Manganese
inhaled from the shower - A public health threat? Maybe
Main Category: Water Quality / Air Quality News
Article from Medical
News Today
Date: 01 Jul 2005 - 0:00am (PDT)
A new analysis based on animal studies suggests
that showering in manganese-contaminated water for a decade
or more could have permanent effects on the nervous system.
The damage may occur even at levels of manganese considered
safe by the Environmental Protection Agency, according to researchers
from Wake Forest University School of Medicine.
"If our results are confirmed, they could
have profound implications for the nation and the world,"
said John Spangler, M.D., an associate professor of family medicine.
"Nearly 9 million people in the United States are exposed
to manganese levels that our study shows may cause toxic effects."
The study is the first to show the potential for
permanent brain damage from breathing vaporized manganese during
a shower. It was conducted by reviewing the medical literature
and calculating, based on animal studies, the amount of manganese
people would absorb by showering 10 minutes a day.
Because manganese is monitored in public water
supplies, high levels of this naturally occurring metal are
especially found in wells and private water supplies.
Spangler and Robert Elsner, Ph.D., published their
findings in the current issue of Medical Hypotheses, a forum
for ideas in medicine and related biomedical sciences.
The journal publishes "interesting and important
theoretical papers that foster the diversity and debate upon
which the scientific process thrives."
Everyone is exposed to small levels of manganese,
which is found in food and many types of rocks and enters the
air, soil and water. But, at higher levels, manganese is toxic
to the central nervous system and can cause learning and coordination
disabilities, behavioral changes and a condition that is similar
to Parkinson's disease.
Children, pregnant women, the elderly, and patients
with liver disease are at highest risk from manganese toxicity.
Some of these groups have developed manganese poisoning even
at fairly low doses in their water supplies, Spangler said.
The Environmental Protection Agency (EPA) has
set 0.5 milligrams/liter as the upper limit of manganese advisable
in water supplies. The limit, however, is based on odor and
taste of the water. The potential risk of manganese accumulating
in the brain through showering has not been considered by the
EPA in setting this limit. In their analysis, Spangler and Elsner
found that concentrations well below 0.5 milligrams might lead
to brain injury.
"Inhaling manganese, rather than eating or
drinking it, is far more efficient at delivering manganese to
the brain," said Spangler. "The nerve cells involved
in smell are a direct pathway for toxins to enter the brain.
Once inside these small nerves, manganese can travel throughout
the brain."
Elsner and Spangler extrapolated data from rodents
to estimate human exposure to manganese during showering. They
found that after 10 years of showering in manganese contaminated
water, children would be exposed to doses of manganese three
times higher than doses that resulted in manganese deposits
in the brains of rats. Adults would be exposed to doses 50 percent
higher than the rodents.
The researchers said that while limitations to
their calculations do exist, regulatory agencies have not considered
this potential pathway when setting drinking water standards.
"Studies should be carried out among populations
that have experienced high levels of manganese in their water
supplies over long periods of time," Spangler said. "Regulatory
agencies may one day need to rethink existing drinking water
standards for manganese."
The addition of manganese to gasoline as an anti-knock
agent may also be a threat, the researchers said.
"The manganese, as it settles from car exhaust
onto streets and highways, may enter the water supply, increasing
manganese levels in the water we drink and bathe in," said
Spangler.
Media Contacts: Shannon Koontz, shkoontz@wfubmc.edu;
Karen Richardson, krchrdsn@wfubmc.edu; at 336-716-4587
About Wake Forest University Baptist Medical Center:
Wake Forest Baptist is an academic health system comprised of
North Carolina Baptist Hospital and Wake Forest University Health
Sciences, which operates the university's School of Medicine.
The system comprises 1,187 acute care, psychiatric, rehabilitation
and long-term care beds and is consistently ranked as one of
"America's Best Hospitals" by U.S. News & World
Report.
Contact: Shannon Koontz
shkoontz@wfubmc.edu
336-716-2415
Wake Forest University Baptist Medical Center
http://www.wfubmc.edu
