New substances added to HHS
Report on Carcinogens
The U.S. Department of Health and Human Services
today added eight substances to its Report on Carcinogens, a
science-based document that identifies chemicals and biological agents
that may put people at increased risk for cancer.
The
industrial chemical formaldehyde and a botanical known as aristolochic
acids are listed as known human carcinogens. Six other substances =97
captafol, cobalt-tungsten carbide (in powder or hard metal form),
certain inhalable glass wool fibers, o-nitrotoluene, riddelliine, and
styrene =97 are added as substances that are reasonably anticipated to
be human carcinogens. With these additions, the 12th Report on
Carcinogens now includes 240 listings.
"Reducing exposure to
cancer-causing agents is something we all want, and the Report on
Carcinogens provides important information on substances that pose a
cancer risk," said Linda Birnbaum, Ph.D., director of both the National
Institute of Environmental Health Sciences (NIEHS) and the National
Toxicology Program (NTP). "The NTP is pleased to be able to compile this
report." John Bucher, Ph.D., associate director of the NTP added, "This
report underscores the critical connection between our nation=92s health
and what=92s in our environment."
The Report on Carcinogens is a
congressionally mandated document that is prepared for the HHS Secretary
by the NTP. The report identifies agents, substances, mixtures, or
exposures in two categories: known to be a human carcinogen and
reasonably anticipated to be a human carcinogen. A listing in the Report
on Carcinogens does not by itself mean that a substance will cause
cancer. Many factors, including the amount and duration of exposure, and
an individual=92s susceptibility to a substance, affect whether a person
will develop cancer.
Once a substance is nominated by the public or
private sector and selected for consideration, it undergoes an extensive
evaluation with numerous opportunities for scientific and public input.
There were at least six opportunities for public input on each
substance. The NTP used established criteria to evaluate the scientific
evidence on each candidate substance under review. The NTP drew upon the
scientific expertise of several federal agencies, including the National
Institutes of Health, Centers for Disease Control and Prevention, Agency
for Toxic Substances and Disease Registry, U.S. Food and Drug
Administration, U.S. Environmental Protection Agency, U.S. Consumer
Product Safety Commission, and Occupational Safety and Health
Administration.
"The strength of this report lies in the rigorous
scientific review process," said Ruth Lunn, Dr.P.H., director of the NTP
Office of the Report on Carcinogens. "We could not have completed this
report without the significant input we received from the public,
industry, academia, and other government agencies."
A detailed
description of each substance listed in the Report on Carcinogens is
included in the new report.
Two known human
carcinogens:
Aristolochic acids have been shown to cause high
rates of bladder or upper urinary tract cancer among individuals with
kidney or renal disease who consumed botanical products containing
aristolochic acids. Aristolochic acids are a family of acids that occur
naturally in some plant species. Despite a warning issued in 2001 by the
U.S. Food and Drug Administration that advised consumers to discontinue
use of any botanical products containing aristolochic acids, they can
still be purchased on the Internet and abroad, and may be found as a
contaminant in herbal products used to treat a variety of symptoms and
diseases, such as arthritis, gout, and inflammation.
Formaldehyde
was first listed in the 2nd Report on Carcinogens as a substance that
was reasonably anticipated to be a human carcinogen, after laboratory
studies showed it caused nasal cancer in rats. There is now sufficient
evidence from studies in humans to show that individuals with higher
measures of exposure to formaldehyde are at increased risk for certain
types of rare cancers, including nasopharyngeal (the nasopharnyx is the
upper part of the throat behind the nose), sinonasal, as well as a
specific cancer of the white blood cells known as myeloid leukemia.
Formaldehyde is a colorless, flammable, strong-smelling chemical that is
widely used to make resins for household items, such as composite wood
products, paper product coatings, plastics, synthetic fibers, and
textile finishes. Formaldehyde is also commonly used as a preservative
in medical laboratories, mortuaries, and some consumer products,
including some hair straightening products.
Six substances reasonably
anticipated to be human carcinogens:
Captafol was found to induce
cancer in experimental animal studies, which demonstrated that dietary
exposure to captafol caused tumors at several different tissue sites in
rats and mice. Captafol is a fungicide that had been used to control
fungal diseases in fruits, vegetables, ornamental plants, and grasses,
and as a seed treatment. It has been banned in the United States since
1999, but past exposures may still have an effect on health.
Cobalt-tungsten carbide (in powder and hard metal form) showed limited
evidence of lung cancer in workers involved in cobalt-tungsten carbide
hard metal manufacturing. Cobalt-tungsten carbide is used to make
cutting and grinding tools, dies, and wear-resistant products for a
broad spectrum of industries, including oil and gas drilling, as well as
mining. In the United States, cobalt-tungsten hard metals are commonly
referred to as cemented or sintered carbides.
Certain
inhalable glass wool fibers made the list based on experimental animal
studies. Not all glass wool or man-made fibers were found to be
carcinogenic. The specific glass wool fibers referred to in this report
have been redefined from previous reports on carcinogens to include only
those fibers that can enter the respiratory tract, are highly durable,
and are biopersistent, meaning they remain in the lungs for long periods
of time. Glass wool fibers generally fall into two categories for
consumers: low-cost, general purpose fibers, and premium, special
purpose fibers. The largest use of general purpose glass wool is for
home and building insulation, which appears to be less durable and less
biopersistent, and thus less likely to cause cancer in humans
o-Nitrotoluene is listed because experimental animal studies showed
tumor formation at many different tissue sites in rats and mice.
o-Nitrotoluene is used as an intermediate in the preparation of azo dyes
and other dyes, including magenta and various sulfur dyes for cotton,
wool, silk, leather, and paper. It is also used in preparing
agricultural chemicals, rubber chemicals, pesticides, petrochemicals,
pharmaceuticals, and explosives. Workers in the United States are likely
exposed to o-nitrotoluene through the skin or from breathing it during
production and use. o-Nitrotoluene has also been detected in air and
water near facilities that produce munitions, and near military training
facilities.
Riddelliine has been found to cause cancer of the
blood vessels in rats and mice, leukemia and liver cancer in rats, and
lung tumors in mice. This botanical should not be confused with the drug
Ritalin, prescribed for the treatment of attention deficit hyperactivity
disorder. Riddelliine is found in certain plants of the genus Senecio, a
member of the daisy family, grown in sandy areas in the western United
States and other parts of the world. Some common names for Senecio
plants are ragwort and groundsel. Riddelliine-containing plants are not
used for food in the United States, and have no known commercial uses.
However, at least 13 Senecio species have been identified that are used
in herbal medicines or possibly as food in other parts of the world.
Exposure in humans could result from eating or drinking herbal medicine
or teas, honey, or foods contaminated by parts of Senecio plants or
after consuming products from animals that have fed on the
plants.
Styrene is on the list based on human cancer
studies, laboratory animal studies, and mechanistic scientific
information. The limited evidence of cancer from studies in humans shows
lymphohematopoietic cancer and genetic damage in the white blood cells,
or lymphocytes, of workers exposed to styrene. Styrene is a synthetic
chemical used worldwide in the manufacture of products such as rubber,
plastic, insulation, fiberglass, pipes, automobile parts, food
containers, and carpet backing. People may be exposed to styrene by
breathing indoor air that has styrene vapors from building materials,
tobacco smoke, and other products. The greatest exposure to styrene in
the general population is through cigarette smoking. Workers in certain
occupations may potentially be exposed to much higher levels of styrene
than the general population.
The Report on Carcinogens,
Twelfth Edition, is prepared by the National Toxicology Program, an
interagency program headquartered at the National Institute of
Environmental Health Sciences, part of the National Institutes of
Health.
The NTP was established in 1978. The program was
created as a cooperative effort to coordinate toxicology testing
programs within the federal government, strengthen the science base in
toxicology, develop and validate improved testing methods, and provide
information about potentially toxic chemicals to health, regulatory, and
research agencies, scientific and medical communities, and the public.
The NTPis headquartered at the NIEHS.
NIEHS supports research to
understand the effects of the environment on human health and is part of
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