Toxic
mercury contaminating more species, report shows
Jane
Kay, Chronicle Environment Writer Wednesday, September 20, 2006
Mercury pollution from power plants
and other industrial sources has accumulated in birds, mammals and reptiles
across the country, and only cuts in emissions can curtail the contamination,
says a report released Tuesday by a national environmental group.
The
report is the first major compilation of studies investigating mercury buildup in such
wildlife as California clapper rails, Maine's bald eagles, Canadian loons and
Florida panthers. In all, scientists working with the National Wildlife
Federation found 65 studies showing troublesome mercury levels in 40 species.
"From
songbirds to alligators, turtles to bats, eagles to polar bears, mercury is accumulating in
nearly every link of the food chain,'' said Catherine Bowes, an author of the
report who manages the federation's mercury program in the
northeastern states.
High
mercury levels in popular fish such as swordfish and canned albacore tuna
prompted government health warnings in 2004 aimed at pregnant women and
children. Mercury is a neurotoxin that can damage fetuses and cause mental
retardation, learning disabilities, cerebral palsy, blindness and deafness.
The
contamination also can kill or harm wildlife. According to the study:
--
Common loons stopping at Walker Lake in Nevada on their way to Saskatchewan
have been contaminated with mercury lingering from past gold mining operations.
--
At least one endangered Florida panther has died from mercury poisoning, probably from
consuming raccoons with high mercury levels.
--
Western and Clarke's grebes in Clearlake (Lake County) have shown altered
hormone levels because of mercury poisoning.
--
River otters in New York, Maine, Vermont, Massachusetts and Nova Scotia have
elevated levels of mercury and in some places are showing such
neurological effects as difficulty in walking. One otter died from mercury poisoning.
Airborne
mercury, which eventually falls to the land and water, comes mostly from
coal-fired power plants or medical and trash incinerators. Sewage treatment
plants, chlorine-manufacturing plants and runoff from abandoned gold and mercury mines can flow
directly into water and wetlands.
The
main source of mercury in humans comes from consuming big predator fish such as
swordfish, shark, king mackerel, tilefish and albacore tuna, according to the
U.S. Environmental Protection Agency.
Birds
and other wildlife also eat mercury-contaminated fish as well as insects, crayfish
and other small organisms. The mercury accumulates at higher levels up the
food chain to raccoons, mink, river otters, panthers and polar bears, the study
found.
David
Evers, a leading avian ecologist who specializes in contaminants at the
nonprofit BioDiversity Research Institute in Gorham, Maine, said mercury-contaminated insects
contribute to the high levels of the element in birds, bats and some other
wildlife species.
"Traditional,
conventional thinking was that the fish food web was the only pathway of
concern. But our studies have found that there are other food webs of concern,
including insects," Evers said.
The
report from the National Wildlife Federation is consistent with what California
researchers from the U.S. Fish and Wildlife Service, U.S. Geological Survey and
San Francisco Estuary Institute in Oakland have found in California clapper
rails, Caspian and Forster's terns and other shorebirds feeding in the southern
end of San Francisco Bay.
Guadalupe
Creek, which flows through San Jose, carries inorganic mercury from a now-closed mercury mine. The mercury converts to the toxic form, methylmercury,
in the former Cargill salt ponds being restored in the South Bay.
Letitia
Grenier, a conservation biologist at the San Francisco Estuary Institute, has
researched mercury in songbirds in the wetlands. She praised the work of Evers and
other East Coast researchers.
"It's
important for us to open our minds. We should question where there are other
habitats where we could have mercury accumulations. It's great that we're finally
looking at mercury in animals,'' Grenier said.
The
National Wildlife Federation issued the study as part of a lobbying effort for
regulations to control mercury emissions at coal-fired power plants and other
sources.
The
Electric Reliability Coordinating Council, a trade group for power generating
companies, criticized the study Tuesday as redundant, given past studies. In a
statement, spokesman Scott Segal said emissions of mercury have been reduced by
40 percent since 1990.
E-mail
Jane Kay at jkay@sfchronicle.com.
=============================================
Coal-fired power stations 'poison fish with mercury'
Last updated at 22:38pm on 17th September 2007
Scientists have found the first proof that dangerous levels of
mercury in fish come directly from coal-fired power stations and factories.
They say it takes only three years for particles of the toxic
metal to float through the atmosphere after being expelled as a by-product of
burning coal, fall into the oceans and contaminate marine life.
The speed of contamination has shocked scientists.
There are also concerns that the increasing number of coal power
stations in countries such as China could put the world's health at risk.
Scientists have found
the first proof that dangerous levels of mercury in fish come directly from
coal-fired power stations and factories.
Mercury emissions in the atmosphere break down into more toxic methyl
mercury. Until now, there has been controversy over how it gets into the food
chain.
Scientists from the University of Alberta in Canada proved a
direct link with emissions by releasing mercury into a lake in Ontario and
measuring the effects over several years.
Researcher Vincent St. Louis said: "We can say conclusively
that if you reduce mercury emissions it will result in less mercury in
fish."
Some fish have worrying levels of mercury, which can damage the
nervous system of unborn children and have been linked to heart disease and
strokes (ed., And autism).
Children, pregnant women and those trying for a baby are advised
to limit their intake of tuna, marlin, shark and swordfish.