Human Cell Mutagens In Los Angeles Air

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Print media: Jim Bohning, 202/872-6041 (office), [email protected] Broadcast media: Theresa Laranang-Mutlu, 202/872-4371 (office), [email protected] For a copy of the full article: Sally Pecor, 202/872-4451 (office), [email protected]

2/3/97 #12123 News Summary

HUMAN CELL MUTAGENS IN LOS ANGELES AIR

Mutagens agents capable of causing changes in human genes have long been known to be present in urban air, but their detection and potency has mostly been measured with a bacterial test. However, extrapolating the observed mutagenic effects from bacteria to humans continually leads to questions about the relevance of bacterial assays, says Dr. Glen R. Cass of the California Institute of Technology. The research by his group in conjunction with investigators at MIT represents the first time a human cell mutation assay has been applied to an atmospheric particle monitoring network. The results are reported in the February issue of Environmental Science & Technology, a monthly publication of the American Chemical Society.

The Caltech and MIT investigators examined the mutagenic activity of fine particles in the air at sites in central Los Angeles, Azusa, Rubidoux, Long Beach, and San Nicolas Island in southern California. There was no seasonal variation, which Cass suggests de-emphasizes seasonal emission sources such as wood combustion. It also signifies that if mutagens are formed by photochemical changes in the air pollution of the area, the chemical reactions must be occurring during the winter as well as during the summer photochemical smog season.

Generally, there was no difference between the mutagenic potency of the particulate matter in three of the four urban locations, with the average in Long Beach being slightly higher than the rest. Cass believes that the similarity of mutagenic potency across widely separated monitoring sites points to ubiquitous emission sources such as motor vehicle traffic and stationary source fuel combustion. But when the urban sites were compared to San Nicolas Island, which is upwind of the city, there was a pronounced difference, with mutagen concentrations in Los Angeles air ten times greater than the off-shore background site. "Clearly," Cass says, "the city is a source of human cell mutagens."

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