Mutagenicity of fine (< 2.5 μm) airborne particles: Diurnal variation in community air determined by a salmonella micro preincubation (microsuspension) procedure

Abstract

A simple modification of the Salmonella liquid incubation assay previously developed for detecting mutagens in urine was used to determine mutagenic activity of airborne particulate matter. The modification consists of adding ten times more bacteria (approximately 10(9) per incubation tube) and five to ten times less metabolic enzymes compared to the plate incorporation method. The mixture volume is approximately 0.2 ml, and the mixture is incubated for 90 min before pouring it according to the standard protocol. The modified procedure (micro preincubation or microsuspension) was approximately ten times more sensitive than the standard plate incorporation test for detecting mutagens in air particulate extracts and approximately ten to 31 times more sensitive for the chemical mutagens 2-nitrofluorene, 4-nitroquinoline-N-oxide, 2-aminofluorene, and benzo(a)pyrene in bacterial strain TA98. Mutagenic activity was detected in particle extracts obtained from 1 m3 of air (17 micrograms of extract) or less. This microsuspension procedure was applied to air particulate samples collected with low-volume (15-50 liters per min) virtual-dichotomous air samplers. Mutagenic activity was associated exclusively with fine particles (aerodynamic diameters of less than 2.5 microns). Diurnal patterns of mutagenic activity (TA98 revertants per cubic meter air) were investigated by measuring filter extracts from 2-hr samples collected in three San Francisco Bay Area cities during the summer or fall of 1982. Four criteria pollutants--lead, nitrogen dioxide, ozone, and sulfur dioxide--were simultaneously sampled at one location. Mutagenicity from fine particles sampled at this location was highly correlated with lead and much less correlated with nitrogen dioxide, ozone, and sulfur dioxide. The microsuspension procedure is applicable in testing samples of limited mass.

Organic Compound in Airborne Particles and their Genottoxic Effects in Mexico City

“…When rural and urban monitoring sites are studied during different seasons in the year, the plate incorporation assay with TA98 and TA100 furnishes more reproducible and comparative results (Claxton et al, 2004); when the effect of series of strains are compared, the strains YG are more sensitive to mutagenic nitroaromatic than the TA (Claxton et al, 2001). When the sample amount is very small, another important change in the technique is the microsuspension assay that is more sensitive than the plate incorporation assay, this last one differing in the increment of the number of bacteria and in the time of contact to them (Kado et al, 1983(Kado et al, , 1986. Biological effects of organic matter in vivo and in vitro have been scarcely developed in Mexico.…”

Prediction of health risk due to polycyclic aromatic hydrocarbons present in urban air in Rio de Janeiro, Brazil

“…The organic extracts were assayed for mutagenicity using the microsuspension version (Kado et al, 1986) of the Salmonella/microsome assay (Maron and Ames, 1983). Salmonella typhimurium TA98 (frameshift strain) and the derivative strains YG1021 (nitroreductase-overproducing), TA98/1.8-DNP 6 (O-acetyltransferase deficient) and YG1024 (O-acetyltransferase-overproducing) were used with and without metabolic activation (S9 mix fraction).…”

Seasonal variations in the level of mutagenicity: an assessment of respirable particulate matter in Rio de Janeiro, Brazil

“…The organic extracts were assayed for mutagenicity using the microsuspension version [16] of the Salmonella/microsome assay [17]. Salmonella typhimurium TA98 (frameshift strain) and the derivative strains YG1021 (nitroreductaseoverproducing) and YG1024 (O-acetyltransferase-overproducing) [18] were used, with and without metabolic activation (S9 mix fraction).…”