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The
Case Against Hard Plastics
November/December 2008
by Bruce Fellman
There’s
no escaping bisphenol A, an increasingly controversial chemical used since the
1950s to make hard plastics. BPA is found in many products, and because it
often leaches out, especially when subjected to heat, traces of the substance
can be detected in the urine of almost every U.S. citizen.
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In October, Canada banned the substance from baby products.
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A
new Yale study, combined with several others, adds fuel to a growing anti-BPA
fire. Neurobiologist Csaba Leranth, a professor at the medical school, and his
colleagues have found that when monkeys were exposed to BPA at levels approximating
those the Environmental Protection Agency has mandated as safe for humans,
parts of their brains associated with memory and learning did not function
normally. (The research appeared September 16 in the Proceedings of the
National Academy of Sciences.)
Studies
in rodents have implicated BPA, an estrogen-like substance, in reproductive and
developmental problems. But this is the first time the chemical has been shown
to affect the primate brain.
Leranth’s
team investigated whether, in female green monkeys, BPA could affect the number
of spine synapses (which transmit messages) in the brain’s hippocampus and
prefrontal cortex. Leranth notes that “in females, one of the key controllers
of spine synapse density is the hormone estrogen.” He suspects BPA may block
estrogen from playing its normal role in the brain.
The
researchers removed the ovaries of 12 young green monkeys. Three received
estrogen supplements; three were given BPA at the upper limit of the EPA
guidelines; three received estrogen plus BPA; and three received neither. The
team found that BPA “wiped out” estrogen’s effects on spine growth.
“There
was as much as a 60 percent decline in the number of spine synapses,” says
Leranth. In males, androgens are the controlling hormone, and Leranth has found
a similar BPA-induced decline.
Rodents
with fewer spine synapses show memory and learning impairments. Leranth plans
to see whether monkeys experience the same effects.
The
American Chemical Council, an industry trade group, has long maintained that
BPA is safe, and federal regulatory agencies have generally concurred. But a
recent study in the Journal of the American Medical Association found a correlation between higher
BPA levels and increases in heart disease, diabetes, and liver abnormalities. A
review by the U.S. National Toxicology Program found reason for “some concern"
that BPA exposure in fetuses, infants, and children could cause adverse
developmental effects (on the brain, on behavior, on the prostate gland). In
October, Canada banned the substance from baby products.
Leranth
warns that “the biggest impact of BPA is likely to be on female children and
post-menopausal women,” because neither group produces enough estrogen to blunt
the chemical’s effect. Leranth has granddaughters, and he has asked his
daughter to rid her house of as much BPA as possible. “It’s not stuff you want
in your body,” he says.
Ubiquitous
According
to industry figures, around seven billion pounds of bisphenol A are
manufactured annually worldwide. BPA is used in polycarbonate plastics—the hard
plastics—and epoxy materials. These products are often identified with the recycling
number 7.
BPA
is commonly found in the following items:
- Baby
bottles, pacifiers, baby toys, and infant “sippy” cups*
- Reusable
shatterproof sports bottles
- Dental
sealants
- Compact
discs and DVDs
- The
protective lining inside food cans
- Eyeglass
lenses
- Sports
safety equipment
- Microwave
ovenware and utensils
- Electrical
equipment
- Circuit
boards
- Automobile
parts
- Carbonless
restaurant and store receipts
- Paints
and adhesives
- Cell
phones, computers, and other consumer electronics
- Construction
glazing
*Wal-Mart,
Toys “R” Us, and others have recently announced plans to phase out children’s
products containing BPA.  |
