216 7.9 1.6 8.7 

Ahi 185 6.5 9.7 15.1 

Light tuna 127 5.3 7.3 12.8 

Black cod 97 5.3 5.3 3.2 

Red snapper 221 3.8 5.3 3.4 

Mackerel 40 3.0 8.8 5.1 

Cod 115 1.1 12.2 7.8 

Total 59 81 91 

Mean individual estimate mercury intake (μg/day) 7.2 2.7 2.5 

Adapted from Tsuchiya et al. 2009, Table 2. 

Table 8 provides the fish species consumed (percent of total fish consumption) for the Korean 

population. 
Page 26 July 20, 2012 Technical Issue Paper 

Table 8. Fish Species Most Consumed (>4 percent of total) for Korean 

Population 

Species 

Fish Tissue Mercury 

Concentrations 

(μg/kg) 

Percent of total consumption 

Visit 1 (n=108) 

(all participants) 

Visit 1 (n=63) 

(subsample) 

Visit 2 (n=63) 

(subsample) 

Squid 39 23.0 21.2 10.2 

Mackerel 40 12.0 13.1 16.4 

Yellow croaker 53 11.0 13.1 15.4 

Salmon 72 9.1 8.2 7.8 

Flounder/sole 147 6.3 6.0 9.1 

Light tuna 

(Canned) 

127 5.6 4.7 12.2 

Black cod 97 4.8 5.3 0.5 

Pike mackerel 30 4.3 4.6 5.1 

Pollack 22 3.5 4.1 4.4 

Ahi 185 2.9 2.3 4.4 

Total 83 83 86 

Mean individual fish intake (grams/day 59.1 71.7 29.1 

Adapted from Tsuchiya et al. 2009, Table 3. 

For the Koreans, the average estimated mercury exposures for the first visit were 5.3 μg/day (for 

all 108 participants) and 5.1 μg/day (for the subsample of 63 participants) (Table 9). The average 

estimated mercury exposure for the second visit was 2.6 μg/day. There was a significant 

difference in total fish consumption estimates between those participants who returned for a 

second visit and those who did not. However, the percentage that each species contributed to the 

total fish consumption estimates was similar between visits. 

Table 9. Fish Species with Greatest Mercury Intake (>5 percent of total) for 

Korean Population 

Species 

Fish Tissue Mercury 

Concentrations (μg/kg) 

Percent of total mercury for species consumed 

Visit 1 (n=108) 

(all participants) 

Visit 1 (n=63) 

(subsample) 

Visit 2 (n=63) 

(subsample) 

White (Albacore) 

tuna (Canned) 

361 14.0 12.7 15.2 

Flounder/sole 147 10.0 12.6 14.5 

Squid 39 10.0 11.8 4.2 

Light tuna 

(Canned) 

127 7.9 8.6 17.0 

Salmon 72 7.4 8.5 6.1 

Yellow croaker 53 6.4 9.9 9.1 

Ahi 185 4.9 6.0 9.1 

Mackerel 40 4.5 7.5 6.6 

Total 65 78 82 

Mean individual estimate mercury intake (μg/day) 5.3 5.1 2.6 

Adapted from Tsuchiya et al. 2009, Table 4. 
Technical Issue Paper July 20, 2012 Page 27 

At the time of the first visit, over half of the Japanese participants were overexposed to mercury, 

based on hair-mercury levels exceeding the established RfD of 1.2 mg/kg. For the Koreans, 

approximately 13 percent of the participants were overexposed to mercury. This is because the 

average mercury content of the species consumed was lower in this group. Japanese participants 

who were overexposed had three times higher hair mercury levels and had fish consumption 

rates1.5 to 2 times higher than those not overexposed. Overexposed Korean participants had hair 

mercury levels 2.3 to 3 times higher than those not overexposed. For both cohorts, those not 

overexposed consumed fish at a rate of 40–60 grams/day. After the first-year interviews were 

completed, participants were given education materials and advised to switch to alternative fish 

species with lower mercury concentrations. However, the fish species responsible for most of the 

mercury body burden in both populations did not change over time. 

The researchers also estimated n-3 PFA intake for the study participants. This was done using 

DHA+EPA concentrations available in the literature for each species consumed, and then 

deriving DHA+EPA intake values for each participant using their species-specific intake rates. 

Figure 1 shows n-3 PFA intake plotted against hair mercury concentrations. 

Figure 1. n-3 PFA intake and mercury exposure (hair-mercury) compared to the 

mercury RfD and recommended daily allowance of DHA=EPA 

Source: Modified from Faustman 2011, based on Tschuyia et al. 2008a. 

Note that some participants exceeded the mercury RfD and still did not meet the recommended 

dose for n-3 PFAs. The authors conclude that both mercury and n-3 PFA content of fish are 

important in developing consumption guidance. In addition, the study found a 100 percent 

difference in the fish intake between the open-ended and 2-week recall surveys and that the 
Page 28 July 20, 2012 Technical Issue Paper 

open-ended survey data better represented mercury intake as determined from hair mercury 

concentrations. 

c. Institutes of Medicine (2007) 

The National Oceanic and Atmospheric Administration, which regulates U.S. marine fisheries, 

asked the Institutes of Medicine (IOM) of the National Academies to convene a committee to 

examine the scientific evidence on the nutritional benefits and risks from seafood. The IOM 

committee was charged to: 

 identify and prioritize adverse health effects from both naturally occurring and introduced 

toxicants in seafood; 

 assess evidence on availability of specific nutrients in seafood compared to other food sources; 

 determine the impact of modifying food choices to reduce intake of naturally occurring and 

introduced toxicants on nutrient intake and nutritional status within the U.S. population; 

 develop a decision path for U.S. consumers to balance their seafood choices to obtain 

nutritional benefits while minimizing exposure risks; and 

 identify data gaps and recommend future research. 

The IOM committee concentrated on issues affecting marine species and published its final 

report in 2007 (Nesheim and Yaktine 2007). 

For the benefit/risk analysis, the IOM committee evaluated changes in benefits and risks 

associated with changing consumption patterns that may occur as a result of guidance provided 

to consumers regarding fish consumption. The IOM committee examined the impact of foodchoice trade-offs involving calories, saturated fat, EPA/DHA, selenium, and iron. Contaminants 

evaluated, due to availability of data, were methylmercury, dioxins, and dioxin-like compounds. 

This information was used to develop guidance on seafood consumption tailored to four distinct 

population groups (Figure 2): (1) females who are or may become pregnant or who are 

breastfeeding; (2) children up to age 12; (3) adolescent males, adult males, and females who will 

not become pregnant; (4) adult males and females who are at risk of cardiovascular disease. 

Seafoodhealthfacts.org, a joint project of Oregon State University, Seafood Consumer Center, 

Cornell University, and the Universities of California, Delaware, Florida, and Rhode Island, 

modified one of the sample public risk communication graphics from the IOM report when it 

created a seafood health reference guide for healthcare providers (Seafoodhealthfacts.org, 

undated). The Seafoodhealthfacts.org figure includes the FDA action level for mercury, which 

puts the mercury content of the various seafood species into context (Figure 3). This figure 

shows estimated n-3 PFA intake (as EPA + DHA) in a 3-ounce serving of fish against the 

average mercury levels for each species. Those species considered to be low risk for mercury 

exposure are colored green. Yellow species have high average mercury levels that exceed or 

approach the FDA action level of 1 part per million (ppm, or mg/kg) and should be avoided by 

sensitive groups (women who may become pregnant, pregnant and breastfeeding women, and 

young children) according to recommendations by several groups (USFDA, USEPA, IOM, etc.). 

The blue colored species (canned albacore tuna) is considered a good source of n-3 PFAs but 

consumption should be limited due to mercury levels in this species. 
Technical Issue Paper July 20, 2012 Page 29 

Figure 2. Decision pathway representing the balance between benefits and risks 

associated with seafood consumption 

Source: Nesheim and Yaktine 2007 
Page 30 July 20, 2012 Technical Issue Paper 

Figure 3. EPA+DHA and mercury content in representative seafood portions 

Source: Seafoodhealthfacts.org. 
Technical Issue Paper July 20, 2012 Page 31 

d. Mariën and Patrick (2001) 

In 2001, the Washington State Department of Health conducted a methylmercury exposure 

analysis for five populations of fish consumers in Washington: freshwater recreational anglers, 

saltwater recreational anglers, and members of the Tulalip, Squaxin Island, and Suquamish 

Indian Tribes. Fish-consumption data for freshwater recreational anglers were taken from anglers 

fishing at Lake Roosevelt. This lake is bordered by two tribal reservations (Coleville and 

Spokane) and is visited by over 1 million people annually. Data for saltwater anglers were 

obtained from surveys of Puget Sound anglers, including both shoreside anglers and boating 

anglers. Fish consumption rates for the three tribes were obtained from surveys. Mercury data 

were obtained from existing datasets for the fishery that each specific population was using. 

The authors calculated a Tolerable Daily Limit (TDI) to compare to estimated methylmercury 

intakes determine if any the five consumption groups were at risk for overexposure to 

methylmercury. The TDI represents the daily intake of methylmercury that is unlikely to cause any 

adverse health effects. The WDOH TDI was based upon the results of three long-term cohort studies 

of the neurological effects in children whose mothers were exposed to methylmercury in their diet – 

the Faroe Islands, New Zealand, and Seychelles Islands studies. The TDI developed by WDOH fell 

within the range of values from 0.035 to 0.08 microgram per kilogram of body weight per day 

(μg/kg/day). Note that the upper end of this range is close to the USEPA RfD of 0.1 μg/kg/day. 

Freshwater Anglers 

The daily intake of mercury for walleye, kokanee, rainbow trout, and smallmouth bass was 

calculated as the product of the number of meals per month when that species was consumed, the 

usual number of fillets consumed at a meal, the average weight of a fillet of that species, and the 

average fish tissue mercury concentration for that species. The total daily intake was then 

estimated for each person by summing the estimated intakes due to each of the four species. This 

value was then converted to units of μg/kg/day assuming an average adult body weight of 70 kg. 

Of the 343 individual anglers surveyed, most (298 individuals, or 87 percent) had estimated 

mercury intake levels below the upper bound of the TDI. Nearly all of the individuals exceeding 

the TDI were adult males over the age of 50, who are not considered a population of concern 

(women of childbearing age). Assuming the spouses of these more highly exposed older males 

had similar intakes and were of similar age, they also would not represent a population of 

concern. 

Saltwater Anglers 

For saltwater anglers, populations with the highest consumption rates for a particular fish were 

categorized and mercury intake levels for each population were calculated. Estimated daily 

mercury intake for Puget Sound shore anglers ranged from about 0.002 μg/kg/day (tomcod and 

Pacific Hake) to as high as 0.023 μg/kg/day (Pacific cod). Boat angler consumption data were 

calculated for individuals consuming fish from three locations in Puget Sound. Estimated 

mercury intake for the boat anglers ranged from 0.003 μg/kg/day (rock sole) to 0.0095 μg/kg/day 

(Pacific cod). Total mercury intake levels for all fish species among both shore and boat anglers 

was less than the TDI even though the intake calculations assumed fish were consumed 

throughout the year. Species availability for most species is not year round due to fishing 

regulations that restrict when certain species can be caught. The authors separately evaluated 
Page 32 July 20, 2012 Technical Issue Paper 

mercury exposure for anglers consuming salmon using tissue data that had been unavailable 

when the original surveys were conducted. Using median values for coho and Chinook salmon 

(0.04 and 0.1 mg/kg, respectively), intake values were calculated as 0.02 and 0.09 μg/kg/day, 

respectively. Anglers consuming Chinook at rates greater than 0.8 g/kg/day would have 

exposures slightly exceeding the TDI. 

Tulalip, Squaxin, and Suquamish Tribes 

For the tribal exposures, the 90th percentile fish consumption rate for each category (anadromous, 

pelagic, bottom) and species of fish were combined with Washington Department of Wildlife 

median mercury fish concentrations to determine intake levels (Table 10). Salmonid 

consumption was the primary cause for intake values exceeding the TDI. The TDI was exceeded 

by 8 to 14 percent of the Tulalip Tribe population and 10 to 25 percent of the Squaxin Island 

Tribe population when consuming salmon only. The percent of the Suquamish Tribe population 

exceeding the TDI could not be determined from the available data although 25 percent of the 

surveyed population was at or above the TDI. 

Table 10. Estimated mercury intake from fish consumption for Tulalip Tribes, 

Squaxin Island Tribe, and Suquamish Tribes 

a Intake values are based on the assumption that the fish type consumed from a particular group (anadromous, pelagic, 

bottom) is of one type only (provided in fourth column). 

b Data with footnote ‘b’ not included in this revised version of the table. 

c Consumption value based on 86th percentile rate for anadromous fish category. 
Technical Issue Paper July 20, 2012 Page 33 

The authors concluded that most of the individuals within the Tulalip Tribe could reduce their 

mercury intake below the TDI by consuming other anadromous fish as alternatives to Chinook 

(e.g., coho, chum, sockeye, steelhead, or pink salmon). Squaxin Island and Suquamish tribe 

members could also reduce their mercury intake by consuming salmonids other than Chinook. 

Another recommendation was that the Suquamish Tribe individuals that were consuming 

elevated quantities should reduce their intake of these species. The authors also noted that 

background mercury levels present in salmon were resulting in populations being exposed to 

mercury above the TDI. 

e. USEPA/TERA (1999) 

The USEPA and Toxicology Excellence for Risk Assessment (TERA) summarized what was 

known about health benefits and risks from fish consumption in a report published in 1999. The 

report compared the possible health risks of consuming contaminated fish while considering the 

potential health benefits lost by not eating fish, and proposed a framework for comparing the 

benefits and risks quantitatively. 

Benefits described by the USEPA/TERA report included discussions of the beneficial protein, 

fatty acid profiles, and nutrients provided by fish and the various studies to date on CHD and 

heart attack, and other health endpoints which have been described in detail in Section II. At the 

time, however, the authors believed further study was needed to resolve whether fish 

consumption provided significant protection against CHD or heart attack. Contaminants 

considered included DDT (an organochlorine pesticide now banned in the United States) and its 

metabolites, methylmercury, dioxin, PCBs, chlordane (an organochlorine pesticide now banned 

in the United States), and chlorpyrifos (an organophosphate pesticide). 

The USEPA/TERA report concluded that consuming uncontaminated fish (or at least fish that 

are smaller, younger, or in general less contaminated) may provide health benefits, but without 

the potential health risks associated with contamination. Before eating any contaminated fish, 

consumers should consider fish supplies from cleaner water bodies, eating smaller, less 

contaminated fish, and cooking and cleaning methods that reduce contaminants. The eating of 

such “cleaner” fish rather than more contaminated fish would maximize the net benefit of fish 

consumption. However, better estimations of benefits were needed for the general population and 

its sensitive subgroups and that better risk information is needed on the chemicals that commonly 

contaminate fish. The data gaps identified were sufficiently large so as to prevent any definitive 

conclusions from the study or any overall recommendations regarding existing fish consumption 

advisory programs of the United States or other countries. The authors believed further study 

was needed to confirm and extend these preliminary findings.

 
Page 34 July 20, 2012 Technical Issue Paper 

Conclusions 

For those who consume meats, replacing meats with vegetable alternatives (e.g., beans) or fish is 

one strategy to replace saturated fats with monounsaturated fats and reduce cholesterol 

(Lichtenstein et al. 2006; USDA and USDHHS 2010). Increasing seafood consumption of most 

species will lead to increased n-3 PFA intake and reduced risk for major health conditions such 

cardiovascular and coronary heart disease. Health benefits associated with consumption of fish, 

particularly fatty fish such as salmon, are well documented. 

While exposures to methylmercury and persistent organic pollutants may have negative human 

health impacts, there are considerable uncertainties about estimates of these health risks to the 

general population at levels present in commercially obtained seafood (Nesheim and Yaktine 

2007). 

High rate fish consumers such as certain ethnic groups (Japanese, American Indian) can 

accumulate mercury levels that approach or exceed reference doses (Tsuchiya et al. 2008a,b). 

However, Mahaffey et al. (2008) suggest that data on methylmercury and n-3 PFA 

concentrations seafood can be used to guide the selection of individual fish and shellfish species 

that are higher in n-3 PFA and low in methylmercury content (see Figure 2), thereby reducing 

mercury exposure. Further, the risks from lipophilic compounds can be reduced by trimming fat, 

using cooking methods that reduce fat such as broiling, and by eating a variety of species. 

A recurrent theme in recent reviews and analyses is that reducing fish consumption can 

negatively impact the health status of vulnerable populations (Dórea 2008). The evidence 

suggests that the fetus and infants may be among the principal beneficiaries from certain 

nutrients in seafood. Few data are available about the extent to which beneficial components of 

seafood, such as selenium and omega-3 fatty acids, might mitigate risks associated with 

contaminants in seafood (Nesheim and Yaktine 2007). 

Where there are local instances of excessively high levels of contaminants such as PCBs in 

recreationally caught fish, it is important that consumers, especially those in sensitive 

populations, consult with their local health department before consuming locally caught fish. 

 
Technical Issue Paper July 20, 2012 Page 35 

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This page purposely left blank for duplicate printing. 
Technical Issue Paper 

Chemical Contaminants in 

Dietary Protein Sources 

 

Technical Issue Paper 

Chemical Contaminants in 

Dietary Protein Sources 

July 20, 2012 

Toxics Cleanup Program 

Washington State Department of Ecology 

Olympia, Washington 

 

Technical Issue Paper July 20, 2012 Page i 

Table of Contents 

Page

List of Figures and Tables............................................................................................................... ii

Figures....................................................................................................................................... ii

Tables ........................................................................................................................................ ii

Acronyms & Abbreviations ........................................................................................................... iv

Introduction ......................................................................................................................................1

Analysis............................................................................................................................................2

I. Sources of dietary protein ....................................................................................................2

II. Contaminants of interest ......................................................................................................6

A. Metals .............................................................................................................................6

B. Organics .........................................................................................................................6

C. Relative contribution of diet to overall exposure ...........................................................7

D. Relative contribution of each type of protein source .....................................................9

E. Sensitive subpopulations ..............................................................................................17

III. Contaminant concentrations in dietary protein sources .....................................................17

A. Fish and shellfish — Washington State contaminant concentrations ..........................17

B. Other protein sources (meat, eggs, dairy) ....................................................................25

Summary ........................................................................................................................................29

References ......................................................................................................................................30

Appendices 

Appendix A. Contaminant Data Tables Supporting Figures 6, 7, and 9 

Appendix B. Washington State Contaminant Data Summarized from the EIM Database 

 
Page ii July 20, 2012 Technical Issue Paper 

List of Figures and Tables 

Figures 

Page

Figure 1. U.S. per capita meat consumption (historical and forecast to 2021) ..........................2

Figure 2. Annual per capita fish and shellfish consumption in the United States (pounds) ......3

Figure 3. Relative contribution of inorganic arsenic exposure by source ..................................8

Figure 4. Sources of U.S. average daily intake of PCDD/PCDF/PCB TEQs ............................9

Figure 5. Total and inorganic arsenic concentrations of selected protein sources (from 

data in Yost et al. 2004) ............................................................................................10

Figure 6. Sources of dietary inorganic arsenic for children 1 to 6 years (% contribution) ......11

Figure 7. Upper bound PAH15 concentrations (μg/kg) by food group ...................................13

Figure 8. Percent of total daily benzo(a)pyrene intake in a control group of 228 subjects ......14

Figure 9. Exposure pathway for PCDD/PCDF/PCB TEQ intakes from protein sources 

(percent contribution by source) ...............................................................................15

Figure 10. Mean PCB concentration in Chinook salmon fillets .................................................18

Figure 11. Mean PCB concentration in adult Chinook salmon returning to Puget Sound 

(in-rivers versus marine waters*)..............................................................................18

Figure 12. Total PAHs in Washington State mussels (μg/kg dry weight) .................................21

Figure 13. Total mercury concentrations in Washington State mussels (μg/kg dry weight) .....22

Figure 14. PCBs in large fish from Washington State lakes and rivers .....................................23

Figure 15. PCBs (μg/kg) in fish from Puget Sound compared to other common food 

sources.......................................................................................................................24

Tables 

Page

Table 1. Protein and fat content of selected protein food sources ............................................4

Table 2. Benzo(a)pyrene in animal-based protein sources .....................................................12

Table 3. Levels of marker PCBs in composite meat samples (ng/g ww or LOD) ..................16

Table 4. Levels of marker PCBs in composite fish samples (ng/g ww or LOD) ....................16

Table 5. Levels of marker PCBs in composite dairy and egg samples (ng/g ww or LOD) ....16
Technical Issue Paper July 20, 2012 Page iii 

Table 6. Average PCBs in Chinook salmon from in-river versus marine areas of the 

Puget Sound basin .....................................................................................................19

Table 7. Maximum concentration of contaminants detected in fish and shellfish sampled 

at Fidalgo Bay in Anacortes, Washington ................................................................20

Table 8. Mean total PCB concentrations for fish from the Spokane River, Spokane, WA ....20

Table 9. Summary of PCB data (μg/kg wet weight) in hake and pollock from seven 

Puget Sound Basins...................................................................................................25

Table 10. Concentration of total mercury in chicken feed and the different tissues of 

boiler chickens (μg/kg) .............................................................................................25

Table 11. Mean total and total inorganic arsenic concentrations in foods (μg/kg wet 

weight) ......................................................................................................................26

Table 12. Concentrations of PAHs in milk from western U.S. locations (ng/kg)* ..................27

Table 13. TEQ concentrations of CDD/CDFs and PCBs in milk (pg/kg) ................................27

Table 14. Mean TEQs of 17 PCDD/Fs and 4 dioxin-like PCBs in U.S. meats (ng/kg lipid) ...28

Table A-1. Sources of dietary inorganic arsenic for children 1 to 6 years (% contribution) ........2

Table A-2. Lower bound and upper bound PAH15 concentrations (μg/kg) by food group .........2

Table A-3. Estimated TEQ intake from dietary protein sources ...................................................3

Table B-1. Contaminant concentrations in selected Washington State freshwater fish ...............3

Table B-2. Contaminant concentrations in selected Washington State invertebrates ...................4

Table B-3. Contaminant concentrations in selected Washington State marine/anadromous 

fish...............................................................................................................................6

Table B-4. Mercury concentrations (μg/kg) in selected Washington State fish ...........................8

Table B-5. Mercury concentrations (μg/kg) in selected edible Washington State 

invertebrates ................................................................................................................9

Table B-6. Dioxin TEQ concentrations (ng/kg) in selected Washington State fish and 

invertebrates ..............................................................................................................10

Table B-7. PCB concentrations (total congeners, μg/kg) in selected Washington State 

freshwater fish and shellfish .....................................................................................12

 
Page iv July 20, 2012 Technical Issue Paper 

Acronyms & Abbreviations 

ATSDR Agency for Toxic Substances and Disease Registry 

CDD chlorinated dibenzo-p-dioxin 

CDF chlorinated dibenzofuran 

DHHS U.S. Department of Health and Human Services 

EIM Ecology Environmental Information Management (database) 

Ecology Washington State Department of Ecology 

FAO Food and Agriculture Organization 

MTCA Model Toxics Control Act 

n-3 PFA Omega-3 polyunsaturated fatty acid 

NMFS National Marine Fisheries Service 

PAH polycyclic aromatic hydrocarbon 

PCB polychlorinated biphenyl 

PCDD polychlorinated dibenzo-p-dioxin 

PCDF polychlorinated dibenzofuran 

pg/g picogram per gram 

TEQ toxic equivalent 

TSD Fish Consumption Rates Technical Support Document 

USDA U.S. Department of Agriculture 

USEPA U.S. Environmental Protection Agency 

USFDA U.S. Food and Drug Administration 

WDOH Washington Department of Health 

WHO World Health Organization 
Technical Issue Paper July 20, 2012 Page 1 

Introduction 

Ecology received comments on the draft Fish Consumption Rates Technical Support Document

(TSD) (Ecology 2011), which noted that other protein sources, such as beef, chicken, pork, and 

dairy products, may contain contaminants that would be considered to pose unacceptable health 

risks under the Model Toxics Control Act (MTCA). Some reviewers requested that the TSD 

address the potential health risk if people eat less fish. Others suggested that the TSD should 

include some information regarding the contaminant concentrations in Washington State fish and 

shellfish. 

This Technical Issue Paper summarizes contaminant concentrations in animal protein sources 

(meat, eggs, dairy products, seafood), including contaminant data for Washington State fish and 

shellfish collected within the past 10 years, and discusses the relative contribution of dietary 

protein sources to human exposures associated with these contaminants. It is a targeted 

examination of the issues raised by review comments received on the draft TSD, and was 

prepared within a limited time frame. Therefore, it may not include all available information on 

this subject. 

The health benefits and risks associated with consuming seafood are reviewed in Technical Issue 

Paper: Health Benefits and Risks of Consuming Fish and Shellfish. That Technical Issue Paper 

also describes the toxicity of the major contaminants commonly found in fish and shellfish. 

 
Page 2 July 20, 2012 Technical Issue Paper 

Analysis 

I. Sources of dietary protein 

Protein in the diet provides a source of calories and amino acids that assist in building and 

preserving body muscle and tissues (USDA and DHHS 2010). Protein is found in both animal 

and plant foods. Animal sources include seafood, meat, poultry, eggs, and milk and other dairy 

products. Plant sources of protein include beans, peas, nuts, seeds, and soy products. Table 1 

summarizes protein and fat content for common animal food sources, which are the focus of this 

Technical Issue Paper. 

Over the past three decades in the United States, per capita consumption of chicken has 

increased, beef consumption has decreased, and pork consumption has remained fairly stable 

(Figure 1). Consumption of all three meat categories decreased somewhat over the period 2005 

to 2011. Per capita fish consumption in the United States has increased slightly in the last 

decade, but as of 2010, fish and shellfish consumption is at about the level of the late 1980s 

(Figure 2). Per capita consumption of fish and shellfish is much lower than the consumption of 

chicken, beef, or pork. 

Figure 1. U.S. per capita meat consumption 

(historical and forecast to 2021) 

Source: USDA 2012 
Technical Issue Paper July 20, 2012 Page 3 

Figure 2. Annual per capita fish and shellfish consumption in the United States 

(pounds) 

Source: NMFS 2011 
Page 4 July 20, 2012 

Table 1. Protein and fat content of selected protein food sources 

Food

Serving 

Measure

Weight 

(g)

Protein 

(g) Total Fat

Fatty Acids

Saturated 

(g)

Monounsaturated (g) 

uns

Meats

Beef, ground 83% lean (broiled) 3 oz 85 22 14 5.5 6.1 Beef, roast lean only (oven cooked) 3 oz 85 23 11 4.2 4.5 Lamb, leg, lean only (roasted) 3 oz 85 24 7 2.3 2.9 Pork, loin chops, lean only (broiled) 3 oz 85 26 7 2.5 3.1 Pork, cured bacon, cooked 3 slices 19 6 9 3.3 4.5 Pork, cured ham, lean (roasted) 3 oz 85 21 5 1.6 2.2 

Poultry

Chicken, breast meat, skinless (roasted) half-breast 86 27 3 0.9 1.1 Chicken, drumstick, skinless (roasted) 1 drumstick 44 12 2 0.7 0.8 Chicken, liver (simmered) 1 liver 20 5 1 0.4 0.3 Turkey, dark meat (roasted) 3 oz 85 24 6 2.1 1.4 Turkey, ground (cooked) 1 patty 82 22 11 2.8 4 Turkey, light meat (roasted) 3 oz 85 25 3 0.9 0.5 

Seafoods

Crab, king (moist heat cooked) 3 oz 85 16 1 0.1 0.2 Fish, cod (cooked dry heat) 3 oz 85 20 1 0.1 0.1 Fish, flatfish, flounder/sole (cooked dry heat)

3 oz 85 21 1 0.3 0.2 

Fish, rockfish (cooked dry heat) 3 oz 85 20 2 0.4 0.4 Fish, salmon, sockeye (cooked dry heat) 3 oz 85 23 9 1.6 4.5 Fish, salmon, Chinook (smoked) 3 oz 85 16 4 0.8 1.7 Fish, tuna, light, canned in water, drained 3 oz 85 22 1 0.2 0.1 Mollusks, clams (raw) 3 oz 85 11 1 0.1 0.1 
Technical Issue Paper July 20, 2012 

Food

Serving 

Measure

Weight 

(g)

Protein 

(g) Total Fat

Fatty Acids

Saturated 

(g)

Monounsaturated (g) 

uns

Mollusks, oyster (raw) 6 medium 84 6 2 0.6 0.3 Shrimp, canned, drained solids 3 oz 85 20 2 0.3 0.2 

Dairy Products and Eggs

Butter, salted 1 tbsp 14.2 trace 12 7.2 3.3 Cheese, cheddar 1 oz 28 7 9 6 2.7 Cheese, cottage (2% low fat) 1 cup 226 31 4 2.8 1.2 Cheese, mozzarella part-skim, low moisture

1 oz 28 8 5 3.1 1.4 

Cheese, ricotta, part skim milk 1 cup 246 28 19 12.1 5.7 Milk, 2% reduced fat 1 cup 244 8 5 2.9 1.4 Yogurt, plain low fat 8 oz 227 12 4 2.3 1 Egg, whole 1 large 50 6 5 1.6 1.9 

Modified from Gebhardt and Thomas 2002 http://www.ars.usda.gov/SP2UserFiles/Place/12354500/Data/hg72/hg72_2002.pdf 

The serving sizes used in this table are generally standardized units of measure and may not represent the portion of food a person actually eats on one occasion. tbsp = tablespoon; oz = ounce; 
Page 6 July 20, 2012 Technical Issue Paper 

II. Contaminants of interest 

A. Metals 

For the purposes of this Technical Issue Paper, the two metals of interest include mercury and 

arsenic. 

a. Mercury 

The presence of mercury and mercury compounds in biological organisms is undesirable and 

potentially hazardous (Eisler 2000). Mercury is widespread in the environment due to natural and 

anthropogenic releases. Inorganic mercury is converted to the organic form methylmercury by 

bacteria. Methylmercury is the primary form of mercury in fish and shellfish tissues. 

Methylmercury is of concern due to its negative health effects (described in Technical Issue 

Paper: Health Benefits and Risks of Consuming Fish and Shellfish), and its ability to biomagnify 

in food chains in aquatic environments. It is most concentrated in larger and long-lived predatory 

species such as sharks and tuna. 

b. Arsenic 

Arsenic is a relatively common element present in air, water, soil, plants, and all living tissues 

(Eisler et al. 2000). Natural sources of arsenic are geologic, and some rocks and soils have 

naturally high arsenic content. Large quantities of arsenic-containing compounds (arsenicals) are 

released into the environment as a result of industrial and agricultural activities. Low levels of 

arsenic are commonly found in foods. Organic forms of arsenic may be transformed into organic 

forms by bacteria, fungi, algae, and plants. The primary organic form is arsenobetaine, which is 

rapidly excreted in the urine and generally considered non-toxic (ATSDR 2007). Arsenic 

(primarily the inorganic forms of arsenic) is of concern due to its negative health effects 

(described in Technical Issue Paper: Health Benefits and Risks of Consuming Fish and 

Shellfish). 

B. Organics 

Organic contaminants of interest that occur in foods include polycyclic aromatic hydrocarbons 

(PAHs) and dioxin-like compounds—polychlorinated dibenzo-p-dioxins (PCDDs), 

dibenzofurans (PCDFs), and biphenyls (PCBs). 

a. PAHs 

There are thousands of PAH compounds, and these compounds are ubiquitous in nature, largely 

as a result of natural processes such as forest fires and microbial synthesis. Anthropogenic 

sources include vehicle exhaust, manufacturing of coal tar pitch and asphalt, petroleum refining, 

and open burning. The largest sources of PAHs in Washington are wood burning stoves and 

fireplaces. Other major sources include creosote-treated wood, vehicles, leaks and improper 

disposal of motor oil, and small engines (e.g., lawn mowers and garden equipment). PAHs have 

been detected in animal and plant tissues, sediments, soils, air, surface water, drinking water, 

industrial effluents, river water, well water, and groundwater. PAH concentrations in marine 

clams and mussels tend to be highest in industrialized areas. PAH levels in fish and most 

crustaceans, however, are usually low because these organisms can rapidly metabolize PAHs. 
Technical Issue Paper July 20, 2012 Page 7 

Therefore, while most aquatic organisms rapidly accumulate PAHs from the ambient medium 

(water, sediments), PAHs show little tendency to biomagnify because most are rapidly 

metabolized (Eisler 2000). PAHs are of concern because several PAHs are carcinogenic, 

mutagenic, or teratogenic to fish and other aquatic life, amphibians, birds, and mammals, 

including humans. 

b. Dioxins 

Dioxin-like compounds include PCDDs, PCDFs, and certain PCBs (discussed below). The term 

dioxins refers to 75 congeners of PCDD and 135 congeners of PCDF (Fiedler 1998). PCDD/Fs 

enter the environment naturally through forest fires or volcanic activity (Eisler 2000). Human 

sources include municipal incinerators, pulp and paper mills that use chlorine for bleaching, and 

aerial application of some types of pesticides. (PCDDs are trace impurities and their presence in 

manufactured chemicals is not intentional or desired.) PCDD/Fs are found as mixtures of 

individual congeners in environmental matrices such as soil, sediment, air, and plants and lower 

animals (Fiedler 1998). Dioxins are of concern due to their toxicity (described in Technical Issue 

Paper: Health Benefits and Risks of Consuming Fish and Shellfish) and ability to bioaccumulate 

and biomagnify in food chains. 

c. PCBs 

PCBs are a group of 209 synthetic organic chemicals that were used as insulating and cooling 

agents in the electricity generating industry, and that had a number of other industrial 

applications (e.g., as additives to caulks and paints to improve durability). The production and 

sale of PCBs was banned in the United States in the late 1970s, but these compounds have 

persisted in the environment in soils, sediments, and organisms. PCBs are of concern due to their 

toxicity (described in Technical Issue Paper: Health Benefits and Risks of Consuming Fish and 

Shellfish) and ability to bioaccumulate and biomagnify in food chains. 

C. Relative contribution of diet to overall exposure 

a. Mercury 

Dietary intake is the most important source of non-occupational exposure to mercury (ATSDR 

1999). The other major source of mercury body burden is inhalation of elemental mercury 

volatilized from dental amalgams. Other sources are ingestion of drinking water, inhalation of 

vapors, medical treatments (e.g., mercury compounds used as preservatives in vaccines), and 

even some cosmetics and tattoo inks. Individuals living in the vicinity of former primary 

production or mining sites or current secondary production sites, chloralkali plants, pulp and 

paper mills, coal-fired power plants, or other facilities where mercury is released (e.g., municipal 

waste incinerators), or hazardous waste sites may be exposed to mercury through several 

exposure pathways, including inhalation, dermal, and oral exposures. Individuals living near 

municipal and medical waste incinerators, power plants fired by fossil fuels (particularly coal 

fired plants), or hazardous waste sites may inhale vapors or particulates contaminated with 

mercury from ambient outdoor air. 
Page 8 July 20, 2012 Technical Issue Paper 

b. Arsenic 

Estimates of inorganic arsenic intake in the U.S. adult population identified drinking water and 

food as the two largest sources (Figure 3) (Meacher et al. 2002; CDC 2009). Dietary exposure to 

inorganic arsenic occurs naturally and is unavoidable. Due to the relatively high use of water in 

the preparation of food, individuals in regions with higher arsenic concentrations in water likely 

also have higher dietary intake of inorganic arsenic (Yost et al. 2004). Background arsenic in 

drinking water in the United States varies by region, depending on local geology. 

Figure 3. Relative contribution of inorganic arsenic exposure by source 

c. PAHs 

Food is the major contributor to total intake of PAHs in the general population, with smaller 

contributions from water and air (FAO/WHO 2006). Smokers and people exposed 

occupationally will have additional exposures to PAHs. For smokers, the PAH intake from 

smoking may be of similar magnitude to intake from the diet (European Food Safety Authority 

2008). Most foods contain 1 to 10 μg total PAHs/kg fresh weight. Cereals and cereal products 

are major contributors of PAHs to the diet in many countries due to the high consumption rates 

of these foods. Vegetable fats and oils are also major contributors due to the high PAH 

concentrations in this food group. PAHs form directly during food processing (drying and 

smoking) and cooking (grilling, roasting, frying). Grilled and barbequed foods can have high 

PAH levels; smoking and barbequing fish and meats increases total PAH content by up to 100-

fold. PAHs form on or near meat surfaces rather than the interior; therefore, foods cooked 

without being exposed to smoke do not show significant levels of PAHs (Kazerouni et al. 2001). 

Some population groups may have higher intakes of PAHs, for example, people who regularly 

cook food over open fires or barbeques (ATSDR 1995). 
Technical Issue Paper July 20, 2012 Page 9 

d. Dioxins 

Inhalation, water consumption, soil ingestion, dermal contact, and vegetable fat ingestion 

contribute only a small percentage of overall exposure to dioxins (Birnbaum 2005). Figure 4 

shows the relative contributions of dietary and other sources to dioxin toxic equivalents (TEQs). 

In the U.S. Environmental Protection Agency (USEPA) Dioxin Reassessment, dose estimates 

(that included the dioxin-like compounds PCBs as well as PCDD/Fs) were provided for 

inhalation, soil ingestion, soil dermal contact, water ingestion, and for 10 food ingestion 

categories including beef, pork, poultry, other meats (game, lamb, unidentified meat in 

casseroles, etc.), eggs, milk, dairy, marine fish, freshwater fish, and vegetable oils (Lorber et al. 

2009). The dose estimates were dominated by ingestion of animal food products (beef, pork, 

poultry, other meats, dairy, eggs, milk, and fish), which comprised 93 percent of total exposures. 

Figure 4. Sources of U.S. average daily intake of 

PCDD/PCDF/PCB TEQs 

Source: Birnbaum 2005 

D. Relative contribution of each type of protein source 

a. Mercury 

The U.S. Food and Drug Administration (USFDA) Total Diet Study found that nearly all of the 

mercury in the U.S. diet comes from meat, fish, and poultry, with fish and shellfish being the 

principal source (Mahaffey 2009). Methylmercury in fish is the primary route of organic mercury 

acquisition in humans (Dórea 2008). A United Kingdom dietary study found that fish supplied 

most of the mercury in the average diet (25 percent); in that study, mercury concentrations 
Page 10 July 20, 2012 Technical Issue Paper 

ranged from less than 5 μg/kg in meat, eggs, and milk, up to 54 μg/kg in fish (Ysart et al. 1999). 

However, the use of fishmeal in farm animal feeds is likely to impact human foods by increasing 

exposure to methylmercury (Dórea 2008). Researchers in Sweden found that mercury in animal 

products raised on fish meal can correlate with hair mercury levels (a widely used biomarker of 

fish consumption) in non-fish eaters (review in Dórea 2008). [Note that SAIC attempted to 

acquire published paper(s) with the metals data from the Total Diet Study but only found papers 

estimating intake by source; the papers did not include the actual ranges found in the food 

products that were used to estimate intakes (e.g., Gunderson 1995).] 

b. Arsenic 

Fish and shellfish contain the highest concentrations and are the largest dietary source of arsenic, 

generally in organic forms (Yost et al. 2004; ATSDR 2007). As noted in Technical Issue Paper: 

Health Benefits and Risks of Consuming Fish and Shellfish, organic forms such as those found in 

seafood are generally considered non-toxic. Yost et al. (2004) presented total and inorganic 

arsenic concentrations for animal-based protein sources (Figure 5; data supporting this figure are 

presented in Table 11). While saltwater fish and shrimp had total arsenic concentrations greatly 

exceeding those of other sources, the inorganic arsenic concentrations of all of the sources were 

small and within one order of magnitude of each other. Inorganic arsenic was not detected in 

tuna or milk. 

Figure 5. Total and inorganic arsenic concentrations of 

selected protein sources (from data in Yost et al. 2004) 
Technical Issue Paper July 20, 2012 Page 11 

Yost et al. (2004) examined intake of inorganic arsenic in children ages 1 to 6 years and found 

that fish and shellfish contributed less than 1 percent of the daily dietary intake (Figure 6, data 

table presented in Appendix A). Meat and poultry contributed slightly more (just over 1 percent) 

and dairy products another 14 percent. Young children were investigated because they are often 

considered to be a sensitive sub-population that is vulnerable to arsenic exposures from soil and 

subject to higher exposures on a body weight basis. Inorganic arsenic was specifically evaluated 

because it is considered the most toxicologically significant. Grain and grain products 

contributed nearly 50 percent of the inorganic arsenic in the diet of young children. Of the 

animal protein sources, dairy products contributed the most inorganic arsenic (14 percent), 

followed by meat and poultry (1.2 percent), eggs (0.5 percent), and then fish/shellfish (0.1 

percent). 

Figure 6. Sources of dietary inorganic arsenic for children 1 to 6 years 

(% contribution) 

c. PAHs 

Kazerouni et al. (2001) measured concentrations of benzo(a)pyrene in 200 food items. Table 2 

summarizes some of the results for animal-based protein sources. Cooking method greatly 

affected the concentration of benzo(a)pyrene in foods, with grilled foods generally containing 

more than broiled or fried foods and very well-done grilled meats containing more than medium 

or well-done meats. 
Page 12 July 20, 2012 Technical Issue Paper 

Table 2. Benzo(a)pyrene in animal-based protein sources 

Food 

Cooking 

Method 

Portion Size 

(g) 

Concentration 

(μg/kg)* ng/portion 

Hamburger Oven-broiled - very well 85 0.01 0.8 

Hamburger Grilled - medium 85 0.09 8.0 

Hamburger Grilled – well 85 0.56 48 

Hamburger Grilled - very well 85 1.52 129 

Steak Oven-broiled - very well 112 0.01 1.0 

Steak Grilled - very well 112 4.86 544 

Chicken, boneless Oven-broiled - very well 96 0.48 46 

Chicken, boneless Grilled - well 96 0.39 37 

Chicken, boneless Grilled - very well 96 0.40 38 

Crab Not given 38 0.1 3.8 

Perch fillet Grilled - well 85 0.19 16 

Pork chops Oven-broiled - well 112 0.01 1.0 

Pork chops Pan-fried - well 112 0.01 1.0 

Butter NA 10 ND ND 

Cheese, cottage NA 113 0.07 8.0 

Eggs NA 100 0.03 3.0 

Milk, whole NA 244 0.02 5.0 

Yogurt, 

flavored/frozen 

NA 227 0.18 41 

Modified from Kazerouni et al. 2001 

*ND = not detected; limit of detection was 0.005 μg/kg 

The European Food Safety Authority (2008) recently presented data for 15 priority PAHs 

(PAH15) in food samples taken throughout Europe. The PAHs included: benz(a)anthracene, 

benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)fluoranthene, benzo(ghi)perylene, 

benzo(a)pyrene, chrysene, cyclopenta(cd)pyrene, dibenz(a,h)anthracene, dibenzo(a,e)pyrene, 

dibenzo(a,h)pyrene, dibenzo(a,i)pyrene, dibenzo(a,l)pyrene, indeno(1,2,3-)pyrene, and 5-

methylchrysene. The highest concentrations were reported for processed fish, molluscs, and 

smoked molluscs (Figure 7; data presented in Appendix A). 
Technical Issue Paper July 20, 2012 Page 13 

Figure 7. Upper bound PAH15 concentrations (μg/kg) by food group 

Modified from European Food Safety Authority 2008 

WDOH evaluated the PAH8 data in the European Food Safety Authority study (White 2012) and 

estimated that PAHs in shellfish could account for up to 20 percent of the PAH intake for a 

shellfish consumer’s diet. PAH8 priority PAHs included the following carcinogenic compounds: 

benz(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(ghi)perylene, 

benzo(a)pyrene, chrysene, dibenz(a,h)anthracene, and indeno(1,2,3-)pyrene. 

In a total daily diet intake study, Kazerouni et al. (2001) found that barbecued meats contributed 

the most benzo(a)pyrene, followed by dairy products, and non-barbecued meats (Figure 8). 

 

0

5

10

15

20

25

30

35

40

Barbequed

meat

Grilled

meat

Other meat Smoked

meat

Fresh fish Processed

fish

Smoked

fish

Molluscs Smoked

molluscs

Upper Bound ofPAH15

concentration (μg/kg)
Page 14 July 20, 2012 Technical Issue Paper 

Figure 8. Percent of total daily benzo(a)pyrene intake 

in a control group of 228 subjects 

Source: Kazerouni et al. 2001 

d. Dioxin 

Dougherty (2000) estimated that fish and shellfish contributed nearly 90 percent of the dioxins in 

the average U.S. consumer’s diet while beef contributed less than 10 percent. More recently, 

Lorber et al. (2009) estimated the total TEQ contributions of dioxin-like compounds (including 

dioxin-like PCBs) from meat, seafood, egg, and dairy products in the diet (Figure 9; data 

presented in Appendix A). This was achieved using average contaminant concentrations in foods 

and food consumption rates. The contribution to TEQs from fish in the diet, as calculated by 

Lorber et al. (2009), was less than 32 percent. 
Technical Issue Paper July 20, 2012 Page 15 

Figure 9. Exposure pathway for PCDD/PCDF/PCB TEQ intakes from protein 

sources (percent contribution by source) 

“Other pathways” includes: consumption of water, inhalation of air, ingestion of soil, dermal contact, and vegetable fat intake. 

e. PCBs 

Dougherty (2000) estimated that fish and shellfish contributed nearly 100 percent of the PCBs in 

the average U.S. consumer’s diet. However, Schecter et al. (2010), using samples of 31 foods 

collected in 2009 from a market-basket survey, calculated that meat sources contributed more 

than seafood, dairy, eggs, and vegetable products combined to daily dietary intake of PCBs (data 

for animal sources provided in Tables 3, 4, and 5). This may have been due to the relative 

quantities consumed, because PCBs were found in fish at similar concentrations (and with 

additional PCB congeners) than in meats. Each of the 209 PCB congeners has been assigned a 

congener number (e.g., PCB-52, which is 2,2’,5,5’-tetrachlorobiphenyl). The specific congeners 

analyzed by Schecter et al. (2010) are denoted by their congener number in the tables below. 

Note that the representative PCBs were not detected in any meats except hamburger, in any fish 

except salmon and canned sardines, or in any dairy products or eggs. Researchers in Japan (Hirai 

et al. 2004), however, found that exposure of farm animals to coplanar PCBs through fish meal is 

an important source of PCBs in meat and milk. Variations in feed-grass concentrations of 

coplanar PCBs were insufficient for explaining levels of these congeners in meat and milk. 

When fish meal was included in modeling calculations, the predicted congener profile came 

close to actual measurements. 

31.5

19.4 16.2

10.7

7.8

6.9

4.3 2

Fish

Beef

Dairy

Other pathways

Milk

Eggs

Other meat

Poultry

Modified from Lorber et al. (2009)
Page 16 July 20, 2012 Technical Issue Paper 

Table 3. Levels of marker PCBs in composite meat samples (ng/g ww or LOD) 

Marker Hamburger Bacon Turkey Sausages Ham 

Chicken 

breast Roast beef 

Lipid 

Content 

(%) 

21.7 36.1 2 23.9 4.3 4.7 4.6 

PCB-52 ND (0.1) ND (0.09) ND (0.04) ND (0.1) ND (0.05) ND (0.05) ND (0.04) 

PCB-101 ND (0.4) ND (0.3) ND (0.1) ND (0.4) ND (0.2) ND (0.2) ND (0.1) 

PCB-118 ND (0.2) ND (0.1) ND (0.06) ND (0.2) ND (0.07) ND (0.08) ND (0.09) 

PCB-153 1.2 ND (0.4) ND (0.2) ND (0.5) ND (0.2) ND (0.3) ND (0.2) 

PCB-138 ND (0.7) ND (0.4) ND (0.2) ND (0.6) ND (0.2) ND (0.3) ND (0.2) 

PCB-180 0.21 ND (0.10) ND (0.04) ND (0.1) ND (0.04) ND (0.06) ND (0.05) 

ww = wet weight; ND = not detected; LOD = level of detection 

Table 4. Levels of marker PCBs in composite fish samples (ng/g ww or LOD) 

Marker Salmon 

Canned 

tuna 

Fresh catfish 

fillet Tilapia Cod 

Canned 

sardines 

Frozen fish 

sticks 

Lipid 

Content 

(%) 

11.9 14.8 11.6 1.6 0.3 10.3 10.3 

PCB-52 0.28 ND (0.06) ND (0.1) ND (0.09) ND (0.07) 0.28 ND (0.06) 

PCB-101 0.51 ND (0.2) ND (0.3) ND (0.3) ND (0.2) 0.67 ND (0.2) 

PCB-118 0.43 ND (0.07) ND (0.2) ND (0.1) ND (0.1) 0.8 ND (0.09) 

PCB-153 1.21 ND (0.3) ND (0.5) ND (0.4) ND (0.3) 1.83 ND (0.3) 

PCB-138 0.93 ND (0.3) ND (0.5) ND (0.3) ND (0.2) 1.8 ND (0.3) 

PCB-180 0.44 ND (0.06) ND (0.1) ND (0.07) ND (0.06) 0.49 ND (0.07) 

ww = wet weight; ND = not detected; LOD = level of detection 

Table 5. Levels of marker PCBs in composite dairy and egg samples (ng/g ww or 

LOD) 

Marker Butter 

American 

cheese 

Other 

cheese Whole milk Yogurt 

Cream 

Cheese Eggs 

Lipid 

Content 

(%) 

91.4 25.3 30.1 3.8 2.9 34 2.9 

PCB-52 ND (0.2) ND (0.1) ND (0.09) ND (0.05) ND (0.03) ND (0.08) ND (0.05) 

PCB-101 ND (0.2) ND (0.3) ND (0.3) ND (0.2) ND (0.08) ND (0.02) ND (0.1) 

PCB-118 ND (0.1) ND (0.2) ND (0.2) ND (0.07) ND (0.04) ND (0.02) ND (0.08) 

PCB-153 ND (0.5) ND (0.4) ND (0.4) ND (0.2) ND (0.1) ND (0.04) ND (0.2) 

PCB-138 ND (0.5) ND (0.4) ND (0.4) ND (0.2) ND (0.1) ND (0.04) ND (0.2) 

PCB-180 ND (0.1) ND (0.1) ND (0.10) ND (0.05) ND (0.03) ND (0.09) ND (0.05) 

ww = wet weight; ND = not detected; LOD = level of detection 
Technical Issue Paper July 20, 2012 Page 17 

E. Sensitive subpopulations 

There are two types of populations that may be considered as sensitive populations when 

considering contaminant exposures: those that are exceptionally sensitive to a particular 

contaminant and those who may receive greater exposure to a contaminant due to age, gender, 

health status, genetic differences, and lifestyle choices such as diet. 

Native tribes and other ethnic groups may eat fish/shellfish at rates significantly higher than most 

consumers. For example, Korean and Japanese Americans in the Puget Sound region have 

seafood consumption rates that are among the highest in the nation (Tsuchiya et al. 2008). As 

discussed in the TSD, many Native Americans in Washington State also consume more seafood 

than the national average. A mercury intake biometric study by Tsuchiya et al. (2008) found that 

one in two persons in the Japanese community was overexposed to methylmercury based on their 

diet and evidence from biological samples analyzed for mercury content. The Korean 

community, however, had about one in ten persons who exceeded the reference dose, even 

though total seafood consumption was about the same as the Japanese cohort. While both 

populations consumed a large amount of seafood, their species preferences (e.g., Japanese 

consumed more salmon and the Koreans consumed more squid) influenced their mercury 

exposure. 

Children are unique in their contaminant exposures for many reasons. They drink more fluids, 

eat more food, and breathe more air per kilogram of body weight, and have a larger skin surface 

in proportion to their body volume than do adults. Their diets often differ from that of adults. 

Nutritional requirements change with age: from placental nourishment to breast milk or formula 

to the diet of older children who eat more of certain types of foods than adults. Behavior and 

lifestyle differences also influence a child’s contaminant exposure. Children crawl on the ground, 

put things in their mouths that an adult would not, and sometimes eat inappropriate things such 

as dirt or paint chips. Children may also spend more time outdoors than adults. As one example, 

children drink more milk on a per body weight basis than do adults. This significantly increases 

their exposures to milk-borne contaminants compared to adults. 

The developing fetus and young children are also sensitive subpopulations because they are more 

susceptible to the toxic effects of some contaminants such as methylmercury. Therefore, women 

of childbearing age, pregnant or nursing women, and young children are considered sensitive 

populations for neurodevelopmental risks from exposure to contaminants in foods. As 

FAO/WHO (2010) note, these same groups are also sensitive populations for 

neurodevelopmental risks from not consuming fish. 

III. Contaminant concentrations in dietary protein 

sources 

A. Fish and shellfish — Washington State contaminant 

concentrations 

The following tables and figures present contaminant concentrations in Washington State 

seafood. Where available, data were selected that reflect different regions of the state. Due to the 

industrial development prevalent around Puget Sound, there are myriad studies of seafood 
Page 18 July 20, 2012 Technical Issue Paper 

contamination from this region. Coastal areas (e.g., Figures 10 and 11) and eastern Washington 

data (Spokane River in Table 8) are also represented in this Technical Issue Paper. Other data 

were selected because they showed regional comparisons of contaminant concentrations (e.g., 

Figure 14). 

Appendix A provides tables of mercury, total PCBs, and dioxin TEQ concentrations that were 

summarized from data taken from the Ecology Environmental Information Management (EIM) 

database. The EIM data included marine, anadromous, and freshwater species, and statistical 

summaries pooled the data by the ecological group and tissue type sampled. Additional 

information on background levels of PCBs and dioxins in Washington State freshwater fish is 

available in Ecology Publication No. 10-03-007 (Ecology 2010). Data analyzed in that report 

that were included in the EIM database are contained within the statistical summaries in 

Appendix A. The tables and figures in this section represent a subset of the contaminant data 

available for different regions of Washington State. 

Figure 10. Mean PCB concentration in 

Chinook salmon fillets 

Source: O’Neill and West 2009 

Figure 11. Mean PCB concentration in 

adult Chinook salmon returning to 

Puget Sound (in-rivers versus marine 

waters*) 

Source: O’Neill and West 2009 

Error bars represent standard error around the means. 

*”In-river” samples were taken from fish collected in the rivers noted, 

whereas “marine” samples were taken from fish collected in marine 

waters of the central or south Puget Sound, as noted. 
Technical Issue Paper July 20, 2012 

Table 6. Average PCBs in Chinook salmon from in-river versus marine areas of the Puget Sou

Location 

Type 

Puget 

Sound 

basin Location 

Nf Nfa 

% 

SWA1 

Ns 

PCBs* 

(μg/kg) 

% 

Lipids 

Fish 

Age 

(years) 

SW A

(yea

In-river 

North Nooksack River 133 120 3.3 28 37 3.45 3.6 2.5 North Skagit River 125 114 3.5 29 40 4.83 4.1 2.6 Central Duwamish River 171 159 12.6 65 56 7.34 3.8 2.4 South Nisqually River 92 90 5.6 20 41 3.76 3.4 2.3 South Deschutes River 113 77 0.0 34 59 1.74 3.9 2.4 

All in-river sites 634 560 5.9 176 49 4.82 3.8 2.4 

Marine 

Central Central sound 60 60 76.7 12 86 5.74 2.8 1.3 South South sound 69 68 2.9 16 69 4.15 3.5 2.3  All marine sites 129 128 37.5 28 76 4.83 3.2 1.9 

Total All sites 763 688 11.8 204 53 4.82 3.7 2.3 Modified from O'Neill and West 2009 * wet weight basis Nf= number of salmon collected; Nfa = number of fish in the sample whose age was estimated (i.e., “aged fish”); %SWA1 = percentage of aged fish that spent one winaverage age of the fish in the sample; SW Age = average salt water age of sample; length is the average length of the fish in the sample 
Page 20 July 20, 2012 Technical Issue Paper 

Table 7. Maximum concentration of contaminants detected in fish and shellfish 

sampled at Fidalgo Bay in Anacortes, Washington 

Chemicals 

Contaminant maximum concentration (ppm) 

Horse 

Clams Manila Clams 

Bent nose 

Clams 

Macoma 

Clams 

Starry 

Flounder 

English 

Sole 

Arsenic total 2.82 3.14 3.84 n/a 1.35 3.1 

Mercury 0.009 0.03 0.02 n/a 0.071 0.0077 

Total Dioxin TEQ 7.0E-8 1.2E-7 7.6E-7 6.9E-7 1.75E-7 1.68E-7 

Red Rock Crab Dungeness Crab 

Tissue Other* 

Hepatopancreas Tissue Other* Hepatopancreas 

Arsenic total 5.95 4.69 7.31 10.47 6.81 6.54 

Mercury 0.058 0.026 0.060 0.088 0.051 0.049 

Total Dioxin TEQ 1.8E-7 1.53E-6 6.57E-6 1.44E-7 5.82E-6 1.05E-5 

Source: WDOH 2010 Health Consultation for Fidalgo Bay 

Total Dioxin TEQ – sum of dioxin/furans toxic equivalent (TEQ) 

PPM – parts per million, na – not available 

* Other soft tissues (viscera) 

Table 8. Mean total PCB concentrations for fish 

from the Spokane River, Spokane, WA 

Location Species Total mean PCBs (μg/kg, ww) 

Fillet samples 

Plante Ferry Rainbow Trout 55 

Mission Park Rainbow Trout 153 

Mission Park Mountain Whitefish 234 

Ninemile Rainbow Trout 73 

Ninemile Mountain Whitefish 139 

Upper Long Lake Mountain Whitefish 43 

Upper Long Lake Brown Trout 130 

Upper Long Lake Smallmouth Bass 37 

Lower Long Lake Mountain Whitefish 76 

Lower Long Lake Smallmouth Bass 67 

Whole body samples 

Stateline Largescale Sucker 56 

Plante Ferry Largescale Sucker 122 

Mission Park Largescale Sucker 1,823 

Ninemile Bridgelip Sucker 69 

Upper Long Lake Largescale Sucker 327 

Lower Long Lake Largescale Sucker 254 

Source: WDOH 2007; ww - wet weight 
Technical Issue Paper July 20, 2012 Page 21 

Figure 12. Total PAHs in Washington State mussels (μg/kg dry weight) 

Source: Puget Sound Action Team 2007. 

 
Page 22 July 20, 2012 Technical Issue Paper 

Figure 13. Total mercury concentrations in Washington State mussels (μg/kg dry 

weight) 

Source: Puget Sound Action Team 2007. 

 
Technical Issue Paper July 20, 2012 Page 23 

Figure 14. PCBs in large fish from Washington State lakes and rivers 

Source: Hardy and McBride 2004 

KOK=kokanee, SMB=smallmouth bass, NP=northern, pikeminnow, MWF=mountain whitefish, RT=rainbow trout, CT=cutthroat trout.
Page 24 July 20, 2012 Technical Issue Paper 

Figure 15. PCBs (μg/kg) in fish from Puget Sound 

compared to other common food sources 

Samples include fish from Puget Sound and results are reported in micrograms per kilogram sampled. Commercial foods were sampled as part 

of the U.S. Food and Drug Administration’s total diet study and market-basket survey. In most cases, data are limited by small sample sizes. 

Source: Puget Sound Action Team 2007 
Technical Issue Paper July 20, 2012 Page 25 

Table 9. Summary of PCB data (μg/kg wet weight) in hake and pollock from 

seven Puget Sound Basins 

Pacific Hake Walleye Pollock 

ΣPCBs 

Str. Juan 

de Fuca 

Strait of 

Georgia 

Hood 

Canal 

Whidbey 

Basin 

Elliott 

Bay 

Main 

Basin 

South 

Sound 

Hood 

Canal 

Elliott 

Bay 

Main 

Basin 

na 3/3 3/3 10/10 10/10 11/11 12/12 3/3 3/3 1/1 4/4 

min 2.7 3.4 9 29 29 23 32 6.9 120 11 

max 6.6 6.6 38 67 72 68 34 8.4 120 26 

mean 4.2 5.3 15 44 45 33 33 7.6 nc 15 

10th %. 2.7 3.4 9 30 30 24 32 6.9 nc 11 

Median 3.3 5.7 10 41 44 28 33 7.4 nc 12 

90th % 6.6 6.6 33 65 67 52 34 8.4 nc 26 

a Number of samples with detected values/number of samples analyzed 

“nc” indicates statistics that were not calculated because there were fewer than three detected values 

In cases where no analyte was detected, the minimum (min) and maximum (max) values are presented as “<” the average limit of quantitation 

for that analyte. 

B. Other protein sources (meat, eggs, dairy) 

Very little information was available regarding contaminant concentration in other protein 

sources in Washington State. Therefore, this section summarizes available data from various 

U.S. and international sources.

a. Mercury 

As described above, the U.S. Total Diet Study found that nearly all methylmercury in the U.S. 

diet is from fish and shellfish (Mahaffey 2009), but concerns have been raised about the potential 

for fish meal to increase contaminant levels in farm animals (Dórea 2008). This may be less of a 

concern for beef and cow’s milk, however, because cows can demethylate methylmercury in the 

rumen and therefore absorb less mercury (ATSDR 1999). A study conducted in Pakistan (Shah et 

al. 2010) showed mercury uptake in chicken tissues from mercury in the chicken feed (Table 10). 

Table 10. Concentration of total mercury in chicken feed and the different tissues 

of boiler chickens (μg/kg) 

Poultry 

farms Feed 

Age groups Chicken tissues 

(weeks) Leg Breast Liver Heart 

Farm-1 15.1 ± 0.77 1–3 3.24 ± 0.23 3.49 ± 0.26 4.94 ± 0.49 3.27 ± 0.32

4–6 2.66 ± 0.36 2.93 ± 0.22 3.55 ± 0.51 2.19 ± 0.26

Farm-2 12.8 ± 0.36 1–3 2.87 ± 0.21 2.59 ± 0.34 3.98 ± 0.38 2.84 ± 0.41

4–6 2.15 ± 0.17 2.47 ± 0.21 3.43 ± 0.37 2.50 ± 0.41

Farm-3 16.5 ± 0.25 1–3 2.47 ± 0.14 3.86 ± 0.09 5.54 ± 0.33 2.93 ± 0.24

4–6 2.14 ± 0.23 2.53 ± 0.26 4.34 ± 0.49 2.27 ± 0.32

Farm-4 12.2 ± 0.61 1–3 2.14 ± 0.23 2.79 ± 0.26 4.04 ± 0.49 3.17 ± 0.32

4–6 1.57 ± 0.21 2.11 ± 0.34 3.28 ± 0.38 2.44 ± 0.41

Farm-5 8.57 ± 0.47 1–3 1.97 ± 0.21 2.11 ± 0.34 3.28 ± 0.38 2.44 ± 0.41

4–6 1.27 ± 0.14 1.86 ± 0.09 2.54 ± 0.33 2.13 ± 0.24

Modified from Shah et al. 2010 

*dry weight basis 
Page 26 July 20, 2012 Technical Issue Paper 

b. Arsenic 

Inorganic arsenic concentrations appear to occur in a relatively narrow concentration range 

across protein types, as shown by the data from Yost et al. (2004) (Table 11). 

Table 11. Mean total and total inorganic arsenic concentrations in foods 

(μg/kg wet weight) 

Food Mean Total Arsenic 

Mean Total Inorganic 

Arsenic3

Meat and Poultry 

Beef 51.5 0.39 J 

Chicken 86.4 0.89 J 

Pork 13.5 0.67 J 

Seafoods 

Freshwater finfish 160 1.0 J 

Saltwater finfish 2,356 0.55 J 

Shrimp 1,890 1.9 J 

Tuna 512 1.0 U 

Dairy products and Eggs 

Milk1,2 2.2 1.0 U 

Butter 1.8 1.17 J 

Eggs 20 0.98 J 

Modified from Yost et al. 2004 

1 both whole and skim milk were analyzed; results combined and applied to all milk products 

2 As3+ concentration was 0.18 μg/kg J 

3Where no arsenic was detected (after blank-correcting), one-half the value of the method detection limit was given with a U designation. When 

the concentration of arsenic in food (after blank-correcting) was detected above the blank concentration but below the method detection limit, 

the value was given a J designation. Undetected samples have been included at one-half of the detection limits. All averaged values were 

computed as follows: (1) If one or more, but not all, values to be averaged were non-detected, 50 percent of the detection limit(s) was used in 

calculating the average concentration and (2) Mean values have a U or a J qualifier if all values used to calculate the mean were U or J 

qualified, respectively. 

c. PAHs 

As shown in Table 2 and described in Section 2.3.2, PAHs in protein sources are highly 

influenced by cooking methods. Schaum et al. (2003) evaluated cow’s milk samples from 

locations across the United States for PBTs including PAHs. The PAHs analyzed were 

acenaphthylene, anthracene, benzo(a)pyrene, fluorene, naphthalene, phenanthrene, and pyrene 

(Table 12). Acenaphthene and benzo(a)pyrene were not detected in any samples analyzed by 

Schaum et al. (2003). 
Technical Issue Paper July 20, 2012 Page 27 

Table 12. Concentrations of PAHs in milk from 

western U.S. locations (ng/kg)* 

PAH July 2000 January 2001 

Acenaphthylene 44.6 39.8 

Anthracene ND 40.8 J 

Fluorene 57.6 J 127.2 

Naphthalene 947.1 882.3 

Phenanthrene 431.0 640.8 

Pyrene 98.9 151.2 

Modified from Schaum et al. 2003 

West locations included: Portland, Tacoma, Spokane, Sacramento, San Francisco, Las Vegas, and Honolulu 

Data from the original paper was in ng/L, which is roughly equivalent to ng/kg (density of milk is about 1.003) 

Detected PAHs only; acenaphthene and benzo(a)pyrene were not detected in any samples from any locations in the study 

d. Dioxins/PCBs 

Table 13 presents the dioxin concentrations in milk samples taken across the United States. The 

Far West location included samples from Washington, Oregon, California, and Hawaii. 

Table 13. TEQ concentrations of CDD/CDFs and PCBs in milk (pg/kg) 

CDD/CDF PCB Totala

Composite 

location 

July 

2000 

January 

2001 Mean b

July 

2000 

January 

2001 Mean b Mean b

New England 12.85 8.89 10.87 9.53 8.29 8.91 19.78 

Mid-Atlantic 11.67 14.21 12.94 14.37 8.3 11.34 24.28 

South Central 17.53 19.14 18.34 6.93 9.57 8.24 26.59 

North Central 20.48 10.35 15.42 11.36 7.13 9.25 24.66 

West Central 17.94 18.59 18.27 5.31 5.16 5.24 23.5 

Southwest 13.27 6.21 9.74 6.71 6.29 6.5 16.24 

Far South 18.13 35.82 26.98 8.07 7.59 7.83 34.81 

Far West 22.5 13.2 17.85 8.8 8.33 8.57 26.42 

Modified from Schaum et al. 2003 

CDD/CDF = chlorinated dibenzo-p-dioxin/ chlorinated dibenzofuran 

Data from the original paper was in pg/L, which is roughly equivalent to pg/kg (density of milk is about 1.003)

aThis is the sum of the CDD/CDF seasonal mean and the PCB seasonal mean. 

bAverage of summer and winter concentrations. 

 
Page 28 July 20, 2012 Technical Issue Paper 

Table 14 presents dioxin (PCDDs, PCDFs, plus a subset of four dioxin-like PCB congeners) 

concentrations (as mean TEQs) in uncooked meat samples from the United States. 

Table 14. Mean TEQs of 17 PCDD/Fs and 4 dioxin-like PCBs in U.S. meats 

(ng/kg lipid) 

Contaminant 

beef 

N = 139 

pork 

N = 136 

chicken 

N = 151 

turkey 

N = 84 

mean PCDD/F TEQ 0.55 (0.51) 0.14 (0.04) 0.12 (0.04) 0.36 (0.34) 

mean dioxin-like-PCB* TEQ 0.11 (0.11) 0.02 (0.01) 0.05 (0.05) 0.25 (0.25) 

Adapted from Huwe et al. 2009 

*PCBs analyzed were the coplanar congeners 77, 81, 126, and 169 

 
Technical Issue Paper July 20, 2012 Page 29 

Summary 

Contaminants occur in many food sources and for some, food is the major contributor to intake 

in the general population (i.e., those not exposed occupationally). Mercury, arsenic, PAHs, 

dioxins, and PCBs all have food as the major source of intake. 

 Over the past three decades, per capita chicken has increased, beef consumption has 

decreased, and pork and seafood consumption has remained fairly stable. 

 In the United States, fish and shellfish are the primary dietary source of mercury and 

arsenic (organic forms). Shellfish may contribute significantly (~20 percent) to the PAH 

intake for shellfish consumers. 

 Inorganic arsenic (generally considered to be the more toxic form) is present in low 

concentrations in most animal-based protein sources, but dietary intake is largely from 

cereals, water used in cooking, vegetables, and fruits and fruit juices. 

 Nearly all of the dietary intake of mercury in the United States comes from animal-based 

protein sources, with fish and shellfish being the principal sources. PAH concentrations 

in foods are largely influenced by cooking methods. 

 Dietary intake studies show dioxin TEQs come largely from animal-based protein 

sources, with fish contributing roughly one-third of total TEQs. 

 If fish and shellfish consumption increases in the future, exposure to methylmercury 

could increase. Actual increases would depend on the species consumed, as some contain 

higher average concentrations of mercury (for more on this topic, see Technical Issue 

Paper: Health Benefits and Risks of Consuming Fish and Shellfish). 

Direct comparison of contaminant concentrations in dietary protein sources is difficult due to 

variations in the way these data are presented in the literature. Concentrations are presented as 

wet weight or dry weight, cooked or uncooked, lipid-normalized or total, and using a variety of 

units. Data were collected during different time periods, in different locations, and using 

different analysis methods. 

 
Page 30 July 20, 2012 Technical Issue Paper 

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Page 34 July 20, 2012 Technical Issue Paper 

This page purposely left blank for duplicate printing. 
Technical Issue Paper July 20, 2012 Page A-1 

Appendices 

Appendix A. Contaminant Data Tables Supporting 

Figures 6, 7, and 9 

 
Page A-2 July 20, 2012 Technical Issue Paper 

Table A-1. Sources of dietary inorganic arsenic 

for children 1 to 6 years (% contribution) 

Exposure Pathway 

Percent 

Contribution 

Fruits and fruit juice 20.9 

Fish & Shellfish 0.1 

Dairy products 14 

Meat & poultry 1.2 

Water used in cooking 4.1 

Eggs 0.5 

Grain & grain products 47.3 

Condiments, fats, oils 0.5 

Vegetables & vegetable 

products 6.3 

Legumes, nuts, seeds 1 

Modified from Yost et al. 2004 

Table A-2. Lower bound and upper bound PAH15 concentrations 

(μg/kg) by food group 

Food Group N Lower Bound Upper Bound 

Barbequed meat 31 12.18 12.48 

Grilled meat 21 11.27 11.77 

Other meat 49 0.96 1.43 

Smoked meat 167 2.97 3.61 

Fresh fish 6 0.19 2.82 

Processed fish 29 31.9 33.86 

Smoked fish 153 3.51 4.03 

Molluscs 167 19.57 20.14 

Smoked molluscs 11 18.23 18.65 

N: number of samples 

PAHs analysed included: benz(a)anthracene, benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)fluoranthene, 

benzo(ghi)perylene, benzo(a)pyrene, chrysene, cyclopenta(cd)pyrene, dibenz(a,h)anthracene, dibenzo(a,e)pyrene, 

dibenzo(a,h)pyrene, dibenzo(a,i)pyrene, dibenzo(a,l)pyrene, indeno(1,2,3-)pyrene and 5-methylchrysene. 

Processed fish included fish canned in oil. 

 
Technical Issue Paper July 20, 2012 Page A-3 

Table A-3. Estimated TEQ intake from dietary protein sources 

Exposure Pathway 

PCDD/PCDF/PCB TEQ Intakes 

(pg/day)1

Percent 

Contribution 

Fish 10.9 31.5 

Beef 6.7 19.4 

Dairy 5.6 16.2 

Other sources2 3.7 10.7 

Milk 2.7 7.8 

Eggs 2.4 6.9 

Other meat3 1.5 4.3 

Poultry 0.7 2.0 

Total: 34.5 -- 

Modified from Lorber et al. (2009) 

Notes: 

1. Non-detects set at zero 

2. Other sources included consumption of water, air inhalation, ingestion of soil, soil dermal contact, and vegetable fat intake 

3. Other meats included game, lamb, and other unidentified meats. 

 
Page A-4 July 20, 2012 Technical Issue Paper 

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Technical Issue Paper July 20, 2012 Page B-1 

Appendix B. Washington State Contaminant Data 

Summarized from the EIM Database 

The following tables of mercury, total PCBs, and dioxin TEQ concentrations were summarized 

from data taken from the Ecology Environmental Information Management (EIM) database. The 

EIM data included marine and freshwater species. Statistical summaries pooled the data by 

marine vs. freshwater, species type, and ecological niche (deposit feeding vs. filter feeding 

shellfish, pelagic vs. demersal fish vs. salmonids, etc.). Further breakdown of the data was by 

tissue type analyzed (e.g., whole body vs. fillet for fish, muscle vs. hepatopancreas for crabs). 

Data included in the summary statistics were restricted to samples collected within the last 10 

years. PCB congeners were summed to create Total PCB values; however, not all possible 

congeners were analyzed in every sample. Species were grouped as follows: 

Anadromous 

Bull trout (can also occur as a freshwater species) 

Chinook salmon 

Coho salmon 

Cutthroat trout (can also occur as a freshwater species) 

Steelhead (can also occur as a freshwater species [rainbow trout]) 

Sockeye salmon (can also occur as a freshwater species [kokanee]) 

White sturgeon (can also occur as a freshwater species) 

American shad (this may be a freshwater occurring species too) 

Pacific lamprey 

Freshwater 

Salmonids (if EIM data assigned FW, then kept FW) 

Brook trout 

Brown trout (aka German brown trout) 

Cutthroat trout (can also occur as an anadromous species) 

Rainbow trout (can also occur as an anadromous species [steelhead]) 

Kokanee (can also occur as an anadromous species [sockeye salmon]) 

American shad (usually an anadromous species) 

Lake trout 

Mountain whitefish 

Lake whitefish 

Pygmy whitefish 

Smelt 

Bass 

Largemouth bass 

Smallmouth bass 

Other freshwater fish 

White sturgeon (can also occur as an anadromous species) 
Page B-2 July 20, 2012 Technical Issue Paper 

Northern pike 

Walleye 

Northern pikeminnow 

Black crappie 

Bluegill 

Pumpkinseed 

Peamouth 

Rock bass (sunfish family) 

Yellow perch 

Burbot 

Bridgelip sucker 

Common carp 

Grass carp 

Brown bullhead 

Channel catfish 

Largescale sucker 

Unidentified sucker 

White sucker 

Marine Demersal 

Arrowtooth flounder 

Butter sole 

English sole 

Flathead sole 

Pacific dover sole 

Pacific sand sole 

Pacific sanddab 

Pacific slender sole 

Rock sole 

Speckled sanddab 

Starry flounder 

unidentified flounder 

Other Marine Fish 

Lingcod 

Pile perch 

Shiner perch 

Striped seaperch 

Invertebrates 

Bivalves – deposit feeding: macoma clam, “unidentified” clams 

Bivalves – filter feeding: softshell, Manilla, horse, littleneck, Asiatic, geoduck, and butter 

clams; blue mussels, Pacific oysters, Kumomoto oysters 

Bivalves – freshwater: Asiatic (Corbicula) clam 

Crabs: Dungeness, rock, graceful 

Crayfish: Pacific signal crayfish 
Technical Issue Paper July 20, 2012 Page B-3 

Table B-1. Contaminant concentrations in selected Washington State 

freshwater fish 

Count Minimum Maximum Mean

BASS

Fillet, skin on

dioxin TEQ (ng/kg) 35 0.028 0.57 0.18

mercury (μg/kg) 403 20 1,800 234

PCB, Sum of Congeners (μg/kg) 20 0.25 25 6.5

Fillet, skin off

mercury (μg/kg) 115 26 790 240

FRESHWATER SALMONID

Fillet, skin on

dioxin TEQ (ng/kg) 12 0.081 1.0 0.40

mercury (μg/kg) 60 17 250 93

PCB, Sum of Congeners (μg/kg) 49 0.29 384 25

Fillet, skin off

mercury (μg/kg) 1 64 64 64

Whole Organism

PCB, Sum of Congeners (μg/kg) 66 0.94 450 35

OTHER FRESHWATER FISH

Fillet, skin on

dioxin TEQ (ng/kg) 84 0.032 11 0.44

mercury (μg/kg) 265 11 1,900 187

PCB, Sum of Congeners (μg/kg) 31 0.044 611 41

Fillet, skin off

dioxin TEQ (ng/kg) 9 0.21 1.1 0.49

mercury (μg/kg) 12 17 410 152

PCB, Sum of Congeners (μg/kg) 1 2.4 2.4 2.4

Whole Organism

dioxin TEQ (ng/kg) 22 0.14 0.65 0.38

mercury (μg/kg) 24 24 290 160

PCB, Sum of Congeners (μg/kg) 12 28 253 97

Data provided by Laura Inouye, Washington Department of Ecology, 

 - queried from the Environmental Information Management Database 

 - limited to the most recent 10 years (2002 - 2012) 

 - non-detects not included in calculations 

 
Page B-4 July 20, 2012 Technical Issue Paper 

Table B-2. Contaminant concentrations in selected Washington State 

invertebrates 

Count Minimum Maximum Mean

BIVALVE, DEPOSIT FEEDER

Whole organism, not shell

dioxin TEQ (ng/kg) 24 0.02 20 1.7

BIVALVE, FILTER FEEDER

Muscle

dioxin TEQ (ng/kg) 12 0.016 0.16 0.1

mercury (μg/kg) 34 5 33 11

Whole organism, not shell

dioxin TEQ (ng/kg) 73 0.015 1.6 0.2

mercury (μg/kg) 197 3.2 82 9.2

Whole organism, not shell, not gut

dioxin TEQ (ng/kg) 13 0.017 0.35 0.1

mercury (μg/kg) 72 3.6 61 18

Skin

mercury (μg/kg) 20 1 36 7.4

Viscera, abdominal and thoracic

dioxin TEQ (ng/kg) 5 0.055 0.099 0.1

mercury (μg/kg) 77 4 74 20

Gut ball

dioxin TEQ (ng/kg) 4 0.17 0.44 0.3

mercury (μg/kg) 2 45 48 47

FRESHWATER BIVALVE

Whole organism, not shell

dioxin TEQ (ng/kg) 29 0.41 5.6 1.2

mercury (μg/kg) 25 5 16 9.4

CRAB

Muscle

dioxin TEQ (ng/kg) 46 0.027 0.74 0.2

mercury (μg/kg) 26 20 70 43

Muscle, visceral

dioxin TEQ (ng/kg) 9 0.028 0.38 0.2

mercury (μg/kg) 9 31 110 67

Whole organism, not exoskeleton

dioxin TEQ (ng/kg) 7 0.14 1.5 0.6

Whole organism, not exoskeleton, not gut

dioxin TEQ (ng/kg) 10 0.011 0.3 0.1

Hepatopancreas

dioxin TEQ (ng/kg) 54 0.18 41 6.1

mercury (μg/kg) 22 20 220 55
Technical Issue Paper July 20, 2012 Page B-5 

Table B-2. Contaminant concentrations in selected Washington State 

invertebrates 

Count Minimum Maximum Mean

CRAYFISH

Whole organism, not exoskeleton, not gut

PCB, Sum of Congeners (μg/kg) 1 0.87 0.87 0.9

SHRIMP

Whole organism

dioxin TEQ (ng/kg) 6 0.16 0.34 0.2

mercury (μg/kg) 6 23 50 37

SEA CUCUMBER

Muscle, somatic

mercury (μg/kg) 18 16 88 32

Data provided by Laura Inouye, Washington Department of Ecology, 

 - queried from the Environmental Information Management Database 

 - limited to the most recent 10 years (2002 - 2012) 

 - non-detects not included in calculations 

 
Page B-6 July 20, 2012 Technical Issue Paper 

Table B-3. Contaminant concentrations in selected Washington State 

marine/anadromous fish 

Count Minimum Maximum Mean

ANADROMOUS FISH

Fillet, skin on

dioxin TEQ (ng/kg) 107 0.044 4.6 0.37

mercury (μg/kg) 136 5.8 610 103

Fillet, skin off

mercury (μg/kg) 2 37 54 46

Whole organism

dioxin TEQ (ng/kg) 17 0.51 1.5 0.78

mercury (μg/kg) 35 29 100 54

Whole organism, not fillets

mercury (μg/kg) 10 22 41 33

MARINE DEMERSAL FISH

Fillet, skin on

mercury (μg/kg) 43 5 130 37

Fillet, skin off

dioxin TEQ (ng/kg) 25 0.086 1.0 0.34

mercury (μg/kg) 28 20 190 78

Muscle

dioxin TEQ (ng/kg) 35 0.011 0.36 0.054

mercury (μg/kg) 3 10 40 23

Whole organism

dioxin TEQ (ng/kg) 27 0.071 1.7 0.50

mercury (μg/kg) 50 5 56 17

Whole organism, not shell

dioxin TEQ (ng/kg) 26 0.023 0.30 0.077

mercury (μg/kg) 23 4 27 11

Whole organism, not fillets

dioxin TEQ (ng/kg) 16 0.16 1.2 0.66

Viscera, abdominal and thoracic

dioxin TEQ (ng/kg) 20 0.029 0.18 0.088

Skeleton

mercury (μg/kg) 8 18 62 38

OTHER MARINE FISH

Fillet, skin on

dioxin TEQ (ng/kg) 2 0.084 0.092 0.088

mercury (μg/kg) 4 40 97 69

Whole organism

mercury (μg/kg) 25 10 30 22
Technical Issue Paper July 20, 2012 Page B-7 

Table B-3. Contaminant concentrations in selected Washington State 

marine/anadromous fish 

Count Minimum Maximum Mean

Whole organism, not fillets

dioxin TEQ (ng/kg) 2 0.14 0.17 0.16

mercury (μg/kg) 2 56 220 138

Data provided by Laura Inouye, Washington Department of Ecology, 

 - queried from the Environmental Information Management Database 

 - limited to the most recent 10 years (2002 - 2012) 

 - non-detects not included in calculations 

 
Page B-8 July 20, 2012 Technical Issue Paper 

Table B-4. Mercury concentrations (μg/kg) in selected Washington State 

fish 

Count Minimum Maximum Mean

FRESHWATER FISH

BASS

Fillet, skin on 403 20 1,800 234

Fillet, skin off 115 26 790 240

FRESHWATER SALMONID

Fillet, skin on 60 17 250 93

Fillet, skin off 1 64 64 64

OTHER FRESHWATER FISH

Fillet, skin on 265 11 1,900 187

Fillet, skin off 12 17 410 152

Whole organism 24 24 290 160

MARINE/ANADROMOUS FISH

ANADROMOUS FISH

Fillet, skin on 136 5.8 610 103

Fillet, skin off 2 37 54 46

Whole organism 35 29 100 54

Whole organism, not fillets 10 22 41 33

MARINE DEMERSAL FISH

Fillet, skin on 43 5 130 37

Fillet, skin off 28 20 190 78

Muscle 3 10 40 23

Whole organism 50 5 56 17

Whole organism, not shell 23 4 27 11

Skeleton 8 18 62 38

OTHER MARINE FISH

Fillet, skin on 4 40 97 69

Whole organism 25 10 30 22

Whole organism, not fillets 2 56 220 138

Data provided by Laura Inouye, Washington Department of Ecology, 

 - queried from the Environmental Information Management Database 

 - limited to the most recent 10 years (2002 - 2012) 

 - non-detects not included in calculations 

 
Technical Issue Paper July 20, 2012 Page B-9 

Table B-5. Mercury concentrations (μg/kg) in selected edible 

Washington State invertebrates 

Count Minimum Maximum Mean

BIVALVE, FILTER FEEDER

Muscle 34 5 33 11

Whole organism, not shell 197 3.2 82 9.2

Whole organism, not shell, not gut 72 3.6 61 18

Skin 20 1 36 7.4

Viscera, abdominal and thoracic 77 4 74 20

Gut ball 2 45 48 47

FRESHWATER BIVALVE

Whole organism, not shell 25 5 16 9.4

CRAB

Muscle 26 20 70 43

Muscle, visceral 9 31 110 67

Hepatopancreas 22 20 220 55

SHRIMP

Whole organism 6 23 50 37

SEA CUCUMBER

Muscle, somatic 18 16 88 32

Data provided by Laura Inouye, Washington Department of Ecology, 

 - queried from the Environmental Information Management Database 

 - limited to the most recent 10 years (2002 - 2012) 

 - non-detects not included in calculations 

 
Page B-10 July 20, 2012 Technical Issue Paper 

Table B-6. Dioxin TEQ concentrations (ng/kg) in selected Washington State 

fish and invertebrates 

Count Minimum Maximum Mean

FRESHWATER FISH

BASS

Fillet, skin on 35 0.028 0.57 0.18

FRESHWATER SALMONID

Fillet, skin on 12 0.081 1.0 0.40

OTHER FRESHWATER FISH

Fillet, skin on 84 0.032 11 0.44

Fillet, skin off 9 0.21 1.1 0.49

Whole organism 22 0.14 0.65 0.38

MARINE/ANADROMOUS FISH

ANADROMOUS FISH

Fillet, skin on 107 0.044 4.6 0.37

Whole organism 17 0.51 1.5 0.78

MARINE DEMERSAL FISH

Fillet, skin off 25 0.086 1.0 0.34

Muscle 35 0.011 0.36 0.054

Whole organism 27 0.071 1.7 0.50

Whole organism, not shell 26 0.023 0.30 0.077

Whole organism, not fillets 16 0.16 1.2 0.66

Viscera, abdominal and thoracic 20 0.029 0.18 0.09

OTHER MARINE FISH

Fillet, skin on 2 0.084 0.092 0.09

Whole organism, not fillets 2 0.14 0.17 0.16

INVERTEBRATES 292 0.011 41 1.5

BIVALVE, DEPOSIT FEEDER

Whole organism, not shell 24 0.020 20 1.7

BIVALVE, FILTER FEEDER

Muscle 12 0.016 0.16 0.056

Whole organism, not shell 73 0.015 1.6 0.22

Whole organism, not shell, not gut 13 0.017 0.35 0.14

Viscera, abdominal and thoracic 5 0.055 0.099 0.068

Gut ball 4 0.17 0.44 0.27

FRESHWATER BIVALVE

Whole organism, not shell 29 0.41 5.6 1.2
Technical Issue Paper July 20, 2012 Page B-11 

Table B-6. Dioxin TEQ concentrations (ng/kg) in selected Washington State 

fish and invertebrates 

Count Minimum Maximum Mean

CRAB

Muscle 46 0.027 0.74 0.16

Muscle, visceral 9 0.028 0.38 0.19

Whole organism, not exoskeleton 7 0.14 1.5 0.62

Whole organism, not exoskeleton, not gut 10 0.011 0.30 0.080

Hepatopancreas 54 0.18 41 6.1

SHRIMP

Whole organism 6 0.16 0.34 0.21

Data provided by Laura Inouye, Washington Department of Ecology, 

 - queried from the Environmental Information Management Database 

 - limited to the most recent 10 years (2002 - 2012) 

 - non-detects not included in calculations 

 
Page B-12 July 20, 2012 Technical Issue Paper 

Table B-7. PCB concentrations (total congeners, μg/kg) in selected 

Washington State freshwater fish and shellfish 

Count Minimum Maximum Mean

FRESHWATER FISH

BASS

Fillet, skin on 20 0.25 25 6.5

FRESHWATER SALMONID

Fillet, skin on 49 0.29 384 25

Whole organism 66 0.94 450 35

OTHER FRESHWATER FISH

Fillet, skin on 31 0.044 611 41

Fillet, skin off 1 2.4 2.4 2.4

Whole organism 12 28 253 97

INVERTEBRATES

CRAYFISH

Whole organism, not exoskeleton, not gut 1 0.87 0.87 0.9

Data provided by Laura Inouye, Washington Department of Ecology, 

 - queried from the Environmental Information Management Database 

 - limited to the most recent 10 years (2002 - 2012) 

 - non-detects not included in calculations 
Technical Issue Paper 

Salmon Life History and Contaminant 

Body Burdens 

Technical Issue Paper 

Salmon Life History and Contaminant 

Body Burdens 

July 20, 2012 

Toxics Cleanup Program 

Washington State Department of Ecology 

Olympia, Washington 

 

Technical Issue Paper July 20, 2012 Page i 

Table of Contents 

Page

List of Figures and Tables............................................................................................................... ii

Figures....................................................................................................................................... ii

Tables ........................................................................................................................................ ii

Acronyms & Abbreviations ........................................................................................................... iii

Introduction ......................................................................................................................................1

Analysis............................................................................................................................................2

I. Salmon life history review ...................................................................................................2

A. Summary of life history information in the draft TSD ..................................................2

B. Summary of additional life history information from TSD comments ..........................2

C. Enhanced summary of Puget Sound salmonid life history strategies ............................3

II. Salmonid body burdens......................................................................................................16

A. Summary of salmonid body burden information in the draft TSD ..............................17

B. Summary of salmonid body burden information from the draft TSD comments ........17

C. Salmonid body burden accumulations by life stages, rates, and location ....................19

III. Can salmonid contaminant body burden be attributed to a specific location? ..................31

Summary ........................................................................................................................................34

References ......................................................................................................................................36

 
Page ii July 20, 2012 Technical Issue Paper 

List of Figures and Tables 

Figures 

Page

Figure 1. Mean and SEM total PAHs detected in juvenile Chinook salmon tissue 

composites ....................................................................................................................21

Figure 2. Mean concentrations of total PCBs (ng/g wet weight and ng/g lipid) in whole 

bodies of juvenile Chinook salmon from the Lower Columbia River and Estuary ......24

Figure 3. Mean concentrations of total DDTs (ng/g wet weight and ng/g lipid) in whole 

bodies of juvenile Chinook salmon from the Lower Columbia River and Estuary ......24

Figure 4. Mean PCB concentration in Chinook salmon fillets ....................................................28

Figure 5. Mean PCB concentration in adult Chinook salmon returning to Puget Sound (inrivers versus marine waters) .........................................................................................28

Figure 6. Concentration of PCBs, DDTs, and hexachlorobenzene in six herring populations 

from Puget Sound and the Strait of Georgia .................................................................31

Tables 

Page

Table 1. Estimated body burdens of persistent organic pollutants in returning adult 

Chinook salmon and Chinook smolts ...........................................................................29

 
Technical Issue Paper July 20, 2012 Page iii 

Acronyms & Abbreviations 

DDT dichlorodiphenyltrichloroethane 

DEHP di-2-ethylhexyl phthalate 

DNA deoxyribonucleic acid 

DPE dialkyl phthalate ester 

Ecology Washington State Department of Ecology 

EDC endocrine disrupting chemical 

FAC fluorescent aromatic compound 

FCR fish consumption rate 

HCH hexachlorocyclohexane 

LDW Lower Duwamish Waterway 

PAH polycyclic aromatic hydrocarbon 

PBDE polybrominated diphenyl ether 

PBDE polybrominated diphenyl ether 

PBT persistent bioaccumulative toxics 

PCB polychlorinated biphenyl 

PCDD polychlorinated dibenzo-p-dioxin 

PCDF polychlorinated dibenzofuran 

PCN polychlorinated napthalene 

PFC perfluoroalkyl compound 

POP persistent organic pollutant 

PSAMP Puget Sound Assessment and Monitoring Program 

SaSI Salmonid Stock Inventory 

TEQ toxic equivalent 

tPAH total polycyclic aromatic hydrocarbon 

tPCB total polychlorinated biphenyl 

TSD Technical Support Document 

WDFW Washington Department of Fish and Wildlife 

 
Page iv July 20, 2012 Technical Issue Paper 

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Technical Issue Paper July 20, 2012 Page 1 

Introduction 

The Washington State Department of Ecology (Ecology) received many and divergent comments 

about including or excluding salmon from the default fish consumption rate for Washington 

State fish-consuming populations. Consideration of salmon consumption depends on several 

different technical- and policy-related factors, including salmon life cycle, salmon chemical 

contaminant body burden, and Native American treaty reserved rights. New technical 

information and policy-related questions were provided to Ecology to further evaluate issues 

related to the consumption of salmon. 

This Technical Issue Paper integrates information provided in the public review comments on 

the salmon life cycle and survival strategies with the information currently in the draft Fish 

Consumption Rates Technical Support Document (TSD). This integration and analysis considers, 

in part, where salmon contaminant body burdens are obtained in relation to the salmon life cycles 

and survival strategies. This Technical Issue Paper also examines factors that may affect 

decisions to include or exclude consumption of salmon in site-specific sediment risk 

management and cleanup decisions. It is a targeted examination of the issues raised by review 

comments received on the draft TSD, and was prepared within a limited time frame. Therefore, it 

may not include all available information on this subject. 

 
Page 2 July 20, 2012 Technical Issue Paper 

Analysis 

This section presents a review of salmon life history, a summary of literature on where and when 

salmonids obtain contaminant body burdens, and an assessment of the adequacy of currently 

available information to support site-specific salmon consumption criteria or advisories. Each 

topic includes a brief summary of the information presented in the draft TSD, followed by a 

summary of the public comments received on that topic. The analysis then provides further 

reviews or information summaries for additional clarity on each technical topic. 

I. Salmon life history review 

The draft TSD, specifically Appendix E, provides background information about the life cycle 

and survival strategies of those salmonids that both occur in Washington State waters and are 

consumed in quantity by its residents. Reviewers of the draft TSD provided very few comments 

with respect to new or missing life history information. Rather, comments largely focused on 

where and when body burdens are accumulated in a given salmon’s life. Body burden 

accumulation is discussed in the next section of this Technical Issue Paper. However, in an effort 

to provide additional species-specific information, a summary of available information 

comparing life histories is included here. While this section is not an exhaustive literature review 

for Pacific Northwest salmonids, it is a suitable summary for salmonid life history comparison 

that provides a foundation for the following section on salmonid body burdens. 

A. Summary of life history information in the draft TSD 

Appendix E of the draft TSD provides background information about the life cycle and survival 

strategies for Chinook, coho, pink, sockeye, and chum salmon, as well as steelhead and cutthroat 

trout (Ecology 2011). The draft TSD Appendix E tables provide a general overview of the 

salmonids reviewed. Table E-1 of the draft TSD summarizes general rearing habitats and 

migrational behaviors, while Tables E-5 and E-6 provide summary information on seasonal 

occurrence, habitat use, and the range of life expectancy for each of the seven salmonids. Tables 

E-7 through E-10 provide creel data for freshwater and marine systems. Lastly, Tables E-11 

through E-13 provide Salmonid Stock Inventory (SaSI) summaries, including stock-specific 

status for salmonids occurring near the Port Angeles Harbor and adjacent areas. SaSI is the 

Washington Department of Fish and Wildlife’s (WDFW) standardized, uniform approach to 

identifying and monitoring the status of Washington’s salmonid stocks. 

B. Summary of additional life history information from TSD 

comments 

Very little new information on the life history of salmonids was provided in comments received 

on the draft TSD. However, one reviewer (NCASI 2012) referred to Fresh et al. (2005) for a 

summary of juvenile salmonid life history strategies. Even though this table provides a different 

display of available life history information, it was technically consistent with the tables 

provided in Appendix E of the draft TSD. However, one of the important points noted in their 

comments was that Chinook salmon not only display more residency, but, as they mature, 

Chinook salmon tend to eat more fish than other salmon. This point is relevant for the following 
Technical Issue Paper July 20, 2012 Page 3 

sections of this document that discuss the regional and species-specific differences between 

salmon in their uptake of toxins. 

Additionally, a few other comments received (Weyerhaeuser 2012; Nippon Paper 2012) referred 

to their support of the 2003 AMEC paper titled Evaluation of the Fish Consumption Rate 

Selected by Oregon DEQ for the Development of Ambient Water Quality Data. This paper, when 

referring to salmonid bioaccumulation in the Columbia River basin, stated that “most 

anadromous species spend only a small fraction of their lifetime in the Columbia River,” with the 

majority accumulated in marine habitats. While this is true for some species, or some “types” of 

species, this is an oversimplification due to the complex life history strategies of salmonids. For 

a more-detailed description of salmonid life histories and general periods of occurrence, please 

refer to the following section titled Enhanced summary of Puget Sound salmonid life history 

strategies. 

Although the draft TSD was not intended to be a comprehensive review of the variable life 

history strategies of all Pacific Northwest salmonids, by watershed, and the degrees by which 

these differences could play a role in body burden accumulation, these comments do indicate that 

some additional life history summary would be helpful in this process. In an effort to more fully 

describe these differences, a slightly more comprehensive review of these life history strategies 

is provided in the following sections. 

C. Enhanced summary of Puget Sound salmonid life history 

strategies 

This summary is not intended to be an exhaustive literature review for Pacific Northwest 

salmonids, but rather a summary of relevant information to aid in the interpretation of 

contaminant body burdens and other issues discussed in subsequent sections of this Technical 

Issue Paper. It is not intended to provide a comprehensive review of habitat requirements, such 

as dissolved oxygen, stream depth/velocity, temperature, or turbidity, and the potential effects 

these may have on salmonid life stages. Seven species of salmonids were briefly reviewed in the 

draft TSD (Chinook, coho, sockeye, chum and pink salmon, and steelhead and cutthroat trout). 

Due to their relative absence as a human food resource compared to the other salmonids, this 

Technical Issue Paper does not include a life history review summary for cutthroat trout (similar 

to the previous exclusion of bull trout in the draft TSD). 

Although each of the six species reviewed here are salmonids, their life history strategies can 

vary substantially. Table E-1 of the draft TSD indicates, for these six species, whether juveniles 

rear in rivers, estuaries, or lakes. It also indicates the general areas of migration: nearshore, 

continental shelf, or mid-oceanic. Table E-5 of the draft TSD provided additional life history 

detail for a variety of salmonid species, including general life expectancy. Additionally, Table 

E-6 provides a summary of the complex differences in habitat use for rearing and spawning life 

stages of the various Pacific Northwest salmonids. However, even with species-specific 

differences in their life histories, an aspect that each of these salmonids have in common is that 

they are anadromous. That is, they hatch from eggs in fresh water, mature in marine waters, then 

return to fresh water as adults to spawn. What follows is a more detailed species-specific 

summary than was provided in the draft TSD. Knowledge of where fish hatch, rear, migrate, and 

forage is important to understand how each of these species may differ in their accumulation of 

toxic body burdens. 
Page 4 July 20, 2012 Technical Issue Paper 

When information is too voluminous for inclusion, the reader will be referred to the source for 

further review. For example, in 2002 WDFW updated the SaSI report by classifying the status of 

489 Washington State salmonids and steelhead stocks (WDFW 2002). These SaSI status reports, 

along with other references, were briefly reviewed for general stock-specific background 

information. For a detailed description of the data and summaries of these salmonid stocks, 

please see the WDFW SaSI web page (http://wdfw.wa.gov/fish/sasi/). 

Some of the life history questions that arose during the draft TSD review process include 

seasonal occurrence, habitat use, distribution, foraging, and life expectancy. Relative to more 

resident species such as perch and starry flounder, salmonids have large and highly variable 

distributions over their lifespan; occurrence and habitat use are a function of the needs of a given 

lifestage. However, even range and age at out-migration can be highly variable within a given 

species (e.g., steelhead and coho juveniles, and resident Chinook). Relative to fish species that 

are much longer lived such as English sole, spiny dogfish, white sturgeon, sablefish, yelloweye 

rockfish, and rougheye rockfish, estimated to live as long as 22, 75, 104, 114, 121, and 205 

years, respectively (Love 1996; Berkeley et al. 2004), salmonids have short life spans, generally 

living from 2 to 6 years. In addition, compared to other bony fish species, salmonids have very 

large eggs. This provides the developing embryos and alevins with sufficient food resources to 

survive until they begin foraging as fry. However, egg size is highly variable between salmonids. 

This difference is important as body burden of lipophilic toxins can be transferred from adult 

salmon to their young via the fatty content of the eggs. The species-specific life history 

information that follows is intended to supplement the information previously provided in the 

draft TSD. For an in-depth summary of Chinook salmon life histories, please refer to Myers et al. 

(1998), Healey (1991), and Quinn (2005), among many others. 

a. Chinook Salmon 

Chinook salmon (Oncorhynchus tshawytscha) is the largest of the Oncorhynchus species, 

typically reaching 8 to 10 kg, although Chinook salmon have been documented in excess of 45 

kg (Healey 1991; Quinn 2005). Resident Puget Sound Chinook salmon, however, are typically 

on the smaller end of this scale. Chinook salmon occur throughout the northeastern coast of the 

Pacific Ocean, and are considered one of the most sought after of the salmon species by 

commercial and tribal fishermen, sport anglers, and human consumers. 

Due to their relatively large size, Chinook salmon generally spawn in larger rivers or streams 

than other salmonids (Healey 1991; Quinn 2005). Chinook salmon can be highly variable 

between and within given watersheds. They have various in-migration (e.g., spring versus fall) 

and out-migration (e.g., ocean-type versus stream-type) times that can vary within a given 

system, stock, or run of fish (WDFW 2002; Healey 1991; Myers et al. 1998; Duffy 2003, 2009; 

Duffy et al. 2005; Redman et al. 2005; Quinn 2005). Spring Chinook typically produce streamtype juveniles, whereas fall Chinook typically produce ocean-type juveniles (Quinn 2005). In 

general, Chinook salmon adults return to their natal streams in spring and fall where they can 

hold for several months prior to spawning (WDFW 2002; Quinn 2005). With some exceptions, 

for Chinook populations in the state of Washington, ocean-type Chinook occur within Puget 

Sound and the lower Columbia River tributaries, while spring-type Chinook occur in tributaries 

further up the Columbia River (Myers et al. 1998). 
Technical Issue Paper July 20, 2012 Page 5 

The life history habits of juvenile Chinook salmon vary widely, and a full understanding and 

classification of these differences is still in progress (Redman et al. 2005). For this summary, a 

four strategy classification of behavior in emerging Chinook salmon is described here, with one 

strategy for stream-type, and three strategies for ocean-type. 

Egg 

Chinook salmon have the largest eggs compared to the other Pacific Northwest salmonids, 

ranging from 210 to 420 mg (Allen and Hassler 1986; Beacham and Murray 1993). The eggs of 

Puget Sound Chinook stocks are larger eggs of Chinook that occur in most other watersheds 

(Myers et al. 1998). Adult ocean-type Chinook salmon, which are generally larger in size than 

stream-type Chinook, also appear to produce larger eggs (Myers et al. 1998). As a result of the 

relatively larger eggs, Chinook fry are also relatively large upon emergence, averaging 33 to 37 

mm in length and ranging from 0.12 to 0.47 gram (Healy 1991; Myers et al. 1998; Quinn 2005). 

Fry 

After emergence, stream-type Chinook spend a year or more in the river before migrating 

downstream (Healey 1991; Myers et al. 1998; Duffy 2003, 2009; Duffy et al. 2005; Quinn 2005). 

Once entering the marine environment, stream-type Chinook spend very little time in the 

estuaries before migrating toward coastal waters (Duffy 2003, 2009; Duffy et al. 2005). Oceantype fry display a very different type of behavior. Myers et al. (1998) summarized literature 

documenting three distinct phases of ocean-type juveniles migrating to marine habitats. One 

phase, or strategy, is the immediate type that migrates to the ocean soon after yolk resorption at 

30 to 45 mm in length. During years of poor environmental conditions, another behavioral phase 

may occur, with ocean-type juveniles remaining in fresh water for a year, although this is 

relatively uncommon. The most common behavior for ocean-type fry migrants is to migrate to 

marine habitats at 60 to 150 days post-hatching, or as fingerling migrants, migrating downstream 

in the late summer or autumn of their first year. Emergent Chinook fry in freshwater habitats, 

like fry of other Pacific salmonids, depend on shaded nearshore habitat with slow-moving 

currents, where they forage on drift organisms, including insects and zooplankton (Healey 1991). 

In general, ocean-type parr (the freshwater stage of juvenile salmon, which usually occurs in the 

first one to two years of life) usually migrate to estuarine areas from April through July with 

some variability (peak out-migration occurring from May to early July), becoming smolts 

(juveniles that have transitioned from fresh water to salt water) soon after entering marine 

waters. Duffy et al. (2005) found that wild ocean-type Chinook out-migrate to Puget Sound 

waters from March to July, while hatchery Chinook occupy nearshore Puget Sound waters soon 

after release and in pulses from May to June. Once reaching the marine environment, they then 

spend a few weeks or longer rearing in the estuary (Duffy 2003, 2009; Duffy et al. 2005). 

Juvenile 

Due to their longer residence time in freshwater systems prior to out-migration, stream-type 

Chinook are much larger, averaging 73 to 134 mm, than ocean-type Chinook upon reaching the 

estuary (review in Myers et al. 1998). Entering the estuary at a larger size allows spring-type 

juveniles to move offshore more quickly than ocean-type juveniles (Healey 1991). 

Growth rates of juvenile Chinook salmon are dependent on the most abundant and available food 

resources. Ocean-type juveniles can grow at a faster rate than stream-type individuals when food 
Page 6 July 20, 2012 Technical Issue Paper 

is not limited (review in Myers et al. 1998). However, Duffy (2009) found that insects, a staple 

for stream-type juveniles, can provide a higher caloric content, and therefore promote faster 

growth than other food resources such as decapod larvae when food resources are equally 

abundant. Upon entering marine habitats, hatchery-produced smolts occur at a larger size than do 

their wild counterpart (Duffy 2009). Once reaching the marine waters of Puget Sound, juvenile 

ocean-type Chinook occupy nearshore habitats from April to June, before shifting to more 

offshore habitats from July to September (Duffy 2009). Estuaries are extremely important for 

foraging and nearshore-migrating juvenile salmon (Simenstad et al. 1982; Simenstad and Cordell 

2000). Further, juvenile salmonids do not limit their use of estuarine habitats to their natal 

estuaries, as juvenile salmonids have also been found to enter and utilize non-natal estuaries 

during their marine nearshore migration (Shaffer et al. 2008). Duffy (2009) found that the size of 

ocean-type juveniles immediately prior to this offshore movement was strongly related to 

survival. By early fall, it was presumed that juvenile Chinook salmon in Puget Sound either 

migrate towards the Pacific Ocean or to deeper waters of Puget Sound (Duffy 2009). Coastal 

rearing populations of juvenile Chinook salmon are largely piscivorous (fish eating), but also 

consume euphausiids, amphipods, copepods, pteropods, and cephalopods (Brodeur 1990). 

Subadult 

Once reaching the ocean, Chinook salmon are distributed in both coastal and offshore waters 

(Quinn 2005). In the ocean, ocean-type Chinook are distributed along coastal waters, whereas 

stream-type can be found offshore and throughout the central Pacific (Healey 1991; Myers et al. 

1998). The diet of oceanic maturing Chinook consists mainly of squid, with fish, euphausiids, 

and pteropods also present (Brodeur 1990). Those salmonids that mature and occur within 

coastal waters have a diet primarily composed of fish, with euphausiids, decapod larvae, and 

cephalopods also present (Brodeur 1990). Salmonids mature in oceanic and coastal waters from 

1 to 6 years, although 2 to 4 years is more typical, before returning to their natal streams to 

spawn (Myers et al. 1998). 

Adult 

Mature adult Chinook salmon can return to their natal streams months in advance of spawning; 

however, both spring-run and fall-run fish begin spawning in the fall (Quinn 2005). Within much 

of the Puget Sound region, adult fall-run Chinook salmon start entering estuarine and riverine 

waters as early as August and begin spawning in their natal rivers and streams from midSeptember to November, but this can continue through January (Myers et al. 1998; Quinn 2005). 

Spring-run Chinook salmon enter Puget Sound and Columbia River waters in April and May, 

although spawning does not begin until August and September (Myers et al. 1998). Upon 

entering these freshwater systems, ocean-type adults are larger than spring-type adults. It has 

been postulated that this is in part due to the additional 3 to 5 months longer that ocean-type 

adults remain in the marine environment prior to entering their natal streams (Myers et al. 1998; 

Duffy 2003, 2009; Duffy et al. 2005). It is likely that both of these factors play a role in the 

larger size of ocean-type adults. 

Fat Content of Chinook 

Fat content between salmonid stocks within a given system can vary substantially between years, 

seasons, sexes, and runs. Seasonal abundance of food in the ocean can alter size at entry as well 

as fat content upon entry. Within the Klamath River, Hearsey (2011) found that spring Chinook 
Technical Issue Paper July 20, 2012 Page 7 

salmon, entering rivers months in advance of spawning, had much higher overall fat content 

compared to fall-run Chinook. However, due to their long period of freshwater residence prior to 

spawning, upon spawning, fall-run fish generally had a higher overall fat content. Hearsey 

(2011) found that male and female Chinook generally had the same fat content upon entry, but 

the females had a much lower fat content by the time spawning occurred. This is attributed to 

females using their fat reserves (muscle lipids and triacyglycerol deposits) during upstream 

migration and gonadal development of the eggs. Lipid content is an important factor as lipophilic 

contaminants can occur at higher numbers in these fish. Then as the female converts this energy 

during gonadal development, the fatty eggs from females with higher body burdens receive 

maternal transferred contaminants at elevated levels. 

b. Coho Salmon 

Like other salmonids in Washington State, coho salmon (Oncorhynchus kisutch) are hatcheryreared and released throughout the state. Although some of the cited literature reviews hatcheryreleased fish, this life history summary is intended to focus primarily on natural spawning or 

wild fish behaviors. 

Along the northeastern coast of the Pacific, coho salmon range from Monterey Bay, California, 

to Point Hope, Alaska, and the Aleutian Islands (Laufle et al. 1986). Coho salmon typically reach 

3.5 to 4.5 kg (Sandercock 1991), although they have been documented to reach as many as 14 kg 

(Laufle et al. 1986). Sandercock (1991) found that adult coho returning to British Columbia 

waters ranged from 53 to 67 cm (21 to 26 inches). For populations in and around Washington 

State, returning adult coho salmon are generally 3-year-olds, and spend approximately 18 months 

in fresh water and 18 months in marine habitats (Sandercock 1991). A small percentage of 

sexually mature males (jacks) return to fresh water to spawn after only 5 to 7 months in the 

ocean. Compared to Chinook salmon, coho tend to spawn in smaller streams of modest gradient 

(Quinn 2005). 

In general, coho salmon do not have the broad variation in life history habits that occurs in other 

salmonids such as Chinook and sockeye salmon and steelhead. With some variation, adult coho 

salmon generally return to their natal streams to spawn in fall (Laufle et al. 1986; Sandercock 

1991; Quinn 2005). After emerging, the fry generally remain within freshwater streams for a 

year or two before migrating downstream. A more detailed summary of the life history 

characteristics of coho salmon is provided below. For a more detailed, in depth summary of coho 

salmon life histories, please refer to Laufle et al. (1986), Sandercock (1991), and Quinn (2005), 

among others. 

Egg 

For coho salmon populations, there is considerable variation in egg size within and among 

populations (Fleming and Gross 1990). In general, longer female body length within a 

population resulted in a larger egg produced. Along the Pacific coast, coho salmon have been 

shown to have a significant negative relationship between latitude and egg size (Fleming and 

Gross 1990). In other words, all other factors equal, coho salmon in California have larger, albeit 

fewer, eggs than those in Puget Sound, which are larger than those in systems further north. In 

general, coho salmon eggs within Washington State range from 160 to 295 mg, depending on 
Page 8 July 20, 2012 Technical Issue Paper 

location, and from 4.5 to 6.0 mm in diameter (Fleming and Gross 1990; Laufle et al. 1986; 

Quinn 2005). 

Fry 

Following hatching, coho alevin do not emerge from the gravel until 2 to 3 weeks after hatching 

(Laufle et al. 1986). Emergence has been detected from March to July (Laufle et al. 1986). Coho 

salmon fry are approximately 30 mm upon emergence (Quinn 2005). Although some fry migrate 

to marine waters soon after emergence, the majority disperse both up- and downstream, 

remaining in streams to rear as juveniles for one to two years before migrating downstream 

(Laufle et al. 1986; Quinn 2005). Following emergence, coho fry begin feeding on a variety of 

insects, including dipterans, ephemopterans, and plecopterans (Laufle et al. 1986). Fry that are 

not displaced (washed out) by freshets grow larger, reside longer, and establish territories within 

their natal freshwater systems (Sandercock 1991). Over-wintering habitats, particularly offchannel flood plain habitats, are critical for growth and survival of young coho salmon. 

Juvenile

While residing in freshwater streams, the maturing juvenile coho diet progressively includes 

larger prey items to sustain their growth. At this stage their diet begins to include crustaceans and 

fish, including co-occurring salmonids (i.e., pink and chum salmon) (Laufle et al. 1986). In fact, 

when co-occurring with other similar-sized juvenile salmonids, juvenile coho are more 

aggressive and outcompete other salmonids, including juvenile Chinook, for food resources 

(Laufle et al. 1986; Sandercock 1991). As a result, juvenile coho grow at a faster rate than cooccurring salmonids of other species. Both age and size of juvenile coho salmon are believed to 

be triggers for downstream migration (Laufle et al. 1986). Within this region, coho smolts 

typically leave fresh water and migrate to marine habitats to enter the smolting process in the 

spring (April to June) (Sandercock 1991). Once entering marine waters, coho smolts spend little 

time rearing in estuaries, instead migrating toward coastal waters (Quinn 2005). Juvenile, adult, 

and subadult coho diets in marine waters tend to vary with fish size and coastal region occupied. 

Juvenile coho diets, while occurring in nearshore sublittoral habitats, primarily consist of 

decapod larvae, euphausiids, amphipods, polychaetes, and crustaceans (Fresh et al. 1981, as 

summarized by Laufle et al. 1986; Quinn 2005; Sandercock 1991). Juvenile and subadult coho 

occurring further offshore generally consume decapod larvae, euphausiids, amphipods, and fish 

(principally herring) (Fresh et al. 1981, as summarized by Laufle et al. 1986; Brodeur 1990). 

Subadult 

Although some coho salmon move to offshore waters, typically subadults continue to feed and 

mature in these coastal waters of the northeast Pacific (Quinn 2005). An additional group 

appears to rear in the Strait of Georgia, and possibly Puget Sound (Laufle et al. 1986). For those 

coho that move offshore, this migration appears to begin in July and August (Laufle et al. 1986). 

Coho captured in oceanic waters tended to have diets dominated by fish and squid, although 

euphausiids, amphipods, and pteropods were also present (Brodeur 1990). The majority of coho 

originating from Washington streams migrate to coastal waters off Oregon and Washington, with 

low numbers occurring in Oregon and British Columbia waters (Laufle et al. 1986). Very few 

Washington coho appear to migrate to Alaskan coastal waters (Laufle et al. 1986). Both subadult 

and adult coho salmon usually occur in the top 10 meters of marine water, except when these 

surface waters become too warm (Laufle et al. 1986). 
Technical Issue Paper July 20, 2012 Page 9 

Adult 

Young adult coho occurring offshore of the Columbia River are generally larger than their Puget 

Sound conspecifics, which may be due in part to their preying almost exclusively on fish (i.e., 

anchovy, surf smelt, whitebait smelt, herring, and juvenile Chinook and rockfish), although diets 

of mature coastal coho can also include euphausiids, crab larvae, amphipods, and squid (Laufle 

et al. 1986; Brodeur 1990). While some adult male coho salmon return after spending only one 

summer at sea, the majority of coho return after spending two, and sometimes three, summers at 

sea (Laufle et al. 1986; Quinn 2005). There are some run timing differences between coastal and 

inland Washington stocks of coho salmon, but adults begin returning to estuaries and outlets of 

their natal streams from July to September (Laufle et al. 1986). Except for earlier arriving jacks, 

sexually mature adults migrate up natal streams and rivers from August to November and spawn 

from November to December, and occasionally as late as February or March (Laufle et al. 1986; 

Sandercock 1991). In general, coho spawn in streams and small rivers that have relatively fast 

flow (Laufle et al. 1986; Sandercock 1991; Quinn 2005). 

c. Sockeye Salmon 

This section describes the general life history of anadromous forms of sockeye salmon 

(Oncorhynchus nerka); it does not describe life history patterns of land-locked sockeye salmon, 

known as kokanee. Mature adult sockeye salmon are small relative to other species in this 

region, reaching weights between 2 and 4 kg (4.4 and 8.8 lbs) (Quinn 2005). Along the coast of 

the northeast Pacific Ocean, sockeye salmon populations range from the Sacramento River in 

California to the Arctic (Burgner 1991). Within the state of Washington, a number of stocks exist 

including Lake Pleasant, Ozette Lake, Lake Washington, Baker Lake, and a few runs in the 

Columbia River drainage including Lake Wenatchee. Sockeye salmon have one of the most 

diverse patterns of life history among Pacific Northwest salmon species. For example, age at outmigration to marine systems from their natal streams not only varies between systems, and 

within systems, but can vary among related individuals. As a result, the summary presented here 

is considered a general overview of sockeye salmon life histories, not an all-inclusive review. 

Sockeye salmon migrate from marine waters to natal freshwater systems in the summer months. 

Many times these systems include a nursery lake, in which juveniles rear and adults may hold 

prior to spawning. Adult sockeye salmon return to Lake Washington from June through August, 

with peaks from mid-June to mid-July (Newell 2005). When conditions are right, the adults 

migrate to suitable spawning habitat to dig a nest (redd) and spawn. In some systems sockeye 

salmon spawning can occur on lake beaches, inlets or outlets of lakes, and in outwash fans of 

lake tributaries (Gustafson et al. 1997). For an in-depth summary of sockeye salmon life histories 

please refer to Pauley et al. (1989), Burgner (1991), and Gustafson et al. (1997). 

Egg 

The number of eggs produced by a female sockeye salmon is relatively high (averaging 3,500), 

yet sockeye salmon produce some of the smallest eggs of the Pacific salmon (5.3 to 6.6 mm in 

diameter) (Pauley et al. 1989). As a result, when sockeye fry emerge, they are also small, 

averaging 26 to 29 mm (Quinn 2005). Lake Washington sockeye salmon eggs hatch 

approximately 51 to 124 days after fertilization. Hendry et al. (1998) found that incubation 

duration is strongly linked to water temperatures, with eggs incubating in warmer (12.5°C) 

waters hatching in less than half the time as those incubating in colder water (5°C). 
Page 10 July 20, 2012 Technical Issue Paper 

Fry 

The hatched alevin then take an additional 24 to 60 days to emerge from the gravel as fry, with 

warmer temperatures reducing the time for emergence. Sockeye salmon emerge as fry generally 

in April or May (Pauley et al. 1989), with some variability associated with temperature. As might 

be expected, fry length and weight have been found to be positively correlated with egg weight 

(Hendry et al. 1998). While there is some variability with post-emergent behavior (Gustafson 

et al. 1997), after emergence, fry generally migrate toward a lake that they will use as a nursery 

(and will migrate either upstream or downstream to reach a lake). However, some forms will 

remain in the natal stream for a portion of their rearing. Regarding their entry into marine waters, 

two types of sockeye salmon occur: the ocean-type (or sea-type) that migrates to marine waters 

in the first year of their life, and the stream-type that may rear in rivers and lakes for a year or 

more before migrating to marine habitats (Gustafson et al. 1997). 

Juvenile 

Once entering a lake system, juvenile sockeye begin preying upon available zooplankton and 

insect larvae. Juvenile sockeye in Washington generally migrate from their nursery lakes to 

marine habitats in March and continuing through June, with peak out-migration occurring in 

April and May (Appendix C-5 in Gustafson et al. 1997). Upon entering marine waters, estuarine 

use by juvenile sockeye salmon (smolts at this point) is limited, although some ocean-type 

sockeye may use these habitats before migrating toward coastal waters. Once entering salt water, 

juvenile sockeye salmon migrate northward to the Gulf of Alaska in coastal waters, but then by 

autumn move away from coastal habitats and use offshore waters for growth to maturation 

(Gustafson et al. 1997). In offshore marine waters, sockeye juveniles tend to disperse and not 

form defined schools (Burgner 1980, as cited in Pauley et al. 1989). 

Subadult 

Sockeye spend 2 to 4 years at sea before returning to their natal systems to spawn (Burgner 

1991; Quinn 2005). Sockeye have long gill rakers to allow foraging on a variety of plankton 

species while in the ocean. As there is some dietary overlap between sockeye and pink salmon 

while at sea, during even-numbered years, when pink salmon abundance is relatively low, 

maturing sockeye salmon that migrated to the Bering Sea saw their diet of euphausiids, 

copepods, fish, and squid increase (Davis et al. 2005). For all years, and many regions, larger 

sockeye tended to have greater proportions of fish and squid in their diet (Brodeur 1990; Davis 

et al. 2005). For sockeye populations off the Oregon and Washington coasts, larval fishes 

(Osmeridae) and euphausiids can be dominant prey resources (Brodeur 1990). In other nearby 

regions, amphipods, copepods, and euphausiids were dominant (Brodeur 1990). As these fish 

reach maturity, they begin their return migrations from offshore and coastal waters towards the 

estuaries and river mouths of their natal river, streams, and lakes. 

Adult 

Upstream migration of sockeye stocks is highly variable depending on region and other factors, 

such as day length and water temperature (Burgner 1991). Adult sockeye salmon return to Lake 

Washington from June through August, with peaks from mid-June to mid-July (Newell 2005); 

however, these fish delay spawning until fall. Upon returning to these systems, reproductively 

mature adults average between 2 and 4 kg (4.4 and 8.8 lbs) (Quinn 2005). However, as 
Technical Issue Paper July 20, 2012 Page 11 

reproductive sockeye that enter these systems exhibit little or no feeding behavior, some 

reduction in size may occur prior to their upstream migration to spawn in the fall. Within Lake 

Washington there are variations in sockeye salmon breeding behavior. Some of the returning 

adults hold deep in the lake for up to six months before spawning in the Cedar River that flows 

into the south end of the lake (Newell 2005). Other smaller populations, those that spawn in 

tributaries that flow into the north end of the lake or on the lake’s beaches, spawn at different 

times (Newell 2005). This is believed to be a strategy for maximizing the survival of eggs, 

alevins, and fry as spawning timing is correlated with emergence timing, and therefore the best 

environmental conditions to optimize survival for the next generation (Brannon 1987, as cited in 

Newell 2005). 

d. Chum Salmon 

Chum salmon (Oncorhynchus keta) have the broadest distribution of all salmonid species 

(Pauley et al. 1988) and range along the Northeast Pacific coast from Monterey Bay, California, 

to the Arctic Ocean (Pauley et al. 1988; Salo 1991; Johnson et al. 1997). Similar to pink salmon, 

adult chum salmon prefer to spawn in the lower reaches of their natal streams (Pauley et al. 

1988; Quinn 2005). Chum salmon produce larger eggs than do the smaller sockeye and pink 

salmon (Beacham and Murray 1993; Quinn 2005). Similar to pink salmon or ocean-type 

Chinook, juvenile chum migrate from their freshwater redds to marine waters almost 

immediately after emergence (Pauley et al. 1988; Salo 1991; Johnson et al. 1997; Quinn 2005). 

Chum salmon generally live 3 to 5 years and are relatively large compared to other salmonids, 

second only to Chinook; chum typically average 3.6 to 6.8 kg (8 to 15 lbs) (Salo 1991; Quinn 

2005) and records indicate they can attain weights of up to 20.8 kg (46 lbs) (Johnson et al. 1997). 

Adult chum lengths typically average 53 to 79 cm (21 to 31inches), although they have been 

reported to reach sizes in excess of 108 cm (42.5 in) (Johnson et al. 1997). What follows is a 

summary by lifestage for chum salmon, with a focus on those populations that occur in 

Washington State. For an in-depth summary of chum salmon life histories please refer to Pauley 

et al. (1988), Salo (1991), and Johnson et al. (1997). 

Egg 

Female chum salmon lay between 900 and 8,000 eggs (Pauley et al. 1988) that range in weight 

from 248 to 349 mg (Beacham and Murray 1993). These eggs are extremely sensitive to changes 

in the environment, with a high degree of mortality (up to 90 percent) in the developing eggs 

(Pauley et al. 1988). Depending on environmental conditions, the eggs hatch to become alevins 

50 to 130 days later. The alevins remain in the gravel another 30 to 50 days, until their yolk sac 

is absorbed (Pauley et al. 1988). Having depleted the energy stores in their yolk sacs, alevins 

emerge from the gravel as fry in the spring (Pauley et al. 1988). 

Fry 

Emerging fry are relatively large, ranging from 32 to 38 mm (Quinn 2005). While their time in 

freshwater is limited, these fry rely on aquatic insects as their primary food resource after their 

yolk-sac is absorbed. Most chum salmon fry spend only a few days to a few weeks rearing in 

fresh water before migrating toward marine habitats from March to May (Pauley et al. 1988; 

Salo 1991; Johnson et al. 1997; Quinn 2005). A much smaller number of fry may rear in 

freshwater streams but migrate to marine waters by the end of their first summer. Chum salmon 

utilize estuarine habitats for a few more weeks before migrating to coastal, then offshore waters. 
Page 12 July 20, 2012 Technical Issue Paper 

Once reaching marine habitats, chum salmon form dense schools as they rear in nearshore 

habitats (Pauley et al. 1988; Salo 1991). The Hood Canal shoreline is said to serve as a nursery 

and rearing habitat for a significant portion of all chum salmon originating from Washington 

State rivers (Pauley et al. 1988). While in this environment, chum fry stay in very shallow, 

nearshore habitats and consume a number of epibenthic invertebrates, including gammaridean 

amphipods, harpacticoid copepods, cumaceans, and mysids (Pauley et al. 1988). This 

environment not only provides them with a readily available food resource, but also protects 

them from larger predators such as cutthroat trout. Most chum fry enter estuaries by June and 

leave them by mid to late summer. 

Juvenile 

By the time chum fry leave estuaries and begin moving to coastal waters, size becomes a key 

factor for their survival. Chum salmon that enter these waters when they are less than 55 mm are 

less likely to survive than larger juveniles (Pauley et al. 1988). For those fish that remain in 

estuaries through the summer, more typical sizes are 150 to 225 mm (Pauley et al. 1988). At this 

size juvenile chum generally begin to move to offshore neritic habitats, feeding on euphausiids, 

calanoid copepods, hyperiid amphipods, larvaceans, and fish larvae (Simenstad and Kinney 

1978). A number of age 2 chum salmon do occur within Puget Sound waters (Pauley et al. 1988), 

although the absence of age 3 chum suggests that all chum salmon spend time rearing in the 

Pacific Ocean (Pauley et al. 1988). 

Subadult 

Once reaching coastal waters, the juvenile chum disperse and are widely distributed. Dietary 

studies of chum salmon along the British Columbia coast vary, with dominant food items of 

younger, maturing chum salmon including amphipods, euphausiids, pteropods, and fishes 

(Brodeur 1990). As chum grow larger and mature, their diet shifts to larger prey items, including 

amphipods, euphausiids, and crustaceans, but also an increase in squid and fishes (Brodeur 

1990). In general, chum salmon originating from Washington streams and rivers, and rearing in 

the open ocean, do not return as mature adults until age 3 or 4 (Pauley et al. 1988). 

Adult 

Chum salmon can be reproductively mature as 3, 4, or 5-year-old fish (Pauley et al. 1988). In 

some systems, chum salmon are the last of the salmon to migrate upstream to spawn (Pauley 

et al. 1988). While most systems support only a summer and fall run of returning adult chum, 

Puget Sound rivers produce early (mid-August – October), normal (November – December), and 

late (January – March) runs (Pauley et al. 1988). In systems such as Hood Canal, chum salmon 

migration and spawning times are separated by up to a month, resulting in summer-run fish 

(spawning in early September to mid-October) and fall-run fish (spawning in early November to 

late December) (Johnson et al. 1997). Even though data are limited, coastal runs of chum salmon 

occur in October and November, with spawning taking place as late as December (Johnson et al. 

1997). 

As with other salmonids, adult chum may mill at a river’s mouth, or estuary, for a period before 

initiating their upstream migration (Johnson et al. 1997). Once beginning their upstream 

migration, adult chum no longer continue to feed (Pauley et al. 1988). Chum salmon survival is 

limited once they enter fresh water. Studies have indicated that, once entering fresh water, adult 
Technical Issue Paper July 20, 2012 Page 13 

chum may die within 11 days but may survive as long as a month (Pauley et al. 1988). Although 

chum salmon in Washington State generally spawn in the lower portions of rivers and streams, in 

some systems, such as the Skagit River, chum salmon migrate 170 km or more (Hendrick 1996, 

as cited in Johnson et al. 1997). After the female digs out a redd, and lays somewhere between 

900 and 8,000 eggs that are immediately fertilized by a male, the pair defends the redd(s) until 

eventually dying in the following days. 

e. Pink Salmon 

Pink salmon (Oncorhynchus gorbuscha) are the most abundant salmon along the coast of the 

northeast Pacific Ocean and are also the smallest at maturity (Bonar et al. 1989; Heard 1991; 

Quinn 2005). Mature adult pink salmon are approximately 1.0 to 2.8 kg (2.2 to 6.2 lbs) when 

they return to their natal streams to spawn (Bonar et al. 1989; Heard 1991; Quinn 2005). Pink 

salmon only live for 2 years, with very little variability. In systems south of the Fraser River, 

most pink salmon adults return to their natal streams in odd years (Bonar et al. 1989; WDFW 

2002; Quinn 2005). Twelve of the thirteen pink salmon populations in Washington spawn only 

in odd years, with an additional even-year population occurring in the Snohomish River (Hard et 

al. 1996). Pink salmon are more abundant in the northern river systems (e.g., Nooksack, Skagit, 

Stillaguamish, and Snohomish Rivers) than in southern river systems (e.g., Puyallup and 

Nisqually Rivers) (Hard et al. 1996). Though less abundant, populations also occur in Hood 

Canal (e.g., Hamma Hamma, Duckabush, and Dosewallips Rivers) and the Strait of Juan de Fuca 

systems (e.g., upper Dungeness, lower Dungeness, and Elwha Rivers) (Hard et al. 1996). 

As pink salmon adults spawn near river mouths, and fry migrate downstream immediately after 

emergence, this salmon species spends the least amount of time in fresh water (Bonar et al. 1989; 

Heard 1991). Although some smaller coastal and Columbia River runs occur, within Washington 

State two of the rivers supporting the largest pink salmon runs are the Snohomish and Puyallup. 

These two rivers support commercial netting and sport fishing, activities that occur in marine, 

estuarine, and freshwater portions of the respective systems. 

Within four to six weeks of entering estuaries, the adults go through a transformation, with the 

males developing a large hump on their backs, enlarged heads, and the development of large 

teeth (Bonar et al. 1989; Heard 1991). The hump in male pink salmon is so pronounced 

compared to other salmonids it has resulted in the species being nicknamed humpies. Following 

spawning, the vast numbers of spawned out pink salmon begin to die off, with dead and dying 

adult pink salmon littering the banks and shallows. A variety of predators and scavengers (e.g., 

eagles, bears, and gulls) utilize this readily available food resource (Heard 1991). The remaining 

carcasses decay, with their bodies providing nutrients in the nearby downstream vicinity of their 

spawning grounds. A summary description of the life history characteristics of pink salmon is 

provided below. For an in-depth summary of pink salmon life histories please refer to Bonar et 

al. (1989), Heard (1991), and Quinn 2005).

Egg 

The eggs produced by pink salmon are smaller (about 6 mm in diameter) than other larger 

salmonid species (Bonar et al. 1989; Quinn 2005). Depending on the region and in-stream 

temperatures, fertilized pink eggs can take from five to eight months before fry emerge and 

migrate downstream (Heard 1991). Accounting for some variability between years and systems, 
Page 14 July 20, 2012 Technical Issue Paper 

pink salmon eggs laid in August to October generally hatch between late January and early 

March (Hard et al. 1996). Newly hatched alevin remain in the gravel for a few weeks utilizing 

their yolk sac. These alevin can average 21.3 mm in length. 

Fry 

With some variability, pink salmon fry emerge from the gravel primarily in March and April 

(Hard et al. 1996). Once the yolk sac is depleted, the alevins emerge as fry some 41 to 64 days 

(average 52 days) post-hatching. These newly emerged fish range from 29 to 33 mm long with 

an average length 31.5 mm (Heard 1991; Quinn 2005). There is very little or no freshwater 

rearing as pink salmon fry migrate seaward upon emergence from the gravel, and so their 

downstream migration also occurs in March and April (Hard et al. 1996). Pink salmon 

originating from Puget Sound and Hood Canal streams and rivers appear to use nearshore areas 

extensively for early rearing during their first few weeks of entry into marine habitats (Jewell 

1966, as cited in Hard et al. 1996). While little is known about their behavior as the fry are 

exiting Puget Sound proper, Hiss (1994, as cited in Hard et al. 1996) found that fry occurrence in 

Dungeness Bay (near Sequim) peaked in April and they were gone by late May. These fish 

ranged in length from 35 to 75 mm. Findings suggest that most out-migrating pink salmon enter 

the open ocean by late summer or early fall (Hard et al. 1996). However, like some Chinook and 

coho, a small portion of the pink salmon population appears to adopt residency in Puget Sound 

for the marine phase of the life cycle (Hard et al. 1996). 

Juvenile/Subadult 

Pink salmon fry migrate so rapidly to the sea, and so little is known about the juvenile and 

subadult behavior at sea, that for pink salmon the juvenile and subadult life history categories are 

combined. Once reaching estuarine and marine habitats, pink salmon migrate toward the open 

ocean within the first couple of months. By September the majority of pink salmon migrate 

hundreds of miles out in the open sea to grow and mature (Hartt and Dell 1986, as cited in Hard 

et al. 1996; Bonar et al. 1989; Heard 1991). Stomach contents of ocean-caught pink salmon were 

found to include fish, amphipods, euphausiids, pteropods, salps, squid, crustacean larvae, 

chaetognaths, and polychaetes (Bonar et al. 1989; Brodeur 1990; Pearcy et al. 1984). They spend 

approximately eighteen months rearing in the open ocean before their eastward migration to their 

natal streams and rivers (Bonar et al. 1989; Heard 1991). 

Adult 

Adult pink salmon begin migrating toward the river mouth of their natal stream from June to 

September, with peaks in some systems, such as the Snohomish, in the month of August (Heard 

1991; Hard et al. 1996). Most pink salmon returning to Washington rivers and streams are 

believed to travel east through the Strait of Juan de Fuca, with some additional use of the 

Johnstone Strait/Strait of Georgia corridor (Hard et al. 1996). Once reaching their natal streams, 

adult pink salmon, in general, do not migrate far upstream, preferring to spawn within a few 

miles of the estuary. However, in the Snohomish River pink salmon spawn as far upstream as the 

Sultan River (approximately 23 miles), in the Puyallup River primarily above 12.5 river miles, 

and in the Nisqually River main stem between river mile 22 and 40 (Hard et al. 1996). In 

Washington and southern British Columbia, spawning generally occurs from August to October 

(Hard et al. 1996). Adult pink salmon spawn in dense numbers near riffles with clean gravel, an 
Technical Issue Paper July 20, 2012 Page 15 

activity that takes from one to eight days (Heard 1991). After spawning the adults aggressively 

defend their respective redds until they eventually die, 11 to 21 days later (Heard 1991). 

f. Steelhead 

Steelhead (Oncorhynchus mykiss) range from central California to the Bering Sea and Bristol 

Bay, Alaska (Pauley et al. 1986). This species can occur as both anadromous (steelhead) and 

resident (rainbow trout) fish (Pauley et al. 1986). This brief life history summary focuses on 

naturally spawning, or wild, steelhead populations, and not the resident rainbow trout or hatchery 

produced stock of either form. A significant difference between steelhead and salmon is that 

steelhead, in fresh water, can maintain a life history as rainbow trout, and steelhead can be repeat 

spawners. Adult spawners of either steelhead or rainbow trout can produce either, or both, 

freshwater or anadromous juveniles (Quinn 2005). The discussion below focuses on the 

anadromous, or steelhead, form of the species. 

Comparing the size of an average steelhead to a given salmon species needs to take into account 

the age of a given steelhead. Unlike some of the larger salmonids that die after spawning, 

steelhead can return to spawn in multiple years. As a result, steelhead can spawn up to four times 

and have been documented to live as long as 8 or 9 years (Pauley et al. 1986). Because steelhead 

grow larger in the productive marine environment, fish that stay in these habitats longer are 

typically larger. Studies investigating this have found that steelhead range in size from 47 cm 

(18.5 inches) for a 1-year saltwater resident to 88 cm (34.6 inches) for a 4-year saltwater resident 

(Maher and Larkin 1954, as cited in Pauley et al. 1986). Steelhead are prevalent throughout 

streams and tributaries of the Puget Sound and Columbia River (Pauley et al. 1986). Both winter 

and summer steelhead types, or races, occur within Washington State streams and rivers. 

Typically adult steelhead return to streams and rivers in the winter or summer and spawn in the 

spring and summer, with fry emerging in just a few weeks. Upon emergence, steelhead typically 

rear in the freshwater streams and rivers between 1 and 3 years. Following their downstream 

migration to marine waters, these fish rear and mature in the ocean for 1 to 3 years before 

returning to freshwater systems as adults to spawn (Pauley et al. 1989; Quinn 2005). Because 

steelhead can be repeat spawners, the age and size of returning adults varies considerably. A 

summary description of the life history characteristics of steelhead is provided below. For an indepth summary of steelhead life histories please refer to Pauley et al. (1986) and Quinn (2005). 

Egg 

Steelhead eggs are typically smaller than salmon eggs, with size varying based on maternal size 

and body condition. Though timing for egg laying and hatching varies between river systems and 

temperature conditions, eggs of both summer- and winter-run fish begin to hatch from April to 

June, 4 to 7 weeks following adult spawning. Alevins emerge soon after, rapidly absorb their 

yolk, and are free swimming within 3 to 7 days (Pauley et al. 1986). These newly emerged fish 

are active foragers on microscopic organisms, moving toward insects and larger prey items as 

they grow. 

Fry 

By the summer of their first year, steelhead fry are consuming bottom-dwelling aquatic and 

terrestrial insects (Pauley et al. 1986). As they continue to grow, young steelhead fry become 
Page 16 July 20, 2012 Technical Issue Paper 

parr. Steelhead parr can remain in fresh water from 1 to 4 years, although 2 to 3 years is more 

common. Steelhead parr actively forage from spring to fall but become relatively inactive during 

winter months (Bustard and Narver 1975, as cited in Pauley et al. 1986). It is at the parr stage 

that steelhead begin their downstream migration toward marine habitats. 

Juvenile 

Juvenile steelhead migrate downstream typically in spring (although this can be from January to 

July) of their second, third, or fourth years in freshwater habitats, finally entering marine waters 

and becoming smolts. Size at smoltification in steelhead has been correlated with survival. Small 

steelhead entering marine habitats do not survive long. Ideally a steelhead smolt should be at 

least 14 to 16 cm (5.5 to 6.3 inches) to survive this critical period (Pauley et al. 1986). Once 

entering estuaries, juveniles migrate toward coastal waters for a short period before moving 

offshore and into the open ocean. While in the ocean, juvenile steelhead diet shifts again and 

includes amphipods, euphausiids, a variety of fish, and squid (Pauley et al. 1986; Brodeur 1990). 

Subadult 

While in the ocean, subadult steelhead grow rapidly. However, upon entering the ocean, instead 

of forming schools they disperse widely. As a result, little is known about their distribution in 

marine habitats, other than distribution conforming between the 5°C isotherm to the north and 

the 15°C isotherm to the south (Pauley et al. 1986). Subadult steelhead diet while in the ocean 

appears to vary between regions, which may be a factor of available food resources. For those 

fish that occur off Oregon and Washington, cephalopods represent nearly 80 percent of the diet 

with fish representing only 10 percent (Brodeur 1990). Similar aged steelhead in the Gulf of 

Alaska had diets that consisted of 63 percent fish and 31 percent squid (Brodeur 1990). Although 

Columbia River summer-run steelhead generally only spend one summer in the ocean, other 

stocks, including winter-run, spend up to 4 years in the ocean, although 2 to 3 years is more 

common (Pauley et al. 1986). 

Adult 

Stream-maturing (summer) adult steelhead typically enter rivers from August to September, 

remain in the river through fall and winter, then spawn the following spring (Pauley et al. 1986; 

Quinn 2005). Ocean-maturing (winter) steelhead in Washington return during March to April 

and may spawn within a month of entering fresh water (Pauley et al. 1986; Busby et al. 1996, as 

cited in Quinn 2005). Returning adult steelhead rarely eat and grow little if at all once entering 

fresh water to spawn (Maher and Larking 1954, as cited in Pauley et al. 1986). Unlike salmon, 

steelhead do not die after spawning and can spawn up to four times, although two to three is 

more common (Pauley et al. 1986). As a result, post-spawn adult steelhead migrate back toward 

marine habitats within a relatively short period of time after spawning. 

II. Salmonid body burdens 

Over the course of a given salmonid lifespan, these fish occupy a variety of habitats that meet 

specific needs for each lifestage. As they grow from one lifestage to the next, and move from one 

habitat type to the next, their growth is based on the available food resources (Healey 1991, 

Quinn 2005; Duffy 2009). During each period of growth, each lifestage has the potential to 
Technical Issue Paper July 20, 2012 Page 17 

accumulate environmental toxins. This section reviews and summarizes the information provided 

in the draft TSD, and the comments received on the draft TSD. Finally, this section includes a 

summary review of salmonid body burden accumulation. This review refers back to the life 

history summaries described above in an effort to determine whether it may be appropriate to 

attribute body burden accumulation to specific sites. 

A. Summary of salmonid body burden information in the draft TSD 

The draft TSD was written to address human consumption of fish and not the biology of 

Washington State salmonids. However, some explanation of salmonid life history and general 

region of body burden accumulation is warranted. Appendix E of the draft TSD, titled The 

Question of Salmon, summarized the life cycle and survival strategies of selected Washington 

State salmonids. 

Appendix E acknowledges that, by the year 2000, an estimated 58 percent of all salmon 

consumed worldwide was farmed salmon. However, the draft TSD indicated people of 

Washington State not only consume more salmon than other populations, but much of this 

salmon comes directly from wild-caught resources in the Pacific Northwest region. As a result, 

accumulation of body burden by non-farmed salmonids in Washington State is relevant when 

evaluating human health risks associated with consumption of the resource. 

The Appendix E section titled Salmonid Contaminant Body Burden summarizes the role that 

salmonids play in the distribution of bioaccumulative pollutants. Appendix E acknowledges that 

“Pacific salmon exposure to PBTs, and PCBs in particular are, in part, contingent on migratory 

patterns, residency time in Puget Sound, proximity of the salmon to contaminated sediments, 

waste sites, and different behavior and dietary patterns as the fish mature.” Included in this 

summary is the finding of O’Neill et al. (1998) “...that chinook and coho salmon accumulate 

most of their PCB body-burden in the marine waters of Puget Sound and the ocean, and because 

chinook salmon live longer and stay at sea longer than coho salmon they accumulate higher PCB 

concentrations in their muscle tissues.” Further, more than 98 percent of the final body weight of 

most salmon is attained at sea. Appendix E cites the finding of O’Neill et al. (2006) that coastal 

migrants (coho and ocean-type Chinook) have greater body burdens than do more oceanic 

migrants (chum, pink, and sockeye). Further, this study found that resident Chinook, which tend 

to be ocean-type, fall-run fish, were found to have 2 to 6 times the amount of polychlorinated 

biphenyls (PCBs) as non-residents, and 5 to 17 times the polybrominated diphenyl ether (PBDE) 

burden. A final point made in Appendix E with respect to regional variations in accumulation is 

that tributaries in the far southern reaches of Puget Sound lengthen the time that these fish occur 

in the Sound. This is due to greater distances from natal streams to the ocean for both outmigrants and in-migrants. 

B. Summary of salmonid body burden information from the draft 

TSD comments 

Public review comments on the draft TSD represented a wide range of positions with respect to 

where and when in a salmon’s life cycle it accumulates significant portions of its toxic body 

burden, and how this information should be incorporated into the draft TSD. These comments 

are summarized below. 
Page 18 July 20, 2012 Technical Issue Paper 

One reviewer (Yakama 2012) noted that salmon have been shown to acquire contaminants in 

waters that are under Washington State jurisdiction. They pointed out that accumulations occur 

within fresh waters of the Columbia River for juveniles during their out-migration (LCREP 

2007) and in estuarine and inland marine waters of Washington (O’Neill 2011, as cited in 

Yakama 2012). 

Another reviewer (Exponent 2012) pointed out the draft TSD Appendix E appeared to support 

the conclusion that, for most salmon, body burden of bioaccumulative chemicals (e.g., PCBs, 

toxins, mercury) derives mostly from marine waters. They noted that “Washington 

waters/sediments may contribute to body burden depending on the species, run, chemical, life 

cycle characteristics, and range of environmental physical characteristics,” and concluded that 

“variability, dominated by a lack of significant contribution, argues for evaluating the situation 

on a site-specific basis with the exclusion of salmon being the default.” 

A few comments received on the draft TSD (Weyerhaeuser 2012; Nippon Paper 2012) referred 

to their support of the 2003 AMEC paper titled Evaluation of the Fish Consumption Rate 

Selected by Oregon DEQ for the Development of Ambient Water Quality Data and this paper’s 

relevance to the reviewed draft TSD. One of the points made by the AMEC (2003) document 

with respect to freshwater and estuarine occurring fish was that “If there is a permitted discharge 

to a freshwater body, the consumption of estuarine fish and shellfish is likely to be irrelevant. 

Similarly, if there is a discharge to an estuarine area, the freshwater fish upstream will likely not 

be affected. Thus the inclusion of rates of consumption of freshwater and estuarine finfish and 

shellfish is a very conservative assumption for these specific applications” (page 5). 

The AMEC (2003) paper called into question the inclusion of anadromous fish, which are 

consumed by Columbia River Tribal members at rates of three times higher than resident fish 

species, according to the CRITFC (1994) fish consumption survey. They noted that many 

juvenile Chinook salmon in the Columbia River spend several months in the system before 

migrating to a marine feeding area, and that when they return as adults after 2 to 6 years, they 

generally do not feed during their upstream spawning migration, and therefore do not reach 

equilibrium with the surrounding environment. In other words, though potentially occurring 

within a discharge area, migratory fish species such as Chinook salmon do not occur in any sitespecific region for a sufficient length of time to achieve equilibrium with regulated compound 

concentrations in the associated water column. 

One reviewer (NCASI 2012) provided extensive comments, citing many of the same references 

that were cited in the draft TSD. They point out that different species and different runs of the 

same salmon species have very different life history strategies and will accumulate body burdens 

to differing degrees. They state that literature supports the position that the major fraction of 

persistent bioaccumulative toxic (PBT) burden carried by adult salmon originates from the open 

ocean. Their comments noted that resident Puget Sound Chinook, with higher body burdens, are 

an exception as they do not utilize open ocean habitats. Due to this difference, they noted that 

“...it might be appropriate to assess risk to select Puget Sound residents as a separate activity, 

and inclusion of salmon in an FCR [fish consumption rate] used in such a risk assessment may 

well be warranted.” However, due to the large differences in life history, the reviewer felt that it 

is inappropriate to lump all species together as salmon, and should instead apportion numbers 

between salmon species. Their conclusion was that, based on the information provided above, 
Technical Issue Paper July 20, 2012 Page 19 

the consumption of salmon should be excluded from any state-wide default fish consumption 

rate. 

C. Salmonid body burden accumulations by life stages, rates, and 

location 

This section includes a summary of the detailed technical literature review comments provided 

by one specific reviewer, and an additional literature review concerning salmonid body burden 

accumulation conducted during preparation of this Technical Issue Paper. 

a. NCASI review comments (Should salmonid body burden be included as part of the fish 

consumption rate?) 

A key question asked by a number of reviewers of the draft TSD was whether salmonid body 

burden accumulation is sufficiently understood to be included as part of the default fish 

consumption rate. One reviewer in particular, NCASI (2012), provided a summary of their 

literature review on where salmonids accumulate PBT chemicals. A summary of their review is 

included here, as well as an expanded review of additional literature, to further understand what 

the current knowledge is for the rate of uptake, locations where uptake occurs, and those 

salmonid species and life stages for which this information is available. 

The NCASI (2012) comments include a table taken from Fresh et al. (2005), that compared the 

life history variations for six Washington State salmonid species (NCASI [2012] cited the Fresh 

paper as NOAA 2005). NCASI (2012) comments stated that... “These differences are potentially 

significant in that they may lead to differences in the mass (burden) of the chemical 

contaminants (e.g., PBT chemicals) ultimately accumulated by the salmon, and in the fraction of 

this ultimate burden accumulated in freshwater vs. saltwater.” Section I.C of this Technical Issue 

Paper was prepared to provide an even greater understanding of what those life history 

differences are, where these six salmonid species occur at given stages of their life, and the 

principal food items consumed during each life stage. This Technical Issue Paper is not an 

exhaustive summary, but one that allows for comparison on an appropriate scale. 

NCASI (2012) stated that, taken to the extreme, the life history differences of these salmonids 

imply that each run of each salmonid should be evaluated independently to determine where 

contaminants are accumulated. They further stated that this comparison may not be necessary, as 

the work of O’Neill et al. (1998), West and O’Neill (2007), and O’Neill and West (2009) 

indicated that the open ocean is the dominant pathway for PBT chemical uptake by salmonids. 

The NCASI review provided additional references that are included to show that the majority of 

contaminant burden in anadromous fish occurs in marine systems and not freshwater systems. A 

final, albeit very notable, distinction made in their review was the finding by O’Neill et al. 

(1998) that indicated a greater uptake of PBTs in Chinook, in both Puget Sound proper and its 

tributaries, relative to other salmonids. Findings such as this are likely attributable to two factors: 

(1) resident Puget Sound Chinook are generally ocean-type (rearing in marine waters rather than 

extensive periods in fresh water), and (2) they eat more fish, including contaminated herring 

stocks, as a part of their food resource than other salmonids. 
Page 20 July 20, 2012 Technical Issue Paper 

b. Summary of investigations concerning salmonid body burden accumulation 

There is growing evidence in the literature that Puget Sound fish, including salmonids, are 

experiencing biological effects attributable to contaminant exposure (McCain et al. 1990; Stein 

et al. 1995; Landahl et al. 1997; O’Neill et al. 1998; West and O’Neill 2007; O’Neill and West 

2009; Hope 2012). Although there is evidence that adult salmon returning to spawn in 

Washington waters have elevated body burdens of these contaminants, the origin of these 

contaminants is of central importance for resource management and risk reduction. What follows 

is a summary of selected papers that investigated body burden accumulation in salmonids. 

Juvenile accumulation 

In situ biomonitoring of caged, juvenile Chinook salmon (Oncorhynchus tshawytscha) in the 

Lower Duwamish Waterway (Kelley et al. 2011): 

Kelley et al. (2011) conducted a series of 8 to 10 days in situ caged fish exposure studies in 

the Lower Duwamish Waterway (LDW) each July, over a 4-year period (2004–2007). 

Juvenile ocean-type Chinook salmon (Oncorhynchus tshawytscha) were obtained as eggs or 

fry from the University of Washington hatchery and reared at the NOAA Fisheries marine 

lab in Mukilteo, WA. They were raised in freshwater and acclimated to seawater in June of 

each year. The exposure period was chosen to be well below previous studies, indicating that 

residence time in these waters for naturally occurring juvenile Chinook tends to be much 

greater (ranging from 1 week to 2 months). Among other investigative methods, they used 

fluorescent aromatic compounds (FACs) in Chinook salmon bile to evaluate the relationship 

between contaminated sediment and ecological receptors for fish caged in the LDW. At each 

caged fish location they collected sediment and water sample data. 

Their findings indicated that biomarkers among field-exposed Chinook were greater than 

those in control sites. In fact, deoxyribonucleic acid (DNA) adduct analysis indicated there 

were significant differences between the test subjects and the controls, with the exception of 

2007 data, a period when in-water contaminant levels were at their lowest. Further, tissue 

body burden of yearly mean and the standard error of mean (SEM) polycyclic aromatic 

hydrocarbon (tPAHs) were significantly different during the 2005 study period when some of 

the highest tPAHs were detected in water samples (Figure 1), which happened to coincide 

with the only time total PCBs (tPCBs) were detected in water samples. The findings of 

Kelley et al. (2011) indicated that juvenile Chinook, occurring for a relatively short period of 

time in a contaminated estuarine environment, can experience elevated contaminant body 

burden. Similar conclusions were reported by other authors, indicating that contaminant 

accumulation by salmonids can occur within freshwater and estuarine systems (Giesy 1999; 

Meador et al. 2002; Hardy and McBride 2004; Sethajintanin et al. 2004; Fresh et al. 2005; 

Johnson et al. 2007; Yanagida 2012). 
Technical Issue Paper July 20, 2012 Page 21 

Figure 1. Mean and SEM total PAHs detected in 

juvenile Chinook salmon tissue composites 

Source: Kelly et al. 2011 

Studies of uptake, elimination, and late effects in Atlantic Salmon (Salmo salar) dietary exposed 

to di-2-ethylhexyl phthalate (DEHP) during early life (Norman et al. 2007): 

Norman et al. (2007) investigated the uptake, elimination, and late effects in Atlantic salmon of 

hatchery origin where juveniles were exposed to orally administered, and food contaminated 

with, di-2-ethylhexyl phthalate (DEHP). They found diet was the major route for uptake of 

lipophilic compounds. In addition, they found that for this compound and its metabolite, 

salmon were able to excrete the compounds, with body burden concentrations approaching 

background within one week of exposure. The exposure levels in this study demonstrated that 

dietary exposure to DEHP could temporarily increase body burden, but if no longer exposed 

can excrete DEHP to levels more consistent with background, and have no latent effects on 

growth or survival to adulthood. However, they did find that repeated exposure to very high 

doses that did not allow the fish to return to background levels could alter gonadal 

development in males. 

In situ biomonitoring of juvenile Chinook salmon (Oncorhynchus tshawytscha) using biomarkers 

of chemical exposures and effects in a partially remediated urbanized waterway of the Puget 

Sound, WA (Browne et al. 2010): 

Browne et al. (2010) investigated the contaminant effects of Duwamish Waterway PAHs and 

PCBs on caged juvenile Chinook salmon using in situ biomonitoring and molecular biomarker 

analysis. In July 2007, approximately 20 pre-smolt Chinook were placed in four cages for 

eight days at adjacent sites in the Duwamish. Both subject and control fish were of hatchery 

origin. Hatchery-maintained control reference Chinook were not fed because juvenile fish 

caged in the Duwamish system have limited access to prey in the water column and do not 

feed. Biomarkers were compared to control cages of fish at an upstream hatchery. Prior to 
Page 22 July 20, 2012 Technical Issue Paper 

cage placement, sediment samples were collected and analyzed at the selected cage locations. 

High concentrations of total PAHs in sediments were detected at one site, whereas two other 

sites had relatively low concentrations. Waterborne PAHs at all of the sampling sites were 

relatively low (<1 ng/L). Sediment PCBs at the sites ranged from a low of 421 ng/g to 1,160 

ng/g, and there were no detectable waterborne PCBs at any of the sites (detection limit = 10 

ng/L). 

Browne et al. (2010) found no significant differences (<0.05) in biomarker gene expression 

in the Duwamish-caged fish relative to controls, although there was a pattern of gene 

expression suppression at the most heavily PAH-enriched site. The lack of a marked 

perturbation of mRNA biomarkers was consistent with relatively low levels of gill PAHDNA adduct levels that did not differ among caged reference and field fish. Browne et al. 

(2010) found that there was low bioavailability of sediment pollutants for experimentally 

caged juvenile Chinook. Their conclusion was that these findings were potentially reflecting 

low waterborne exposures occurring at contaminated sites within the Duwamish waterway 

that have undergone partial remediation. 

However, a limitation of the Browne et al. (2010) study may be duration of exposure. As the 

majority of Chinook populations in Puget Sound are ocean-type, fall-run fish, they generally 

enter estuaries at a smaller size and stay for a longer period than would spring type Chinook. 

A critical reviewer of this paper may propose an exposure period more consistent with 

naturally occurring pre-smolt Chinook to determine if the findings of no significant 

difference of PAHs and PCBs would stand. 

Contaminant exposure in outmigrant juvenile salmon from Pacific Northwest estuaries of the 

United States (Johnson et al. 2007a): 

Johnson et al. (2007a) investigated contaminant uptake in out-migrant juvenile salmon in the 

Pacific Northwest, including concentrations of PCBs, DDTs, PAHs and organochlorine 

pesticides in tissues and prey of juvenile Chinook and coho salmon from selected estuaries 

and hatcheries in the U.S. Pacific Northwest. Subyearling Chinook were collected using 

beach seines from five Washington and seven Oregon bays and estuaries from 1996 to 2001. 

To ensure field sampling captured wild fish instead of hatchery-reared fish, the authors 

attempted to collect fish from field sites prior to releases from hatcheries or other programs. 

The few hatchery fish that were captured in beach seines were not included in their analyses. 

Additional specimens were collected from hatcheries. Juvenile coho were collected from two 

Washington and three Oregon estuaries in 1998. In addition to tissue testing, bile metabolites 

and stomach contents were evaluated. 

Johnson et al. (2007a) found that Chinook salmon had the highest whole body contaminant 

concentrations, typically 2 to 5 times higher than coho salmon from the same sites. Believed 

to be a function of high lipid content, hatchery Chinook body burdens of PCBs and DDTs 

were higher than estuarine Chinook salmon. Of the twelve estuaries where sampling 

occurred, concentrations of PCBs were highest in Chinook salmon from the Duwamish 

Estuary, the Columbia River, and Yaquina Bay. Each of these systems had fish exceeding the 

2,400 ng/g lipid NOAA threshold for adverse health effects on fish. No significant 

differences were observed in PCB concentrations in coho salmon between sampling sites, 

though sample size was small. 
Technical Issue Paper July 20, 2012 Page 23 

Johnson et al. (2007a) found DDT concentrations in juvenile Chinook were highest in the 

Columbia River and Nisqually Estuary. PAH metabolites concentrations in bile were highest 

in Chinook captured in the Duwamish Estuary and Grays Harbor. When coho and Chinook 

salmon collected from the same sites were compared, ∑DDT concentrations were much lower 

in coho salmon. As PCBs, PAHs, and DDTs were consistently present in stomach contents at 

concentrations correlated with contaminant body burdens from the same sites, it is believed 

that contaminants in estuarine food resources contribute to out-migrant body burden. 

Persistent organic pollutants in outmigrant juvenile Chinook salmon from the Lower Columbia 

Estuary, USA (Johnson et al. 2007b): 

Johnson et al. (2007b) investigated exposure to several persistent organic pollutants (PAHs, 

PCBs, DDTs, and other organochlorine pesticides) in out-migrant juvenile fall Chinook 

salmon in the Lower Columbia River. They also evaluated the potential for adverse effects 

on salmon and the estuarine food web. Three regions were chosen for the collection of whole 

body and gut content samples: Columbia River estuary, Longview, and the confluence of the 

Willamette and Columbia Rivers. Approximately 30 juvenile Chinook were collected via 

beach seine in the summers of 2001 and 2002. Additional fish were captured using a purse 

seine in the Columbia River estuary. Chinook captured included a mix of both hatchery and 

naturally spawned fish. Once captured, fish were sacrificed for whole body and gut content 

analysis. The entire stomach content was collected post-mortem. 

Johnson et al. (2007b) found average whole body concentrations of PCBs in juvenile 

Chinook ranged from 1,300 to 14,000 ng/g lipid (Figure 2). Average whole body 

concentrations of DDT were extremely high, ranging from 1,800 to 27,000 ng/g lipid (Figure 

3). Whole body PCB and DDT concentrations tended to be associated with fish size, not 

distribution by river mile. The authors concluded that this finding was a correlation with 

estuarine residence time, as larger fish required longer residence time. With respect to prey 

items collected from gut contents, PCBs, DDTs, and PAHs were all found in salmon stomach 

samples, indicating that prey is a source of exposure. The authors concluded that since whole 

body contaminant concentrations were poorly correlated with nearby sediment 

concentrations, pelagic as well as benthic sources are important in determining salmon 

exposure. The findings of Johnson et al. (2007b) indicate that concentrations of DDTs and 

PCBs are elevated in out-migrant juvenile Chinook salmon in the Lower Columbia River, 

relative to salmon from undeveloped Pacific Northwest estuaries. 
Page 24 July 20, 2012 Technical Issue Paper 

Figure 2. Mean concentrations of total PCBs (ng/g wet weight and ng/g lipid) 

in whole bodies of juvenile Chinook salmon from the 

Lower Columbia River and Estuary 

Source: Johnson et al. 2007b 

Figure 3. Mean concentrations of total DDTs (ng/g wet weight and ng/g lipid) 

in whole bodies of juvenile Chinook salmon from the 

Lower Columbia River and Estuary 

Source: Johnson et al. 2007b 
Technical Issue Paper July 20, 2012 Page 25 

Adult uptake and transfer of contaminants 

Lipid reserve dynamics and magnification of persistent organic pollutants in spawning sockeye 

salmon (Oncorhynchus nerka) from the Fraser River, British Columbia (Kelly et al. 2007): 

Though accumulations of salmonid body burdens can and do occur during freshwater and 

estuarine occurrence of salmonids, the relative proportion of total adult body burden 

accumulated during juvenile stages has been questioned by some authors (O’Neill and West 

2009). Kelly et al. (2007) investigated spawning sockeye salmon in the Fraser River. From 

June to October of 2001, they collected returning adult fish from as far downstream as 10 

km, and as far upstream as approximately 1,200 km. Unfortunately, their complete 

methodology was not included in the paper, though their target analytes included PCBs and 

polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). 

Their study found that the Fraser River is not a major source of sockeye salmon body burden 

accumulation of PCBs and PCDD/PCDFs, and that marine food sources and pathways are the 

important factors of persistent organic pollutants (POPs) in returning adults. However, other 

important findings were that magnification of toxics occurs during the development of eggs. 

Findings showed a three-fold increase of lipid toxic equivalents (TEQs) in eggs from openocean samples to those taken during spawning. This suggests that lipid reserve depletion 

during upstream migration can increase PCB and PCDD/PCDF concentrations in eggs as the 

adult fish prepare to spawn. 

Kelly et al. (2007) conclude by noting that other globally distributed dioxin-like compounds 

and/or endocrine disrupting chemicals (EDCs) such as polychlorinated napthalenes (PCNs), 

polybrominated diphenyl ethers (PBDEs), hexachlorocyclohexanes (HCHs), endosulfans, 

dialkyl phthalate esters (DPEs), and perfluoroalkyl compounds (PFCs) are undoubtedly 

present in tissues of these salmon. Should magnification and maternal transfer of these 

compounds also occur during spawning, toxicological impacts would affect returning adults 

and early life stage development. Unlike legacy pollutants such as PCBs and PCDD/PCDFs, 

many of these other current use chemicals of concern can be extensively discharged into 

urban/agricultural receiving waters such as the Fraser River. Future research should, 

therefore, focus on accumulation patterns and the cumulative and/or synergistic effects of 

PCBs, PCDD/PCDFs, and other EDCs of emerging concern on the reproductive health and 

population dynamics of Pacific salmon. 

Acquisition of polychlorinated biphenyls (PCBs) by Pacific chinook salmon: An exploration of 

various exposure scenarios (Hope 2012): 

Hope (2012) used models to examine 16 different scenarios to identify where Oregon State 

water quality standards in place for the protection of human health might be effective at 

reducing PCBs in adult fall Chinook salmon. Model scenarios assumed a 130-day juvenile 

residency in fresh water, 50-day juvenile residency in estuaries, and adult fall Chinook 

returning after three to four winters in the ocean (1,860 days). A simplified summary of what 

Hope (2012) applied includes a bioenergetics model and a bioaccumulation model with 

estimates of prey consumption rates to estimate contaminant levels in a given fish on a given 

day at a given location. The model scenarios assumed that prey of adult salmonids included 

20 to 60 percent herring, a substantial PCB source for adult Chinook. However, it was not 

clear if the various model scenarios took into account the region-specific differences in 
Page 26 July 20, 2012 Technical Issue Paper 

herring PCB burdens described by West et al. (2008). While acknowledging that interpreting 

models must be done with caution, Hope (2012) concludes that his model scenarios suggest a 

limited ability of the Oregon water quality standards to meet the expectation of reducing 

contaminant loadings in anadromous species (in this case fall Chinook). 

Marine distribution, life history traits, and the accumulation of polychlorinated biphenyls in 

Chinook salmon from Puget Sound, Washington (O’Neill and West 2009): 

One of the most important papers for understanding body burden accumulations of Chinook 

salmon in Puget Sound is O’Neill and West (2009). They focused on three primary 

objectives; (1) compare PCB levels from Puget Sound Chinook salmon with other West 

Coast populations, (2) evaluate whether PCB accumulation mainly occurred in the freshwater 

or marine habitats, and (3) quantify the relative importance of fish age, fish size (fork length), 

lipid content, and saltwater age (the number of winters spent in salt water) on PCB 

concentration. Maturing and subadult Chinook salmon were sampled in August and 

September from 1992 to 1996. Muscle samples (total of 204) were collected from 763 

individual Chinook. Only a portion of the fish sampled were of naturally spawning runs, with 

hatchery fish representing 98 percent of fish that migrated to salt water as yearlings (30 

percent of the total fish sampled). As a result, a comparison of PCB levels between hatchery 

and wild fish was not possible. An aroclor analysis of the tissues was the selected method. 

Though varying widely among samples, average concentration of PCBs measured in samples 

of skinless muscle tissue from subadult and maturing Puget Sound Chinook salmon was 53 

ng/g fish tissue, which was three to five times higher than average concentrations reported 

for adult Chinook salmon from six other populations on the West Coast of North America 

(Figure 4) (O’Neill and West 2009). Chinook samples collected in the south and central 

portions of Puget Sound had the highest average concentrations (Figure 5). Rivers in the 

northern portion of Puget Sound, while still averaging approximately 40 ng/g, had the lowest 

concentrations of the seven separate groups within the Puget Sound sampling area (Figure 5). 

Although the proportion of Chinook that are caught in Puget Sound relative to the other six 

regions was not represented, estimates have indicated that approximately 14.5 percent of the 

Oregon and Washington commercial Chinook landings were from Puget Sound, with TreatyIndian landings ranging from 72 to 95 percent of Puget Sound-caught Chinook salmon from 

1991 to 2005 (O’Neill 2006). It is important to note that these estimates do not include sportcaught Chinook. 

When comparing regions of body burden accumulation, the analysis of O’Neill and West 

(2009) indicated that, even in the most highly PCB-contaminated river draining into Puget 

Sound, the Duwamish River, the vast majority (>96 percent) of PCB accumulation occurred 

in the marine environment, with little freshwater contribution. They note that these findings 

are not surprising, given that Chinook salmon typically gain 99 percent of their total mass in 

marine habitats. They further estimated that yearling out-migrants (possibly stream-type fish) 

would acquire a similar percentage (>98.7 percent) of their total mass in marine habitats. 

O’Neill and West (2009) found wide variations in contaminant burden for Puget Sound 

Chinook, suggesting that behavioral differences varied considerably among individual Puget 

Sound Chinook salmon. Variation may be related to fish size, and diet shifts that occur with 

size. They suggest that two mechanisms appear to be at work here: (1) growth dilution of 
Technical Issue Paper July 20, 2012 Page 27 

PCB associated with the addition of weight accumulated by older fish, and (2) a reduction in 

dietary PCB inputs associated with feeding on cleaner prey resources offshore for these older 

Chinook. 

That the variation of contaminant burden within Puget Sound is region-specific is an 

indication that there may be minimal straying, or some geographic isolation that occurs, 

between north and south sound resident Chinook. Because the pelagic food web in Puget 

Sound is more heavily contaminated than that in the coastal waters (West et al. 2008), 

resident Puget Sound Chinook salmon, particularly those that occur within inner Puget Sound 

(an urbanized basin), experience a much more contaminated environment than non-resident 

populations. The urbanization of the inner Sound and the extended residence in these waters 

for Chinook originating from South Sound tributaries contributes to the findings that fish 

residing and feeding in central and southern Puget Sound probably would be exposed to 

higher PCB levels than fish feeding in northern areas of the sound. 

In an investigation of inland marine herring stocks, a substantial portion of subadult and adult 

Chinook salmon diets, West et al. (2008) found that Pacific herring from central Puget Sound 

are more highly contaminated with PCBs than those from northern Puget Sound and the 

southern Strait of Georgia. As a result, O’Neill and West (2009) conclude that the wide range 

of PCB levels observed for Puget Sound Chinook salmon reflects their degree of residency 

and distribution while feeding within the inland marine waters. Although the authors 

concluded that Puget Sound Chinook PCB burdens appear to be a function of duration of 

residency and distribution while feeding within the inland marine waters, they also stated that 

behavioral differences of individual fish with respect to diet, overwintering, and movement 

within the inland marine waters was not fully understood. 

As indicated by O’Neill et al. (2006) and Cullon et al. (2009), the body burden of Puget 

Sound salmonid populations has implications for populations utilizing these fish as a 

substantial portion of their diet. Although these studies focused on the effects salmonid body 

burdens would have on southern resident killer whale populations, the findings can be used 

as an indicator of health risks associated with the consumption of contaminated food 

resources from Puget Sound waters. 

 
Page 28 July 20, 2012 Technical Issue Paper 

Figure 4. Mean PCB concentration in 

Chinook salmon fillets 

Source: O’Neill and West 20091

Figure 5. Mean PCB concentration in 

adult Chinook salmon returning to 

Puget Sound (in-rivers versus marine 

waters) 

Source: O’Neill and West 2009 

Error bars represent standard error around the means. 

Persistent organic pollutants in Chinook salmon (Oncorhynchus tshawytscha); implications for 

resident killer whales of British Columbia and adjacent waters (Cullon et al. 2009): 

In a study designed to investigate the effects of contaminated food resources for Southern 

Resident Killer Whales, Cullon et al. (2009) measured POP concentrations in Chinook 

salmon (Oncorhynchus tshawytscha). A total of nine smolts and 24 adult Chinook were 

collected in 2000 and 2001 over an area ranging from Johnstone Strait to southern Puget 

Sound, at the Deschutes hatchery. Adult Chinook were collected from the central Strait of 

Georgia, whereas Washington fish were collected at the mouth of the Duwamish River and at 

a Deschutes River hatchery. Once collected, samples were prepared and analyzed for stable 

isotope analysis, contaminant analysis, and lipid determination. Scale analysis showed that 

all but three of the adult Chinook appeared to migrate to marine waters in their first year. 

 

1 Science Panel requested finding out what percentage of the total number of Chinook salmon consumed is represented by each of these 

seven regions. This information was requested from both authors of O’Neill and West (2009). Mr West suggests Ms. O’Neill is the most 

appropriate respondent. Ms. O’Neill is out of the country until approximately July 2012, but was able to respond in brief. She stated that this 

may be available with sufficient time to coordinate with the CTC, PFMC, and WDFW for the relevant publications, then create a summary. 
Technical Issue Paper July 20, 2012 

Table 1. Estimated body burdens of persistent organic pollutants in returning adult ChinooChinook smolts Source: Cullon et al. 2009 
Page 30 July 20, 2012 Technical Issue Paper 

Based on their analysis, Cullon et al. (2009) concluded that 97 to 99 percent of PCBs, 

PCDDs, PCDFs, dichlorodiphenyltrichloroethane (DDT), and hexachlorocyclohexane (HCH) 

in returning adult Chinook were acquired during their time at sea, not in fresh water or 

estuaries (Table 1). However, it is important to note that the sample size for this 

investigation, considering the large area investigated, was very limited. Additionally, 

although the samples originated from both hatchery and wild-caught fish, the study’s results 

did not differentiate between the two types (possibly due to limited sample size). An 

interesting finding was that even though they were found to have lower lipid concentrations, 

Chinook collected further south had higher POP concentrations than Chinook sampled in 

more northern areas. 

Thirty years of persistent bioaccumulative toxics in Puget Sound; Time trends of PCBs and 

PBDE flame retardants in three fish species (West and O’Neill 2007): 

West and O’Neill (2007) were interested in evaluating Puget Sound PCB tissue concentration 

trends in English sole, Pacific herring, and coho salmon. They combined, screened for 

comparable methodologies, and analyzed Puget Sound Assessment and Monitoring Program 

(PSAMP) data that had been collected over a 30-year period. As the needs of this issue paper 

are for salmonid accumulations, a review of the English sole is not presented. However, as 

herring are an important food resource for salmonids in Puget Sound, their summary is 

included. Data were regionally organized into North, Central, and South Puget Sound. The 

analysis of PCB concentrations in herring showed that northern Puget Sound fish had much 

lower concentrations than those in central and southern portions of the sound. Concentrations 

of PBDEs in Pacific herring were roughly one-half to one-third of their PCB concentrations, 

with concentrations from 2001 to 2006 of central Puget Sound herring ranging from 40 to 85 

ng/g wet wt., total PBDEs. The authors note that there was no apparent time trend in any 

stock, as early data were very limited. 

The summary review by West and O’Neill (2007) of historic data indicated that PCBs in 

muscle tissue of coho salmon in central Puget Sound decreased over time from over 200 ng/g 

wet weight in one composite sample from 1975 to 86 ng/g in 1987, and generally less than 50 

ng/g in the 1990s. Data were not presented for coho occurring in southern or northern 

portions of the sound. In comparison to coho, Pacific herring from central and southern Puget 

Sound stocks have remained nearly three times that of coho salmon from central Puget 

Sound. No species analyzed were found to have a reduction in PCBs from 1990 through 

2005. West and O’Neill (2007) hypothesized that the lack of a declining trend in PCBs over 

the past 15 years is the result of biotic recycling of PCBs through the food web. 

Spatial extent, magnitude, and patterns of persistent organochlorine pollutants in Pacific herring 

(Clupea pallasi) populations in Puget Sound (USA) and Strait of Georgia (Canada) (West et al. 

2008): 

West et al. (2008) investigated the geographic distribution and magnitude of three POPs in 

three Puget Sound populations and three Strait of Georgia populations of Pacific herring. 

Their summary on herring is included due to the herring’s importance as a food resource for 

selected species of adult salmonids. Methods included mid-water trawls from 1999 to 2004, 

collecting a total of 1,055 pre-spawn herring for all locations combined. They found Puget 

Sound herring were 3 to 9 times more contaminated with PCBs, and 1.5 to 2.5 times more 
Technical Issue Paper July 20, 2012 Page 31 

contaminated with DDTs, than Strait of Georgia herring (Figure 6). The authors concluded, 

considering the distinct differences between the populations, that the stocks appeared to be 

isolated from each other geographically, allowing for the environmental exposure to 

contaminants to be regionally expressed. Therefore, although herring represent a mobile 

source of POPs, they appear to stay regionally isolated. This is relevant to Puget Sound 

salmonid populations as heavily burdened Puget Sound herring are a notable source of 

bioavailable POPs in the Puget Sound food web, and their regional distribution may have a 

corresponding regional effect on their predators, including resident Puget Sound Chinook. 

Figure 6. Concentration of PCBs, DDTs, and hexachlorobenzene in six herring 

populations from Puget Sound and the Strait of Georgia 

Source: West et al. 2008 

III. Can salmonid contaminant body burden be 

attributed to a specific location? 

A central question related to site-specific consumption is: can a salmonid’s body burden be 

attributed to a location in which it occurs for a specific time in its life? 
Page 32 July 20, 2012 Technical Issue Paper 

The life history strategies of different salmon species, and runs within given salmon species, are 

highly variable. Life history variation between salmonids begins at a very early age. Slight 

differences occur between species due to the time it takes for a given egg to hatch, with prehatching duration differences affected by environmental conditions, as well as species-specific 

differences. In general, eggs take some number of weeks to hatch, and the alevins remain in the 

gravel for a few more weeks until they consume their yolk sac reserves. It is at emergence from 

the gravel where life history patterns begin to vary substantially between and within species. 

Some salmon, such as pink, chum, and ocean-type Chinook salmon, migrate downstream within 

the first few weeks, with some exceptions. Other species, such as stream-type Chinook, coho, 

and sockeye salmon and steelhead, remain in freshwater streams or rivers to rear for 1 to 3 years 

before migrating toward marine habitats. 

The differing behavior within species (e.g., stream-type vs. ocean-type Chinook) illustrates how 

difficult it is to make generalizations, even within a given salmonid species. Estuarine rearing is 

also highly variable between and within salmonids, with some species and types rearing for 

prolonged periods in these habitats, while others spend a few days to a few weeks during their 

shoreline out-migration. Salmonid food resources are also very different, which is likely a life 

history strategy that allows co-occurring species to partition the available resources and 

minimize direct competition. Some salmonids, both as juveniles and adults, use available 

planktonic food resources, some use epibenthic resources, while others as they grow larger are 

mainly piscivorous. Age at maturity varies between species; some species (pink salmon) reach 

maturity at age 2 with little variation. Other species are much more variable, reaching maturity at 

ages 3, 4, 5, or even 6 years of age (e.g., Chinook and chum). 

A few salmonids (Chinook, coho, and pink) that originate from Puget Sound show some form of 

residency behavior (Laufle et al. 1986; Duffy 2003, 2009; Duffy et al. 2005). All or portions of 

these runs and/or stocks remain in Puget Sound waters for rearing and maturing, never migrating 

to coastal or open-ocean waters. However, likely because their residency forms are less abundant 

than their ocean-going forms, much less is known about possible resident coho and pink salmon 

than resident Puget Sound Chinook. While non-resident Chinook may gain as much as 98 

percent of their total weight while in the ocean (Quinn 2005), resident Chinook complete their 

entire life from egg to returning adult in their natal stream and Puget Sound. Therefore, body 

burden accumulation for resident Chinook salmon may be an indicator of environmental 

conditions within Puget Sound. 

Due to widely varying life histories, most notably the regions where salmonids occur and their 

dietary preferences, it is not appropriate to group all salmonids into a single category to serve as 

site-specific indicators for contaminants. In fact, as a number of authors indicate, almost all 

salmonids accumulate the vast majority of their body burden at sea; accumulation at juvenile life 

stages in freshwater and estuarine habitats contributes a very limited proportion of the total 

accumulation. There is some regional potential, however, for resident Puget Sound Chinook 

salmon. 

It is not surprising that O’Neill and West (2009) found greater than 96 percent of PCB 

accumulation in Puget Sound Chinook occurred in marine habitats. Even more noteworthy, when 

taking into account the life history of these fish, is the finding of O’Neill and West (2009) that 

Puget Sound Chinook have three to five times higher PCB concentrations than those of other 

west coast populations. Considering that the majority of salmonids originating in Puget Sound 
Technical Issue Paper July 20, 2012 Page 33 

are ocean-type, meaning they rear only for a short time in fresh water before migrating to 

estuarine and marine habitats, the total mass of a returning resident adult Chinook is primarily 

obtained in Puget Sound marine habitats. In addition, Puget Sound Chinook return to their natal 

streams to spawn having spent fewer years in marine habitats than some Chinook populations 

elsewhere. Therefore, Puget Sound resident Chinook salmon spend less time accumulating 

contaminants than many other populations, yet have a higher total body burden. 

Another factor potentially relevant to this topic, briefly mentioned by a few authors but not 

investigated in detail, is the lack of understanding of whether there was a threshold response 

effect on juvenile salmonids exposed to contaminants while in freshwater and estuarine habitats. 

It is possible that the subadult and adult salmonids sampled for body burden analysis were those 

fish that did not experience behavioral and physiological abnormalities, post-exposure, that 

would have reduced their survival to adulthood. In other words, subadult and adult fish sampled 

may not be entirely representative of the naturally occurring juvenile population. 

O’Neill and West (2009) showed that there is regional variation within Puget Sound waters and 

resident Chinook in more urbanized waters have greater body burdens. These findings suggest 

that a relationship does exist between contaminants and body burden in these fish. Nonetheless, 

due to their transient nature, these fish will probably not be able to serve as site-specific 

indicators. However, a more complete understanding of their duration of residency and 

distribution while feeding within specific regions of the inland marine waters may enable 

resident Puget Sound Chinook to serve as region-specific indicators in the future. 

 
Page 34 July 20, 2012 Technical Issue Paper 

Summary 

A review of the literature on northeast Pacific Ocean salmon body burden accumulation found 

that there were very few investigations of the origin of steelhead body burden and contaminants 

compared to other salmonids. However, given that steelhead can live many more seasons in 

marine environments than other co-occurring salmonids, with multiple freshwater entries for 

spawning, it would stand to reason that steelhead may have an even higher body burden 

accumulation than these other species. Although other salmonids along the west coast and in 

Puget Sound have lower body burden concentrations of contaminants, Puget Sound Chinook 

salmon have elevated PCB levels that appear to correlate with specific regions within Puget 

Sound. Nearly 22 percent of the maturing and subadult Chinook salmon samples collected from 

Puget Sound by Meador et al. (2002) had PCB concentrations above an effects threshold 

identified for salmonid fishes (i.e., 2,400 ng/g lipids), which included endpoints such as reduced 

growth, altered enzyme and hormone levels, and increased mortality. 

O’Neill and West (2009) summarized that the most contaminated Puget Sound Chinook salmon 

in their investigation, believed to be Puget Sound residents, had concentrations comparable to 

Baltic Sea Atlantic salmon. Only Great Lakes salmon had higher concentrations of PCBs in 

North America, where Chinook salmon and coho salmon populations in the early 1990s were 20 

to 30 times more contaminated with PCBs than the Puget Sound Chinook salmon investigated by 

O’Neill and West (2009). It is alarming that Puget Sound Chinook spend fewer years in marine 

habitats than many other salmonids, have a lower fat content in which lipophilic contaminants 

can be stored than spring-run Chinook, yet have much higher body burdens of PCB 

contaminants. These observations suggest that the food web within Puget Sound has a much 

higher concentration of PCBs than other rivers and estuaries in this region. 

To understand where, when, and how salmonids accumulate their body burden, it is important to 

first note their life history, summarized in Section I, Salmon Life History. Regional occurrence is 

important: where do salmon occur over what portion of their life, and what are they doing in a 

given region that contributes to contaminant uptake (principally, what are the salmon eating and 

where are these prey residing (i.e., getting their exposure)?). While there are many differences 

between salmonids originating from Washington State streams and rivers, salmonid diet and 

where subadults/adults occur while they are maturing appear to be the most important factors. 

The dietary resource of a maturing salmon when it is maximizing growth (by mass) appears to be 

the principal factor for its eventual total body burden. That does not mean that salmonids do not 

accumulate toxins as fry or smolts, as various authors have shown this occurs. However, relative 

to the total body burden by the time a salmon reaches a harvestable size, juvenile contaminant 

uptake does not appear to be a significant factor. 

Salmonid diet is important to consider when studying the uptake of contaminants because some 

salmonids prey on food resources higher up the food chain than others, increasing the total 

biomagnification. For example, a large portion of the pink and sockeye salmon diet is composed 

of planktonic invertebrates. By the time these short-lived prey become food resources, they have 

not lived long enough, or consumed a sufficient number of other prey items, to increase their 

potential for toxic loads. However, the larger species, notably coho and Chinook, will consume 

prey items higher on the food chain (e.g., Osmeridae and Clupeidae), increasing their exposure 
Technical Issue Paper July 20, 2012 Page 35 

risk. Maturing Chinook salmon, more than any other salmonid, is the most piscivorous. The diet 

of a subadult or adult Chinook salmon includes a substantial amount of fish species, herring 

(planktivores) in particular. Feeding higher on the food chain may take advantage of a higher 

caloric resource, but it also means prey items have lived longer (2 to 3 years) and consumed 

more organisms. As a result, prey resources such as herring have been exposed to more 

contaminants and have an elevated body burden (West et al. 2008). For those salmonids preying 

on herring stocks in Puget Sound and the Strait of Georgia, the volume and origin of their food 

resources exposes them to the highest risk. 

Studies have shown that the region in which a salmonid occurs during its growth from juvenile to 

subadult to adult is the most important factor for origin of contaminants in a given fish. For those 

salmonids that mature at sea, at least 96 percent of their POP body burden has been described as 

originating from oceanic waters. Studies have also shown that salmonids with the greatest burden 

are those that mature in polluted waters. Although some very small numbers of coho and pink 

salmon may not migrate to oceanic waters, the stock of greatest note is the resident Puget Sound 

Chinook. A number of authors showed that tissue analysis of this stock has a much higher body 

burden than ocean-migrating stocks. In addition, resident Puget Sound Chinook originating from 

southern Puget Sound tributaries have greater burdens than those to the north. 

As noted above in Section III, the life histories of salmonids are too variable between and within 

species and the habitats they utilize to be used for site-specific evaluation. Ocean-maturing fish 

accumulate the vast majority of their body burden while at sea. However, for resident Puget 

Sound Chinook there does appear to be a correlation between salmon body burden and region of 

occurrence within the inland marine waters. Though the life history of these fish does not make 

them ideal candidates to serve as site-specific indicators, further understanding of their regionspecific differences and origin of burden may enable them to serve as region-specific indicators 

in the near future. 

 
Page 36 July 20, 2012 Technical Issue Paper 

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