Thomas H. Maugh II, Los Angeles Times

The first large-scale human study of a chemical widely used
in plastic products, including baby bottles and tin can linings, found double
the risk of cardiovascular disease, diabetes and liver problems in people with
the highest concentrations in their urine, British researchers reported
Tuesday.


The findings confirm earlier results obtained in animals,
increasing pressure on the Food and Drug Administration to limit use of the
chemical Bisphenol A, commonly called BPA.


 
The chemical is the primary ingredient of polycarbonate
plastics, which are found in myriad modern products, such DVDs, drinking bottles
and lenses of sunglasses.


There have been growing concerns about its
safety as studies in rodents have linked it to diabetes, brain damage,
developmental abnormalities, pre-cancerous changes in the prostate and breast
and a variety of other health problems.


About 7 billion pounds of the
chemical are produced worldwide each year and studies by the Centers for Disease
Control and Prevention have found that 93% of Americans have detectable levels
of the chemical in their urine.


The new findings are published in this week's edition of
the Journal of the American Medical Assn., but were released early to coincide
with an FDA hearing on BPA in Washington.


"This is a human study that
really calls into question FDA's assertion that BPA is safe," said Dr. Anila
Jacob of the Environmental Working Group, an activist group.


An FDA
representative, however, defended the agency's actions at the Tuesday hearing.
"A margin of safety exists that is adequate to protect consumers, including
infants and children, at the current levels of exposure, said Laura Tarentino, a
senior FDA scientist.


Many experts already think the writing is on the
wall for the chemical, however.


A draft report issued earlier this year
by the government's National Toxicology Program, which has no regulatory
authority, concluded that there was "some concern" that the chemical poses a
risk to fetuses, babies and children.


Health Canada, Canada's national
public health department, also earlier this year released a report calling BPA
"a potentially harmful chemical" — becoming the first regulatory body in the
world to do so.


Baby bottle manufacturers are already looking for
replacements for the chemical. And both Wal-Mart Stores Inc. and Toys R Us Inc.
have announced their plans to shift away from products containing
BPA.


BPA was first synthesized in 1891 and came into wide use in the
1940s and 1950s because of the toughness and durability of polycarbonates made
from it.


But some BPA remains intact in the plastic and leaches out over
time, particularly when it comes in contact with hot liquids.


The
chemical industry and the FDA have long relied on two large animal studies which
showed that high concentrations of the chemical fed to the rodents produced no
serious adverse effects.


There have been no previous large studies of the
chemical in humans because researchers considered it inappropriate to administer
the chemical for tests.


Dr. David Melzer of the Peninsula Medical School
in Exeter, Britain, and his colleagues took advantage of results from the
2003-2004 U.S. National Health and Nutrition Examination Survey, which for the
first time measured concentrations of BPA in urine from a representative sample
of 1,455 adults.


They found that the quarter of the population with the
highest BPA levels — which were still at levels the FDA considers safe — were
more than twice as likely to suffer from diabetes and cardiovascular disease as
those in the quarter with the lowest levels.


The cause of the increased
risk is unclear, but two studies reported earlier this year give hints. Spanish
researchers reported in April that in mice, BPA causes pancreatic cells to
increase their production of insulin, leading to the well-known metabolic
syndrome that is a precursor of both diabetes and heart disease.


And an
August study by endocrinologist Nira Ben-Jonathan of the University of
Cincinnati showed that BPA, like estrogen, impairs the ability of human fat
tissue to secrete adiponectin, which protects against heart attacks and
diabetes.