Is There a Threshold Effect for ETS? Results of Data from Chinese Females Who Had Never Smoked

Summary

Although environmental tobacco smoke (ETS) contains compounds which are known to be carcinogenic to humans, does exposure to it in sufficient amounts cause lung cancer or other respiratory diseases in adult women with no history of active smoking? Data from studies in Hong Kong show that the association between ETS and lung cancer is extremely weak, if apparent at all. Furthermore, although symptoms of chronic bronchitis are associated with increased risk for lung cancer in never- and ever-smokers, this symptom was not found to be associated with increasing doses of ETS.

The independent role of diet as being more important than ETS in lung cancer etiology among never-smoked subjects is suggested. More frequent consumption of vegetables and fruit have been consistently found to reduce lung cancer risk in various international studies. Data from Hong Kong indicate that increasing amounts of fresh fruit and decreasing amounts of smoked/cured meats/fish decreased risk for squamous or small cell lung tumors. These same dietary habits were found to be more prevalent among wives with non-smoking versus smoking husbands. Since most studies linking ETS with lung cancer have found the relationship to be specific to squamous or small cell tumors, these findings are consistent with the diet and lung cancer association. Therefore, the lifestyles of wives with smoking Husbands are correlated with habits that could independently exert a deleterious effect on health and help explain the controversial worldwide epidemiological findings linking ETS with lung cancer.