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Toxicology studies and cancer risks
I received this posting and thought I should pass it along. I hope it does
not stir up passionate discussions based on peronal feelings, e.g., DU,
media bias, or the LNT.
-- John
John Jacobus, MS, CHP
Area Health Physicist
Radiation Safety Branch
National Institutes of Health
21 Wilson Drive, MSC 6780
Bethesda, MD 20892-6780
USA
Telephone: 301-496-5774
Fax: 301-496-3544
E-mail: jjacobus@mail.nih.gov
jacobusj@ors.od.nih.gov
-----Original Message-----
Date: Thu, 25 Jan 2001 10:37:10 -0500
From: "NIH OLIB (OD)" <olib@OD.NIH.GOV>
Subject: NTP COMPLETES 500th TWO-YEAR RODENT STUDY AND REPORT; SERIES IS T
HE
GOLD STANDARD OF ANIMAL TOXICOLOGY
NATIONAL INSTITUTES OF HEALTH
National Institute of Environmental Health Sciences
NIH NEWS RELEASE
FOR IMMEDIATE RELEASE:
Thursday, January 25, 2001
NIEHS CONTACT: Tom Hawkins
(919) 541-1402
NTP COMPLETES 500th TWO-YEAR RODENT STUDY AND REPORT;
SERIES IS THE GOLD STANDARD OF ANIMAL TOXICOLOGY
The U.S. National Toxicology Program published its 500th
two-year safety test of chemicals in rodents -- a landmark
in a series that has influenced what is allowed in your
drugs, your water, your foods, and your air, for these
reports have often formed the foundation for regulatory
action by the Food and Drug Administration, Environmental
Protection Agency, Occupational Safety and Health
Administration, and Consumer Product Safety Commission.
The 500th report is on ordinary naphthalene, the principle
ingredient in mothballs and the familiar odor in millions
of closets filled with winter's woolens. It is also used
as a restroom deodorizer.
The rat study found clear evidence that naphthalene causes
cancer, a finding that scientists and regulators must
wrestle with to determine if, as commonly used, it presents
a risk to humans as well. An abstract of the study is
available on request or at the web site listed below.
The National Toxicology Program is headquartered at the
National Institute of Environmental Health Sciences.
NIEHS/NTP Director Kenneth Olden, Ph.D., said, "We are
proud of this milestone of health protection. These 500
tests have had a profound effect on our health and the
length of our lives. In 1997 and 1998 alone, nine of these
studies were the basis for regulatory decisions by the EPA,
FDA, and Occupational Safety and Health Administration."
Dr. Olden added, "The National Toxicology Program's testing
prevents disease by identifying hazards and allowing the
regulatory agencies and the marketplace to act on these
results. That is how NTP has its great benefit on human
health."
Since NTP was established in 1978, its reports have
changed how substances are handled in occupational and
home settings, and in the more general environment. Some
examples of chemicals that have been found to cause tumors
in laboratory animals and have subsequently been regulated
or dropped from use, are:
--Tetrachloroethylene, and carbon tetrachloride have been
dropped from home cleaning fluids.
--Mirex, which was restricted in its use as a pesticide and
fire retardant.
--Benzene, an ingredient in gasoline, whose toxicity led to
the collars around gas pump nozzles that limit inhalation
while people fill up their tanks.
--Phenolphthalein, the active ingredient in most over-the-
counter laxatives at the time was removed from the market.
--Dichlorvos - flea collars and pest strips using this
insecticide were removed from the market.
--Various food dyes have been dropped by manufacturers and
regulated by the FDA
--A number of chemicals used in manufacturing have been
restricted or regulated in their use to protect workers.
The entire list of study abstracts and the results of each
can be seen at the NTP web site: http://ntp-server.niehs.nih.gov
Unlike the old cliche that "everything causes cancer,"
almost half the chemicals tested do not produce tumors in
laboratory rodents, and with a few rare exceptions,
chemicals that cause tumors or other diseases in rodents
eventually are found to cause similar if not identical
problems in humans.
Any scientist, organization, or member of the public may
nominate a chemical for NTP testing. Nominated chemicals
are selected on the basis of evidence that they may cause
cancer or sometimes simply because large numbers of people
are exposed. Chemicals may be subjected to one or more
short-term tests before they are selected for complete, in
depth, but more costly two-year rodent studies that take as
many as five years from experimental design to printed
report.
Rodents are the animals of choice since they are relatively
inexpensive to breed and keep but biologically similar to
humans, and because their long use in laboratories has
taught researchers a great deal about them. Using two
species, rats and mice, allows the studies to identify
responses that are the same in both species. If something
causes tumors in both species, and especially in both
genders of each, it is probably very active in causing
tumors. If the chemical causes tumors that are rare--
that is rarely occurring in non-exposed animals-- that
raises additional concern.
NTP studies are done by contract laboratories under the
supervision of an NIEHS study scientist. For the
naphthalene, the NIEHS study scientist was Kamal M. Abdo.
Once the report on a study is prepared, it is peer reviewed
by a panel of outside experts which rigorously analyzes
every aspect of the study and hears from members of the
public who may wish to comment on the study or the draft
report. This exceptionally stringent process has
contributed to the NTP's reputation as the gold standard of
toxicology testing.
The future promises tremendous advances in technologies and
transgenic animals that will mean faster, less expensive
tests, using fewer and in some cases no animals. Even
then, the classic two-year rodent studies will still
provide the fundamental whole animal toxicity data
necessary for validation of these advances.
The National Institute of Environmental Health Sciences
(which is a part of the National Institutes of Health) and
the National Toxicology Program are both in Research
Triangle Park, which lies between Raleigh, Durham and
Chapel Hill, N.C.
----------------------------------
FOR TELEVISION AND MEDIA REQUIRING VISUAL MATERIAL
NTP ARCHIVES OFFERS PHOTO POSSIBILITIES - The 500 studies
completed by NTP can be visually represented by the
extensive collection of microscope slides (over 9 million),
as well as wet and frozen tissue, and paper and microfiche
data, all kept at the National Toxicology Archives. The
newly expanded facility also includes human blood and urine
samples used in NIEHS' revolutionary fertility studies.
The NTP archives constitutes probably the most extensive
toxicology reference library of study data in the world and
is used by scientists from governments, academia, and
private industry from around the world. Researchers come
to the archives to study the expansive collection of
pathology materials and paper data.
------------------------------------
Sidebar: NAPHTHALENE CAUSES CANCER IN RAT STUDY
Naphthalene, the chemical that gives mothballs that strong,
familiar scent, showed clear evidence of causing cancer in
male and female laboratory rats in a two-year study by the
National Toxicology Program headquartered at the National
Institute of Environmental Health Sciences in Research
Triangle Park, N.C. The rats in the study were exposed by
inhalation, just as most people are, in doses comparable to
some human consumer and workplace exposures.
NIEHS-NTP Study Scientist Kamal Abdo said naphthalene was
nominated for study by the National Institute of
Occupational Safety and Health, the Occupational Safety and
Health Administration, and the U.S. Environmental
Protection Agency - all of which are represented on the NTP
Executive Committee -- after some German workers exposed to
naphthalene were found to have a variety of cancers -
including laryngeal, gastric, nasal, and colon cancer.
Regulatory agencies will have the opportunity to review the
study and current labeling and take regulatory action as
appropriate, using other studies and data as well.
The most widely known use of naphthalene is in mothballs
and bathroom deodorizers, but it also has a number of
chemical manufacturing uses, and is used in veterinary
medicine to control lice and as a disinfectant for lesions
and incisions. It enters the human food chain when used on
livestock that then ingest or inhale it. Naphthalene
manufacture and use goes back at least to the early part of
the 20th Century.
------------------------------
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