Sept. 10, 2002 --- An Alabama Cooperative Extension food
scientist has this advice for people disturbed by a widely forwarded
e-mail claiming that microwave cooking of food in plastic wrap
causes cancer: Relax.
In fact, if youíre really intent on reducing
potentially harmful trace amounts of carcinogens in your food during
cooking, she advises giving your frying pan a rest instead.
The e-mail, which has since proven to be largely a
hoax, claims a seventh-grade Arkansas student discovered that two
supposedly cancer-causing substances, DEHA and dioxin, leach into
food from plastic wrap during microwave cooking.
Part of this is true. A seventh-grade Arkansas
student named Claire Nelson was, in fact, curious to learn whether
potentially harmful chemicals released from heated plastic during
microwave cooking ended up in food.
Itís also true that Nelson, working with the
FDA-affiliated Center for Toxicological Research in Jonesboro, Ark.,
tested the effects on olive oil enclosed in plastic wrap during
microwave cooking. Her testing revealed that one of the substances,
known by its initials DEHA, turned up in trace amounts in the oil
after cooking and migrated into the oil at between 200 parts and 500
parts per million. The current FDA standard for DEHA is 0.05 parts
DEHA is a phthalate, one of many types of
plasticizers commonly added to plastics to enhance their
Likewise, xenoestrogens, believed to reduce
sperm-count levels in men and cause breast cancer in women, also
were found in the oil. However, it was difficult for Nelson to
determine how much was too much, since there currently are no FDA
guidelines establishing tolerance levels for xenoestrogens in foods.
This much is true.
What is not true is that DEHA is a known
cancer-causing agent or that dioxin was one of the substances
uncovered during testing, says Dr. Jean Weese, an Alabama
Cooperative Extension System food scientist.
"While some forms of phthalates have been shown to cause health
effects, including cancer, in laboratory mice and rats, DEHA isnít
one of them," Weese says.
"In fact, the most recent studies involving
DEHA and some other phthalates have shown no link with cancer,"
she adds, stressing that the EPA and the European Union agencies
currently do not recognize DEHA as a known carcinogen.
Equally untrue is the claim that dioxin is produced
from plastic wraps during microwave cooking. While dioxin is a
serious health risk, causing a variety of health problems, including
cancer, Nelsonís studies turned up no evidence that dioxin was
released into food during microwave cooking.
"It is true that dioxins are produced by the
burning of plastics, especially polyvinyl chloride, but to my
knowledge, no scientific study has ever shown that dioxins are
formed in plastics heated by microwaves," Weese says.
Indeed, frying is the only form of cooking that has
ever been associated with the production of trace amounts of dioxins
in food. The problem stems from the fact that oils and fats
typically used in frying contain triglycerides.
"Once these substances reach high temperatures
from frying, the fats attached to this glycerol backbone begin
breaking down into peroxide and other substances, including, in some
cases, dioxins and PCBs, another known carcinogen," Weese says.
Under the circumstances, she says, consumers would
be better off putting away the frying pan and broiling your food
She also offers this advice to consumers who still
harbor any lingering concerns about using plastics in the microwave.
First, use only cookware that is labeled for use in
the microwave oven.
Second, avoid using plastic storage containers such
as margarine tubs, takeout containers and other one-time use
containers, all of which can melt or warp, possibly causing
chemicals to migrate into the food.
Third, never use thin plastic storage bags, brown
paper, plastic grocery bags, newspaper or aluminum foil in the
On the other hand, microwave plastic wraps, wax
paper, cooking bags, parchment paper, and white microwave-safe paper
towels are safe to use. And to be extra safe, be sure to not let
plastic wrap touch foods during microwave cooking, Weese advises.
(Source: Dr. Jean
Weese, Extension Food Scientist, 334-844-3269)