February 2, 2006
groups split on secondhand smoke
By John Ritter
SACRAMENTO — California regulators,
the first to brand secondhand smoke an
air pollutant, are convinced it causes
breast cancer in younger women. But
they're butting heads — at least for now
— with conventional wisdom in the cancer
Major national groups — the American
Cancer Society, the National Cancer
Institute, the Centers for Disease
Control and Prevention — won't endorse
the California Environmental Protection
Agency's unprecedented finding, adopted
last week by the state's Air Resources
California links passive smoke, breast
Though a secondhand smoke link to
breast cancer is "certainly possible,"
says Michael Thun, the cancer society's
vice president of epidemiology, "at this
point, there is not broad scientific
According to Jonathan Samet of Johns
Hopkins University, senior scientific
editor of a U.S. surgeon general's
report on secondhand smoke due this
year, "The scientific community is still
watching for the evidence to evolve."
Other researchers say these
organizations are too cautious and
should consider newer, more rigorous
studies that did a better job of
measuring women's exposure to secondhand
"The authors of this report explain
why the previous studies have been
inconsistent and really make a
compelling case," says Andrew Hyland, a
researcher at Roswell Park Cancer
Institute in Buffalo.
'Warning to young women'
Nancy Evans, health science
consultant for the Breast Cancer Fund in
San Francisco, and other advocates for
breast cancer research say young women
shouldn't be denied information about
these risks. It's accepted that
secondhand smoke causes lung cancer and
heart disease, but women under 50 can
think of them as diseases of old age.
"There's enough awareness about
breast cancer that this would be a real
strong warning to young women," Evans
says. CalEPA's report found that
waitresses have the most workplace
exposure to secondhand smoke. Breast
cancer kills 40,000 U.S. women a year.
The Air Resources Board has a history
on the cutting edge. Its directives
since the 1960s to cut tailpipe
pollution forced automakers to make
cleaner vehicles. Automakers have sued
the board over a 2004 decision to
require greenhouse gas reductions. The
board was the first agency, before the
surgeon general, to identify secondhand
smoke as a cause of heart disease.
"That was treated with similar
skepticism," says Cheryl Healton,
president of the anti-smoking American
The board won't decide whether to
adopt tougher restrictions on secondhand
smoke until a study of costs and
consequences is done. Lawyers are
researching whether the board has the
authority to ban smoking in cars when
children are present. A 1999 law
requires the board to pay special
attention to children's heath risks.
Some skeptics of CalEPA's findings
point out that if tobacco smoke causes
breast cancer, the risk for active
smokers should be much higher than for
women exposed to secondhand smoke. It
The cancer society's Thun, in his
comments on the CalEPA report filed with
the air board, said "lack of an
association with active smoking weighs
heavily against the possibility" that
secondhand smoke could raise breast
One theory on the apparent
discrepancy is that smoking damages
ovaries and cuts estrogen production,
but secondhand smoke exposure doesn't,
says Melanie Marty, the CalEPA scientist
who supervised the report. Lower
estrogen levels have been shown to
reduce breast cancer risk.
Newer studies that kept women exposed
to secondhand smoke out of control
groups did find elevated breast cancer
risk among active smokers, the report
It also seems counterintuitive that
younger women would be more at risk than
older women, who presumably have been
exposed to secondhand smoke longer. Risk
was elevated as much as 120% for younger
women but hardly at all for women past
menopause, the CalEPA analysis found.
It's not clear why. What's known is
that a woman's greatest susceptibility
to carcinogens is between puberty and
her first baby. In addition, there's
evidence genes and family history play a
role: women who are more likely to
develop cancer get it at a younger age,
says Laura Esserman, a researcher at the
University of California-San Francisco
who studies breast cancer biology.
More advanced studies
Twenty years ago, the surgeon general
found that secondhand smoke causes lung
cancer. Evidence today that it causes
breast cancer is even stronger, says
Stanton Glantz, a professor of medicine
at the University of California-San
Francisco and a member of the scientific
panel that reviewed CalEPA's report.
"There are more studies, the risk
estimates are more consistently
elevated, and they're higher than they
were for lung cancer," Glantz says.
"Plus, there's all these toxicology
studies and molecular biology they
didn't have back then."
Public health groups' reluctance to
embrace CalEPA's findings shows "very
serious bias against new information,"
Glantz says. "It's a ridiculously
Findings in a forthcoming surgeon
general's secondhand smoke report aren't
public. But "an active line of research"
is whether younger women have a higher
risk of breast cancer, says Terry
Pechacek, associate director for science
in the CDC's office on smoking and
health. He wouldn't comment on CalEPA's
report because he said that might reveal
some of those findings.
"There's no need to be cautious,"
Esserman says. "Get the information
about risk out there and let women be
the judge of whether it's important or
not. For goodness sake, there's about 10
other good reasons to avoid secondhand
smoke anyway, right?"