Study: Tiny Components of SoCal Haze Invade Human Cells
Particles can harm, kill cells that act as disease defense
©2003 Associated Press, 04/07/2003
LOS ANGELES -- Some of the tiniest airborne particles found in urban haze can invade and shut down cells in human lung lining -- and in animal cells that act as a defense against disease -- according to a study by researchers at two universities.
Their findings go beyond previous studies that much larger components of smog are a factor in shortening life span due to reduced lung function, heart disease and cancer. The new study says small particles can penetrate and deform cells such as those in lung lining and kill the cells by cutting off their power source.
The study was conducted by researchers at the University of California, Los Angeles, and the University of Southern California.
"We have had no idea of the biological potency of different size particles in the air," said Dr. Andre Nel, a UCLA researcher and physician who was lead author of the study.
"Even in the (airborne) things so small they are not monitored, there may be danger lurking," Nel said Monday. He said government air-quality monitoring covers particles collected on filters, while his group's study concentrated on particles so small they go right through air filters.
The study collected microscopic particles at two locations in the Los Angeles area and tested them on human cadaver lung lining and mouse protective cells in an effort "to explain how the smallest particles cause adverse health effects," Nel said.
Causing the cell damage in the study were tiny particles that help make up gray urban haze. The particles were collected in the USC campus area and at Claremont, east of Los Angeles, by 10 members of the study team.
Many of the tiniest particles capable of doing the interior damage to cells "are derived from vehicle emissions," Nel said Monday. They measure only one-tenth of a micron (one millionth of a meter) across and even smaller. The particles were at least 25 times smaller than the size of dust and smoke components that are covered in existing environmental air-quality regulations.
Smog particles of 2.5 microns across or larger are currently regulated in an effort to prevent 15,000 premature deaths, 350,000 cases of asthma and 1 million cases of lung problems in children by the year 2020.
The new study is to be published in the journal Environmental Health Perspectives, a publication of the National Institute of Environmental Health Sciences. One of five national particle-pollution research centers established by the government is located at UCLA.
The researchers collected microscopic air particles between November 2001 and March 2002, put them into solution and added it to machropage cells of mice that destroy foreign matter, and to linings deep inside lungs from a human cadaver.
The solution with the particles caused chemical reactions and triggered inflammation such as that of asthma or other respiratory disease, Nel said. But deeper within the cells the tiniest pollution particles also damaged cell structures called mitochondria which combine sugar and oxygen to produce fuel that keeps cells running.
Melanie Marty, chief of air toxicology and epidemiology at the California Office of Environmental Health Hazard Assessment, commented that the UCLA-USC study shows more governmental attention should be directed to the tiniest particles in urban haze "because of their toxicity and ability to produce this stress in the cell."
Fernando Scaglia, a molecular and human genetics professor at Baylor College of Medicine in Houston said damage to mitochondria in cells can also lead to various diseases including Parkinson's and Alzheimer's, as well as strokes and other neurological impairment.
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