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Prenatal mercury linked to cognition, language delays
The Centers for Disease Control and Prevention (CDC) issued a report
several years ago warning that ten percent of women in America are at
risk of having infants with neurological disorders due to prenatal
exposure to high levels of environmental mercury. A new study adds to
the evidence supporting that warning, showing that children exposed to
mercury in utero have a high rate of language and cognitive problems.
The new study involved residents of Tagum, an area of the Philippines
where residents are exposed to high levels of mercury due to mining
activity. G. B. Ramirez et al. analyzed 48 Tagum children's cord blood
and meconium mercury levels, head circumference at birth, and duration
of breastfeeding, and then measured their cognition and linguistic ability
at age 2 using the CAT/CLAMS (a combination of the Cognitive
Adaptive Test and the Clinical Linguistic Auditory Milestone Scale). The
subjects were compared to children from Saranggani, another area of the
Philippines.
"The mercury level in cord blood was negatively correlated with
CAT/CLAMS at two years," the researchers say. They found that the
mercury-exposed Tagum children scored lower than control children on
both the CAT and the CLAMS, and had lower scores in both expressive
language and full-scale development. "Fifteen percent of Tagum subjects
had global delay," they note, "versus 5.48 percent in Saranggani
controls." Length of breastfeeding did not correlate with developmental
scores in this study.
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"Tagum study II: follow-up study at two years of age after prenatal
exposure to mercury," G. B. Ramirez, O. Pagulayan, H. Akagi, A.
Francisco Rivera, L. V. Lee, A. Berroya, M. C. Vince Cruz, and D.
Casintahan, Pediatrics, Vol. 111, No. 3, March 2003, e289-95.
Address: G. B. Ramirez, Research Development Office, Philippine
Children's Medical Center, Quezon City, Philippines,
rdo@hiss.pcmc.org.ph.
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