Birds On the Brink ( like a sentinal canary in a mine.?)

[Guest guest]

http://www.alternet.org/envirohealth/21776/

 

Birds On the Brink

 

By Mark Clayton, Christian Science Monitor. Posted April 15, 2005.

 

 

The pesticide DDT continues to show up in alarming levels in

nonmigrating songbirds.

 

When R. Given Harper set out to understand why North America's

migratory birds were declining, he set a unique course. While other

researchers zeroed in on habitat loss as a key problem, he decided, on

a hunch, to look at an old culprit -- the pesticide DDT -- and its

specific effects on songbirds.

 

The results were intriguing. Traces of DDT and other related chemicals

were showing up in the birds. But the real shock came when Dr. Harper,

a biology professor at Illinois Wesleyan University in Bloomington,

compared his results with DDT levels in nonmigrating songbirds. These

year-round residents of North America -- including a who's who of

birds like the northern cardinal, black-capped chickadee, and

dark-eyed junco -- had more kinds of chemicals and dramatically higher

levels of them than the migrating species.

 

Those are surprising results. Heavily restricted in the United States

since 1972 and a declining problem for eagles, osprey, and other

predatory birds, DDT continues to show up in alarming levels in

nonmigrating songbirds. Does that spell trouble ahead for these

still-healthy species? Are humans at risk? No one knows. But one

lesson seems clear: Beware of what you put into the environment,

because it can be extraordinarily difficult to remove.

 

" These [findings] are reminders that our decisions are going to affect

us for decades, " says Greg Butcher, a senior scientist with the

Audubon Society and author of a recent " State of the Birds " report

that showed many North American species in decline. " There may not be

a toxic effect that kills birds at these levels. But it very well

could affect their embryonic development. "

 

Harper's findings are puzzling partly because of their geographical

specificity. Some 18 species that reside year-round in North America

have roughly 1 to 10 parts per million of DDT -- 2 to 10 times the

levels of those that migrate to Latin America. Also, all 17 of the

organochlorine compounds that Harper tested for -- chemical cousins to

DDT -- appear in each of those nonmigrating species. In contrast, one

to five of the compounds were found in migrating birds.

 

Those are preliminary findings from a yet-to-be published study,

although they build upon Harper's decade of peer-reviewed research on

the same topic. His findings also parallel Canadian and US research

that show organochlorines bioaccumulating in other North American bird

species, experts say.

 

" These birds are the canaries in the coal mine, warning us about

what's going on in our environment, " says Theo Colborn, coauthor of

Our Stolen Future, a 1996 book that focused on developmental problems

caused by pesticides and other man-made chemicals.

 

Such conclusions are premature, say spokesmen for the chlorine

industry. They note that Harper's research has not been peer-reviewed

yet. " It would be a mistake to say, not knowing the levels, how

significant his findings are compared to others, " says Kip Howlett,

executive director of the Chlorine Chemistry Council (CCC), a trade

association in Arlington, Va. Since DDT was banned, bald eagles and

several other species have been rebounding, he says.

 

Just why North American songbirds that do not migrate have high levels

of metabolized DDT and other organochlorines in their bodies remains a

mystery, Harper says in a phone interview.

 

One hypothesis: The US used far more DDT than Latin America, so there

may be a lot still lingering in the soil, he says. About 1.4 billion

pounds were used in the US from World War II until 1972, the

Environmental Protection Agency says.

 

Harper's findings suggest that any reintroduction of banned chemicals

could have " a more immediate and dramatic toxic effect than we saw the

first time around, " Dr. Butcher says.

 

At least 50 countries ban DDT use although it is still legally used

for malaria control in 20 nations, experts say. The US and other

nations have also banned several related organochlorine pesticides,

such as chlordane and dieldrin. Others, such as lindane and

endosulfan, are still registered for use.

 

So far, Harper's research has focused on detecting organochlorine

levels in birds, not on their effects. " We're not certain of the

specific impacts of these compounds on birds, " he says. " We suspect

the presence of these pesticides may at least play a part in the

decline of neotropical migrants and may cause trouble for some

nonmigrants, too. "

 

The DDT and six other organochlorine compounds that Harper found in

the birds are related to chemicals banned by international treaty. The

treaty, the Stockholm Convention, labels them as " persistent organic

pollutants, " or POPs, because they remain in animals, humans, and the

environment for years. They also tend to evaporate in warm climates

and blow on the winds to cold, northern reaches, where they

concentrate. Pesticides like DDT and lindane show up in high

concentrations in Inuit populations, seals, and polar bears, Dr.

Colborn notes.

 

Early next month in Uruguay, more than 50 nations will discuss rules

for adding new chemicals to the POPs ban treaty, which came into force

last year.

 

The US chemical industry and President Bush hailed the treaty, and the

US signed it in 2001. Yet legislation to enact it is currently stymied

in Congress. Legislators disagree whether to include tough language

that would automatically ban new chemicals in the US as they are added

to the treaty list.

 

But until the US ratifies the treaty, it will only be an observer and

not permitted to vote on the new mechanism or on any chemicals that

may be nominated for addition to the list, observers say.

 

" We support the treaty itself and its implementation into US law, "

says Michael Walls, managing director of the American Chemistry

Council, an industry association in Arlington, Va. " We've been

encouraging the Bush administration and Congress to move quickly....

The unfortunate consequences of not having ratified the treaty is that

the US won't have a vote at the first meeting. "

 

One of the first chemicals that some say could be nominated for

addition to the list is lindane, which Harper found in most of his

songbirds in North America. It's a pesticide used to treat seeds and

also an ingredient in shampoo to combat head lice.

 

In California, where lindane-based shampoo is banned, a state agency

reported one rinsing of lindane shampoo could contaminate 6 million

gallons of water, notes Kristin Schafer, program coordinator at

Pesticide Action Network, an environmental group in San Francisco. New

York is also weighing a ban, she says.

 

A major reason scientists worry about DDT and other organochlorines is

that they are powerful " endocrine disruptors, " whose effects on humans

and wildlife are little known. Colborn and Harper charge that such

chemicals can, even in tiny amounts in the body, interfere with embryo

development and harm reproduction and survival.

 

" Every one of these chemicals has an endocrine disruptor effect that

can harm the development of the embryo by interfering with hormones, "

Colborn says. She says there's growing evidence of a link between

organochlorines and learning disabilities and human disorders, which

have multiplied since such chemicals came into common use.

 

But the issue is dosage, not detection, counters the American Council

on Science and Health, a nonprofit group advised by scientists and

others and created to counter activists' claims. " Current levels of

environmental chemicals in the general population are well below those

considered to be associated with adverse effects and thus do not pose

a risk to public health, " it concluded in a 2003 book.

 

And regulation of current pesticides already takes into account

bioaccumulation, writes a spokesman for CropLife America, a trade

group representing pesticide manufacturers, in an e-mail.

 

Deeper studies may be needed to settle the issue fully. Although

pesticides have been thoroughly tested, the human hormone system is so

complex that there are no generally accepted methods to screen

chemicals for adverse health effects, the CCC website says.

 

Glenn Wiser, a senior attorney with the Center for International

Environmental Law, disagrees: " The lesson from the songbirds is that

DDT and other POPs are still used worldwide and are still a problem. "

 

Mark Clayton is a staff writer for the Christian Science Monitor.