|The U.S. Environmental Protection Agency (USEPA) and the Columbia River Inter-tribal Fish Commission (CRITFC) and its member tribes (The Confederated Tribes of the Warm Springs Reservation of Oregon, The Confederated Tribes and Bands of the Yakama Nation, The Confederated Tribes of the Umatilla Indian Reservation, The Nez Perce Tribe) have completed a preliminary survey of toxic chemicals in fish from the Columbia River Basin. The samples were collected from those portions of the Columbia River Basin affected by tribal fishing in Washington, Oregon, and Idaho. |
The survey was designed to answer the following questions:
This survey provides data on those chemicals which are most likely to be accumulated in fish tissue and therefore pose the greatest risks to people. These are the chemicals for which regulatory strategies need to be defined to eliminate or reduce these chemicals in our environment. These results of this survey can be used to design future investigations of chemical sources and the effects of these chemicals on the fishery resources in the basin.
- Are fish from the Columbia River Basin contaminated with toxic chemicals?
- Are there differences in chemical concentrations among fish species and study sites within the basin and other locations throughout the United States?
- Are there potential human health risks from consumption of contaminated fish?
Fish tissue chemical concentrations
The tribal fish consumption patterns defined the types of fish that were collected including whole body and fillet fish tissue from resident and anadromous species and a few egg samples from anadromous species. The anadromous species were: fall and spring chinook salmon, steelhead trout, smelt, and Pacific lamprey. The resident species were: rainbow trout, mountain whitefish, white sturgeon, walleye, largescale sucker, and bridgelip sucker.
Two hundred eight fish samples were collected at 24 sites1 in the basin from July 1996 through December 1997. The results of the fish contaminant survey showed that of the 131 chemicals analyzed 92 were detected in fish tissue.
The concentrations of pesticides were higher in the resident species especially mountain whitefish, white sturgeon, largescale sucker, and whole body walleye than in the rainbow trout, walleye fillet samples than the anadromous fish species. Of the anadromous fish species Pacific lamprey had higher levels of PCBs. The high levels of organic chemicals in whole body walleye and Pacific lamprey appeared to be associated with high amount of fat in these fish types since PCBs and pesticides are readily absorbed by fats. Of the inorganic chemicals measured in fish tissue, zinc was at the highest concentration in all species tested. Zinc is a natural element which occurs at high levels in soils and water. There was no consistent pattern in chemical concentrations across locations.
The chemical concentrations in fish species measured in this survey were compared with fish from other water bodies across the United States and to other food types. The levels we observed in fish from the Columbia River Basin were generally lower than levels reported in the literature from the early 1970s and similar to levels reported in the late 1980s to the present. We also found numerous studies in the literature that documented the presence of toxic chemicals in all types of food as well as fish.
Estimating risks to human health
Risk assessment is a tool which is used to explain what the presence of chemicals in fish mean to the people who eat the fish. The exposure to chemicals in fish depends upon the chemical concentration in the fish tissue, the amount and types of fish eaten, how long and how often fish is eaten, and the body weight of the person eating the fish. For this assessment, exposures to chemicals were estimated for both adults and children of the CRITFC = s member tribes and the general population. In estimating these exposures, it was assumed that a person eats the same type of fish for their lifetime.
Salmon, steelhead trout, smelt and rainbow trout had the lowest levels of chemical contaminants so the risks from consuming these fish were lower than the risks from consuming species which had higher levels of contamination, such as white sturgeon, largescale sucker, and mountain whitefish.
Non-cancer health effects
As fish consumption rates increase, so does the possibility of non-cancer health effects, such as impacts on the immune system, on development, and on the liver. These effects are due primarily to the concentrations of PCBs, DDE, and mercury in fish.
Adults and children in CRITFC's member tribes who consume fish at the highest consumption rates used in this survey (48 meals per month for adults and 20 meals per month for children) have the highest potential for non-cancer effects.
Read the Report Here
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Entire Document (PDF, 820 Kb 284 pp)
Table of Contents, etc (PDF, 47 Kb, 28 pp)
List of Tables and Figures
List of Abbreviations, Acronymns and Units
Executive Summary (PDF, 45 Kb, 9 pp)
Parts 1 & 2 (PDF, 154 Kb, 50 pp)
Fish Tissue Chemical Concentrations
Parts 3, 4 & 5 (PDF, 185 Kb, 33 pp)
Human Health Risk Assessment
Part 6 (PDF, 202 Kb, 68 pp)
Part 7 & 8 (PDF, 74 Kb, 21 pp)
Lead Risk Assessment
Part 9 & 10 (PDF, 143 Kb, 56 pp)
Comparisons of Fish Tissue Chemical Concentrations
Part 11 & 12 (PDF, 48 Kb, 19 pp)
The estimated cancer risks were highest for the more contaminated resident species (e.g., mountain whitefish, white sturgeon, and large-scale sucker) and increased as consumption of fish increased. Adults in CRITFC = s member tribes who eat fish for 70 years at the high ingestion rate (48 meals per month) may have cancer risks that are up to 50 times higher than those for the general public who consume fish about once a month.
These cancer risks are due primarily to exposures to PCBs, dioxins, and furans in all fish species. DDE was an additional contributor to cancer risk in resident species; arsenic in the anadromous species.
The health effects predicted in this survey are based on a limited number of samples from a large geographic area. The health departments of Washington and Oregon have done extensive investigations of chemicals in fish tissue in several specific areas throughout the Columbia Basin. The health departments have issued fish consumption advisories for several of these areas. The results of our survey confirm the need for caution when eating certain fish from these areas.
There are many uncertainties in this risk assessment which could result in alternate estimates of risk. These uncertainties include our limited knowledge of the mechanisms which cause disease, the variability of contaminants in fish, changes in fish tissue concentrations over time and locations, ingestion rates, and the effects of food preparation.
Reduction of chemicals in our environment
Reducing dietary exposure through cooking or by eating a variety of fish will not eliminate these chemicals from the environment. It is the goal of the USEPA and other regulatory agencies to reduce or eliminate toxic chemicals from our environment. This survey helps to focus these efforts on particular chemicals such as PCBs, DDE, dioxins, furans, mercury, arsenic.
- USEPA Contacts:
- Dana Davoli - (206) 553-2135
- CRITFC Contact:
- Charles Hudson (503) 238-0667
1 The fishing sites were located in the following rivers: Clearwater River, Snake River, mainstem Columbia River (lower Columbia below Bonneville, Bonneville pool, Dalles Pool, John Day Pool, Hanford Reach), Klickitat River, Deschutes River, Grande Ronde River, Fifteen Mile Creek, Umatilla River, Wenatchee River, Willamette River, and Yakima River.
Recommendations for eating fish
|The U.S. EPA recommends that people follow the general advice provided by the health departments for preparing and cooking fish:
- Remove fat and skin before cooking
- While cooking, allow fat and oil to drain
- Watch for Fish Advisories
These preparation and cooking methods should help to reduce exposures to PCBs, DDTs, dioxins, and furans, and other organics which accumulate in the fatty tissues of fish.
Note: It is also important to consider the health benefits of eating fish. While fish accumulate chemicals from the environment they are also an excellent source of protein that is low in saturated fats, rich in vitamin D and omega-3 fatty acids, as well as other nutrients.