This ratio has persisted for years. We also see different rates among ethnic and geographical population groups which are inconsistent with smoking habits. For example. the British smoke about as many cigarettes as Americans. but exhibit almost twice the lung cancer rate. British male immigrants to South Africa and New Zealand demonstrate a significantly higher lung cancer rate than native born Caucasians in both these countries despite their cigarette consumptions being similar. There is also an unexplained difference between urban and rural lung cancer when smoking habits are adjusted. This raises the question of air pollution and its relation to lung cancer.
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immigrants