While all commercial gaming in Atlantic City, Michigan and Pennsylvania were temporarily smokefree for a period of time because of the COVID-19 pandemic, smoking has resumed as mask mandates have expired. They did so despite the fact that the science on secondhand smoke has been well-accepted for a long time. The casinos have been encouraged to reinstate smoking by laggards, including The Press of Atlantic City, which questioned the evidence in a recent editorial, Our view: If NJ bans casino smoking, it won’t be due to the science.
Like all recent articles questioning the health effects of secondhand smoke, this editorial is a very selective review of the literature.
Do you know who actually wrote the story?
A few quick reactions:
To say there is “nonexistant scientific support” is, of course, crazy. The first Surgeon General report finding that passive smoking caused lung cancer came out in 1986, a conclusion that was reinforced in the Surgeon General’s updated 2006 report.
The Press wrote “A 2014 evaluation of 40 studies on secondhand smoke, published in the International Journal of Environmental Research and Public Health, could only say ‘secondhand smoking may increase the overall risk of cancer for never smokers, particularly lung and breast cancer.’ Or it may not.” The IJEPH paper they are citing seems to be this one. It reports statistically significant increases in cancer associated with secondhand smoke exposure, particularly lung and breast cancer. The risk increases they report (around 25%) are consistent with the larger literature. The paper’s use of “may” just reflects usual scientific caution. The sentence The Press is quoting in the abstract is “Secondhand smoking may increase the overall risk of cancer for never smokers, particularly lung and breast cancer, and especially in women.” The Press ignored the next sentence: ” Strict implementation of smoking cessation programs should be encouraged, not only to reduce active smoking but also to limit exposure to secondhand smoke [emphasis added].”
The JNCI “paper” The Press cites is not a paper but a news story reporting a meeting presentation: Here is how the news story described the result:
The incidence of lung cancer was 13 times higher in current smokers and four times higher in former smokers than in never-smokers, and the relationship for both current and former smokers depended on level of exposure. However, among women who had never smoked, exposure to passive smoking overall, and to most categories of passive smoking, did not statistically significantly increase lung cancer risk. The only category of exposure that showed a trend toward increased risk was living in the same house with a smoker for 30 years or more. In that group, the hazard ratio for developing lung cancer was 1.61, but the confidence interval included 1.00, making the finding of only borderline statistical significance.
What this means in English is that the risk associated with secondhand smoke was increased by 61% but this did not reach “statistical significance” meaning that the risk of a false positive had to be less than 5%. In this study, the lower bound risk was equal to 5%. This is statistical hair splitting.
The paper’s authors were aware of this. Here is what they said:
So does secondhand smoke cause lung cancer or not? “We can’t say it’s not a risk factor,” said Wang.
Heather Wakelee, MD, associate professor of medicine and oncology at Stanford and one of the study’s senior investigators, explained why. WHI-OS had only 901 cases of lung cancer, and only 152 of those occurred in never-smokers. “It’s hard to say anything conclusive with such small numbers,” said Wakelee.
Another problem is that measuring exposure to passive smoke is hard. “Living with a husband who smokes a lot with the windows closed is reported the same as living with one who smokes a little, mostly on the porch,” said Wakelee. (The study measured passive smoking in years, not pack-years.)
Moreover, of the nearly 40,000 nonsmokers in the WHI-OS, only about 4,000 reported no exposure to cigarette smoke. “That means almost everybody had passive-smoking exposure,” said Wakelee, “so it’s very hard to say that that exposure is causing the problem—it’s hard to tease out a difference.
So, the headline on the JNCI news story (“No Clear Link Between Passive Smoking and Lung Cancer”) didn’t accurately report what the scientists who conducted the study said.
I tracked down the subsequent full peer reviewed paper. The abstract says,
Among NS [nonsmokers], prolonged passive adult home exposure tended to increase lung cancer risk. These data support continued need for smoking prevention and cessation interventions, passive smoking research, …
The most important thing, however, is to consider this in the context of the larger literature. As noted above, the fact that secondhand smoke causes lung cancer has been accepted for 35 years since the 1986 Surgeon General report. This new study simply adds to that (already overwhelming) case.
I didn’t look up the specific COVID studies The Press cited, but the evidence on COVID and smoking is complicated. There are problems with most studies of smoking and risk of COVID infection, many of which show a protective effect. The problem with these studies is that they are based on people who were tested not a random sample of the population (PDF page 53), so have sampling biases. We have tried to estimate the direction of that bias but could not figure out a defendable way to do it.
In contrast, there is a lot of strong and consistent evidence that smoking makes COVID worse (PDF page 50 and following) once you get it, including increasing the risk of serious illness and death. Also see my blog; this entry is a bit dated but everything published since then is consistent with what it has to say.
The bottom line: When confronted with claims that the science is not there to support smokefree environments, go back and check the original sources and the broad consensus documents produced by the WHO, CDC and other authorities.