TOXIC chemicals in our bodies

[Guest guest]

Burden of proof -- what we don't know about the toxic chemicals in

our bodies -- by Elizabeth Sawin in Soapbox

<http://www.gristmagazine.com/soapbox/sawin031903.asp?source=daily>

19 Mar 2003

Scientists call the accumulation of chemical contaminants (such as PCBs,

mercury, and pesticides) within a person's body the " body

burden. " Body burden is just a number, a concentration in parts per

billion or micrograms per liter. But the term calls forth an image, too,

of a body bent over and struggling beneath a heavy load. When scientists

start taking about body burden, I think about real bodies -- my own and

my children's.

<http://www.gristmagazine.com/images/dot_clea.gif>

[body burden]

Thanks to a new report from the U.S. Centers for Disease Control and

Prevention, we have a better sense than ever before of the body burden of

the typical U.S. citizen. In the Second National Report on Human Exposure

to Environmental Chemicals , CDC scientists measured the levels of 116

chemicals in the blood and urine of 2,500 volunteers. The study found

detectable levels of 89 chemicals, including pesticides, phthalates,

herbicides, pest repellents, and disinfectants.

Chemical by chemical, the report documents the average concentration of

contaminants in the bodies of the people studied. But what does all this

data mean? At what concentration do these chemicals become

dangerous?

For all but a handful of chemicals, nobody knows the answer to this

question. The report acknowledges as much, in one understated sentence:

" Research studies, separate from the Report, are required to

determine which blood or urine levels are safe and which cause

disease. "

This is not easy research. The questions involved are complex. What do

you measure to determine safety? How relevant are animal studies to

questions about human health? Do safe levels differ for children, who eat

and respire more per pound of body weight than adults?

<http://www.gristmagazine.com/images/dot_clea.gif>

[Our Stolen Future]

These have always been the questions of toxicology, but new questions are

emerging, too. The website associated with the book Our Stolen Future,

which introduced the idea of endocrine disruptors to the general public

in 1996, collects scientific papers and news stories that track

discoveries about the health effects of chemical exposures. The papers

collected there make it clear that we need to add three new questions to

the way we think about safe levels of chemicals.

1. Could a given chemical have health effects a long time after exposure?

For chemicals that interfere with cell-signaling systems, such as hormone

systems, subtle impacts during early development can cause trouble after

a long latency. Traditional tests for the safety of chemicals look for

immediate effects, not those that emerge years after exposure.

2. Has a given chemical been tested for low-dose effects? Traditionally,

chemicals are tested for safety at lower and lower doses, until a

concentration is discovered that has no ill effects. All doses below that

threshold are usually assumed to be harmless. But for some chemicals, the

dose-response relationship is not that simple. Unexpected effects can

appear at lower concentrations than the " safe dose " as a

biologically active chemical " hijacks " cellular processes.

Because it focuses on testing for outright damage by toxic chemicals,

traditional toxicology may miss this low-dose effect.

3. Is a given chemical safe when mixed with other chemicals? Most studies

of chemical safety examine the effects of one chemical at a time, but in

real life, people are exposed to complex mixtures of contaminants. New

studies, such as one on the impact of a commercially available

weed-killer mixture on pregnant mice, suggest that mixtures of chemicals

can have effects that none of the chemicals have on their own.

No wonder the CDC report can't say much about the safe levels of the

chemicals it measured. Looking for effects from very low doses over very

long time periods is difficult enough. Try to do that for all possible

real-world combinations of chemical exposure and the task grows

exponentially.

[Vitruvian man]

<http://www.gristmagazine.com/images/dot_clea.gif>

Maybe some day our science will reach a level of sophistication that can

give us solid assurances about chemical safety. But that's a distant

goal, not a current reality. Until then, we are all walking, breathing

experiments in toxicology. Until then, we are all living with

risk.

However, there was one definitive and telling finding in the CDC report:

The body burdens of lead, DDT, PCBs, and hexachlorobenzene have all

decreased since the last CDC study. Guess what? These are all chemicals

that have been banned or strictly regulated in the U.S. That's great

news. It means that the pollution of our bodies, like the pollution of

our rivers or our air, is reversible.

But a river doesn't come back to life until the pollution is cut off at

the source, and the same will be true for our bodies. So the CDC finding

gives us a clear mandate of where to go from here: If a lower body burden

seems like a sensible, desirable thing, then we need to limit the

chemicals to which we are exposed. That's no small task. The number of

artificial chemicals in our environment is astounding. The CDC tested for

the presence of 116, but the U.S. EPA estimates that at least 80,000

chemicals -- 690 times the number tested by the CDC -- are produced and

used today.

If we keep assuming that all chemicals are harmless until we uncover the

exact doses, combinations, and lag times that will make us sick, our

bodies are going to remain polluted for a long, long time. Wouldn't it

make more sense to put the burden of proof of safety on the chemical

manufacturers, rather than the burden of the chemicals on our

bodies?

- - - - - - - - -

Elizabeth Sawin is a mother, biologist, and systems analyst. A member of

Cobb Hill Cohousing, she lives on an organic farm in Hartland, Vt. She

works at the Sustainability Institute, a think-do tank founded by Donella

Meadows.

 

******

Kraig and Shirley Carroll ... in the woods of SE Kentucky

http://www.thehavens.com/

thehavens

606-376-3363

****************************************************************

Looking for a Miracle? Learn how Clayton Tedeten was

blessed by God!

http://www.ncpmiracle2.com/

ID: # 2651 for

Environmental

Damage

Repair

****************************************************************

To CONFIRM your

BELIEF in a better world where

people. help people - Contact thehavens

****************************************************************

A way to build

TRUE residual income with TWO $500

certificates for products - just pay shipping & handling!

http://www.thehavens.fgg.com

****************************************************************