Mutagenic and clastogenic activity of direct-acting components from air pollutants of the Silesian industrial region

The effects of seasonal weather on the genotoxicity, cytokinetic properties, cytotoxicity and organochemical content of extracts of airborne particulates in Mexico City

Extracted organic material (EOM) from PM10 airborne particles collected during three distinct seasons in Mexico City was assayed for genotoxicity, cytokinetic effects and cytotoxicity. Using sister chromatid exchange (SCE) for genotoxicity, replication index (RI) and mitotic index (MI) for cytokinetics, and microscopic evaluation (cell death) for cytotoxicity on human lymphocytes exposed to increasing concentrations of EOM, this study showed that the extent of genotoxic, cytokinetic, and cytotoxic change caused by pollutants depended at least in part on the seasonal weather. Bioactivated extracts of samplings in April (warm and dry), August (warm and rainy) and November (cool and dry) produced the highest rate of genotoxicity (SCE) in November and the lowest rate in April. Without bioactivation the rates were still highest in November but equally low in April and August. Thus, almost all of the genotoxic responses in the bioactivation experiments during these latter months were from promutagens. However, in November equally large amounts of mutagens and promutagens were present. Cytokinetics (RI and MI) showed steady decreases as the concentration of EOM was increased, independent of bioactivation and weather. Cytotoxicity (cell death) occurred when higher concentrations of EOM were used. EOM was the least cytotoxic in April and most cytotoxic in November. Bioactivation was not required for cytokinetic change and cytotoxicity, suggesting that the agents involved may be different from the genotoxic agents. Using gas chromatography/mass spectroscopy (GC/MS) it could be shown that the type of pollutant chemicals in the EOM also depended on the weather. In particular, all 15 polycyclic aromatic hydrocarbons (PAH) studied were present in November EOM whereas four different PAH were absent in the other 2 months. Generally the amounts were less in the EOM collected in April and August. Conversely, nitro-PAH compounds were greater in number in April EOM but higher in amount in November EOM. The significance of these findings is discussed.

HSP70 overexpression increases resistance of V79 cells to cytotoxicity of airborne pollutants, but does not protect the mitotic spindle against damage caused by airborne toxins

Exposure of Chinese hamster V79 cells to extracts of airborne pollutants induced formation of multipolar or incomplete mitotic spindles. To find out whether overexpression of the HSP70 chaperone protein could protect spindles against airborne toxins we constructed V79 cells stably transfected with an expression vector containing rat heat-inducible hsp70.1 gene under the control of a constitutive CMV promoter. When cells were incubated with extracts of airborne pollutants (5-20 microg/ml) no protective effect of the HSP70 protein against mitotic spindle damage was observed. Moreover, at 20 microg/ml of extracts of airborne toxins the frequency of mitotic malformations was even higher in HSP70-overexpressing cells than in control ones. Extracts of airborne pollutants of 50 microg/ml blocked the formation of mitotic figures both in control and HSP70-overexpressing cells and led to destruction of cell nuclei. However, the HSP70-overproducing cells exhibited higher survival rates when exposed to heat shock and airborne toxins than the control ones, as determined by MTT assay. This suggests that HSP70 overexpression-a frequent feature of cancer cells-should be considered as a factor facilitating survival of cells with damaged mitotic spindles and aberrantly segregated chromosomes.

Genotoxicity of organic extracts of airborne particles in somatic cells of Drosophila melanogaster

Complex mixtures extracted from air filters exposed for 24 h in two sessions (27 July and 02 August 1991) and at two locations (Merced, downtown, and Pedregal de San Angel, south-west) in Mexico City were analysed. The organic extracts were from airborne particles equal or smaller than 10 microns (PM10), and from total suspended particles (TSP). These organic extracts were assayed in the somatic mutation and recombination test (SMART) in wings of Drosophila melanogaster using two different crosses as well as in the Salmonella/microsome assay using strain TA98 with and without S9 fraction. The presence of polycyclic aromatic hydrocarbons (PAH) in the extracts was determined by gas chromatography. The genotoxic activities observed in the two test systems were comparable with the indirect mutagens producing greater response than the direct mutagens. The quantities of particulate matter as well as the genotoxic activities were higher on 02 August than on 27 July 1991 for both locations. The amounts of airborne particles and the resulting genotoxic activities were higher at Merced than at Pedregal. In both biological systems, PM10 were more genotoxic than TSP. These results demonstrate the sensitivity of the Drosophila wing SMART-which is an in vivo eukaryotic genotoxicity assay-as a biological monitor of environmental pollution related to airborne particles.

Ambient air pollutants in upper Silesia: partial chemical composition and biological activity

The air monitoring system in Upper Silesia has provided abundant data on airborne pollutants. Air quality in this region is bad: a concentration of several gases, volatile compounds, metals, and complex mixtures of organic compounds carried by small particulate matter exceeds both daily and yearly admissible levels. About 250 individual polycyclic aromatic hydrocarbonds (PAHs) were identified in airborne pollutants, and hundreds of not identified compounds are seen on gas chromatographic profiles as minor peaks. Among PAHs are present compounds with known carcinogenic potency for humans. Seasonal variation with distinctly lower concentration of pollutants in summer than in winter was noticed. Fifteen PAHs including benzo[a]pyrene (B[a]P) determined by GC-MS method in 20 measuring points showed constant relative proportions. Thus B[a]P could be used as a representative compound for other PAHs. In urban areas, a core of Silesia values for B[a]P concentration ranged from 60 to 90 ng/m3 in winter to 5 to 20 micrograms/m in summer. Mutagenicity tested on Salmonella strains showed seasonal variation with distinctly higher values in winter. Environmentally exposed humans showed a higher level of PAH-DNA adducts in WBC than the control population from rural area. Total organic extract of small particulate matter exhibited both direct and indirect mutagenic activity, induced formation of micronuclei in bone marrow cells of BALB/c mice, induced chromosomal rearrangements, and increased sister chromatid exchange index.

Two years' air mutagenesis monitoring in a northwestern rural area of Italy with an industrial plant

The mutagenicity of organic extracts from inhalable airborne particles, collected in a northwestern rural area of Italy in which an industrial plant producing chemical intermediates is present, was assessed during the years 1989 and 1990. The Ames plate test with Salmonella strains TA98 and TA100 with and without metabolic activation was used. Eight sites in the first and three sites in the second year were monitored once and twice a month respectively. Results show that the mutagenicity of air particulate matter reaches maximum values in the cold months and is not dependent on plant activities. In addition, a correlation analysis between mutagenicity data and number of vehicles seems to indicate traffic emissions as the main source of mutagens.

A cytogenetic study of cows from a highly industrial or an agricultural region

An examination was made of the frequency of chromosomal aberrations and sister-chromatid exchange in the blood lymphocytes of cows from an industrial region (aluminium smelting plant, lignite quarries, briquette factory, electric plants, mechanical plants. The control group consisted of cows from an agricultural region. In cows from the industrial region a significantly higher level of chromosomal aberrations was observed than in cows from the agricultural region (5.82 +/- 0.46 vs. 2.11 +/- 0.31 per 100 cells). In older, 7-12-year-old cows from the industrial region a slightly higher level of chromosomal aberrations was observed, and a significantly higher level of gaps than in younger cows. The frequency of SCE in the blood lymphocytes of cows from the industrial region was also higher and reached 7.47 +/- 2.33 per cell, while in cows from the agricultural region it was only 6.38 +/- 1.88, but these differences were not significant statistically. However, significant differences were observed in the number of SCE between the age groups within the industrial region P < or = 0.001) in favour of the younger animals. The results obtained indicate that the industrial pollution emitted into the environment may have a genotoxic character. Thus cytogenetic examination of cattle may be a useful test for monitoring industrial pollution.

A cytogenetic study of men environmentally and occupationally exposed to airborne pollutants

The level of sister-chromatid exchanges (SCE), high-frequency cells (HFC), chromosomal aberrations (CA) as well as the proliferation rate index (PRI) were measured in peripheral blood lymphocytes from three groups of volunteers. The environmentally exposed donors were residents from the vicinity of a coke factory; the occupationally exposed persons were cokery workers, while rural region inhabitants served as a control group. Compared with the control group, statistically significant increases of SCE and HFC, as well as decreased cell kinetics (PRI) were observed for both occupationally and environmentally exposed groups. The effect was especially pronounced when only smokers were taken into account. A statistically significant increase of CA was observed in the environmentally exposed group when CA including gaps (CA + G) were evaluated. The proportion of HFC was found to be the most sensitive method to detect genetic effects on the tested human population. This study demonstrates the usefulness of all 4 biomarkers (SCE, HFC, CA and PRI) in monitoring populations exposed to ambient pollution and clearly indicates effects from residential as well as occupational exposure to industrial air pollutants.

Influence of airborne suspended matter on mitotic cell division

The effect of organic extracts of airborne suspended matter collected in the highly polluted industrial region of Silesia (Poland) on mitotic cell division was evaluated in the Chinese hamster V79 cell line. Crude benzene extracts as well as sequential elution solvent chromatography (SESC) fractions were investigated for their ability to affect the mitotic index, the proportion of anaphases-telophases to metaphases (AT/M ratio), the cloning efficiency and to produce aneuploid cells. The incidence of cell division disturbances in V79 cells exposed to extracts increased in a concentration-dependent manner. Mitotic arrest, manifested as a highly increased mitotic index and a concomitant decrease in the AT/M ratio, was found for the crude extract at a dose corresponding to 0.75 m3 of air. Comparable effects were noticed for SESC fraction 4, probably containing monophenol compounds. A strong dose-dependent reduction of cloning efficiency of V79 cells demonstrated cytotoxic activity of both the crude extract and fraction 4.

Correlation between mutagenicity of airborne particles and air pollution parameters in eleven Italian towns

Organic extracts from airborne particles collected in 11 Italian towns between February and April, 1988, were tested for mutagenicity on TA98 and TA100 (± S9), and their nitroreductase (NR) deficient Salmonella strains, by the use of the Ames plate incorporation assay. Mutagenic responses were fitted by an equation which takes into account toxic effects on tester organisms. Generally parallel responses were obtained with the two Salmonella strains, but the TA98 gave, mostly, higher increases of revertants over the control level. No dramatic decreases in mutagenicity were observed with the NR derivative strains, except in a few cases with TA98NR and, more frequently, with TA100NR strains. During air sampling, temperature, atmospheric pressure, light, wind strength and direction, SO2, CO, NO2, O3 and non-methanic hydrocarbons (NMHC) concentrations were continuously monitored. Meteorological variables seem not to be significantly correlated with mutagenicity variations, while the highest correlation (r = 0.91) was observed between induced reversion in TA98 (+ S9) and NMHC concentration in air. Therefore, in spite of the wide range of different types of towns included in the study, air NMHC concentration can be considered a good predictor for the mutagenicity of the total organic material extracted from particles of urban air.

Seasonal variations in mutagenic activity of air pollutants at an industrial district of Silesia

Organic material from airborne particulate pollutants collected over a 7-month period at a highly industrialized region in Silesia (Poland) was tested for mutagenicity using the Ames test. Sequential elution solvent chromatography (SESC) was used for the separation of crude benzene extracts. Five out of 8 fractions showed mutagenic activity with differential direct and indirect responses. The mutagenicity of each active fraction was tested during the whole sampling period (from August to February 1984/1985) and seasonal variations were observed. All of the fractions, except fraction 3, showed only quantitative distinctions in mutagenic potential, expressed as a number of revertants per m3 of air. Over a period of 7 months, a steady increase of activity of fractions 2 and 4 was observed but the type of mutagenic response, indirect and direct respectively, remained unchanged in the summer and winter months. Fraction 3 (the most abundant component, probably containing polar derivatives of PAHs and heterocyclics) differed quantitatively and qualitatively between summer and winter time. From August to December samples showed enhanced mutagenic potency upon addition of rat liver microsomal enzymes, whereas in January a 4-5-fold increase in direct response was noted. This significant increase in direct mutagenic activity was accompanied by a considerable decrease in mean air temperature and resulted most probably from the intensive use of coal for domestic heating.

Comparative study of sister-chromatid exchanges and chromosomal aberrations induced by airborne particulates from an urban and a highly industrialized location in human lymphocyte cultures

Cytogenetic effects induced by extracts of airborne particulates in human lymphocyte cultures were studied with regard to local and seasonal variations. Samples of airborne particulates were collected from an urban and a highly industrialized area in March and October, respectively. All extracts of particulates induced a significant increase of sister-chromatid exchanges (SCE) in a dose-dependent manner. Referring to the induction of sister-chromatid exchanges, local and seasonal differences were observed. Samples from the industrialized area revealed the highest activities. In addition, SCE rates found for March samples were always higher than those for October for both locations. Furthermore, a remarkable, significant induction of chromosomal aberrations occurred with all samples from both locations and sampling periods. Aspects of health risk evaluation for exposed human populations are discussed with respect to the observed cytogenetic effects of airborne particulates in human lymphocyte cultures.