Posted By Adrian Watson
Dear All,
The relative risk of lung cancer from involuntary smoking at work in never smokers is around 1.03 -1.05, i.e. it is increased by 3-5% above persons who have never smoked nor been exposed to involuntary smoking at work.
The risk of lung cancer from involuntary smoking at work in non smokers is increased by up to 1.34, i.e. it is increased by up to 40% above persons who have never smoked nor been exposed to involuntary smoking at work.
The Sources for this iare IARC Monograph on Tobacco Smoking and Involuntary Smoking Table 2.8 pp 1266 & Table 2.10 pp1269-70 (IARC 2004) & Environmental tobacco smoke and risk of respiratory cancer and chronic obstructive pulmonary disease in former smokers and never smokers in the EPIC prospective study BMJ, doi:10.1136/bmj.38327. 648472.82 (published 28 January 2005)
The incidence of lung cancer in non-smokers not exposed to non-voluntary smoking was 80, (95% CI 60-110) per 100,000 in the EPIC prospective study.
From above you can calculate that the increased risk in never smokers leads to additional 4 (3-6) lung cancers deaths per 100,000 persons exposed to involuntary smoking at work. It should be noted that ex smokers have an increased risk of lung cancer but this is not as large a risk as smokers.
If we use an example of employers working in pubs, bars, nightclubs, hotels and restaurants as an example. I have used this as an example because the author of an Estimate of deaths attributable to passive smoking among UK adults: database analysis [BMJ, doi:10.1136/bmj.38370.496632.8F (published 2 March 2005)] used this group in his study.
He stated that there 320,262 people worked in pubs, bars, and nightclubs, and 829,401 worked in hotels and restaurants. He stated that 30% of the workforce smoked and 11% of the general working population were exposed to environmental tobacco smoke at work.
As a general calculation you can calculate that 45(95% CI 34-70) persons will suffer early death in these industries if everybody in these industry sectors were never smokers and were all exposed to involuntary smoking at work.
This is obviously wrong as some workers are smokers and some workers will not be exposed to non-voluntary smoking at work. If 30% of these workers are smokers, then the exposed population in our example is not 1,149,663 but 804,764 exposed persons i.e. the total population minus smokers.
If you believe that the average exposed rate of 11% is too low, as does the author of the paper, you have to approximate the number exposed to environmental tobacco smoke. The author of the paper believes 100%, but I would guess that around 50% of persons working in pubs, bars, and nightclubs and 30% of persons working in hotels and restaurants are exposed to environmental tobacco smoke at work. This would mean that the exposed population is 325,929. This means that if all these persons were never smokers than the additional number of lung cancer deaths in pubs, bars, nightclubs, hotels and restaurants is 13 (95% CI 10-20).
The author of the paper referred to above, estimated that 20 % of these populations were stable, and would be at risk. If you accept these assumptions then there would be 3 (95% CI 2-4) excess deaths from lung cancer in these industries. If you use the risk rates of 1.34 instead of 1.05 then the estimates of excess deaths for non-smokers from at work is 21 (95% CI 14-28). As can be seen the estimates are open to challenge.
Regards Adrian Watson