Identify a population segment (by race, ethnicity, economic status, geographical location, etc.). Then, explain the relationship between health inequality/inequities and common biological or behavioral risk factors that have been linked to a particular disease in that population segment. Finally, describe the relationship between health inequality/inequities and life expectancy for that population.
Thesis: poorer people are more likely to smoke than richer people, resulting in poorer people being more likely to develop lung cancer.
'Several studies from different parts of the world have shown that smoking and other forms of tobacco use are much higher among the poor' [World Health Organization website, 2014], that is, a person's socio-economic status directly affects their propensity to smoke. This may not be true in every country, and is truer for males than females, but the negative association between smoking and class has been particularly strong in the US [Stellman and Resnicow, 1997; Stellman and Stellman, 1980].
It has also long been known that the prevalence of all-cause premature death is higher among the lower social classes the world over, due to stresses of lifestyle, poorer living conditions, poorer diet. In more modern times, substance abuse can be added to this list, including the smoking of tobacco (and also the consumption of cheap alcoholic drinks).
As early as 1956, the British Doctor's Study run by Doll and Bradford-Hill showed that smoking likely caused certain diseases, including heart attacks and heart disease. The evidence was extremely strong that it causes lung cancer. When the cohort study (that was begun in 1951) was completed in 2001, these results were strengthened. Moreover, calculations regarding reduced life-expectancy amongst smokers were made based on the complete dataset. These and a list of the specific suspected health risks are given in Godtfredsen and Prescott (2001). Of particular interest was that the British Doctor's Study suggested that long-term smokers lived an average of 10 years less than non-smokers. Doll was also able to determine that smoking cessation at 50 years of age cut the risk of premature death in half, while cessation at 30 nearly eliminated the risk altogether. The 'Mortality' and 'Cancer' sections on the Wikipedia page on 'Health effects of tobacco' gives similar (updated for more recent times) statistics, for example - male and female smokers lose an average of 13.2 and 14.5 years of life, respectively; each cigarette that is smoked is estimated to shorten life by an average of 11 minutes.
Looking at whether social class and the habit of smoking add or multiply the likelihood of certain diseases is a complex problem, still under study [Stellman and Resnicow, 1997]. People of lower class may consume fewer fresh fruit and vegetables, a lifestyle choice that has shown to be related to increased incidence of lung cancer for example [Wang and Hammond, 1985]. Stellman (1985) showed that smokers were less likely to consume foods high in vitamins A and C, C in particular being found mainly in fresh fruit and vegetables, but also offal. In Japan, Gao et al (1993) reported a strong protective effect against lung cancer in smokers who consumed
fresh fruits and vegetables frequently. In addition to diet, occupation may also increase the risk of lung cancer. For example Hammond et al (1979), Blot & Fraumeni (1981) showed that the effects of working near asbestos and of smoking were likely to be multiplicative. Other carcinogenic materials found in workplaces (chemicals, radioactive substances) would perhaps similarly multiply with the effects of smoking. Since working as a manual labour/doing 'dirty' work is the reserve of the lower classes, those that do this kind of job (and where carcinogens are in the work environment) may be at higher risk of lung cancer. Finally, there may be genes associated with increased lung cancer risk. Within the poorer levels of the world population, different ethnicities may show higher propensity towards lung cancer, but this may also correlate with social conventions of race such as diet. Herbert et al (1991) reviewed Black-White differences in rates of lung, larynx and other cancers and suggested that ethnic differences in diet are also important.
The evidence from the various sources examined suggests that being poorer, or of lower social class, does indeed increase the likelihood of a person smoking, and that smoking does very likely cause lung cancer. However, the picture is made more complicated by other confounding factors involved, including diet, occupation and ethnic race. Poorer diets, low in fresh fruit and vegetables, occupations involving proximity to carcinogenic substances and race (either by genes, or lifestyle habits such as diet, or class) have been shown to modify the risk of lung cancer. If these lifestyle choices (or simply limitations) are connected strongly to socio-economic class, then they may fully explain higher incidence of lung cancer amongst poorer persons, increased further by the habit of smoking. Access to education and healthcare, exercise levels and stress levels are other important factors that affect health risk in general. The important question is that, if the smoking (and passive smoking) could be entirely removed from the equation, would the incidence of lung cancer in the general population, and most particular amongst poorer persons where the smoking contingent mostly resides? The evidence suggests 'yes', particularly the Doll and Hill British Doctor's Study. The practical problem then is to find effective measures for helping smokers quit. Studies continue to be done in this area, for example that by the COMMIT Research Group (1995). Innovations in products to help smokers quit include the nicotine patch. More recently the electronic cigarette has been developed that avoids the smoking of tar (found in cigarettes), and can have differing levels of nicotine in the fluid. Few studies have been carried out on the safety of the device as it is relatively very new compared to standard cigarettes.