Point:
http://www.newscientist.com/news/news.jsp?id=ns99996091
Passive smoking danger was underestimated
11:22 30 June 04
NewScientist.com news service
The health risks of passive smoking may have been substantially underestimated, according to the first large-scale study looking at tobacco-derived chemicals in the blood of non-smokers.
The new study puts passive smokers’ risk of developing coronary heart disease at more than double earlier estimates, which were based only on studies of non-smokers living with a partner who smokes.
The large difference can be attributed to non-smokers breathing in cigarette smoke at work, in bars and other smoky environments outside the home, the researchers suggest.
Between 1978 and 1980, more than 2000 British men aged between 40 and 59 years underwent a blood test for cotinine, a break-down product of nicotine from cigarette smoke. Cotinine remains in the blood for up to 48 hours, and so is an indicator of a person’s exposure to smoke up to two-days’ prior to testing.
The men were rated in four groups according to their blood cotinine levels, and the incidence of coronary heart disease in the groups was measured over a 20-year period.
Elevated concentrations
Researchers at St George’s Medical School and the Royal Free UCL Medical School in London, UK, found that elevated concentrations of blood cotinine levels among the non-smokers were associated with a 50 to 60% greater risk of coronary heart disease. Earlier partner-smoking studies estimated the increased risk of heart disease in passive smokers at just 25 to 30%.
Peter Whincup, at St George’s Medical School, notes: “The relative risk of coronary heart disease associated with high levels of passive smoking is greater than that estimated by partner smoking alone, even at exposure levels of 20 cigarettes a day or more."
He acknowledges that living with someone who smokes is an important component of exposure to passive smoking, but says "it accounts for less than half the variation in cotinine concentration among non-smokers and does not take account of additional exposure in workplaces and in public places, particularly pubs and restaurants".
On Wednesday, the British Medical Association will present UK prime minister Tony Blair with 4500 letters from doctors calling for a ban on smoking in public places. Whincup agrees, saying: “We advocate restricting passive smoking wherever possible, including in public places.”
However, the researchers note that the actual future risks of passive smoking could be less than measured in their study, due to the decline in public and workplace smoking over recent years. Also, the study found that the risk of stroke was not significantly related to cotinine concentrations.
Journal reference: British Medical Journal (DOI: 10.1136/bmj.38146.427188.55)
http://www.newscientist.com/news/news.jsp?id=ns99992251
Passive smoking dents children's IQ
12:13 07 May 02
NewScientist.com news service
Secondhand smoke shaves points off kids' IQ, a study of over 4000 American children suggests. Even those exposed to small amounts of cigarette smoke have slightly lower cognitive abilities.
"These levels may not be meaningful for an individual child, but they have huge implications for our society because millions of children are exposed to environmental tobacco smoke," says Kimberly Yolton of the Cincinnati Children's Hospital Medical Center in Ohio.
Yolton's team looked at levels of a breakdown product of nicotine called cotinine in the blood of 4399 children aged between six and 16. They also examined their scores on a number of intelligence tests, using data from a countrywide survey known as NHANES-III done between 1988 and 1994. To rule out any children who might be smoking themselves, only those with cotinine levels lower than 15 nanograms per millilitre were included.
Even after allowing for factors such as poverty, parents' educational levels and blood lead levels, the researchers found an association between cotinine levels and lower cognitive performance, Yolton told a meeting of the Pediatric Academic Societies in Baltimore on Monday.
As little as one nanogram of cotinine per millilitre of blood appeared to reduce IQ scores by an average of two points. One parent smoking less than a pack a day could produce that level in a child.
Smoking in pregnancy
Reading scores declined by about one point for every nanogram of cotinine, for instance, and maths scores by about three-quarters of a point. There was a nine-point difference in reading scores between the 25 per cent of kids with the highest levels and the 25 per cent with the lowest.
Though passive smoking has already been linked to language and reasoning deficits in children, this study is the first to show that extremely low exposure can have such an effect.
But Jo Nanson of the University of Saskatchewan in Saskatoon says the results should be interpreted cautiously because of possible confounding factors. She says mothers who smoke during pregnancy are known to reduce their child's IQ, for instance, and if the parents are smoking now, they were probably smoking then. "It needs some careful statistical analysis," Nanson warns.
But Yolton says that when they allowed for this in the subset of kids for whom data on prenatal exposure was available, it made no difference.
http://www.newscientist.com/news/news.jsp?id=ns99994998
Passive smoking kills one bar worker a week
14:15 17 May 04
NewScientist.com news service
Secondhand tobacco smoke kills at least 3600 people a year in the UK, according to a new study, including the death of one pub or bar worker every week.
Konrad Jamrozik at Imperial College, London, UK, says exposure to secondhand smoke in all workplaces leads to the deaths of around 700 people a year.
He examined all deaths in 2002 from lung cancer, ischaemic heart disease and stroke in British people under the age of 65, and combined this data with data on exposure to smoking at home and work.
The study is the first to calculate deaths as a result of secondhand smoke in bar staff, says Jamrozik. But it "is a conservative estimate" he toldNew Scientist. The findings, presented at a conference at the Royal College of Physicians in London on Monday, have led to renewed calls for a public smoking ban in the UK.
"The estimates look very much in line with what other studies have shown," says Robert West, director of tobacco studies at University College London. "They add more weight to what is now pretty much an overwhelming argument in favour of a public smoking ban."
Deborah Arnott, director of campaign group Action on Smoking and Health (ASH) UK agrees: "These are truly shocking figures. They show the urgent need for a new law to end smoking in the workplace."
Active and passive
Jamrozik's mathematical analysis used an epidemiological model to combine several sets of data. Death figures came from the UK Office for National Statistics for 2002 and information on what proportion of the population are exposed to smoke at work and at home was provided by ASH.
For example, about 30 per cent of the UK population smokes, while 42 per cent of under 65s are exposed to secondhand smoke at home. Eleven per cent of under 65s are exposed to other people's smoke in their workplace.
Combining this data with information on the relative risk of disease among, active smokers, passive smokers and non-smokers allowed Jamrozik to calculate estimates for the number of deaths caused by passive smoking.
People working in pubs and bars are especially at risk as they are exposed to three times the levels of smoke that a non-smoker living with a smoker experiences. As a result, these workers are almost twice as likely to die from related diseases than those exposed to smoke at home.
Factory fumes
Pro-smoking group Forest dispute the figures. "Once again we are presented with estimates, calculations and 'likely risk'. Where is the hard evidence that passive smoking is killing people?" says director Simon Clark.
But West says that even allowing for a margin of error in Jamrozik's study, the figures are "pretty horrific". He told New Scientist: "If factories were putting out fumes that caused that level of death, they would be closed down."
He adds that the public smoking bans in Ireland and New York did not lead to "mass insurrections" as feared.
Carol Black, president of the RCP notes: "Making these places smoke-free not only protects vulnerable staff and the public, it will also help over 300,000 people in Britain to stop smoking completely."
Counterpoint:
http://www.newscientist.com/news/news.jsp?id=ns99993737
Controversy over passive smoking danger
00:01 16 May 03
NewScientist.com news service
The link between passive smoking and lung cancer and coronary heart disease may be "considerably weaker" than generally believed, according to a controversial new study.
For nearly 40 years, researchers followed 35,500 non-smokers in California who were married to smokers. The team has now concluded that there were no statistically significant associations between the second-hand tobacco smoke these people were exposed to and deaths from coronary heart disease, lung cancer and chronic obstructive pulmonary disease (COPD).
"The results do not support a causal relation ..., although they do not rule out a small effect," say researchers James Enstrom at the University of California and Geoffrey Kabat at New Rochelle, New York.
The study, published in the British Medical Journal, acknowledges funding from the tobacco industry and has provoked fury from the anti-smoking lobby.
"The tobacco industry has been desperately trying to disprove the harmful consequences of passive smoking for years. This paper is just the latest in a long campaign to sow the seeds of doubt about the dangers of breathing in environmental tobacco smoke," says Amanda Sandford, of Action on Smoking and Health in the UK.
"Flawed" study
The British Medical Association has called the study "flawed" and highlight the "overwhelming evidence" showing a link between passive smoking and lung cancer, heart disease and as a trigger for asthma in children.
But George Davey Smith, a clinical epidemiologist at the University of Bristol, UK, told New Scientist: "I don't think the scientific data are biased and the analyses are fine". However, the authors "overplay the negative interpretations" of their findings, says Davey Smith, who has written an editorial to accompany the paper.
Enstrom and Kabat examined a subset of the 118,000 people who took part an American Cancer Society study from 1959 to 1998. Health in households where one spouse was a smoker was compared with couples who had both never smoked.
There was no statistically significant increase in the risk of dying from coronary heart disease, lung cancer or COPD in spouses whose partner smoked. The authors do note that the risk data for COPD suggests an association is possible.
But Davey Smith says combining the relative risk of COPD death for men and women in the "most accurately classified exposure groups" reveals a statistically significant increased risk of 65 per cent. This analysis was not done by the authors.
Big numbers
"The study's strengths are that it has very big numbers and a very long follow-up in quite a lot of depth," he says. "But being married is not a good measure of how much tobacco smoke gets in the lungs."
This would mean the effects of passive smoking would be underestimated by the study, he says, because some smoking spouses may spend far less time in the same room as their partners. However, Davey Smith also notes that other studies of non-smokers married to smokers have demonstrated harmful effects of passive smoking.
The BMJ has been criticised for publishing what ASH calls "such biased" research. But the journal defended its decision in a statement: "The decision to publish a paper is only taken after careful consideration. It is inevitable that some research may at times be regarded as controversial."
Responding to the criticism, Kabat told New Scientist that he strongly supports anti-smoking legislation. He argues that political motives should not quash science. "There are other studies from that period which have not come in for criticism. Why? Because they found the desired result," he says. "You can't suppress studies you don't like."
Journal reference: British Medical Journal (vol 326, p 1057)
