Secondhand smoke (SHS) and lung cancer plus other health effects

I’ve had a bit of concern today from vapers and a libertarian about the evidence on secondhand smoke exposure and lung cancer. They plied my with a small range of documents eagerly anticipating…um..not sure what..to change my mind perhaps. However I’m touched by their interest in my knowledge and point of view. Anyone getting enthusiastic about science is a good thing.

I’ve read some of the material. Thought well perhaps this is a good time for another one of my mini-reviews on the subject of secondhand smoke exposure and disease.

There’s a list of 5 the articles referred to in the tweets at the end of this blog.

One of the papers is a genetic study and whilst it finds some genetic differences between lung cancers in smokers and some lung cancers in non-smokers it is not evidence that second-hand smoke does not cause lung cancer in non-smokers.

One study is unpublished, not peer reviewed and is funded by the tobacco industry. This study does not outline any methodology and the written interpretation of the data is different to my conclusions from the same data. Their reasons for not interpreting the data as it should be are attributed to a vague discussion of possible bias. Nor are the relative merits of each study included discussed or summarized. This is important – if you lump loads of crap studies with good ones the results tend to get clouded. Bigger is not necessarily better either. A poorly designed study with a big sample size just gives you a bigger pile of bullshit.

The Boffetta et al study is a case-control study conducted in 1998. They found no association between childhood exposure to secondhand smoke and lung cancer. They found weak evidence of a dose-reponse relationship between exposure to smoke and lung cancer. However their study was conducted across many different sites, had varying site methodologies and there is large variation in study outcomes per site.

The Enstrom et al study is a reasonably good one. Thanks for this reference. However as stated by the author it suffers greatly from mis-classification of exposure and focuses only on exposure to smoke via spouse when there would have been considerable exposure to environmental tobacco smoke for people with non-smoking spouses via work and recreation.

Then beyond this selection there are some more recent reviews. One very comprehensive one is the US Department of Health and Human Services published in 2006. This report finds:

Major Conclusions This report returns to involuntary smoking, the topic of the 1986 Surgeon General’s report. Since then, there have been many advances in the research on secondhand smoke, and substantial evidence has been reported over the ensuing 20 years. This report uses the revised language for causal conclusions that was implemented in the 2004 Surgeon General’s report (USDHHS 2004). Each chapter provides a comprehensive review of the evidence, a quantitative synthesis of the evidence if appropriate, and a rigorous assessment of sources of bias that may affect interpretations of the findings. The reviews in this report reaffirm and strengthen the findings of the 1986 report. With regard to the involuntary exposure of nonsmokers to tobacco smoke, the scientific evidence now supports the following major conclusions:

1. Secondhand smoke causes premature death and disease in children and in adults who do not smoke.

2. Children exposed to secondhand smoke are at an increased risk for sudden infant death syndrome (SIDS), acute respiratory infections, ear problems, and more severe asthma. Smoking by parents causes respiratory symptoms and slows lung growth in their children.

3. Exposure of adults to secondhand smoke has immediate adverse effects on the cardiovascular system and causes coronary heart disease and lung cancer.

4. The scientific evidence indicates that there is no risk-free level of exposure to secondhand smoke.

5. Many millions of Americans, both children and adults, are still exposed to secondhand smoke in their homes and workplaces despite substantial progress in tobacco control.

6. Eliminating smoking in indoor spaces fully protects nonsmokers from exposure to secondhand smoke. Separating smokers from nonsmokers, cleaning the air, and ventilating buildings cannot eliminate exposures of nonsmokers to secondhand smoke.

There is also this very recent meta-analysis with a detailed and transparent methodology and an analysis of bias from Japan. A very thorough study. This study finds that

Secondhand smoke exposure in the home during adulthood results in a statistically significant increase in the risk of lung cancer.

In addition to those studies there are numerous studies which show significant reductions in a range of serious illness and deaths following laws which prevent people from smoking inside public spaces. For example, this study on hospitalisation for acute coronary syndromes (bad things happening to hearts) in Scotland which found a 67% decrease. There are other studies like this with consistent results.

Basically taking the cigarette smoke outside has resulted in a much more pleasant, safer environment indoors for both smokers and non-smokers. I’m not about to worry that there is a lack of good evidence for laws requiring people to take the smoke outside. My conclusions remain unchanged despite the smoking guns aka damp squibs offered. There is sufficient evidence of second-hand smoke causing a range of horrible diseases including lung cancer.

These are the research studies and information from various tweets.
1. Hainaut P, Pfeifer GP Patterns of p53 G–>T transversions in lung cancers
reflect the primary mutagenic signature of DNA-damage by tobacco smoke. Funding from National Cancer Institute and European Community

2. Enstrom James E, Kabat Geoffrey C, Smith Davey. Environmental tobacco smoke and tobacco related mortality in a prospective study of Californians. Funding from the American Cancer Society however one of the authors has competing interest and received support from tobacco companies

3. Boffetta et al Multicenter case-control study of exposure to environmental tobacco smoke and lung cancer in Europe. Funding from European Commission DG-XII (contract No. EV5V-CT94-0555) for the coordination; in France, Association pour la Recherche sur le Cancer, European Commission (90CVV01018), and Caisse Nationale d’Assurance Maladie des Travailleurs Sociaux; in Germany 1, the Federal Ministry for Education, Science, Research and Technology (grant No. 01 HK 546) and the Federal Ministry of Work and Social Affairs (grant No. IIIb 7-27/13); in Germany 2, the Federal Office of Radiation Protection, Salzgitter (grant No. St Sch 1066, 4047, 4074/1); in Germany 3, the Federal Office of Radiation Protection, Salzgitter (grant No. St Sch 4006, 4112); in Italy 1, MURST, the Italian Association for Cancer Research (AIRC), and the Regione Piemonte-Ricerca Finalizzata; in Italy 2, the National Research Council (contract No. 91.00327.CT04) and the Italian Association for Cancer Research; in Portugal 1, Junta Nacional de Investigao Cientifica e Tecnolo’gica (JNICT, contract No. PMCT/C/SAU/815.90); in Portugal 2, Comissa ~p de Fomento de Investigao em Cuidados de Salde; in Spain, the Spanish Ministry of Health (Ref. 89002300); in Sweden, the Swedish Match (8913/9004/ 9109/9217) and the Swedish Environmental Protection Agency (5330071-1); and in the U.K., the Imperial Cancer Research Fund, the Department of Health, the Department of the Environment, and the European Commission.

4. Peter Lee, Barbara Forey,  Jan Hamling and Alison Thornton Epidemiological evidence on environmental tobacco smoke and lung cancer. Funded by Tobacco Company

5. A blog by Frank Davis. 110 Passive Smoking Studies. Source of table of studies doesn’t have a reference – Frank links back to another blogger and there’s no clear indication of the source of the table in his blog either. 

 

Serendipity, a couple of STI’s, meningitis and MeNZB….

Late last year I had the privilege of being called in to join a team led by Helen Petousis-Harris to help with the design, data management and analysis of two similar studies designed to answer an odd question? Did the MeNZB vaccine have an effect on gonorrhoea infections?

The MeNZB vaccine was designed to protect New Zealand’s children and teenagers against an epidemic of Meningitis B. This disease occurs when a bacteria called Neisseria meningitidis (type B) invade, replicate and cause painful mayhem and destruction within and around the three layers of cells which form a lining (meninges) around your brain and spinal cord. Neisseria gonorrhoea is a related bacteria which causes a different disease – gonorrhoea or “the clap”. Neisseria gonorrhoea most commonly invade cells which make up the lining of sexual organs, penis, vagina, cervix etc, then also successfully invade cells of the immune system which gather to help fight off the invading bacteria. These two types of bacteria, N. meningitidis and N. gonorrhoea are related and sequencing of their DNA indicates they are about 80-90% similar.

Gonorrhoea, when diagnosed, is usually treated with antibiotics. However in recent years it has been notorious and newsworthy due to development of resistance to that antibiotics that we have available for treating it. If untreated then gonorrhoea can cause more serious disease such as pelvic inflammatory disease and infertility.

Gonorrhoea is considered a disease in need of a vaccine. Much effort and many years have been dedicated to finding a vaccine with limited success to date.

A group of researchers with an interest in Neisseria bacteria species noted that some data from Cuba, Norway and New Zealand suggested a possible effect of a vaccine for meningococcal B on gonorrhoea. These data were mainly coincidental declines in rates of gonorrhoea following meningococcal B vaccination campaigns.

In order to find out with more certainty if it was the vaccine for MeNZB that also helps protect people against gonorrhoea we conducted a case-control study. In this type of study we compare people who have the disease of interest with a group of people who are generally comparable to those who have the disease but do not have the disease. The control group must have the same risk of the disease as the group who developed the disease. For example, the control group needs to have people of the same ages, be living in the same area, have similar behaviour, similar gender composition, similar ethnic composition because all these thing influence whether or not you can develop a disease alongside other factors of influence such as a vaccine. You then find out what proportion of your cases has had the vaccine and compare that to the proportion of controls who have had the vaccine. If the vaccine really does help to prevent the disease then you expect a much lower proportion of people who are vaccinated to be cases compared to the proportion of controls who are vaccinated.

In order to control effectively for different risks due to sexual behaviour we needed controls that were likely to have had similar high risk behaviour. For this reason our controls were people who developed a different bacterial sexually transmitted disease, chlamydia.

Once we found our cases and controls and found out whether or not they had been vaccinated with MeNZB we did a type of statistical test called logistic regression. This is a test make sure that any difference we found between the proportion of controls vaccinated and the proportion of cases vaccinated is a real difference caused by the vaccine and not a difference that could arise easily by chance. We also used the statistical test to make sure that differences in proportion of genders, proportions of different ethnicities etc between the case and control groups did not explain the difference in proportion of vaccinated individuals.

We did find a difference in the proportion vaccinated amongst cases compared to controls that was unlikely to be due to chance. People who received three doses of the MeNZB vaccine and are at risk of developing gonorrhoea appear to be about 30% less likely to develop gonorrhoea.

This is very exciting. It gives us more clues as to what a successful vaccine against gonorrhoea needs. However it is the first study showing such an effect and more studies on the mechanisms and epidemiology are needed. Indeed we are also conducting a cohort study to see if our findings are consistent when using a different method. So stay tuned.

 

Cost of Healthy food versus Unhealthy food

I tweeted recently about healthy food choices versus unhealthy food choices being more expensive and possibly prohibitively expensive for people with low incomes. A paper recently tweeted about by Boyd Swinburn attempts to address this issue and concludes that healthy food is not more expensive.

Boyd Swinburn tweet

So it seems I’ve been labouring under false pretences.  However I read the paper and I’m not entirely convinced. I think the authors are glossing over an issue that I think may be an under appreciated contribution to the obesity epidemic.

Firstly, the unhealthy basket as described by the author comprises more take-aways and convenience food. The healthy basket contains more nutrients with healthy, raw foods most of which aside from fruits, will need a time, co-ordination and cost to turn into appetizing, palatable meals. To simplify, I think, the authors are comparing apples with pears. They are comparing a basket comprised partly of pre-prepared foods with unprepared foods. I think it’s a little naive to pretend time isn’t money. You know the old adage “time is money.”  Plus processing cost such as electricity, water bills etc. There’s also the thinking and planning time required to find suitable recipes that combine what’s in your basket in a meaningful healthy, satisfying way. In a busy modern household this time cost isn’t insignificant.

Secondly our family has recently made an attempt to improve our diet to be more inline with recommendations i.e. less processed carbohydrates, more vegetarian meals but maintaining protein in the form of cheese, tofu, eggs. We’ve stuck to seasonal fruit & veg and our grocery bill has gone up circa $100.00 per week. I know this is an anecdote and maybe if we spent more time looking for bargains or analysing our shopping. Now where can I get that time?

I’ve had to replace de-cluttering/house-garden maintenance with recipe planning and cooking time. We’ve had some jolly tasty fresh meals but I’m starting to trip over plastic boxes and the cupboards are developing a more chaotic state, not to mention the weeds taking over. I may not live to appreciate the benefits of my healthy diet, I’ll suffocate under an avalanche of rampant consumerism and unkempt, inedible chlorophyll!!!

 

 

E-cigarettes are less harmful – the 95% subjective ranking

I have been guilty of being imprecise on twitter – so I’ll elaborate on word press about my concerns with the e-cigs are 95% less harmful than cigarettes figure.

Firstly allow me to be clear – the public health England report on e-cigarettes is an important document that is excellent bar its reference to and use of the 95% figure. The report was needed to address growing irrational and prohibitionist agenda’s which seem to underlie some public health responses to e-cigarettes. This figure was arrived at after a panel of experts subjectively assigned a level of harm based on different criteria to different substances. Professor Larry Phillips, one of the authors of the study explains it on “More or less” and concedes it is a subjective ranking and that is ok because he asserts all other numbers arrived at in science are just as  “subjective”. This is where I disagree strongly. His throwaway comment when you consider it in detail makes a mockery of science to date. While science and the scientific process hasn’t been perfect it has enabled significant progress and is generally more objective than other processes. The process he used IS much more subjective than other studies used in science. Is he qualified to make this sort of pronouncement about the quality of his method relative to others? He isn’t a scientist. Perhaps it reflects his own profession’s tendency for rubbery figures and very speculative estimates (I’m attempting humour here by creating faux scientist versus economist repartee and making a sweeping generalisation). Whilst I acknowledge that any science involving people will have degrees of subjectivity creeping in – by and large there have been processes and methodologies evolved which do help minimise the subjectivity creeping into estimates.

My concern about the 95% figure is due in part to the below mentioned sort of outcome of discussions about it I’ve had with other people.

I’ve asked several friends, colleagues and acquaintances how they think the 95% less harmful figure was derived (these are people who are not scientists, most not involved in health care as professionals). It’s very unlikely they’ll ever question or look in detail at how the 95% figure was actually derived. Their response, prior to me telling them how the number is derived, is fairly consistently that it’s been derived from a study of health outcomes of real people or experiments/studies on the effects on cells etc or animals. When I explain that it was a ranking done by experts, albeit incorporating different categories of harm, they are dismayed and think it is deceptive and an untrustworthy way of presenting the relative harms or lack thereof.

This figure, the way it has been derived and Professor Larry Phillips assertion, I fear, contribute significantly to mistrust and discrediting of science.

Perhaps his method of assessing a complex issue will in time be another robust method for us but it is currently new, untested & the 95% figure is NOT robust or as equally “subjective” as other scientific methods that have had more road testing. It should not have been referred to in a government report which by this action gives the methodology an aura of credibility & rigour it doesn’t warrant.

I also think the Lancet has been disingenuous in it’s criticism of the report. One industry rep on the panel was not the problem and there is much about the report to support.

Thanks very much to Alan, Lorien and some other vapers who I really appreciate having twitter conversations with and who prompted this blog. I love your consistent careful and respectful questioning of my tweets. I appreciate your dedication and think you are a positive force currently in public health.

I probably have much less conflict of interest than most other people on e-cigs. I’m not making money from them, I don’t need to publish on them and I’m not funded to do tobacco control work. I work on vaccines and immunisation now. My Dad died of lung cancer and I hate the thought of many other people suffering in the same way he did.

French playgrounds to be smoke-free: a selection of my thoughts on outdoor smoking bans

There is a growing trend for smoking to be banned in many outdoor public spaces. The policy is often supported with a potential of a fine for the person who is breaching the ban. Canada, U. S. A and Australia all have bylaws or state legislation that prohibit smoking in a number of outdoor public settings including outdoor dining venues, playgrounds, building entrances and beaches. The recent announcement is that France is set to prohibit smoking in children’s playgrounds.

I waver considerably when I think about smoking restrictions in outdoor spaces. I do not like the potential that these bans have to stigmatize or ostracize smokers. On the other hand as a mother I like being able to enjoy outdoor public spaces without my children being exposed to smoke.

One important question that I think needs an answer is: do increasing prohibitions on where you are allowed to smoke help people to stop smoking?

There is some evidence emerging that they do – although the evidence is not strong yet and I haven’t done a systematic review of the studies relating to this question.

With respect to helping or encouraging people to stop smoking, there are two recent studies that I think are relevant. The first was a study set in California. Zablocki and others (2014) found that people who smoke who thought that their city had bans on smoking in outdoor are more likely to reduce their smoking or quit smoking than those who think there aren’t any bans on smoking in outdoor public spaces. The second examined the effect of bans on smoking at outdoor dining and entertainment venues (termed patios in Canada) on smoking cessation in Canada. Chaiton and colleagues interviewed a sample of people at different times. People who reported they had attended outdoor dining venues that didn’t ban smoking were less likely to succeed at quitting smoking compared to those who reported they attended smoke-free dining venues or no outdoor dining venues.

Surveys, such as one by Wilson and colleagues (page 80), that report support among smokers for bans on smoking in some outdoor public setting have certainly helped to strengthen my approval for them. Smoker support for outdoor smoking bans tends to be higher for venues where children are likely to be.

My own current thoughts on e-cigarettes…

E-cigarettes have frequently become the topic of acrimonious debate. They represent a dilemma for public health. On one hand they offer a less harmful alternative for smokers. On the other hand they are an addictive risk for young vulnerable non-smokers. They may also have risks associated with longer term use or risks that manifest themselves later in a person’s life. There is very little control of quality and therefore safety of many of the different types of e-cigarettes.

Using e-cigarettes is generally known as vaping. I strongly support making e-cigarettes more easily accessible to smokers than smoked tobacco. It is better that smokers quit entirely but many smokers report that vaping has helped or reduce their smoking. There is mixed evidence from clinical studies on how effective they are at helping cessation. However there is one study from the University of Auckland that demonstrates they are as effective as nicotine replacement therapy.

At the moment, I do not support making e-cigarettes more highly regulated than smoked tobacco. That just seems weird and ridiculously inconsistent. However I think what does need stringent monitoring and restriction is how we promote and advertise e-cigarettes, particularly in countries where tobacco advertising in most mainstream media is banned.

Communications about e-cigarettes need to emphasise our lack of knowledge about risks and that if used with nicotine they will be addictive and potentially tie the user to a life-long obligation/burden with unknown risk to health. Non-smokers need to be strongly discouraged. However we also need to make it clear that a switch to vaping if you can’t quit smoking is vastly preferable to continued smoking based on current knowledge.

Finally I’m a scientist and my thoughts and positions are both fallible and subject to change based on good data and research.🙂

Pohutukawa and friends

I was inspired to do this post by the recent campaign to save six pohutukawa trees along Great North Rd.

Oh and by a beautiful day on Tiritiri Matangi Island.

???????????????????????????????The red pohutukawas stood out along the densely growing cliff face as you look North from the path that heads from the wharf. The red in the foreground on the beach is a carpet of pohutukawa flower filaments and anthers.

Here is tieke admiring pohutukawa from the branches of what I think is a Coprosma sp.

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Here is profusely flowering pohutukawa being photo bombed by flax (so cheeky)

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Here is pohutukawa, nestled in to look at the view across Hauraki gulf with cabbage trees.

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I was so very lucky to catch a kokako enjoying itself bathing. Then to my delight it flew and perched directly above me.

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Finally here is pohutukawa (this one opting for a less profuse but nonetheless elegant floral display) standing proud with kanuka

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To the six pohutukawa’s on Great North Road we send our love & if our roots could move we’d be on that 360 degree ferry and down SH1 to stand with you…