Safety Questions
Consumers often ask the Food and Drug Administration
about the
safety of preservatives, and if there's a system in place to
make
sure preservatives are safe.
Many preservatives are regulated under
the food additives
amendment, added to the Federal Food, Drug, and Cosmetic
Act in
1958. The amendment strengthened the law to ensure the safety
of
all new ingredients that manufacturers add to foods. Under these
rules,
a food manufacturer must get FDA approval before using a new
preservative, or
before using a previously approved preservative in
a new way or in a
different amount. In its petition for approval,
the manufacturer must
demonstrate to FDA that the preservative is
safe for consumers, considering:
* the probable amount of the preservative that will be consumed with
the
food product, or the amount of any substance formed in or on the
food
resulting from use of the preservative
* the cumulative effect of the
preservative in the diet
* the potential toxicity (including cancer-causing)
of the preservative
when ingested by humans or animals.
Also, a preservative may not be used to deceive a consumer by
changing the
food to make it appear other than it is. For example,
preservatives that
contain sulfites are prohibited on meats because
they restore the red color,
giving meat a false appearance of
freshness. (The U.S. Department of
Agriculture regulates meats, but
depends on the FDA regulation to prohibit
sulfites in meats.)
The food additive regulations require the preservative to
be
of food grade and be prepared and handled as a food ingredient.
Also,
the quantity added to food must not exceed the amount needed
to achieve the
manufacturer's intended effect.
Regulations about the use of nitrites
demonstrate the scrutiny
given to the use of additives. Nitrites, used in
combination with
salt, serve as antimicrobials in meat to inhibit the growth
of
bacterial spores that cause botulism, a deadly food-borne
illness.
Nitrites are also used as preservatives and for flavoring
and
fixing color in a number of red meat, poultry, and fish
products.
Since the original approvals were granted for specific uses
of
sodium nitrite, safety concerns have arisen. Nitrite salts can
react
with certain amines (derivatives of ammonia) in food to
produce nitrosamines,
many of which are known to cause cancer. A
food manufacturer wanting to use
sodium nitrites must show that
nitrosamines will not form in hazardous
amounts in the product
under the additive's intended conditions of use. For
example,
regulations specify that sodium nitrite, used as an
antimicrobial
against the formation of botulinum toxin in smoked fish, must
be
present in 100 to 200 parts per million. In addition,
other
antioxidants, such as sodium ascorbate or sodium erythorbate, may
be
added to inhibit the formation of nitrosamines.
As scientists learn more
about the action of certain chemicals
in our bodies, FDA uses the new data to
reevaluate the permitted
uses of preservatives. Two examples are the commonly
used
preservatives butylated hydroxyanisole (BHA) and sulfites.
BHA
BHA and the related compound butylated hydroxytoluene (BHT)
have
been used for years, mostly in foods that are high in fats and
oils. They
slow the development of off-flavors, odors, and color
changes caused by
oxidation. When the food additives amendment was
enacted, BHA and BHT were
listed as common preservatives considered
generally recognized as safe
(GRAS). GRAS regulations limit BHA and
BHT to 0.02 percent or 200 parts per
million (ppm) of the fat or
oil content of the food product.
Lawrence Lin,
Ph.D., of FDA's Center for Food Safety and
Applied Nutrition, explains,
"The 0.02 percent allowed relates only
to the product's fat
content. For example, if a product weighs 100
grams and one of those grams is
fat, the quantity of BHA in the
product cannot exceed 0.02 percent of that
one gram of fat."
BHA is also used as a preservative for dry
foods, such as
cereals. But because such foods contain so little fat, the
amount
of BHA allowed cannot be measured against the percentage of
fat,
explains Lin. Therefore, as manufacturers petitioned FDA
for
approvals for this use, the agency set limits for each type of
food.
On cereals, for example, FDA limited BHA to 50 ppm of the
total
product.
In 1978, under contract with FDA, the Life Sciences
Research
Office of the Federation of American Societies for
Experimental
Biology (FASEB) examined the health aspects of BHA as part of
FDA's
comprehensive review of GRAS safety assessments. FASEB
concluded
that although BHA was safe at permitted levels, additional
studies
were needed.
Since that evaluation, other studies suggested that
at very
high levels in the diets of laboratory animals, BHA could
cause
tumors in the forestomach of rats, mice and hamsters, and
liver
tumors in fish. Many experts examined the data and concluded
the
tests did not establish that such problems could exist in
humans,
mostly because humans do not have forestomachs. Other
studies
showed that BHA was protective, inhibiting the effect of
some
chemical carcinogens, depending on the conditions of the
tests.
Studies on BHA were reviewed by scientists from the United
Kingdom,
Canada, Japan, and the United States. Their findings were
published in 1983
in the Report of the Working Group on the
Toxicology and Metabolism of
Antioxidants and reviewed in the 1990
Annual Review of Pharmacology and
Toxicology. The 1983 report
stated that data from a Japanese study showed a
high incidence of
cancerous tumors and papillomas (benign tumors of the skin
or
mucous membranes) of the forestomach of treated rats and that
the
effect was dose-related. The report also mentioned the
possible
existence of a no-effect level, based on dose response, and
noted
that the level which produced cancer in this study was
many
thousands of times higher than the level to which humans
are
exposed.
In November 1990, Glenn Scott, M.D., a physician then
living
in New York who has since moved to Cincinnati, filed a
petition
with FDA, asking the agency to prohibit the use of BHA in
food.
Scott cited animal studies to support his request. Before acting
on
Scott's petition, however, FDA asked FASEB to reexamine the
scientific
data on BHA. By March 1994, FASEB is scheduled to
provide FDA with a report
on the most current scientific
information bearing on the relationship of BHA
ingestion to cancer
in animals.
Sulfites
Sulfites are used primarily as antioxidants to prevent
or
reduce discoloration of light-colored fruits and vegetables, such
as
dried apples and dehydrated potatoes. They are also used in
wine-making
because they inhibit bacterial growth but do not
interfere with the desired
development of yeast.
Sulfites are also used in other ways, such as for
bleaching
food starches and as preventives against rust and scale in
boiler
water used in making steam that will come in contact with
food.
Some sulfites are used in the production of cellophane for
food
packaging.
FDA prohibits the use of sulfites in foods that are
important
sources of thiamin (vitamin B1), such as enriched flour,
because
sulfites destroy the nutrient.
Though most people don't have a
problem with sulfites, some
do. FDA's sulfite specialist, consumer safety
officer Joann Ziyad,
Ph.D., points to a bookcase full of binders and says,
"Those are
the case histories of adverse reactions to sulfites
that have been
reported to FDA. Since 1985, when the agency started reporting
on
sulfites through the Adverse Reaction Monitoring System, over
1,000
adverse reactions have been recorded."
As reports of
adverse reactions mounted, FDA asked FASEB to
reexamine the use of sulfites.
FASEB's report, released in 1985,
concluded that sulfites posed no hazard to
most Americans, but that
they were a hazard of unpredictable severity to
people who were
sensitive to the substance. Based on the FASEB study, FDA
estimated
that more than 1 million asthmatics are sensitive or allergic
to
the substance.
In 1986, FDA ruled that sulfites used specifically
as
preservatives must be listed on the label, regardless of the amount
in
the finished product. Sulfites used in food processing but not
serving as
preservatives in the final food must be listed on the
label if present at
levels of 10 parts per million or higher.
Regulations issued in 1990 extended
these required listings to
standardized foods.
Also in 1986, FDA banned
the use of sulfites on fruits and
vegetables intended to be eaten raw, such
as in salad bars and
grocery store produce sections. Grocers and
restaurateurs were
using them to maintain the color and crispness of fresh
produce.
(Even before the FDA ban, industry trade groups had persuaded
many
of their members to stop using sulfites on fresh produce.)
FDA plans
to repropose a ban for sulfites on fresh, peeled
potatoes served or sold
unpackaged and unlabeled, such as for
french fries in restaurants. An earlier
FDA rule dealing with
sulfites on potatoes was invalidated by the court in
1990 on
procedural grounds.
In addition, sulfite-sensitive consumers are
learning how to
avoid sulfites. Consumer awareness combined with FDA actions
have
slowed the number of adverse reaction reports. Ziyad says that
from
1990 to 1992, fewer than 40 were reported, and at press time,
there
had been only three reports in 1993.
Ziyad says the only way FDA can
know about sulfite-sensitivity
problems is through consumer and physician
reports. Adverse
reaction reporting is totally voluntary, and FDA
encourages
physicians to report patients' reactions to sulfites. But there
are
times when such reactions are not medically treated because
the
individual doesn't go to the doctor with the condition or the
symptoms
are not recognized. Such information would help FDA
evaluate the current
status of problems with foods among sulfite-
sensitive individuals.
The
agency's Adverse Reaction Monitoring System collects and
acts on complaints
concerning all food ingredients including
preservatives. If you experience an
adverse reaction from eating a
food that contains sulfites, describe the
circumstances and your
reaction to the FDA district office in your area (see
local phone
directory) and send your report in writing to:
Adverse
Reaction Monitoring System (HFS-636)
200 C St., S.W.
Washington, DC 20204
Puzzling It Out
Preservatives are a puzzle for many consumers that
can
sometimes raise safety concerns. Even though these concerns
are
usually unfounded, some industry publications are reporting
attempts
to find naturally occurring substitutes for synthetic
antioxidants. In a 1990
article, one such publication, Inform, says
alternatives to synthetics are
commercially available in the United
States, although most are generally more
costly or have other
drawbacks. For example, tocopherol (vitamin E),
generally is not as
effective in vegetable fats and oils as it is in animal
fats. Also,
some herbs and herb extracts, such as rosemary and sage, can do
the
work of antioxidants, but they impart strong color or flavors.
And
just because these are plant-derived doesn't necessarily mean they
are
always safe. Inform points to the FDA rule that newly
identified natural
antioxidants, like other new food additives,
must undergo rigorous
toxicological tests before they can be
approved.
As an additional
alternative to synthetic antioxidants, the
edible oil industry is
increasingly using ultraviolet-barrier
packaging and filling under nitrogen
to protect the product's
stability.
FDA scientists will continue to
carefully evaluate all
research presented to the agency on new preservatives
to ensure
that substances added to food to preserve quality and safety
are
themselves safe.
Judith E. Foulke is a staff writer for FDA Consumer.
A Sulfite by Any Other Name ...
People who are sulfite-sensitive should
know which foods may
possibly contain sulfites. But it's not always obvious
by the
chemical names on the label which ingredients are
sulfites.
Currently, there are six sulfiting agents allowed in
packaged
foods. The names by which they are listed on food labels are:
* sulfur dioxide
* sodium sulfite
* sodium and potassium bisulfite
*
sodium and potassium metabisulfite
They are used in the following food categories at these typical
maxium
residual sulfur dioxide equivalent levels:
baked goods 30 ppm
beer 25 ppm
wine 275ppm
tea 90
ppm
condimens
& relishes 30 ppm
vinegar 75 ppm
dairy producst
200 ppm
processed seafood
products, other than
dried or frozen 25
ppm
shrimp,
fresh & frozen 100 ppm
lobster, frozen 100
ppm
gelatin 40 ppm
grain products 200 ppm
gravies & sauces 75
ppm
jam & jellies 30 ppm
nut products 25 ppm
plant
protein
isolates 110 ppm
dried fruit 2,000 ppm
fruit juices 1,000 ppm
in concentrates
300 ppm in regular-strength juice
glace fruit 150
ppm
maraschino
cherries 150 ppm
dehydrated
vegtables 200
ppm
dehydrated
potatoes 500 ppm
canned vegtables 30 ppm
frozen
potatoes 50 ppm
vegatable juice 100 ppm
filled crackers 75 ppm
soup
mixes 20 ppm in dry mix
sugar 20 ppm
sweet sauces
and syrups 60
ppm
molasses 300 ppm
The symptom most reported by sulfite-sensitive people is
difficulty
breathing. Other problems range from stomachache and
hives to anaphylactic
shock. In addition to knowing which food
preservatives are sulfites and which
foods are likely to contain
them, sulfite-sensitive consumers can help
themselves avoid health
problems by following these suggestions:
* Read food labels and choose foods that don't contain sulfites.
* Be
aware that foods served in restaurants, especially potato products
and some
canned foods, could contain sulfites. Ask the waiter if
sulfites are used in
what you plan to order.
For example, lemon juice in your tea or splashed on your salad
could be a
source of sulfites. Fresh-squeezed lemon is OK, but
bottled lemon juice often
contains sodium bisulfite.
--J.E.F.
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