The Centers for Disease Control and Prevention is expected to release its third snapshot of the chemicals average American carry in their blood and urine. The National Report on Human Exposure to Environmental Chemicals is the world's most extensive assessment of human exposure to natural and synthetic chemicals in the environment.
Among the most reassuring data to emerge from the CDC report, researchers say, are those reflecting levels of lead in the blood of children ages 1 through 5. The figure, which was at 4.4 percent in the early 1990s, was reported at 1.6 percent in the recent study, which covers the years from 1999 to 2002.
Levels of cotinine, a marker of exposure to secondhand smoke, also dropped significantly, the report said. Compared with results of the 1988-1991 tests, levels of cotinine fell by 68 percent in children, 69 percent in adolescents, and 75 percent in adults.
The biomonitoring data lists 148 substances, 38 of which were measured for the first time. The 38 include pyrethroid insecticides and organochlorine pesticides, once commonly used in agriculture. The 475-page report, the third released by the CDC, also measures levels of metabolites, the chemicals that result when products are broken down in the body.