Clean Water Advocacy - Newsroom - AMSA in the News
Burning Coal - Major Source of Mercury
EXPENSIVE TO CLEAN: Answers to problem remain as slippery as the element itself.
By John Krist, Senior reporter
May 12, 2001
Within the next few days, a task force headed by Vice President Richard Cheney
will unveil the Bush administration's energy strategy, which, Cheney said two
weeks ago, will call for increased production of fossil fuels such as oil,
natural gas and coal.
"Whatever our hopes for developing alternative sources and for conserving
energy, the reality is that fossil fuels supply virtually a hundred percent of
our transportation needs and an overwhelming share of our electricity
requirements," Cheney told an audience of reporters, editors and publishers in
Toronto during the annual meeting of the Associated Press. "For years down the
road, this will continue to be true."
Coal also figures prominently in the omnibus energy bill introduced earlier this
year by Senate Republicans, which would authorize tens of millions of dollars
for programs intended to promote its consumption and hold down its cost.
There are sound reasons for coal's popularity as an industrial fuel. It is
relatively cheap (half as expensive as natural gas) and the United States has a
lot of it -- enough to last at least 275 years at current consumption rates,
according to the federal Energy Information Administration's estimate of
recoverable reserves.
Coal combustion, however, is also the leading source of industrial mercury
emissions in the United States. Coal-fired electrical generating plants alone
emit at least 43 tons of the toxic element into the air each year, according to
the Environmental Protection Agency, a third of the total from all industrial
sources. Efforts to encourage more use of coal may, therefore, increase the risk
to human health posed by one of the most troubling pollutants of the industrial
age -- a contaminant so potent and so pervasive that recent studies have
suggested it threatens the health of thousands of infants born each year.
Coal naturally contains a trace amount of mercury. The concentration is tiny --
10 tons of Gulf Coast basin coal, which has the highest mercury content of all
domestic coal sources, contains only about as much of the toxic element as a
household fever thermometer. But the United States burns a prodigious amount of
coal, more than 1 billion tons a year, according to the Energy Information
Administration, or EIA. Ninety percent of that is consumed by the power
industry, which used coal to generate 56 percent of the nation's electricity
last year. (California, with its tough air-quality regulations and vast network
of hydropower dams, derives only 21 percent of its electricity from coal.)
Burning coal emits a variety of problematic substances: carbon dioxide, a
greenhouse gas that most climate scientists believe is causing the planet to
heat up; sulfur dioxide, the major ingredient in acid rain; fine particulate
matter, or soot, which the EPA has said contributes to as many as 15,000
premature deaths from respiratory disease annually in the United States.
The Clean Air Act has forced reductions in most smokestack pollutants. There is
no limit, however, on the amount of mercury that power plants are allowed to
release. Until last year, power plants were not even required to keep track of
their mercury emissions under the EPA's Toxics Release Inventory, or TRI,
reporting system. Even now, most utility plants still don't have to report their
mercury releases because they are below the threshold in the TRI regulations,
according to the EPA.
Mercury released into the air, scientists believe, eventually falls back to the
surface in dust or rain and ends up in lakes and rivers. Once mercury is in the
water, micro-organisms may convert it to methylmercury, an even more dangerous
form, which can make its way into the food chain and accumulate in living
tissue. Methylmercury is capable at high doses of causing severe birth defects,
devastating neurological damage, even death. Chronic low-level exposure,
particularly in fetuses and children, causes more subtle neurological damage,
such as learning disabilities, difficulty concentrating and delayed motor-skills
development.
According to a National Academy of Sciences report issued last year, 60,000
children born each year in the United States are at increased risk of brain
damage because their mothers consume mercury-contaminated fish. In March, the
Centers for Disease Control and Prevention released a landmark study of
Americans' exposure to 27 environmental chemicals and found that 10 percent of
women of childbearing age have mercury levels in their bodies high enough to
pose a potential threat to their fetuses should they become pregnant. That would
represent about 6 million women, or 375,000 annual births.
In reaction, lawmakers in Sacramento, Washington, D.C., and statehouses across
the country have introduced scores of bills this year intended to slow the flow
of mercury into the environment or protect consumers from contamination. State
and federal regulatory agencies have also begun taking steps to address the
issue, proposing limits on mercury in power plant emissions and sewage plant
discharges.
Yet all such attempts are complicated by ambiguity. Mercury behaves in complex,
unpredictable ways in the air, in the water, in fish, even in human beings. It
is expensive to remove. It makes its way into water and food from natural as
well as industrial sources. Some of those sources may be thousands of miles
away, not subject to American environmental laws. Its mere presence in the air,
soil and water, while hazardous, does not necessarily pose a health risk to any
given individual.
"We all know that the science of the mercury cycle is complex," David Jones, an
administrator in the EPA's western regional office, told a gathering of
researchers and policy makers at a conference last fall in San Francisco. "But
there is another equally complex issue that we have also been exploring in the
last 10 years, and which will become increasingly important over the next 10
years. It's more complex because it involves not only science but also
economics, public policy, land use, risk assessment and the personal lives and
finances of many individuals. And that is the issue of what we do when we verify
that there are elevated levels of mercury in soil, or sediments or air. When is
mercury contamination so severe that it is worth cleaning up?"
To put it more simply, how worried should American consumers be about increasing
amounts of mercury in the environment and in the food supply? And what should
they do about it?
A burning issue
A boom in coal consumption likely will come whether or not federal lawmakers
encourage it. The rising price of natural gas, coupled with the shorter time it
takes to build a coal-fired plant, has prompted plans for construction of 20,860
megawatts of coal-powered electrical generating capacity over the next decade,
according to Energy Ventures Analysis, an industry consulting group. (A megawatt
is enough electricity to power 1,000 homes.)
Economic growth in the world's industrializing nations, particularly in Asia,
will boost global coal consumption from 4.7 billion tons in 1999 to 6.4 billion
tons by 2020, according to the EIA's "International Energy Outlook 2001."
Coal is by far the leading source of human-caused releases of mercury into the
environment. In a 1998 report to Congress on toxic substances released from
electric utilities, the EPA estimated that 5,000 to 5,500 tons of mercury enter
the planet's air and water each year from natural and human sources. About 1,000
tons per year are natural, emitted during volcanic and geothermal activity or
from erosion or evaporation of mercury ore deposits. About 2,000 tons per year
come from re-emissions of mercury associated with past activity (contaminated
runoff from old mines, evaporation from contaminated soil and water bodies or
disturbance of sediments deposited years ago in lakes and streams). The
remaining 2,000 to 2,500 tons are the result of current industrial activity.
In the United States, coal-fired utilities account for about a third of the
approximately 150 tons of mercury emitted into the air each year, according to
the EPA. Municipal waste incinerators account for about 20 percent of the total,
or 30 tons, and medical waste incinerators contribute 10 percent, or 15 tons.
The EPA issued regulations for mercury from municipal waste incinerators in 1995
and for medical waste incinerators in 1997. The agency projects that within the
next two years, compliance with those regulations will have decreased mercury
emissions from waste incinerators by more than 90 percent compared with 1995
levels.
Mercury emissions from coal-fired utility plants are unregulated. The EPA
announced in December that it would propose such regulations within the next two
years, declaring "there is a plausible link" between power-plant emissions and
methylmercury in fish.
"Mercury emissions from utility steam generating units are considered a threat
to public health," the agency concluded.
The Edison Electric Institute, or EEI, and the Utility Air Regulatory Group
filed suit in federal court in Washington, D.C., seeking to delay the
regulations and to force EPA to seek additional input from industry before
moving ahead with plans to require potentially costly emission-control
technology.
"It is vastly premature to conclude that such a stringent approach is necessary
to protect public health," said Dan Riedinger, a spokesman for the EEI.
The utility industry also maintains that it is unclear how much power-plant
emissions have to do with methylmercury levels in the fish people eat, because
that mercury might come from any number of natural and industrial sources.
"Current research and information do not indicate there is a direct link between
electric utility mercury emissions and levels of mercury in fish that
potentially affect health," the EEI says in a fact sheet distributed last month.
The institute has called for more research into the issue.
Federal lawmakers aren't waiting for additional research.
On March 15, 15 senators, including Sens. Dianne Feinstein and Barbara Boxer of
California, introduced S. 556, "The Clean Power Act of 2001." It would require
that mercury emissions from power plants be reduced 90 percent from 1999 levels
before Jan. 1, 2007. On March 27, 50 members of the House introduced a nearly
identical bill, HR 1256 ("The Clean Smokestacks Act of 2001"), requiring the
same reduction. On April 3, 15 members of the House introduced HR 1335, "The
Clean Power Plant Act of 2001," which would require power plant operators to
remove 90 percent of the mercury from their smokestack emissions.
The bills' prospects are uncertain. All three also would require dramatic cuts
in nitrogen oxide, sulfur dioxide and carbon dioxide emissions from power
plants. President Bush, however, has already made clear his opposition to such
curbs, reversing a campaign pledge by announcing in March that the federal
government would not limit power plant emissions of carbon dioxide for fear it
would reduce electricity supplies during a time of turmoil in the nation's
energy markets.
On the other hand, the administration has sent signals it may embrace mercury
controls. Last month, the EPA under new Administrator Christie Whitman filed a
motion in federal court seeking to dismiss the industry lawsuit over the
proposed mercury regulations, even though that proposal was made in the final
days of the Clinton administration.
Cynics will find another reason to question the prospects of legislation
imposing tough new emission standards on power plants. The coal industry gave
$3.8 million to candidates for federal office in the 2000 election cycle, $3.3
million of that to Republicans, according to the Center for Responsive Politics,
a nonpartisan watchdog group that tracks campaign expenditures. Electric
utilities spent $19 million on last year's elections, of which $12.9 million
went to Republican candidates. Republicans control both chambers of Congress.
Another bill introduced in March bypasses the issue of source control and takes
direct aim at the Food and Drug Administration's regulation of seafood.
Introduced by Sen. Patrick Leahy, D-Vt., and Sen. Tom Harkin, D-Iowa, S. 555
would require the FDA to develop a tolerance for methylmercury in commercial
fish, to replace the FDA "action level."
The distinction is an important one. The action level is a mere guideline and
gives the FDA no enforcement power. Food that exceeds an FDA tolerance, however,
can be ordered off supermarket shelves. The bill would also require the agency
to resume testing fish for methylmercury to ensure compliance.
The action level is defined as the amount of a toxic substance in food above
which the FDA recommends the item not be sold or consumed. For mercury in fish,
the FDA action level is one part per million.
Something in the air
While it is true that mercury enters the environment and the food chain from
many sources, many researchers have concluded that airborne industrial emissions
are a prime culprit. One reason is that high mercury levels have been found in
bodies of water where there is no other plausible source -- no old mines in the
watershed, no nearby industrial polluters, no sewage plant discharges.
Collected in places as widely distributed as California's Lake Tahoe, Florida's
Everglades and high-elevation lakes in New Zealand and Nova Scotia, the data
confirm a dramatic rise in mercury levels in sediments with the advent of the
industrial age.
Even more to the point, scientists testing rain and snow falling from the skies
in New England and the Great Lakes region have determined the mercury content of
precipitation exceeds the EPA's standard for protection of wildlife in lakes and
streams. In Maine's Acadia National Park, along the coast of New Hampshire, in
Massachusetts, Rhode Island and Vermont, mercury levels in rain are up to four
times the EPA's standard, the National Wildlife Federation, or NWF, reported
last year. Similar data have been collected in Michigan, Minnesota, Wisconsin,
Illinois, Indiana and Ohio, the NWF reported in 1999.
Citing a long list of laboratory studies, the NWF says mercury contamination is
associated with a wide range of effects on fish and wildlife, including stunted
growth in algae, bacteria and trout; lower reproductive rates in fish and birds;
malformed limbs in frogs; and hormonal and immune-system disruption in fish.
Mercury contamination has been linked to the deaths of great white herons, loons
and endangered Florida panthers, according to the NWF.
Although fossil-fuel combustion is responsible for the largest share of
atmospheric mercury emissions, consumers also bear responsibility for putting
mercury into places where it can enter the food chain and ultimately wind up on
their own dinner tables. Mercury is a component in scores of household and
medical products. If not recycled or disposed of properly, such products can
release mercury into the air and water.
Although the amount of mercury disposed of in landfills fell from 755 metric
tons in 1990 to 295 metric tons in 1996, according to the U.S. Geological
Survey, few states require that mercury-containing items be recycled. Several
states, including California, are considering legislation to reduce the use of
mercury; federal legislation has also been proposed.
At the federal level, Sen. Susan Collins, R-Maine, in February introduced a bill
that would prohibit sale of mercury-containing fever thermometers without a
prescription (discarded household thermometers are responsible for 17 tons of
mercury going into landfills or incinerators each year in the United States,
according to the EPA). Her bill, S. 351, also would authorize funding for a
nationwide program to collect such thermometers and exchange them for ones that
do not contain mercury. It would also establish a federal task force charged
with developing a long-term plan for the permanent elimination of mercury from
the manufacturing sector.
In California, lawmakers this session are considering two bills intended to
reduce the amount of mercury entering the environment.
Assemblywoman Hannah-Beth Jackson, who represents parts of Ventura and Santa
Barbara counties, has introduced AB 751, which would require waste handlers and
recyclers to treat old fluorescent bulbs (which contain small amounts of
mercury) as hazardous waste. The bill would exempt households and businesses
that discard fewer than 30 bulbs a month.
Sen. Byron Sher, D-San Jose, has introduced a more wide-ranging bill, SB 633. It
would ban sale of mercury-containing fever thermometers in California without a
prescription. The bill would ban the sale of mercury-containing novelty items
such as jewelry and games, and prohibit schools from purchasing liquid mercury
or mercury-containing compounds for use in the classroom. It also would require
auto dismantlers to remove mercury-containing switches from junked cars and to
handle the switches in the same manner as hazardous waste.
Ten other states are considering legislation to ban sale of mercury
thermometers, according to the Mercury Policy Project. Eight are considering
bills to require that mercury-containing items be separated from municipal
waste, and six are considering legislation that would force manufacturers to
take back discarded products containing mercury.
Something in the water
In California, where mercury leaching from old mines and mining debris outweighs
airborne pollution as an environmental threat, regulators are beginning to
toughen water quality standards in order to reduce the potential health risk
posed by contaminated fish.
In Sacramento County, which lies downstream from the mercury-laced gold fields
in the Sierra Nevada foothills and upstream of the contaminated waters of San
Francisco Bay, the regional sanitation district has been ordered to limit the
amount of mercury in its sewage plant discharge to 5.1 pounds a year. That limit
would drop to zero in four years if the Central Valley Regional Water Quality
Control Board has failed by then to establish a total maximum daily load, or
TMDL, for mercury in the Sacramento River.
A TMDL sets a limit for the amount of a particular contaminant entering a body
of water, intended to ensure that it meets federal Clean Water Act standards.
The Regional Water Quality Control Board allocates a percentage of that total
load to each source of the pollutant in the watershed. Those sources --
industrial facilities, municipal sewer plants, water agencies -- must then
reduce their emission of that pollutant to meet their share of the TMDL.
Removing five pounds of mercury from the Sacramento Regional County Sanitation
District's annual discharge would be a monumental task, said Mitch Maidland, an
associate engineer in the district's Policy and Planning Division.
"Looking at this on a daily basis, the amount of mercury discharged is
equivalent to half a milliliter," he said. "This is roughly the amount of
mercury in a drop from an eye dropper. For comparison, the amount of water
discharged from the regional plant in a day would occupy a 39-story building
with a footprint the size of a football field."
Maidland said the Sacramento district has estimated it would cost $1 billion to
construct a treatment plant sophisticated enough to remove all mercury from the
district's discharge.
In the case of most pollutants, it typically is easier and cheaper to clean up
the source of the contamination than to spend millions or billions of dollars to
remove it after it has entered the water system. That's not necessarily the case
when it comes to mercury. That's because the immediate source of most of the
contaminant in sewer discharges is walking around on two legs.
"Eighty percent of it comes from human feces and urine," said Margie Nellor,
assistant head of the technical services department for the Sanitation Districts
of Los Angeles County.
Mercury leaching from dental fillings and ingested in food eventually is
excreted from the human body and ends up in the sewer system. In most urban
areas, that's the largest source of mercury discharged from treatment plants,
according to the Association of Metropolitan Sewerage Agencies, or AMSA.
Common household cleaning products also contain small amounts of mercury,
according to a study released last year by the AMSA. Although the amount present
in any one item is too small to pose a health risk, the products are so widely
used that together they account for as much as 15 percent of the mercury in
municipal sewer discharges.
The prominent role of household sewage complicates the traditional regulatory
approach to mercury contamination. In the next five years, Nellor said, the EPA
likely will ask the states to adopt new, stricter limits on mercury in
wastewater. Municipal sanitation agencies fear the new limits would mirror that
imposed already on the Great Lakes region, where discharges cannot contain more
than one part mercury per trillion parts of water.
It is theoretically possible to meet that standard -- reverse osmosis will
remove pretty much every drop of mercury from the wastewater, producing a sewer
plant discharge that's purer than municipal tap water. The question sanitation
agencies want answered is whether that enormous expense would be justified by
the benefit to human health.
Hazard does not equal risk
Mercury is hazardous. Breathe enough of its vapor or swallow enough of it in
liquid form and you'll die. Methylmercury, a form of the element that often can
be found in fish, is even more hazardous. Tiny quantities may cause death or
inflict irreversible damage on the human brain.
Does it follow that millions of pounds of liquid mercury in California's
watersheds and thousands of pounds of mercury vapor in the nation's air pose a
risk to public health? Perhaps.
Toxicologists need to know at least three things before they can determine the
risk an environmental contaminant poses to human beings: By what route will
people be exposed? What dose are they likely to receive? How much of the
contaminant does it take to cause harm?
In the case of mercury, the answer to the first question is straightforward. The
primary pathway by which human beings come into contact with the element's most
dangerous form, methylmercury, is consumption of contaminated fish.
Ambiguity begins creeping in with the second question. The dose depends on how
much fish a person eats, how often, of what variety, and from which body of
water, because methylmercury levels vary greatly from place to place and from
species to species.
An average adult living in Southern California eating supermarket fish perhaps
once or twice a week faces no health risk at all from the millions of pounds of
mercury in California's environment or from the 100,000 pounds dumped in the
nation's air each year by coal-fired power plants. A pregnant woman who eats
striped bass from San Francisco Bay once a day, on the other hand, could well be
damaging her child's brain. Given those extremes -- and keeping in mind that a
society's financial resources are limited -- how much should be spent to clean
up past contamination and prevent it in the future? Would it make more sense to
spend that money on some other health program?
The answer to the toxicologists' third question is even less clear. Although the
dangers of high-level exposure are well-known (thanks to well-studied
mass-poisoning episodes in Japan and Iraq), the data are less clear about the
effects of chronic lower-level exposure, particularly in children. Most of what
scientists know about long-term dietary exposure to methylmercury comes from
just two studies, one being conducted in the Faroe Islands and the other in the
Seychelles.
In the Faroe Islands, off the coast of Denmark, people are exposed to elevated
methylmercury levels in the flesh of pilot whales. In the Seychelles, an
archipelago in the Indian Ocean, 85 percent of the population consumes fish
daily.
Children in both studies have comparable levels of mercury in their bodies. In
the Faroe Islands study, researchers have reported that children are suffering
neurological damage as a consequence -- subtle disturbances in language ability,
attention, memory and motor skills.
Children in the Seychelles study, however, have not shown such effects.
In a paper published in the Journal of the American Medical Association in
August 1998, the Seychelles researchers concluded that their data suggest "it
would be inadvisable to forgo the health benefits of fish consumption to protect
against a small risk of adverse effect at the levels of MeHg (methylmercury)
found in ocean fish in the U.S. market."
That conclusion has been disputed and the researchers' methodology criticized by
other scientists, who have suggested the tests administered to determine
neurological status among the Seychelles children were not sensitive enough to
detect subtle damage. Critics have also noted that many species of fish consumed
by Americans have higher levels of methylmercury than those eaten in the
Seychelles.
The conflicting results have left many experts bemused.
"We don't know what the real toxicological effect is," said Russ Flegal,
chairman of the Department of Environmental Toxicology at the University of
California, Santa Cruz. "One study shows effects, and one doesn't."
The debate is not merely academic. Cleaning up mercury contamination is
expensive, and the cost rises as the emission target drops. If the EPA, for
example, were to decide that sewage plants nationwide should limit mercury in
their discharges to one part per trillion, public agencies would be forced to
spend billions of dollars on new treatment facilities. Set the allowable level
at 50 parts per trillion, and most major urban areas probably would be in
compliance already.
Extrapolating from the level of mercury in water and air emissions to the level
of methylmercury in fish is even more difficult, because scientists do not fully
understand how the element moves from one state to the other. Yet environmental
groups, elected officials and some public-health experts are calling for
immediate and potentially costly changes in state and federal regulations to
protect human health -- even though it is unclear just how much protection
consumers need, or how much protection any particular action would confer.
It is unsatisfying, in a way, simply to call for more study of the issue.
Throughout the history of the industrial age, that has been a delaying tactic
employed by polluters unwilling to accept legal, financial and moral
responsibility for their actions. And to public officials, whose careers are
measured in two- and four-year intervals, it is difficult to postpone action
until a five- or six-year research project has been completed.
Yet the understanding of mercury pollution is still rather primitive, compared
with other industrial contaminants.
"I think that with mercury, we're where we were 10 years ago with respect to
lead," Flegal said, referring to another developmental neurotoxin, which
eventually was proved to pose a grave threat to children's health. "My gut
feeling is that mercury is comparable in its sublethal neurological effects to
lead. But I don't know for sure."
Not everyone is willing to wait for certainty before trying to limit the amount
of mercury entering the environment. Khalil Abu-Saba, a former student of
Flegal's who now writes pollution regulations for the San Francisco Bay Regional
Water Quality Control Board, is among them.
Abu-Saba takes mercury in the environment seriously, so seriously that he has
17th century alchemists' symbols for mercury and its chemical interactions
tattooed on his arm. When public officials and business leaders argue with him
about his efforts to reduce mercury flowing into San Francisco Bay -- where fish
are too contaminated for pregnant women to eat -- he has a curt response.
"Mercury has been around for 150 years and civil servants can't be fired," he
says. "Deal with it."