Science for the People
[an error occurred while processing this directive]
March 2002
Download in Adobe Acrobat (PDF) format (496 K)
Features
Is Harding Covering Up for Dow?
Gregory V. Button
For a Clean and Safe Detroit: Close the Country's Largest Incinerator
Mary Beth Doyle and Brad Van Guilder
Westland Activist Cheryl Graunstadt
Monica Heger
Columns
Book Review
Planes, Trains, and Automobiles ... Bikes and Ferries, Too
Gregory V. Button reviews Jim Motavalli's "Breaking Gridlock"
Science for the People
ADHD Levels May Be Higher; PCBs and Infant Development; Men With PCBs Likely to Father Boys; Flame Retardant in the Environment
At the Ecology Center
Annual Meeting; Profile of Jeff Gearhart; New Website; Open Space Zoning Conference; Hybrid Car and Fuel Cell Announcements
Recycle Ann Arbor
Calculating Your Eco Footprint
By Mary Beth Doyle
ADHD Levels May Be Higher Than Estimated
A study by the National Institute of Environmental Health Sciences finds that the prevalence of Attention Deficit-Hyperactivity Disorder (ADHD) may be higher than previously estimated. Researchers from the University of North Carolina School of Medicine in Chapel Hill reported that when they queried parents in a “typical” county of rural and suburban homes (Johnston County, N.C.), the parents reported more than 15 percent of boys in grades one through five had been diagnosed with ADHD, and two-thirds of those were taking medication for the condition. Asking the parents was a key to the higher figures, the researchers thought, because school nurses might not be aware of children who are receiving medication treatment entirely at home.
“Treatment rates are usually viewed as abnormally high if they exceed the 3–5% prevalence estimate for ADHD cited in an American Psychiatric Association manual in 1994,” said the report’s authors. “Therefore, the national public health impact of ADHD may be greatly underestimated by both educators and public health officials.”
Some studies have suggested that environmental contamination may play a role in the development of ADHD.
Rowland, Andrew, et al. “Prevalence of Medication Treatment for Attention Deficit-Hyperactivity Disorder Among Elementary School Children in Johnston County, North Carolina.” American Journal of Public Health 92, no. 2 (February 2002).
Exposure to PCBs After Birth May Affect Infant Development
Exposure to polychlorinated biphenyls (PCBs) after birth can hinder brain development, according to a study published in The Lancet. While earlier studies have suggested that prenatal exposure to PCBs may affect development, the study found exposure after birth may also have a detrimental effect.
The researchers tested 171 healthy babies and their mothers. Prenatal exposure was assessed by measuring PCB levels in umbilical cord blood; postnatal exposure was estimated by measuring PCBs in the mother’s breast milk and in the infants’ blood.
The study found that children whose mothers had the highest levels of PCBs in their breast milk were more likely to exhibit low levels of development, both physically and mentally. However, the adverse effect was less pronounced in children with a stimulating home environment.
Breast milk is still the best food for infants. Studies have shown that breastfeeding, even in a contaminated environment, has a positive impact on the development of children. Breast-feeding provides many physical and psychological benefits to mothers and babies not available to infants fed on formula milks. Indeed, breast milk contains substances that help the child develop a stronger immune system and other protections against environmental pollutants and pathogens.
Walkowiak,, J., et al. “Environmental Exposure to Polychlorinated Biphenyls and the Quality of the Home Environment: Effects on Psychodevelopment in Early Childhood.” Lancet 358, no. 9,293 (November 2001): 1,602–1,607.
Men With High Levels of PCBs More Likely to Father Boys
A Michigan State University study indicating that men with higher levels of PCBs in their bodies are more likely to father boys than girls is more evidence of the effects environmental contaminants can have on the human body.
The study used data from three separate studies in which PCB levels were measured in the bodies of men who ate fish taken from Lake Michigan. The researchers found that of the 208 children born to those men, more than 57 percent were boys. The researchers did not detect that the PCB levels of mothers affected the number of boys or girls.
“We do not wish to say that having a baby boy is bad, it’s just that there were more of them,” said Wilfried Karmaus, the MSU associate professor of epidemiology who directed the study. “A change in the proportion of boys to girls, however, indicates that environmental contaminants may play a role in human reproduction.”
Karmaus, Wilfried, et al. “Parental Concentration of Dichlorodiphenyl Dichloroethene and Polychlorinated Biphenyls in Michigan Fish Eaters and Sex Ratio of Offspring.” Journal of Occupational and Environmental Medicine 44, no. 1 (January 2002): 8–13.
High Levels of Flame Retardant Found in Environment
Michigan State University researchers have found that Lake Michigan salmon have some of the highest levels of polybrominated diphenyl ethers (PBDE) contamination. In individual fish, PBDE concentrations in the fish were highly correlated with the level of polychlorinated biphenols (PCBs), leading the researchers to suggest that PBDEs are as prevalent as PCBs in the environment.
A second study has found that PBDE levels in North Americans appear to be doubling every two to five years. PBDE levels were measured in the breast milk from women in Denver and Austin. Researchers note that the levels of PBDEs were approaching levels of PCBs in breast milk.
PBDEs, commonly used as a flame retardant, have come under scrutiny recently because they are very persistent in the environment, and studies suggest that they may have many of the same adverse health effects as PCBs. Like PCBs, PBDEs have been found to interfere with the hormone system of laboratory animals. PCBs are no longer in production, but PBDEs are still produced and used in many consumer products. Exposure to PCBs and PCBEs is thought to be primarily through consumption of fatty animal foods such as meat, fish, poultry, eggs, and dairy products.
Manchester-Neesvig, John, et al. “Comparison of Polybrominated Diphenyl Ethers (PBDEs) and Polychlorinated Biphenyls (PCBs) in Lake Michigan Salmonids.” Environmental Science and Technology 35, no. 6 (March 2001): 1,072–1,077.
Betts, K. “Rapidly Rising PBDE levels in North America.” Environmental Science and Technology 36, no. 12 (December 2001): 50A–52A.