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G Löfroth

Publications and source records attributed to G Löfroth.

At least 37 records · Page 2Linked to original sources
PubMed1984

Short-term bioassays of fractionated emission samples from wood combustion.

Extracts of an emission sample from wood burning, consisting of particles and volatiles, have been fractionated on an HPLC silica gel column into five fractions of increasing polarity. Nonfractionated samples and the individual fractions have been tested in three different short-term bioassays: the Ames Salmonella assay, the sister chromatid exchange (SCE) induction-test in Chinese hamster ovary cells (CHO), and the cell transformation test on Syrian hamster embryo (SHE) cells. Most of the total activity was found in the volatile part of the sample with all three bioassays, whereas the particle extract had the highest activity per unit mass extracted. The second most polar fraction contained most of the mass and was also highly active in all assays. The most polar fraction was very potent in the Salmonella assay, but showed only a weak response in the eukaryotic bioassays. Storage of the samples for several months at 0 degrees C revealed that the bacterial mutagens present in the most polar fraction were labile; the mutagenicity was almost totally lost after 1 year's storage.

Animals↗
PubMed1984

Short-term bioassays of nitro derivatives of benzo[a]pyrene and perylene.

Several nitroarenes derived from benzo[a]pyrene and perylene and the parent hydrocarbons have been assayed for mutagenicity in the Salmonella microsome test and for affinity for the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-receptor protein in rat liver cytosol. 1- and 3-nitrobenzo[a]pyrene are mutagenic in the absence of S9 and have a response pattern in several Salmonella strains resembling that shown by 1-nitropyrene. 6-Nitrobenzo[a]pyrene, 3-nitroperylene as well as the parent unsubstituted hydrocarbons require S9 for activation. The 3,6- and 3,7-dinitroperylenes and a mixture of 3,9-/3,10-dinitroperylene are all mutagenic in the absence of S9. The response pattern of 3,9-/3,10-dinitroperylene resembles that shown by 1,6- and 1,8-dinitropyrenes. The nitro derivatives which are active in the absence of S9 are all inactivated by the addition of an incomplete S9 lacking NADP but activity is regained in the presence of the complete S9 for 1-and 3-nitrobenzo[a]pyrene and 3,6-dinitroperylene, showing that these compounds are also activated by S9 enzymes. Benzo[a]pyrene, 1- and 3-nitrobenzo[a]pyrene, 3-nitroperylene and the mixture of 3,9-/3,10-dinitroperylene have a high affinity for the TCDD-receptor protein whereas the affinity is low or below the detection level for the other compounds. These results are in good agreement with known structural requirements for receptor binding.

Animals↗
PubMed1983

Compounds in urban air compete with 2,3,7,8-tetrachlorodibenzo-p-dioxin for binding to the receptor protein.

Acetone extracts of filter-collected urban airborne particulate matter contain compounds which can competitively inhibit 2,3,7,8-[1,6-3H]tetrachlorodibenzo-p-dioxin (TCDD) binding to the rat liver TCDD-receptor protein. The concentration of conventional polycyclic aromatic hydrocarbons (PAHs) or chlorinated dioxins and dibenzofurans cannot account for more than 1-30% of the observed competition for [3H]TCDD binding to the receptor protein. The difference in potency between samples collected in urban areas during different periods of the year and a background sample is 25-400-fold. Collecting samples in the presence of increased concentrations of nitrogen dioxide, nitrous acid, nitric acid or ozone did not increase the amount of compounds with receptor affinity. However, with nitrogen dioxide and especially with nitric acid, a substantial increase of the mutagenic effects in the Ames Salmonella assay in the absence of mammalian activation as well as a degradation of several PAHs were noted. Affinity for the TCDD-receptor protein, mutagenicity in the absence of mammalian metabolic activation in the Ames Salmonella assay and PAH-content are characteristics of urban particulate matter showing the presence of compounds, that represent potential health risks. The compounds with affinity for the receptor may constitute a group of substances different from both conventional PAHs and direct-acting mutagens.

Air Pollution↗
PubMed1983

Mutagenicity of extracts from typewriter ribbons and related items.

Extracts of typewriter ribbons and carbon papers were found to be mutagenic in the Salmonella/microsome assay with strain TA98. Fractionation of ribbon extracts indicates that at least 2-3 different classes of mutagenic component are present in these extracts. Nitro-containing compounds may be responsible for the high mutagenicity observed for some of the ribbon extracts in the absence of S9. The results indicate that impurities in the products may be causing part of the mutagenic effect.

Ink↗
PubMed1983

Bioassay of extracts of ambient particulate matter.

Organic extracts from airborne particles collected at various sites in Scandinavia have been tested for mutagenicity in the Ames Salmonella/microsome assay. Extracts from particles in the respirable size fraction (diameter less than 3 microns) were mutagenic with and without metabolic activation. The mutagenic activity varied from day to day, mainly due to variations in meteorological parameters, especially wind speed and atmospheric stability. A seasonal variation could also be observed, with the highest average values in winter time. Samples collected in urban areas were considerably more mutagenic than samples from background areas. The results suggest that exhaust from motor vehicles are the most important source of mutagenic particles in urban areas. Comparison of roof top samples with street level samples indicated that atmospheric reactions cause transformation of nonpolar compounds in the primary emission to more oxygenated mutagenic compounds. It is, however, not known to which degree this causes an overall increase of the mutagenic activity. The mutagenic activity of emissions from stationary combustion sources have also been studied, and residential heating by burning solid fuels in small combustion units have been shown to be a major contributor to mutagens in the environment.

Air Pollutants↗
PubMed1980

Mutagenic activity in photocopies.

Extracts from several different photocopies were mutagenic in the Ames Salmonella assay. The mutagenic behavior was similar for extracts from copies and corresponding toners indicating that toners are directly responsible for the mutagenicity. The mutagenicity is caused by at least two classes of compounds which may be present either alone or in combination in any toner.

Animals↗
PubMed1971

Diethyl pyrocarbonate: formation of urethan in treated beverages.

Isotope dilution analyses with tritium-labeled diethyl pyrocarbonate show that the carcinogen urethan is formed in orange juice, white wine, and beer. Commercial use of the antimicrobial food additive diethyl pyrocarbonate can result in urethan concentrations of 0.1 to 0.2 milligram per liter in orange juice and of the order of 1 milligram per liter in white wine and beer.

Ammonia↗
PubMed1970

DDT in Milk.

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Letter↗