CHICAGO - Levels of a chemical found in secondhand smoke has dropped sharply in Americans during the past decade, but children and blacks carry amounts that are twice as high as those in the overall population, according to a new federal report.
The findings by the U.S. Centers for Disease Control and Prevention muted encouraging news about a decline in levels of the chemical found in Americans of all ages.
Measuring the effects of secondhand smoke was one of several goals of the CDC's sweeping report, which for the first time found widespread exposure to a group of chemicals found in common household insecticides.
The study also renewed concerns about mercury levels in some women. About 6 percent of the women tested nationwide had levels of mercury in their blood at or near a federal safety limit intended to prevent harm to a developing fetus.
The CDC tested 148 chemicals and heavy metals in the blood and urine of 2,400 Americans, the most substances ever measured. More than three dozen were measured in the general population for the first time.
Agency leaders said the presence of a chemical in the human body doesn't mean it can cause disease. But in many cases, scientists say, there is little or no research to gauge what levels of a chemical are safe or its potential health effects.
"We think it is an astonishing opportunity for us to hone in our research," said Dr. Julie Gerberding, the CDC director.
The report also highlighted the ways public awareness campaigns and government regulations have led to a sharp reduction in exposure to many potentially toxic chemicals.
The proportion of children ages 1 to 5 with elevated lead levels fell to 1.6 percent from 1999 to 2002, down from 4.4 percent during the early 1990s, the report said.
Describing the decline as an "astonishing public health achievement," Gerberding said it was related to the removal of lead from gasoline and efforts to screen and treat children for lead exposure, most of which comes from lead-based paint in older homes.
The Chicago Tribune is a Tribune Publishing newspaper.