Is It Safe to Heat Food in Plastic?
Are These Chemicals Making Us Sick?
With BPA and phthalates, there's nothing like the smoking-lung
cancer connection, but there are lots of smoking guns. The research is still in
its early days, and much of what we know comes from work with animals. Also,
not all phthalates have been linked to health problems. But many prominent
scientists believe these chemicals may cause a range of problems related to our
- Lower sperm counts and other reproductive abnormalities: Since the
late 1990s, after Hunt found that mice in BPA-contaminated cages developed egg
abnormalities, she and dozens of other researchers have linked the chemical to
reproductive problems in rodents, including lower sperm counts and abnormal
eggs. Phthalates, too, may cause reproductive problems. In 2006, when Harvard
researchers studied 463 men seeking treatment at a fertility clinic, the
scientists reported that men with higher levels of certain phthalates in their
urine had lower sperm counts and sperm motility, as well as damage to sperm
DNA, all of which affect the ability to impregnate a partner.
In one of the most important human studies so far, Swan measured phthalates in
85 pregnant women in three U.S. cities — Los Angeles, Minneapolis, and
Columbia, MO. In that 2005 study, women with the highest phthalate levels were
most likely to give birth to sons with smaller penises, smaller testes, and
"reduced ano-genital distance" (the space between the testes and the
anus). In other words, these baby boys were somewhat de-masculinized, which
could signal impaired semen quality and decreased fertility later on. "The
results were dramatic," Swan says. "We were surprised by how strong the
link was. And, based on animal studies, we're concerned about possibly serious
health consequences for these boys as they get older."
- Early puberty: "We think girls are maturing younger and
younger," says Mount Sinai's Dr. Galvez, "and we're now trying to find
out if endocrine disruptors play a role." Her center is involved in a large
study that is tracking 1,200 girls, currently ages 6 to 8, for five years. But
there are already clues. In Puerto Rico, researchers have been studying girls
who have developed breasts at extremely young ages (before 8, and most starting
before 2). Their 2000 study showed that these children had phthalate levels, on
average, almost seven times higher than those in a control group of girls.
While the researchers stress that this correlation does not prove there's a
link, their report concludes, ominously, that "if the hypothesis holds
true, premature sexual development in Puerto Rico may prove to be an
unfortunate example of the impact of endocrine-disrupting environmental
chemicals at a critical stage of human development."
- Cancer: Early puberty, in turn, has been linked to an increased risk
of breast cancer. BPA, too, causes precancerous growths in lab animals, both
prostate and breast abnormalities. But in humans it's hard to prove cause and
effect with 100 percent certainty, says Andrea Gore. "We're exposed to so
many things, and our mothers ate and drank this or that and 50 years later we
get breast cancer," she says. "How can you go back and say, 'It must be
- Obesity and diabetes: In one study of adult men, those with
higher-than-average phthalate levels tended to have a larger waist
circumference and increased insulin resistance, precursors to diabetes. In a
study of mice, the ones fed BPA were more likely to give birth to offspring who
- Neurobehavioral abnormalities: In a lengthy review article,
published in 2007, researchers reported that low doses of BPA during
development affect brain structure, function, and behavior in rats and
If the Chemicals Are So Risky, Why...
In 1988, when the Environmental Protection Agency (EPA) set a safe consumer
limit for BPA — you could ingest 50 micrograms per one kilogram of body weight
per day — it used the old-school tests. Typically, that meant dosing rodents
with high levels of the chemical and looking for disease (or death), then
reducing the amount of chemical until it had "no observed adverse
effect." Usually, a fraction of that level is what's allowed in our food
and consumer products.