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July 17, 2008
In recent decades, many have claimed that cancer is rising because of increased use of human-made chemicals. But if chemicals were a source of health problems, one might expect that as chemical use increased around the world, there would be a measurable adverse effect on life expectancy, cancer rates, or other illnesses. Yet in developed nations, where chemical use has greatly increased, people are living longer, healthier lives. According to the the World Health Organization, which is a division of the World Health Organization, the average worldwide human life span has increased from 45 years in 1950 to about 66 in 2000, and it will most likely continue to increase to 77 years by 2050. According to the Centers for Disease Prevention and Control, U.S. life expectancy reached currently 77.8 years in 2004.
Moreover, cancer trends are anything but alarming. Scientists Richard Doll and Richard Peto note in their landmark study on cancer that rates remained nearly constant in the United States during the 20th century except for increases caused by smoking. Improvements in medical technology, more accurate identification and reporting of cancer cases, and—most important—increasing life expectancies that result in more people in the older age groups in which cancer is more likely only make it appear as if rates have increased. Scientists Bruce Ames and Lois Swirsky Gold report that overall cancer rates, excluding lung cancer, have declined 16 percent since 1950. This increase in cancer among the elderly is best explained by improved screening.
The National Cancer Institute (NCI), in its annual report on cancer, has also reported that rates for overall cancer are down in recent years (see figure 1). Rates for almost all specific cancers also are falling. Researchers report that even lung cancer is falling, as a result of reduced smoking rates over the past 25 years.5 They do not mention environmental exposures in the discussion of cancer trends.
It is true that developed nations have higher cancer rates than developing nations and that there was an increase in cancer incidence during the 20th century. The WHO reports that developed nations face cancer rates that are more than twice as high as that of developing nations. The data clearly indicate, however, that chemical use and related pollution are not sources of this problem. Other factors better explain these trends. In particular, cancer is largely a disease related to aging, which means that along with the improvements in life expectancy come increased cancer rates. Also, rates will appear even larger because the median age of the population is getting older. Not surprisingly, the WHO reports that cancer deaths and incidence grew 22 percent between 1990 and 2000. Those trends are expected to continue regardless of chemical use because, as the WHO reports, the number of individuals older than 60 will triple by 2050.