UNIVERSITY OF CALIFORNIA-BERKELEY
Tuesday, October 12, 2010

Exposure to dirty air is linked to decreased function of an immune system gene and appears to increase the severity of asthma in children, according to a joint study by researchers at Stanford University and the University of California-Berkeley.

While air pollution is known to be a source of immediate inflammation, this new study provides one of the first pieces of direct evidence that explains how some ambient air pollutants could have long-term effects.

The findings, published in the October issue of the Journal of Allergy and Clinical Immunology, come from a study of 181 children with and without asthma in Fresno and Palo Alto.

The researchers found that air pollution exposure suppressed the immune system’s regulatory T-cells (Treg), and that the decreased level of Treg function was linked to greater severity of asthma symptoms and lower lung capacity. Treg cells are responsible for putting the brakes on the immune system so that it doesn’t react to nonpathogenic substances in the body that are associated with allergy and asthma.

When Treg function is low, the cells fail to block the inflammatory responses that are the hallmark of asthma symptoms.

The findings have potential implications for altered birth outcomes associated with polluted air, much the same as those noted for the effects of cigarette smoke.

“When it came out that cigarettes can cause molecular changes, it meant the possibility that mothers who smoked could affect the DNA of their children during fetal development,” said study lead author Dr. Kari Nadeau, a pediatrician at Stanford’s Lucile Packard Children’s Hospital and an assistant professor of allergy and immunology at Stanford’s School of Medicine.

“Similarly, these new findings suggest the possibility of an inheritable effect from environmental pollution.”

While previous studies have found associations between pollution, especially motor vehicle exhaust, and an increased risk of developing asthma, few have traced its molecular pathway so completely, the study authors said.

“The link between diesel exhaust and asthma could simply have been that the particulates were irritating the lungs,” said Nadeau. “What we found is that the problems are more systemic. This is one of the few papers to have linked from A to Z the increased exposure to ambient air pollution with suppressed Treg cell levels, changes in a key gene and increased severity of asthma symptoms.”

The researchers noted that Treg cells are important for other autoimmune disorders, so the implications of this study could go beyond asthma.

http://www.berkeley.edu/news/media/releases/2010/10/05_asthma.shtml

Breast cancer linked to traffic-related air pollution
INGRID PERITZ
Montreal— From Thursday’s Globe and Mail
Published Wednesday, Oct. 06, 2010 7:45PM EDT

Women living in areas with high levels of traffic-generated air pollution may be at greater risk for breast cancer, Montreal researchers have found.

Scientists from McGill University and the University of Montreal say that while their findings are “disturbing,” they insist the subject needs more investigation.

“This is really a dramatic association,” said study co-author Mark Goldberg, a McGill environmental policy professor. “We never thought that breast cancer would be related to air pollution. We were shocked.”

“This is really a dramatic association,” said study co-author Mark Goldberg, a McGill environmental policy professor. “We never thought that breast cancer would be related to air pollution. We were shocked.”

The researchers used maps measuring pollution from cars and other vehicles at 130 spots around Montreal; then they crossed the information with the home addresses of postmenopausal women diagnosed with breast cancer.

The results, published in the journal Environmental Health Perspectives, were “startling,” the researchers said. Even after taking risk factors such as family history into account, they found that the incidence of breast cancer was markedly higher in more polluted zones.

“Women living in the areas with the highest levels of pollution were almost twice as likely to develop breast cancer as those living in the least polluted areas,” said Prof. Goldberg, a researcher with the McGill University Health Centre.

The researchers examined exposure to smog-causing nitrogen dioxide, and found the risk for breast cancer rose about 25 per cent with every increase of nitrogen dioxide of five parts per billion.

Air pollution wasn’t only a problem for people living next to busy downtown streets or expressways. It also rose on neighbourhood streets if there was a school nearby and parents left their cars idling while dropping off their children.

“These are small pockets of air pollution,” said co-author France Labrèche, an epidemiologist at the University of Montreal.

The findings add to the weight of evidence linking air pollution to a range of health problems. Research has already established a connection to lung cancer and cardiovascular disease.

But the researchers cautioned that their study does not conclude that nitrogen dioxide causes breast cancer, and more study is needed. “One study is not enough to be able to assert that there is a causal relationship,” Prof. Labrèche said.

Also, the authors did not factor in the amount of time women spent indoors or outdoors, or how much time they spent at home.

Still, it should prompt decision-makers to try to reduce urban air-pollution through measures like improving public transit or even synchronizing traffic lights to reduce idling, the researchers said.

The authors crossed over results from air-pollution measurements in 2005 and 2006; they then extrapolated the data to find calculations for the mid-90s, the years they tracked home addresses for women with breast cancer.