The urine mutagenicity assay system: studies related to recovery, storage, and concentration procedures.
A urine mutagenicity test for assaying airborne exposure was examined. Airborne particles were collected on glass fiber filters with a high volume sampler 10 meters (m) above the ground. Diesel emission particles were obtained from the exhaust pipe of a diesel truck; coal (8002059) dust was taken from a bituminous coal mine. Urine samples collected from nonsmokers were pooled and divided into several subsamples. Subsamples were spiked with 400 micrograms (microg) 2-aminoanthracene (613138) (AA), 1.2 milligrams (mg) benzo(a)pyrene (50328) (BaP), 12microg aflatoxin-B1 (1162658), 1.2 grams (g) dimethylnitrosamine (62759) (DMN), 12mg 20- methylcholanthrene (56495) (MC), 3.6microg 2,4,7-trinitro-9- fluorenone (129793) (TNF), 750mg nitrosated coal dust extract, 45mg diesel emission particle extract, or 326mg airborne particle extract. Chemicals, complex mixtures, and urine concentrates were tested for mutagenic activity with the Ames Salmonella microsome assay system. The plate incorporation and preincubation tests with or without S9 activation were employed using tester strain TA-98 or TA-1535. Mutagenic activity did not decrease when urine samples spiked with BaP, aflatoxin-B1, or MC were stored up to 28 days; a 50 percent decrease in mutagenic activity was found when urine samples spiked with TNF were stored at minus 70 degrees-C for 28 days. No mutagenic activity was detected when the urine sample was spiked with DMN; recovery was around 80 percent for AA and TNF but less than 10 percent for BaP and MC. At similar concentrations, the concentrate from aflatoxin-B1 spiked urine produced 4 times more revertant colonies than controls. The recovery of different coal dust samples was 10 percent. A 4 fold increase was found in diesel emission particles when both acetone and methylene-chloride were used for elution instead of acetone alone. The authors conclude that the mutagenic activity of chemically spiked urine remains unchanged after 7 days, then decreases by about 50 percent for some compounds after 28 days of storage.