A major National Research Council study of 1984 found that there was no health hazard data available for 78 percent of the chemicals in commerce, and an Environmental Defense Fund update found little change had occurred a dozen years later. The federal government’s National Toxicology Program tests about ten to twenty chemicals a year for carcinogenicity (but not for the numerous other possible adverse effects of chemicals); but meanwhile five hundred to a thousand new chemicals enter commerce annually, so our knowledge base steadily declines.131
