Children more vulnerable to harmful effects of lead

Contrary to prevailing assumptions, children are more vulnerable to the harmful effects of lead exposure at the age of 6 than they are in early childhood, according to a Cincinnati Children’s Hospital Medical Center study to be presented May 4 at the annual meeting of the Pediatric Academic Societies in Honolulu.

“Although we typically worry about protecting toddlers from lead exposure, our study shows that parents and pediatricians should be just as, if not more concerned about lead exposure in school-aged children,” says Richard Hornung, Dr.P.H., a researcher in the division of general and community pediatrics at Cincinnati Children’s and the study’s main author.

The researchers found that blood lead concentrations (BPb) at age 6, compared to those at younger ages, are more strongly associated with IQ and reduced volume of gray matter in the prefrontal cortex of the brain, which is involved in planning, complex thinking and moderating behavior.

Overall, the children’s average BPb levels peaked at 13.9 micrograms of lead per deciliter of blood at age 2, then declined to an average of 7.3 micrograms per deciliter by age 6. For children, however, with the same average blood lead levels through age 6, those who received more of their exposure at age 6 had substantially greater decrements in intellectual ability than those more heavily exposed at age 2.

“Lead toxicity is difficult to recognize in a clinical setting, but it can have devastating effects,” says Bruce Lanphear, M.D., director of the Cincinnati Children’s Environmental Health Center and the study’s senior author. “We found that children may be particularly vulnerable to lead exposure just as the child approaches school age, during a period of rapid cognitive development.

Because IQ tests were not administered to children older than 6, it is unknown whether older children are even more vulnerable to environmental lead exposure, according to Dr. Hornung.

Approximately 310,000 U.S. children age 1 to 5 years have blood lead levels greater than 10 micrograms per deciliter, the level at which the Centers for Disease Control and Prevention recommends public health actions be initiated. But research has consistently shown that blood lead levels considerably lower than 10 micrograms per deciliter are associated with adverse effects.

Federal and state regulatory standards have helped to minimize or eliminate the amount of lead in U.S. consumer products and occupational settings, according to the National Institute of Environmental Health Sciences (NIEHS). Today, the most common sources of lead exposure in the United States are lead-based paint in older homes, contaminated soil, household dust, drinking water, lead crystal and lead-glazed pottery.

While extreme lead exposure can cause a variety of neurological disorders, such as lack of muscular coordination, convulsions and coma, lower lead levels have been associated with measurable deficits in children’s mental development and behavioral problems. These include hyperactivity, or ADHD, lowered performance on intelligence tests, and deficits in fine motor function, hand-eye coordination and reaction time. Chronic lead exposure in adults can result in increased blood pressure, decreased fertility, cataracts, nerve disorders, muscle and joint pain as well as problems with memory or concentration.

Source: Cincinnati Children's Hospital Medical Center

Related stories:

Researchers study hidden homicide trend
Gun-related homicide among young men rose sharply in the United States in recent years even though the nation's overall homicide rate remained flat, according to a study by researchers at the Johns Hopkins Bloomberg School of Public Health. Between 1999 and 2005, homicide involving firearms increased 31 percent among black men ages 25 to 44 and 12 percent among white men of the same age. The study is published in Online First edition of the Journal of Urban Health.
Study indicates grape seed extract may reduce cognitive decline associated with Alzheimer's disease
A compound found in grape seed extract reduces plaque formation and resulting cognitive impairment in an animal model of Alzheimer's disease, new research shows. The study appears in the June 18 issue of The Journal of Neuroscience.
Hearing loss is common in people with diabetes
Hearing loss is about twice as common in adults with diabetes compared to those who do not have the disease, according to a new study funded by the National Institutes of Health (NIH).
NASA data helps pinpoint impacted populations in disaster aftermath
When two catastrophic natural disasters struck within days of each other in May 2008, disaster relief, humanitarian aid, and health officials, as well as members of the news media tapped into a unique set of NASA data products describing the location of the exposed populations. In the hours and days following the cyclone in Burma and the earthquake in China's Sichuan Province, workers had the data they needed to assess the numbers of people possibly affected in these deadly events. What arose was a timely example of how NASA data comes to the aid of officials when such disasters occur.
Road pollution blamed for higher allergy risk in kids
New evidence blames traffic-related pollution for increasing the risk of allergy and atopic diseases among children by more than fifty percent. What's more, the closer children live to roads, the higher their risk.
Increased incidence of melanoma found in rheumatoid arthritis patients treated with methotrexate
A chronic, inflammatory disease of unknown origin, rheumatoid arthritis (RA) affects about 1 percent of adults worldwide. Marked by joint destruction, RA often leads to disability and diminished quality of life. It can also lead to an early death from cancer. Various studies have linked RA to an increased risk of Hodgkin's and non-Hodgkin's lymphoma, leukemia, myeloma, and lung cancer.
Childhood lead exposure is associated with increased risk of criminal arrest in adulthood
Childhood exposure to lead is associated with adult criminal behaviour, including violent crime, finds a new study in this week’s PLoS Medicine. Dr Kim Dietrich and colleagues (University of Cincinnati, USA) studied the association between exposure to lead in the uterus and during early childhood and criminal arrests in adulthood, in poor areas of Cincinnati.
Study reveals link among childhood allergies, asthma symptoms, and early life exposure to cats
A study released by researchers at the Columbia Center for Children's Environmental Health (CCCEH) at Columbia University’s Mailman School of Public Health, shows that cat ownership may have a protective effect against the development of asthma symptoms in young children at age five. The study, published by the Journal of Allergy and Clinical Immunology, found that children with cats in the home were more likely to have made allergy-related antibodies to cats.

News discussion:

Medicine & Health news