CDC Releases Chemicals Survey

BIOMONITORING

Human exposure to lead and cotinine–a by-product of nicotine–have dropped substantially, according to a study of chemicals in humans by the Centers for Disease Control & Prevention. CDC analyzed blood and urine samples of 2,400 people for 148 chemicals, establishing important baselines for future studies.

The chemicals covered in the new survey, which was released on July 21, include dioxins, polychlorinated biphenyls, phthalates, and pesticides. Pyrethroid insecticides and aldrin, endrin, and dieldrin were tracked for the first time. A follow-up survey will measure 309 substances, including brominated flame retardants and perfluorinated compounds, such as those used to make DuPont’s Teflon.

The survey found that the percentage of children aged one to five years with elevated blood lead levels—greater than 10 µg/dL of blood—has "dropped precipitously" CDC Director Julie L. Gerberding said at a press conference. For the years 1976 to 1980, 88% of children in that age group had toxic levels of lead. In the recent survey, only 1.6% of children had dangerous lead levels.

"This is an astonishing public health achievement" that can be attributed primarily to the removal of lead from gasoline, Gerberding said.

Blood levels of cotinine are a measure of exposure to secondhand smoke, Gerberding continued. Blood levels of cotinine in children aged four to 11 dropped 68% in the past decade, a decline she attributes to the number of adults who have stopped smoking.

One troubling finding is that about 5% of the study population aged 20 years and older had cadmium levels in their urine that may be associated with kidney dysfunction and low bone mineral density. High levels of cadmium come from exposure to tobacco smoke, Gerberding said.

The American Chemistry Council applauds "CDC's scientific efforts to understand exposure to natural and man-made substances." It notes, however, that having a chemical in blood or urine does not mean the substance causes adverse effects.