The report also lists wood dust, common in carpentry shops and
saw mills, as a known cause of lung cancer. Fifteen other compounds,
including industrial chemicals, dyes and one compound found in foods
cooked at high temperatures, were also added to the list as probable
The report, published every 2 years by the National Toxicology
Program, contains little new information about the agents it lists.
Instead, it is a collection of known experimental data that the
government uses to keep a running catalog of cancer-causing agents.
Federal agencies and Congress use the list to guide regulations
and legislation governing industrial and environmental health
Wednesday's additions expanded the list to 228 compounds either
"known" or "reasonably anticipated" to cause cancer in humans. It
does not make conclusions about the magnitude of cancer risk posed
by any of the compounds or what types of people may be most
Steroidal estrogens were added to the list for the first time
because of research data linking the compounds to an increased risk
of cancer of the endometrium, or lining of the uterus. They have
also been associated with a rise in breast cancer risk.
Steroidal estrogens are used in hormone replacement therapy for
menopausal women, and physicians are supposed to weigh the risk of
cancer against the benefits of the drugs.
Estrogen replacement therapy is also known to reduce the chances
of ovarian cancer in women who take it.
Broad-spectrum ultraviolet light, found in natural sunlight and
in light used in tanning beds, was also classified as a known
carcinogen because of a strong connection with cancers of the skin,
lips and eyes, according to the report.
The report also upgraded beryllium compounds, which are commonly
used in ceramics shops, nuclear reactors and jewelry making, from a
probable to a known carcinogen.