Air Panel to Act on Cancer Studies
California air regulators are scheduled to vote today on whether to accept findings by state researchers that secondhand smoke causes breast cancer, which could trigger additional regulations on cigarette smokers.
The findings, the first of their kind by a government agency in the United States, concluded that premenopausal women exposed to significant amounts of secondhand smoke suffered a 68% to 120% higher risk of breast cancer.
If the California Air Resources Board votes to recognize secondhand smoke as a contaminant, it could lead to new regulations banning smoking in cars, public beaches, parks and other areas not currently covered by law.
California’s actions are being watched carefully by the tobacco industry, federal health agencies and health advocates, including the U.S. surgeon general’s office, which is due to release its own update on risks of secondhand smoke this year.
The state’s findings were based on a review completed last fall by the environmental health hazard arm of the California Environmental Protection Agency, which analyzed thousands of studies from across the globe on secondhand smoke and disease.
“In the end it became pretty clear,” said Melanie Marty, chief of air toxicology and epidemiology for the state office. “The pattern that emerged from the data was that the link is there between exposure to secondhand smoke and breast cancer in younger women.”
The report also found stronger links between secondhand smoke and sudden infant death syndrome, premature births, and other cancers and respiratory diseases.
Medical researchers have disagreed about whether secondhand smoke causes breast cancer. A 2004 analysis of data by the International Agency for Research did not find a link. Jonathan Samet, an epidemiology professor at Johns Hopkins University who helped write that report and who is senior scientific editor of the upcoming surgeon general’s report, said, “ ‘Cause’ is a big word. That’s why there is a spectrum of opinion.”
He said that although studies quickly and overwhelmingly identified a link between secondhand smoke and lung cancer, the evidence of a connection with breast cancer was “more ambiguous and more difficult to interpret.”
Samet and Marty agreed that the international team did not have access to newer studies reviewed by California researchers.
Samet said continued research was needed because “breast cancer is extraordinarily important, and people desperately want to know its causes.”
Dr. Michael Thun, vice president of epidemiology and surveillance research for the American Cancer Society, said that although he commended Cal/EPA for its “very thorough update” on harmful secondhand smoke, “at this point there is not broad scientific consensus.... There is solid evidence that there are carcinogens in tobacco smoke that cause breast cancer in animals.... This is an active area of research, and it is certainly possible that environmental tobacco smoke does increase breast cancer risk in humans.”
He said it was important for women to know breast cancer might be caused by secondhand smoke.
State scientists defended their conclusions, saying they gave more weight to studies showing breast cancer in rodents exposed to secondhand smoke and to studies in which researchers carefully identified women who did not smoke and were exposed to large amounts of secondhand smoke in childhood, and as adults at home or at work.
“I’m a pretty cautious person myself; I would not stick my neck out on this issue if I did not think it were real,” Marty said. “We had more studies, and we’ve done a much more thorough analysis of the data.”
She noted that the state’s own independent scientific review panel at first questioned why California was making a conclusion no one else had, but that after reviewing the evidence, unanimously endorsed the report and recommended that the Air Resources Board declare secondhand smoke a deadly air contaminant.
“It’s raising everybody’s antennae. We anticipate researchers will start looking at this question more and in particular do a better job of looking at who was exposed and who wasn’t,” Marty said. “It’s common for Cal/EPA documents to be used by other states and other countries.”
Scientists and statisticians hired by tobacco companies to review the state’s findings strongly condemned them in written comments. One researcher called them “woefully inadequate.”
The Air Resources Board will hold a public hearing in Sacramento before voting on whether to accept the findings; as many as 50 speakers are expected to testify. If a majority of the board declares secondhand smoke a toxic air contaminant, it would be required by law to decide within three years if additional regulation is necessary to protect public health.
California is one of a dozen states that ban smoking in office buildings and restaurants, and board members could conclude that action is sufficient, said board spokesman Jerry Martin. They could also expand some existing local ordinances against smoking on beaches and parks, making them statewide bans.
“I think the only things that are left in reality are private buildings, cars, and beaches and parks,” Martin said. “We expect people to request the board look at regulations governing smoking in cars, particularly where children are passengers.”
A study by the air board staff found that although smoking by Californians and related deaths had declined significantly in recent years, nonsmokers were still exposed to an estimated total of 36 tons of nicotine annually.
