Mexico City’s air pollution may be undermining neural and mental functioning in some children…
Mexico Passes National Climate Change Legislation
Recent research by Henrik Svensmark and his group at the Danish National Space Center points to the real cause of the recent warming trend. In a series of experiments on the formation of clouds, these scientists have shown that fluctuations in the Sun’s output cause the observed changes in the Earth’s temperature. In the past, scientists believed the fluctuations in the Sun’s output were too small to cause the observed amount of temperature change, hence the need to look for other causes like carbon dioxide. However, these new experiments show that fluctuations in the Sun’s output are in fact large enough, so there is no longer a need to resort to carbon dioxide as the cause of the recent warming trend. The discovery of the real cause of the recent increase in the Earth’s temperature is indeed a convenient truth. It means humans are not to blame for the increase. It also means there is absolutely nothing we can, much less do, to correct the situation.
Thomas Laprade
Thunder Bay, Canada
Bad air for growing brains and minds
By Bruce Bower
October 10th, 2008
Mexico City’s air pollution may be undermining neural and mental functioning in some children
Mexico City wears a thick coat of air pollution that clogs lungs and takes a toll on hearts and blood vessels. But that’s just the beginning — the metropolis’s dirty air may have contributed to brain inflammation and intellectual deficits in at least some school-age children, a new study suggests.
Among healthy children aged 7 to 18, lifelong Mexico City residents scored lower than their peers from Polotitl?n — a Mexican city with low levels of air pollution — on tests of memory, flexible thinking, novel problem-solving skill and the ability to monitor and change one’s behavior during challenging tasks, scientists report in an upcoming Brain and Cognition. These tests make up part of standard IQ measures for school children.
What’s more, brain scans of many Mexico City youngsters revealed alterations that can impair the prefrontal cortex, a neural region heavily involved in memory and thinking skills, say environmental pathologist Lilian Calder?n-Garcidue?as of the University of Montana in Missoula and her colleagues.
Similar brain alterations, as well as evidence of neural inflammation, appeared in 1- to 2-year-old dogs that had grown up in Mexico City, the investigation finds.
Widespread declines in intelligence of the type and magnitude observed in the new report would have a huge impact on a country’s economic productivity, says psychologist and study coauthor Randall Engle of the Georgia Institute of Technology in Atlanta. “Saving money by failing to curb pollution truly is a matter of ‘pay me now or pay me later,’” Engle says.
Although their findings are preliminary, the researchers hope to conduct a five-year study tracking large groups of children living in areas with low and high air pollution. The most common air pollutants in Mexico City are particulate matter, which contains a complex mixture of various substances, and ozone. Polotitl?n’s air contains low concentrations of all major pollutants.
“The growing brain may be vulnerable to the inflammatory effects of air pollution’s fine particulate matter as well as to specific chemicals that are toxic to brain growth,” comments neuropsychologist Sidney Segalowitz of Brock University in St. Catharines, Canada.
Children in Mexico City and Polotitl?n showed large neural and cognitive differences that need to be confirmed in further work, remarks epidemiologist David Bellinger of Children’s Hospital Boston. The new study didn’t measure the composition of Mexico City air pollution, so chemical culprits possibly responsible for the results remain unknown, Bellinger notes. Children’s increased lead exposure in Mexico City could also have contributed to lower scores on mental tasks, he adds.
Blood testing before admission to the study found no differences in average lead concentrations of Mexico City and Polotitl?n children, Calder?n-Garcidue?as says.
She and her coworkers recruited 55 children from Mexico City and 18 children from Polotitl?n. All children came from middle class families and had no serious health problems.
Mexico City kids generally scored lower on specific memory and reasoning tests than their counterparts did. Using magnetic resonance imaging, or MRI, on a subset of the children, the researchers observed tissue alterations typical of inflammation in the brains of 13 of 23 Mexico City youngsters and 1 of 13 Polotitl?n children.
Neural alterations were located near the front of the brain in tissue that could obstruct nerve transmissions sent to and from the prefrontal cortex.
In three Mexico City children who received another round of MRI scans 11 months after initial testing, frontal-brain tissue alterations remained the same.
Calder?n-Garcidue?as’ team then conducted brain studies of seven healthy Mexico City dogs and 14 healthy dogs from Tlaxcala, another Mexican city with low levels of air pollution. All dogs were mixed breeds and had been reared at animal research facilities.
Comparable inflammation-related tissue alterations in the frontal brain appeared in four of seven Mexico City dogs and none of the others. In tissue analyses, brains of Mexico City dogs also displayed particularly high levels of substances produced by two genes that have inflammatory effects on the brain.
In studies conducted since 2002, the researchers have reported signs of brain inflammation and brain disease in dogs exposed to Mexico City’s air. Earlier this year, the researchers found that chronic exposure to air pollution was associated with markers of brain inflammation and increased brain immune responses in children and young adults who had died suddenly and were studied at autopsy. These individuals also possessed high levels of brain proteins thought to contribute to Alzheimer’s and Parkinson’s diseases.
