Children Still At Risk from Lead Poisoning, Despite Programs Promoting Cleaning and Home Repair

A review of studies shows that children are still at risk of lead poisoning, despite attempts to encourage home cleaning and repairs, and parental awareness.

Lead author Dr. Berlinda Yeoh, a pediatrician at Sydney Childrens’ Hospital in New south Wales, Australia, says of these attempts that "none that have been tried so far have been proven to be effective." The most common cause of lead poisoning in children is ingestion of dust from old lead paint, and Dr. Yeoh cited lead poisoning as an important health issue for children. It can, she said, contribute to behavior and growth problems, anemia, kidney damage, and other physical, cognitive and behavioral impairment.

Although the sale of lead paint in the United States was prohibited as long ago as 1978 children today can still ingest paint from peeling walls, broken plaster or old painted window sills. 12 U.S. studies, encompassing 2239 children, were examined, and analyzed 2 types of parental interventions—educational and environmental. Educational intervention taught awareness of lead poisoning and methods of preventing dust and lead exposure in the home; environmental intervention suggested making repairs, cleaning and painting.

The Cochrane Library carried the review, and the reviewers’ findings that educational programs for parents had no effect on children’s blood lead levels, which was also the case for environmental programs. Soil abatement, or the replacement of lead-contaminated soil around the home, was also analyzed and 2 studies showed that this significantly reduced childrens’ blood lead levels, although insufficient data prevented recommending these practices as effective. Even studies that combined both educational and environmental interventions failed to reduce children’s blood lead levels.

Dr. Yeoh pointed to other sources of lead exposure—at day care or relatives’ home, for example—which might make home dust removal programs ineffective.

A further reason might be lack of time to be cleaning thoroughly, said Dr. Yeoh. Based on these results, "it is difficult to support the use of the interventions examined in this review as a general population health measure, given their cost and the lack of data showing positive reductions in blood lead levels," the authors said.

Susan Buchanan, M.D., a clinical assistant professor at the University of Illinois at Chicago School of Public Health, called the review "a very thorough evaluation of current literature. It takes so little lead dust to poison a child that it doesn’t matter how clean your house is, your child is still going to have exposure to lead dust," she said.

"As adults, our neurological systems are somewhat immune to the dramatic effects of lead," Buchanan said. However, very young children often put objects in their mouths—increasing their ingestion of house dust and dirt—that in turn affects their developing neurological systems, she said.

"We have to use the knowledge we have—there is lead in dust, so as much dust removal as possible should still be recommended," she said. However, to "continue screening is critical because if high blood lead levels are caught, then health department inspectors can be used to point out obvious sources of lead in the home," Buchanan said.

The review noted that a coauthor, Bruce Lanphear, was an investigator in two of the studies included in this review.

Source: Health Behavior News Service

Low Level Lead Exposure Leads to Chronic Renal Disease in Animal Study

While lead exposure has long been associated with hypertension, arteriolosclerosis and kidney disease, a new animal study from the University of Florida, Gainesville indicates that even low level exposure to lead accelerates chronic renal disease–primarily by raising blood pressure and accelerating injury to kidney tissues and blood vessels.

The study used male rats which were fed a standard diet. In addition, 16 of the rats were given water with lead acetate at a dosage resulting in similar or slightly lower than the levels observed in subjects with occupational lead exposure. Thereafter they underwent remnant kidney (RK) surgery and afterwards continued on the lead acetate for 12 more weeks.

A control group also underwent RK surgery but without lead acetate. At eight and 12 weeks after surgery, the body weight of all the rats was measured and systolic blood pressure was assessed. Twelve weeks after RK surgery, kidney tissue was collected for histologic and molecular biologic studies from both groups.

Study Results
Lead treatment was well tolerated and resulted in modest elevations in whole blood lead levels. However, the lead exposure reduced body weight, increased blood pressure and worsened renal dysfunction.

Specifically, lead exposure:

  • was associated with higher systolic blood pressure and worse renal function, and with a tendency for greater urinary protein; and
  • while scarring in the renal capillary system tended to be worse in lead treated rats, the most striking finding was that kidney tissue disease (arteriolar disease, peritubular capillary loss, tubulointerstitial damage and macrophage infiltration) worsened with lead exposure. These developments were associated with the significantly increased renal expression of monocyte chemoattractant protein-1 mRNA.

According to Dr. Richard J. Johnson, the seior researcher, "This study examined the effect of mild, chronic lead intoxication in an experimental model of chronic renal disease. The dose of lead administered resulted in mild toxicity. This degree of lead poisoning was sufficient to cause higher blood pressures and accelerate the progression of renal failure."

Source: American Journal of Physiology—Renal Physiology (Online Edition)