Friday, October 18, 2002 - 12:42 a.m. Pacific
High levels of pesticide DDT found
in Lake Chelan trout
By Craig Welch
Seattle Times staff reporter
A spot check by the Environmental
Protection Agency has found lake
trout from the crystalline waters of
Lake Chelan containing high
concentrations of DDT, enough to
concern state officials who say they
need more tests to gauge the
public-health risk.
Of 143 lakes randomly checked
nationwide by the EPA, Lake
Chelan's DDT levels were the
highest. But diagnosing the extent of
the problem, and determining
whether the public should be warned
about eating fish, will be difficult.
Not only is the lake huge — more
than 50 miles long and 1,500 feet
deep — but public-health officials
contend there's little concrete
knowledge about the risks of adults
eating fish laced with trace amounts
of DDT, a pesticide banned in 1972,
the same year Congress passed the
Clean Water Act.
Further, the kind of water-quality
tests done by state and federal
biologists are not comprehensive enough to determine whether it is
safe to regularly eat the fish over a lifetime. For that, biologists
need extensive tissue samples, a costly, time-intensive job that
often doesn't get funded.
"Right now we have little detailed data from around the state, either
from water bodies or from fish," said Dave McBride, state
Department of Health toxicologist. "People could be consuming fish
that are unsafe that we just don't know about. But we don't want to
scare people away from fish because it's a great source of
protein."
Even so, the EPA survey, given to the Department of Health in late
August, raised a red flag, McBride said.
"We don't consider it a grave emergency, but it's definitely
something we have to look at."
DDT's toxic legacy
The use of DDT was so widespread for so long, health officials
presume traces are in much of our food. In high concentrations, it is
a probable carcinogen, and can affect immune-, liver- and
nervous-system function.
But there's limited information about long-term exposure to the kind
of low doses sometimes associated with fish.
DDT came into widespread use in the late 1940s, and was applied
often to Washington orchards until the mid-1960s primarily to fight
infestations of coddling moths. Though it was banned in the United
States, it's still used elsewhere in the world.
DDT rarely binds to water. Instead, it attaches to sediment and has
leached into many Eastern Washington streambeds, from Mission
Creek near the Wenatchee River to the Okanogan River. In the
1980s, DDT was one of the most commonly found pollutants in
waterways nationwide.
A persistent poison that can remain toxic for decades, it gets
sucked up by small organisms and passed to larger ones. It builds
up and concentrates in fat tissue, particularly in bigger, older fish.
DDT also has been found in Lake Chelan kokanee eggs, which led
state officials to believe it can be passed to offspring. DDT gained
national attention for thinning the eggshells of eagles that ate
severely contaminated fish.
"You get this magnifying effect on up the food chain," said Randy
Coots, a state Department of Ecology water-quality specialist.
In the lower Yakima River, health officials conducted years of study,
including fish-consumption surveys and sampling. They determined
lactating women eating highly fatty fish could pass DDT on to
infants through breast milk. Because some Native American and
immigrant populations subsisted on Yakima River bottom fish,
health officials urged limiting consumption to one bottom fish per
week.
Lake Chelan is another matter.
State water-quality regulators at Department of Ecology knew 15
years ago residue from the long-lasting insecticide had
accumulated in a few bottom-feeders, such as sucker fish, as well
as in rainbow trout and land-locked kokanee near some drainages.
But state health officials said they were unaware of the years of
DDT-laden fish samples taken from Lake Chelan until this summer,
when the latest findings from EPA were obtained.
Now, "we need to definitely address this," McBride said.
Limitations to the EPA study
In 2000, the EPA, as part of a four-year national snapshot of
contaminated fish, took samples from Lake Chelan and four other
randomly selected Washington lakes. It captured just five lake trout
near the mouth of Stink Creek, near Wapato Point, blended the
edible portions, and tested for toxins. The results: DDT registered
1,481 parts per billion — almost 50 times higher than the federal
health criteria of 32 parts per billion, criteria based on assumptions
about how much fish people eat over a lifetime. But EPA officials
cautioned against reading too much into their limited findings.
EPA toxicologist Pat Cirone said the sample size was too small to
infer anything about the rest of the lake. The fish also were taken
near Stink Creek, which is known to have historically leached
pesticides into the lake.
As for Chelan's No. 1 ranking in the survey, there are DDT-polluted
waterways all over the country, including Eastern Washington, and
some likely have higher concentrations — they simply weren't
tested as part of the 2000 survey, said EPA's Lillian Herger, who
coordinated the study in the Northwest. "It sounds dire, but it's of
limited value."
Still, state regulators had hoped clean sediments by now would
have done more to dilute and cap the DDT-contaminated lake
bottom, and it would slowly be working out of the food chain.
"It was alarming to me — I have no problem saying that," said the
Department of Ecology's Dave Schneider, who works with the Lake
Chelan Water Quality Committee. "We're very concerned. To find
those numbers are still that high — that's significant."
It was also the first time he could recall DDT being found in lake
trout, a popular sport fish people frequently catch and eat.
Last year, angler John Hossack caught a state-record 35-pound
lake trout there. Hossack estimated he's caught 250 or more fish in
the lake over the past 10 years and, "except for my big one, I've
eaten everything we've ever caught," he said.
But while anglers may take dozens of trout each year, health
officials know little about who eats which fish — and how much.
There's even less information about how — or whether — trace
DDT at chronic low levels affects adults.
"For a lot of chemicals, studies looked only at the most sensitive
populations," McBride said. "It might be that adults can tolerate it at
those levels. We don't know."
More problematic: Until more sampling is done, it's not clear how
far the DDT contamination extends beyond the Stink Creek
drainage, or if runoff elsewhere may have carried the pesticide into
the lake.
To gauge how widespread the contamination might be, McBride
said, health officials would need samples of some 500 fish — at a
cost of $1,000 per fish or more.
Coots, with the Department of Ecology, already is putting together
a plan to sample more fish next summer.
In the meantime, health officials have said anyone concerned could
follow guidelines issued for the lower Yakima when eating fish
caught near Stink Creek. Those guidelines urge people to avoid
eating more than one bottom fish a week, to not eat the skin, and to
barbecue or broil fish.
Craig Welch: 206-464-2093 or cwelch@seattletimes.com.
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