UCLAscientists have discovered how chronic exposure to low levels of carbonmonoxide (CO) damages the inner ear of young rats, resulting in permanenthearing loss. At the Cal/OSHA's exposure limit of0.0025 percent — or 25 parts per million CO in the air — the gas creates oxidative stress, a condition that damages thecochlear cells, leading to impairment of the auditory nerves.
Tobaccosmoke, gas heaters, stoves and ovens all emit CO,which can rise to high concentrations in poorly ventilated homes. Infantsand children are particularly vulnerable to CO exposure because they spend agreat deal of time in the home. No policies exist to regulate CO in the home.Most commercial home monitors sound an alarm only 20 minutes after CO concentrationsreaches 70 parts per million — nearly three times the 25 parts per millionlimit set by Cal/OSHA.
Thisis the first time that inhaled CO has been linked to oxidative stress, a knownrisk factor in many disorders, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, Lou Gherig's disease andcardiovascular disease. Tobacco smoke, which contains CO, aggravates many ofthese diseases. The UCLA findings highlight the need for policy-makersto reexamine the regulation of car exhaust, tobacco smoke, smog, and heatingand cooking appliances.
JohnEdmond, professor of biological chemistry; Ivan Lopez, assistant professor ofhead and neck surgery; and Douglas Webber, postdoctoral fellow; at the DavidGeffen School of Medicine at UCLA, are available for interviews.
The research appears in theJune 1 issue of the Journal of Neuroscience Research.
TheUniversity of California's Tobacco-related Disease Research Program and theStein-Oppenheimer Foundation.