Draft Report Details Toxic Chemicals in Basin Fishby CBB, Columbia Basin Bulletin - February 15, 2002
A Columbia River Basin Fish Contaminant Survey that suggests Native Americans are at greater risk than the general public is cause for concern, but not alarm, a spokesman for the Columbia River Inter-Tribal Fish Commission said this week.
The U.S. Environmental Protection Agency, CRITFC and its member tribes completed a preliminary survey of toxic chemicals in fish from the Columbia River Basin and released a draft report Feb. 8.
The survey findings address fish tissue chemical concentrations, fish consumption patterns and risk to health of Native Americans.
Salmon, steelhead trout, smelt and rainbow trout had the lowest levels of chemical contaminants so the risks for consuming these fish were lower than the risks from consuming species which had higher levels of contamination, such as white sturgeon, large-scale sucker and mountain whitefish.
"It is important that people understand what the study was designed to do and what it wasn't designed to do," said Charles Hudson at CRITFC.
The survey was designed to answer three questions:
Hudson said the survey is a "snapshot" of today's environmental circumstances.
"What it doesn't do is calculate risk to past and future generations," Hudson said. "It does not calculate rates of disease in individuals, it does not identify the sources of contaminants and it is not a study of fish health.
"Certainly we have levels of contaminants, but the study does not conclude whether the fish themselves are healthy or not. It also does not analyze multiple exposure of chemicals from sources other than fish.
"Do we have a level of contaminants? Yes, and there is a health risk, but again, the survey was not intended to specify those health risks. It's not so simple that we can ask 'Are fish safe to eat?' The study wasn't designed to give us that answer."
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 types of fish surveyed include fall and spring chinook salmon, steelhead trout, smelt and Pacific lamprey. Resident species include rainbow trout, mountain whitefish, white sturgeon, walleye, large-scale sucker and bridgelip sucker.
A total of 280 fish samples were collected at 24 sites in the basin from July 1996 through December 1997.
The "usual and accustomed" fishing sites included the Clearwater River, Snake River, mainstem Columbia River (lower Columbia below Bonneville, Bonneville pool, Dalles pool, John Day pool and Hanford Reach), Klickitat River, Deschutes River, Grande Ronde Rver, Fifteen Mile Creek, Umatilla River, Wenatchee River, Willamette River and Yakima River.
The results of the survey showed that of 131 chemicals analyzed, 92 were detected in fish tissue. The concentrations of pesticides were higher in the resident species, especially mountain whitefish, white sturgeon, large-scale sucker and whole body walleye than in the rainbow trout, walleye fillet samples and the anadromous fish species.
Of the anadromous fish species, Pacific Lampreys had higher levels of PCBs (polychlorinated byphenyls, which have been used, among other things, to insulate and cool electrical equipment, such as transformers). 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, according to the draft survey.
Of the inorganic chemicals measured in fish tissue, zinc was at the highest concentration in all species tested. Zinc is a natural element that occurs at high levels in soils and water. The survey indicated there was no consistent pattern in chemical concentrations across locations.
The chemical concentrations in fish species measured in the survey were compared with fish from other water bodies across the United States and to other food types. The levels observed in the Columbia River Basin survey were "generally lower" than levels reported in the late 1980s to the present. The survey also found numerous studies that documented the presence of toxic chemicals in all types of food, as well as fish.
Hudson said staffs and governments from the CRITFC tribes (The Confederated Tribes of the Umatilla Indian Reservation, the Confederated Tribes of the Warm Springs Reservation of Oregon, the Confederated Tribes and Bands of the Yakama Nation and the Nez Perce Tribe) will need to carefully study the data and speak directly to respective tribal members.
"The tribes need to take this home and look at it and we know they will," Hudson said. "We suspect we'll be asked to participate in the next step, which probably will be to prepare a tribal-specific study."
This survey, Hudson said, prompts a number of issues, including the source of contaminants, at what life stage the fish are exposed, and to research the link between contaminants and fish health.
It may be difficult, Hudson said, to explain the study to tribal members.
"The study was of collective samples from different locations and it appears there was more emphasis on the mainstem than tributaries," he said. "In that sense, the study stands a bit apart from other similar studies on contaminants that were tributary specific."
The exposure to chemicals in fish depends on 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, the survey said. For this assessment, exposures to chemicals were estimated for both adults and children of 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.
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, according to the survey. These effects are due primarily to the concentrations of PCBs, DDE (an environmental breakdown product of the pesticide known as DDT) and mercury in fish. Adults and children in CRITFC's member tribes who consume fish at the highest consumption rates used in the survey (48 meals per month for adults and 20 meals per month for children) have the highest potential for non-cancer effects.
The estimated cancer risks were highest for the more contaminated resident species (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," the survey states.
The cancer risks are due primarily to exposures to PCBs, dioxins (umbrella name for a class of 75 chemical compounds that contain carbon, hydrogen, oxygen and chlorine - an unavoidable by-product in a variety of different processes including chemical manufacturing, incineration of municipal garbage, refining some metals, burning leaded gas in automobiles and the manufacture of paper products), and furans (organic chemicals with similar toxicological effects as dioxins) in all fish species. DDE was an additional contributor to cancer risk in resident fish; arsenic in the anadromous species.
The health effects predicted in the 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 and the results of the EPA/CRITFC survey "confirm the need for caution when eating certain fish from these areas."
Hudson said, however, that eliminating fish from the Native American diet would be an "unacceptable outcome and an undesirable temporary fix as well."
The survey indicates there are many uncertainties in its risk assessment that could result in alternative estimates of risk. The uncertainties include a limited knowledge of the mechanisms that 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.
Reducing dietary exposure through cooking or by eating a variety of fish will not eliminate these chemicals from the environment, the survey said.
"It is the goal of the EPA 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 and arsenic," the survey said.
Hudson said he suspects there may be some political "exploitation" of the data.
"That would be unfortunate," he said. "The tribes and general public can benefit from this study. It would be reprehensible to misrepresent the data. This information is too sensitive to allow that kind of exploitation to happen."
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