Mortality Rate for Some Forms of Cancer

Much of the information regarding how cancer develops and how it can be treated was painfully learned only after humans began getting the same types of cancer from exposure to a given chemical, or mixture of chemicals, over time. Examples of these chemicals are discussed below. 

Due to the difficulties involved with identifying chemical causes of cancer discussed earlier (e.g., latency time), a definite link between secondhand cigarette smoke, also referred to as environmental tobacco smoke (ETS), has only recently 

EPA first looked at thirty available studies of the lung cancer incidence of nonsmoking women whose husbands were smokers. In twenty-four of these studies, there was an increased risk of lung cancer in the women over those whose husbands did not smoke. Less than half of these studies reported a statistically significant increase. However, the probability that this many studies would find significantly higher risks is less than one in ten thousand. 

As is evident from this example, the process starts with identifying general trends, getting more and more specific as you try to eliminate other sources or causes from consideration. The process usually doesn t work as clearly as shown above. As the U.S. ERA reports, it is unprecedented for such consistent results to be seen in epidemiological studies of cancer from environmental levels of a chemical or chemical mixture. In other words, it is rare that epidemiology alone can be used to link cause and effect. This is due to the many variables that are typically not consistent across all the people included in the studies. These variables that influence toxicity are discussed in chapter 6. 

The lung cancers discussed above represent a form of cancer with a high lethality rate. Some cancers, such as some forms of skin cancer, are not particularly lethal the death rate from skin cancers is less than most other forms of cancer. Skin cancers are tumors of the skin, including those associated with abnormal growth of moles or discolorations of the skin. 

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Table 4.2. Incidence and Mortality Rate for Some Forms of Cancer ...

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