Blood Weekly (pg. 73)  [Printer-friendly version]
October 12, 2006

NEURODEVELOPMENT INVERSELY RELATED TO BLOOD LEAD LEVELS <10 UG/DECILITER

Neurodevelopment in children is inversely related to blood lead levels
even in the range of <10 mcg/deciliter.

"Increasing evidence suggests that 10 mcg/deciliter, the current Centers for
Disease Control and Prevention screening guideline for children's
blood lead level, should not be interpreted as a level at which
adverse effects do not occur.

"Using data from a prospective study conducted in Mexico City, Mexico,
we evaluated the dose-effect relationship between blood lead levels
and neurodevelopment at 12 and 24 months of age," scientists writing
in the journal Pediatrics report.

According to the authors, "The study population consisted of 294
children whose blood lead levels at both 12 and 24 months of age were
<10 mcg/deciliter; blood lead levels were measured by graphite furnace atomic
absorption spectroscopy.

"Bayley Scales of Infant Development II were administered at these
ages. The outcomes of interest were the Mental Development Index and
the Psychomotor Development Index."

"Adjusting for covariates," wrote M.M. Tellez-Rojo and colleagues in
the Mexico National Institute of Salud Publica in Morelos, children's
blood lead levels at 24 months were significantly associated, in an
inverse direction, with both Mental Development Index and Psychomotor
Development Index scores at 24 months.

"Blood lead level at 12 months of age was not associated with
concurrent Mental Development Index or Psychomotor Development Index
scores or with Mental Development Index at 24 months of age but was
significantly associated with Psychomotor Development Index score at
24 months."

"The relationships were not altered by adjustment for cord blood lead
level or, in the analyses of 24-month Mental Development Index and
Psychomotor Development Index scores, for the 12-month Mental
Development Index and Psychomotor Development Index scores," wrote
investigators.

"For both Mental Development Index and Psychomotor Development Index
at 24 months of age," continued Tellez-Rojo, "the coefficients that
were associated with concurrent blood lead level were significantly
larger among children with blood lead levels <10 mcg/deciliter than it was
among children with levels <10 mcg/deciliter."

Researchers concluded, "These analyses indicate that children's
neurodevelopment is inversely related to their blood lead levels even
in the range of <10 mcg/deciliter. Our findings were consistent with a
supralinear relationship between blood lead levels and neurobehavioral
outcomes."

Tellez-Rojo and colleagues published their study in Pediatrics
(Longitudinal associations between blood lead concentrations lower
than 10 mug/deciliter and neurobehavioral development in environmentally
exposed children in Mexico City. Pediatrics, 2006;118(2):E323-E330).

Additional information can be obtained by contacting M.M. Tellez-Rojo,
Santa Maria Ahuacatitlan, Avenue University of 655, Cuernavaca 62508,
Morelos, Mexico.

The publisher of the journal Pediatrics can be contacted at: American
Acad Pediatrics, 141 North-West Point Blvd., Elk Grove Village, IL
60007-1098, USA.

Keywords: Morelos, Mexico, Pediatrics, Umbilical Cord Blood, Lead,
Neurobehavioral Development.

This article was prepared by Blood Weekly editors from staff and other
reports. Copyright 2006, Blood Weekly via NewsRx.com.