State investigators go fishing for leads on mercury's menace
Seattle Times staff reporter
This reconnaissance work in the chest-high lake grass is a crucial link in a national effort to gauge how pervasive and dangerous the poisonous metal is to human health.
Many of Washington's fresh and salt waterways have yet to be tested, but some that have been checked show mercury at troubling concentrations.
"We've sort of been in a cocoon of ignorance," said Karl Mueller, a state Department of Fish and Wildlife biologist who helped test Bellingham-area lakes. "Low and behold, when we looked for it, there it was."
Mercury can damage human brains, nervous systems, kidneys and lungs, particularly in children, perhaps even at low levels of exposure. A new study for the first time showed some U.S. residents who ate lots of fish — even from the grocery store — carried more of the poison than is considered safe.
Sources of mercury are as common as thermometers and fluorescent lights, diesel fuel and coal-plant emissions. It's found in tooth fillings and old car batteries. It's frequently disposed of in ways that allow it to get into the air or water. In Washington, a handful of industries legally pumped nearly two tons of mercury into the air in 2000, and fuel emissions — from jet fuel to diesel — may have contributed another 750 pounds.
The state Department of Ecology is considering a mammoth undertaking: phasing out the use of most mercury in Washington. But even as it moves to reduce mercury at its source, officials only now are checking to see how widespread the problem is.
Investigators are testing bass, a frequently eaten game species likely to accumulate the toxin, in 20 Washington waterways from Olympia to Spokane. It's the first time fish in those lakes and rivers have been given more than a cursory look.
"We may have missed it because we've not really focused on it," said Dave Serdar, an environmental specialist with the Ecology Department.
In 1999, a Centers for Disease Control and Prevention survey estimated 10 percent of adult women had blood-mercury levels higher than the Environmental Protection Agency considers safe. And a National Academy of Sciences study in 2000 estimated that 60,000 U.S. infants a year face increased risk of brain damage because their pregnant mothers had elevated mercury levels.
Last year, the Food and Drug Administration (FDA) warned pregnant women and women of childbearing age to steer clear of shark, swordfish, mackerel and tilefish. Washington's state Department of Health last year urged those women to eat no more than a single tin of tuna a week.
Just last week, a study by a San Francisco internist concluded that 89 percent of 116 of her patients who ate more than two servings of fish a week had more mercury in their bodies than federal scientists consider safe. More than half had blood-mercury levels double what's recommended, and nearly a quarter had mercury levels four times too high.
"A few were eating within the FDA's current guidelines and still had high mercury," said Dr. Jane Hightower, whose research is scheduled to be published next month in the National Institutes of Health journal, Environmental Health Perspectives.
EPA scientists acknowledge no one has studied the true extent or impact of mercury exposure among adults who eat lots of fish.
When scientists looked at children in two other countries who had been exposed to low levels of mercury, the conclusions were contradictory.
Further, experts still debate how best to balance the nutritional value of eating fish against a risk of mercury contamination. No one says don't eat fish, though some, such as Hightower, recommend picking fish less likely to contain mercury, such as sardines, wild salmon and haddock.
"Methylmercury is toxic to anybody if you give them enough, and it doesn't take very much," said Robert Goyer, who chaired the National Academy of Sciences study. "But it's unlikely that amounts in fish are going to produce any measurable effects in men, or in women outside the childbearing age."
But Hightower said she has treated dozens of adults with elevated blood-mercury levels who complained of similar symptoms — memory and hair loss, aching joints, exhaustion.
"The government cannot tell you at what levels methylmercury causes a problem," Hightower said. "We just don't know."
From 1993 to 2001, there was a 115 percent increase in the number of rivers and lakes where warnings about eating fish have been issued because of mercury contamination. The number of states issuing such warnings jumped to 44 from 27.
Methylmercury, the common, and most toxic, form found in fish, has accumulated in long-lived Puget Sound species, such as rockfish, and at lower levels in chinook salmon. Levels in fish in contaminated areas, such as Sinclair Inlet near Bremerton or Eagle Harbor on Bainbridge Island, can be four times higher than in nonurban settings such as the San Juans.
Following an accidental discovery, the state last year analyzed 273 fish in Lake Whatcom, Bellingham's drinking-water source. They found mercury in smallmouth bass often was higher than FDA limits for fish sold in stores. Officials await final results of tests from nearby Whatcom County lakes.
Mercury occurs naturally, bound in rocks and soils, and it can be released into the air by volcanoes. But the EPA contends industrialization has boosted mercury in the environment up to 500 percent since 1890, through mining, manufacturing, incineration and coal-power.
When deposited in water or sediments, mercury changes to methylmercury, which gets eaten by aquatic species and works its way through the food chain. The larger and older the fish, the more likely it is to have high mercury.
The hazards of mercury are not new. In the 1950s, near Minamata Bay, Japan, thousands of people were sickened and some died after eating seafood severely contaminated by mercury-polluted wastewater. Children born during that period suffered from brain damage similar to cerebral palsy. In the 1970s, hundreds of Iraqis died after wheat grain treated with mercury fungicide was ground into flour and made into bread.
While those incidents are certainly different than the kind of low-level chronic exposure U.S. residents can get from eating the wrong fish, they were the only major human studies available until recently.
In the 1990s, conflicting studies from the Faroe Islands off Denmark and the Indian Ocean's Seychelles Islands gave scientists pause. Some results showed subtle developmental delays and reduced intelligence-test scores in children born to mothers who ate mildly tainted fish.
The Seychelles study, on the other hand, found no health problems during fetal development attributed to mercury exposure at levels higher than U.S. law allows. That led some to conclude the benefits of a fish-rich diet may have canceled out negative effects of mercury.
The impacts of mercury aren't limited to humans. In Minamata Bay, before the extent of the poisoning became known, human health problems first came to light after people saw cats stumbling and falling into the sea and birds plummeting from the sky after eating contaminated fish.
Washington state biologists also have documented mercury-tainted fish with behavior problems, reduced immune responses and impaired gonads, which could affect reproduction.
"We've seen reduced foraging ability, reduced prey-capturing ability," said Mueller, the Department of Fish and Wildlife biologist. "Conversely, they are more susceptible to predation because they might not be on the ball — just not quick on their fins."
Still, exposure standards vary agency by agency. The FDA issues "action alerts" for fish containing more than 1 part per million methylmercury — about average for rockfish in Sinclair Inlet. The World Health Organization's limit is higher. The EPA's is four times more strict.
In Washington, 30 sections of 10 bodies of water — from several areas of Puget Sound to Lake Roosevelt — exceed water-quality standards for mercury. But fish advisories exist in only a half-dozen waterways because health officials make their determination on a case-by-case basis. Officials admit the results appear contradictory and confusing; they are rewriting rules governing how they're issued.
At Moses Lake on a cool October evening, Steve Fischnaller pilots an aging 16-foot aluminum skiff around a bend. Two metal bars hang from the boat bow like crooked arms, dangling electric anodes into the water. Johnson steps on a pedal and hundreds of shocked, tiny fry rise to the surface.
Having already taken sediment samples from the lake, the two men are now electrofishing, seeking 10 good-sized bass, a fish that's high on the food chain, widely distributed and accumulates mercury easily. If Fischnaller's findings trigger alarms, scientists will return for additional studies.
Seven hours after hitting the water, the men have what they need. They bonk the fish with a wooden baton and steer the boat to shore.
The next day they're off to lakes outside Spokane and then to the Okanogan highlands. Results from their tests are expected next year.
Craig Welch: 206-464-2093 or firstname.lastname@example.org.