Vol. 9, No. 2, 2003 Page 2
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.
"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.