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H Tokiwa

Publications and source records attributed to H Tokiwa.

68 records · Page 4Linked to original sources
PubMed1980

Mutagenic and chemical assay of extracts of airborne particulates.

The mutagenic activity of extracts of airborne particulates was evaluated in the Salmonella system. The mutagenicity of airborne particulates was not always correlated with the content of benzo[a]pyrene (B[a]P) in the complex mixtures, especially when the samples were collected at different sites. Large-scale fractionation of extracts of airborne particulates was used to determine the content of specific mutagenic chemicals. The neutral fraction of material soluble in cyclohexane and nitromethane contained the polycyclic aromatic hydrocarbon (PAH) compounds, which accounted for 27.9% of the mutagenic activity of the whole extracts. 9 kinds of PAH compound were identified quantitatively by thin-layer chromatography. They included, per 1000 m3 of air, 12.6 microgram of benzo[e]pyrene (B]e]P), 10.7 microgram of chrysene (CHRY), 10.0 MICROGRAM OF FLUORANTHENE (FL), 6.43 microgram of benzo[ghi]perylene (B[ghi]P), 5.75 microgram of benz[a]anthracene (B[a]A), 5.33 microgram of B[a]P, 3.38 microgram of pyrene (PYR), 1.83 microgram of coronene (COR), and 1.34 microgram of perylene (PERY). Mutagenicity of the ether-soluble acidic, basic and methanol-soluble neutral fractions accounted for 10.9, 9.71 and 6.78% of the total mutagenic activity of crude extract, respectively, when assayed in strain TA98 with liver S9 fraction. The total recovery of mutagenic activity after fractionation was 58%. Two acidic fractions (weak and strong ether-soluble acids) and the methanol-soluble neutral fraction reverted strain TA98 dramatically to prototrophy in the presence of rat-lung S9 fraction more than liver. But the mutagenic chemicals in these fractions remain to be clarified. Direct mutagens were present in essentially all fractions. The particulates, which had diameters ranging from 0.3 to 1.0 micron and were able to penetrate alveoli, contained a high content of mutagens.

Air Pollutants↗
PubMed1980

Occurrence, formation and precursors of N-nitroso compounds in the Japanese diet.

A survey has been made of volatile nitrosamines in 123 fermented foods. These included salt-fermented vegetables, soy sauce, "miso", Japanese "sake" and other fermentation products. No appreciable amount, or only trace quantities, of NDMA and NPYR were detected in vinegar, "sake", wines and whiskies, while minute quantities of NDMA were detected in 31 out of 33 beer samples, where the levels ranged from traces to 13.8 micrograms/l, with an average of 5.1 micrograms/l. The nitrosamine content of salt-dried fish apparently increased when these products were broiled in a city gas range. A method for the determination of N-alkylureas in foods has been developed. A total of 57 food samples, both uncooked and broiled in a gas range or fried, were analysed. No alkylureas could be detected in these samples.

Animals↗
PubMed1977

Detection of mutagenic activity in particulate air pollutants.

Ames's strains of Salmonella typhimurium were used to evaluate the mutagenic activity of airbone particulate materials collected at six different points in the industrial area of Ohmuta and the residential area Fukuoka. Tests were done in presence of rat-liver S-9 fraction isolated from rats that had been treated with Aroclor 1254. When the number of revertant colonies per plate was plotted against the amount of methanol extract of particulate air pollutants, using strain TA98, approximately linear relationships were observed for active samples. Generally, mutagenic activity of the samples increased in proportion to the density of air pollutants. In our system, 38--349 microng of methanol extract, from 0.225--4.51 m3 of air from the factory districts in Ohmuta City gave 100 his+ revertants per plate. On the other hand, 54--2300 microng of air pollutants, from 1.29--14.1 m3 of air from the residential districts in Fukuoka City, gave a comparable activity. Every sample from each area had mutagenic activity. Chemicals in air pollutants were fractionated by alumina column chromatography and identified by gas chromatography and mass spectrometry. More than 28 compounds, including 12 unknown substances were identified as polycyclic hydrocarbons. Twelve of these compounds are already known to be carcinogens and to induce reversions to histidine independence in strain TA98 of Salmonella.

Air Pollutants↗
PubMedDate not supplied

Influence of the microsomal inducer and the incubation system on mutagenicity of complex mixtures.

The mutagenicity of SRM 1649 and 1650 was tested in the presence of rat liver S9 mix which was induced by polychlorinated biphenyl (PCB) or by the combination of phenobarbital and 5,6-benzoflavone. The S9 mix induced by PCB activated benzo[a]pyrene strongly. The S9 mix induced by phenobarbital-5,6-benzoflavone activated the complex mixtures to approximately the same extent as that induced by PCB. This finding indicates that phenobarbital-5,6-benzoflavone instead of PCB may be suitable as an inducer under some conditions. The preincubation procedure for the mutagenicity test was performed by preincubating the test compound, S9 mix and bacteria for 20 min in a water bath. This procedure was as effective as the plate incorporation test.

Air Pollutants↗