Often incomprehensible science, involving dead rats and complex mathematical formulas used to guess the risk from exposure to different chemicals. Environmental Protection Agency's (EPA's) scientific decisions are reviewed by a panel of outside experts called the Scientific Advisory Panel. This board meets periodically to look at EPA decisions such as canceling a pesticide's use, conducting a special review of a problem pesticide or establishing scientific policies on carcinogen rankings or risk assessment. Since 1988 EPA scientists and policymakers have been working to revise the cancer risk assessment guidelines to reflect advances in understanding about how chemicals cause cancer. Many people are urging EPA to look at health effects other than cancer, such as neurotoxic damage. That refers to the central nervous system and can involve temporary symptoms such as nausea or permanent nerve or brain damage.