First, lead is not a good thing to snort. No way, no how.

Remember the Alar scare? PCBs? Coffee?

Some things WILL kill you, lead is one. But scientists have made a few
errors that will take years to untangle. I'm leery of the current rage,
where actual scientific inquiry is damned. I thought creationists were
unable to accept divergent views that scientific inquiry suggests, yet
global warming is unquestionable.

Al Gore saying that the scientists that do not agree with his pet theory
are "deniers", like the holocaust deniers. Bad science does not mean I
or anyone else must suspend our disbelief.

PS. Rachel Carlson's "Silent Spring" was bogus.

wrote:
On Jan 27, 12:03 pm, Too_Many_Tools wrote:
FYI....heavy metal contamination is forever.

TMT

Lead linked to aging in older brains By MALCOLM RITTER, AP Science
Writer

Could it be that the "natural" mental decline that afflicts many older
people is related to how much lead they absorbed decades before?

That's the provocative idea emerging from some recent studies, part of
a broader area of new research that suggests some pollutants can cause
harm that shows up only years after someone is exposed.

The new work suggests long-ago lead exposure can make an aging
person's brain work as if it's five years older than it really is. If
that's verified by more research, it means that sharp cuts in
environmental lead levels more than 20 years ago didn't stop its
widespread effects.

"We're trying to offer a caution that a portion of what has been
called normal aging might in fact be due to ubiquitous environmental
exposures like lead," says Dr. Brian Schwartz of Johns Hopkins
University.

"The fact that it's happening with lead is the first proof of
principle that it's possible," said Schwartz, a leader in the study of
lead's delayed effects. Other pollutants like mercury and pesticides
may do the same thing, he said.

In fact, some recent research does suggest that being exposed to
pesticides raises the risk of getting Parkinson's disease a decade or
more later. Experts say such studies in mercury are lacking.

The notion of long-delayed effects is familiar; tobacco and asbestos,
for example, can lead to cancer. But in recent years, scientists are
coming to appreciate that exposure to other pollutants in early life
also may promote disease much later on.

"It's an emerging area" for research, said Dr. Philip Landrigan of the
Mount Sinai School of Medicine in New York. It certainly makes sense
that if a substance destroys brain cells in early life, the brain may
cope by drawing on its reserve capacity until it loses still more
cells with aging, he said. Only then would symptoms like forgetfulness
or tremors appear.

Linda Birnbaum, director of experimental toxicology at the U.S.
Environmental Protection Agency, said infant mice exposed to chemicals
like PCBs show only very subtle effects in young adulthood. But more
dramatic harm in areas like movement and learning appears when they
reach old age.

Animal studies also show clear evidence that being exposed to harmful
substances in the womb can harm health later on, she said. For
example, rodents that encounter PCBs or dioxins before birth are more
susceptible to cancer once they grow up.

Studying delayed effects in people is difficult because they generally
must be followed for a long time. Research with lead is easier because
scientists can measure the amount that has accumulated in the shinbone
over decades and get a read on how much lead a person has been exposed
to in the past.

Lead in the blood, by contrast, reflects recent exposure. Virtually
all Americans have lead in their blood, but the amounts are far lower
today than in the past.

The big reason for the drop: the phasing out of lead in gasoline from
1976 to 1991. Because of that and accompanying measures, the average
lead level in the blood of American adults fell 30 percent by 1980 and
about 80 percent by 1990.

That's a major success story for environmentalists. But work by
Schwartz and Dr. Howard Hu of the University of Michigan suggests that
the long-term effects of the high-lead era are still being felt.

In 2006, Schwartz and his colleagues published a study of about 1,000
Baltimore residents. They were ages 50 to 70, old enough to have
absorbed plenty of lead before it disappeared from gasoline. They
probably got their peak doses in the 1960s and 1970s, Schwartz said,
mostly by inhaling air pollution from vehicle exhaust and from other
sources in the environment.

The researchers estimated each person's lifetime dose by scanning
their shinbones for lead. Then they gave each one a battery of mental
ability tests.

In brief, the scientists found that the higher the lifetime lead dose,
the poorer the performance across a wide variety of mental functions,
like verbal and visual memory and language ability. From low to high
dose, the difference in mental functioning was about the equivalent of
aging by two to six years.

"We think that's a large effect," Schwartz said.

Hu and his colleagues took a slightly different approach in a 2004
study of 466 men with an average age of 67. Those men took a mental-
ability test twice, about four years apart on average. Those with the
highest bone lead levels showed more decline between exams than those
with smaller levels, with the effect of the lead equal to about five
years of aging.

Nobody is claiming that lead is the sole cause of age-related mental
decline, but it appears to be one of several factors involved, Hu
stressed.

If so, it would join such possible influences as high blood pressure,
diabetes, stroke, emotional stress and maybe education level, said
Bradley Wise of the National Institute on Aging. Nobody knows exactly
what causes mental decline with age, he said.

Although the studies by Hu and Schwartz suggest lead is involved, Wise
and others say they don't prove the link.

"I think many things impact how we age, but I think right now it's
maybe premature to be giving lead a huge role in our age-related
cognitive decline," said Dr. Margit L. Bleecker, director of the
Center for Occupational and Environmental Neurology in Baltimore.
Still, she called the lead hypothesis "a very interesting idea"
deserving more study.

Others were more impressed.

"The new evidence from these studies should concern people" said
epidemiologist Andrew Rowland of the University of New Mexico. "These
two research groups are finding adverse effects on the aging brain at
low levels of lead exposure. More work needs to be done, but these
studies are raising important questions."

In any case, scientists still face some basic mysteries about the
delayed effects of lead. For example, when does it actually harm the
brain? Does a high level in the shinbone merely identify those who
were the most harmed by chronic exposure decades ago? Or does lead in
the bone continue to do its dirty work over a lifetime, leaching into
the bloodstream and continuously hammering the brain?

"I think that both things are happening," Schwartz said, though he
suspects most of the damage occurred in the past, during years of
higher exposure. Hu's suspicions are similar.

Just how lead impairs brainpower is still a mystery. And so is the
question of whether anything can be done to help people who have
absorbed a lot of lead over a lifetime.

A medical procedure called chelation can remove lead from the body,
but it wouldn't help in this case, said experts, who had few
suggestions.

For younger people, prevention is a clearer strategy, Hu said. He
called for tougher federal standards on lead exposure in the
workplace.

And plenty of low-income neighborhoods could use a strong effort to
remove lead from old houses, many of which still have lead paint,
Rowland said. "It's there on the walls, it's on the radiators, it's
underneath the top layers of paint. In places where the paint is
crumbling, there's still exposure going on," he said.

Yet another question: Who really has to worry about long-ago lead
affecting their brainpower? What about people born after the high lead
levels of the 1970s were history?

Schwartz noted that most Americans younger than 30 have gotten much
less lead from the environment than the men in his study did. And Hu
hopes that the lead effect will peter out in the future.

However, Hu points out that there's still lead in the environment, and
exposure remains especially high in many developing countries. And
citing evidence that lead can cross the placenta, he says women who
grew up in the 1970s might dose their fetuses with the metal.

"Kids who grew up in the 21st century have a lot less to worry about"
than their elders, Hu said. But "it's hard for me to be totally
optimistic the current generation is completely scot-free."

___

On the Net:

Lead information:http://www.epa.gov/lead/index.html

Well, it was certainly true of my late father-in-law. He worked in a
lead smelter in Idaho for a while, perhaps a year or more, as a young
man. Then went to logging during WWII, then farming with tractors.
First with leaded gasoline and finally Diesel. When I first met him,
about 1959, he would show off his ability to keep track of his daily
farm records in his brain, then write them down after work.

About 15 years before he passed away at age 90, he began to go down
mentally. finally had to be in a foster care home. His older and
younger brothers did not work in the lead smelter and did not suffer
the mental decline. They died from other problems.

I wonder, sometimes, about my employees and their use of leaded solder
for up to 7 hours a day, 5 days a week. Yes, we are moving to lead
free older, but only as customers specify it.

Paul