IQ and Blood Lead from 2 to 7 Years of Age: Are the Effects in Older Children the Residual of High Blood Lead Concentrations in 2-Year-Olds?
Increases in peak blood lead concentrations, which occur at 18-30 months of age in the United States, are thought to result in lower IQ scores at 4-6 years of age, when IQ becomes stable and measurable. Data from a prospective study conducted in Boston suggested that blood lead concentrations at 2 years of age were more predictive of cognitive deficits in older children than were later blood lead ... 2005-07-18Challenging Assumptions about Lead and IQ
Effects Increase, Not Decrease, in Older Children
The concentration of lead in children's blood peaks at about age 2 years and then declines as hand-to-mouth activity tends to drop off. Much of the practice and research concerning lead poisoning is based on the belief that the most damage is done by that peak. However, lead's effects on IQ cannot be detected until about 4 or 5 years of age, when IQ becomes testable. Thus, researchers assume, if ... 2005-07-18Secondhand Smoke Exposure May Lower Children's IQ by 2 to 5 Points, Study Suggests
[RESEARCH TRIANGLE PARK, NC] Children exposed to environmental tobacco smoke (ETS)—commonly known as "secondhand smoke"—had mildly to moderately depressed scores on tests of math, reading, and visuospatial skills as compared to children who lacked such exposure, according to a study published today in the January issue of the peer-reviewed journal Environmenta... 2005-07-18Exposure to Environmental Tobacco Smoke and Cognitive Abilities among U.S. Children and Adolescents
We used the Third National Health and Nutrition Examination Survey (NHANES III), conducted from 1988 to 1994, to investigate the relationship between environmental tobacco smoke (ETS) exposure and cognitive abilities among U.S. children and adolescents 6-16 years of age. Serum cotinine was used as a biomarker of ETS exposure. Children were included in the sample if their serum cotinine levels were... 2005-07-18