HIGHLY SENSITIVE MUTATION ASSAY FOR MUTAGENICITY MONITORING OF INDOORAIR USING SALMONELLA-TYPHIMURIUM YG1041 AND A MICROSUSPENSION METHOD

A highly sensitive mutation assay for indoor mutagenicity monitoring w as investigated by a combination of Salmonella typhimurium YG strains and the microsuspension method, Tester strains were YG1024, YG1029, YG 1041 and YG1042. YG1041 gave the highest sensitivity in the mutagenici ty test for the extracts of airborne particulates. The sensitivity of the microsuspension assay using S.typhimurium YG1041 in the absence of S9 mix was similar to 200 times higher than that of the preincubation assay using strain TA98, which has been widely used for mutagenicity monitoring of airborne particulates outdoors. Furthermore, a significa nt correlation was observed between mutagenicities determined by the m icrosuspension assay using S.typhimurium YG1041 and TA98, where mutage nicity assay was carried out for airborne particulates collected by a high volume sampler for 24 h every 12 days for 1 year. This new method was also useful for indoor mutagenicity monitoring in which a small a mount of airborne particulates was collected by a low noise sampler fo r 12 h each of 6 consecutive days. The monitoring showed that mutageni city in the daytime is generally higher than that in the night and tha t smoking is an important factor in increasing mutagencity in indoor a ir.