Alberto Zanardini

Monitoring airborne genotoxicants in the rubber industry using genotoxicity tests and chemical analyses.

This research was designed to examine the presence of mutagenic/carcinogenic compounds in airborne pollutants in the rubber industry using an integrated chemical/biological approach. Inhalable airborne particulate matter (PM-10: <10 microm) was collected in four rubber factories using a high-volume sampler equipped with a cascade impactor for particle fractionation. The organic extracts of two different fractions (0.5-10 microm and <0.5 microm) were examined for mutagenicity with the Ames test and for in vitro DNA-damaging activity in human leukocytes by single-cell microgel electrophoresis (Comet assay). The extracts were also studied by gas chromatography/mass spectrometry (GC/MS) for polycyclic aromatic hydrocarbon (PAH) content. Nitrosamines in ambient air were sampled on cartridges and analysed by GC with a thermal energy analyser (TEA) detector. Airborne volatile genotoxins were monitored in situ using a clastogenicity plant test (Tradescantia/micronuclei test). The results showed that airborne particulates were mainly very fine (<0.5 microm) and that trace amounts of genotoxic nitrosamines (N-nitrosodimethylamine: 0.10-0.98 microg/m(3); N-nitrosomorpholine: 0.77-2.40 microg/m(3)) and PAH (total PAH: 0.34-11.35 microg/m(3)) were present in air samples. Some extracts, particularly those obtained from the finest fractions, were mutagenic with the Ames test and genotoxic with the Comet assay. In situ monitoring of volatile mutagens using the Tradescantia/micronuclei test gave positive results in two working environments. The results showed the applicability of this integrated chemical-biological approach for detecting volatile and non-volatile genotoxins and for monitoring genotoxic hazards in the rubber industry.

Monitoring of mutagens in urban air samples

This research was designed to examine the presence of mutagenic/carcinogenic compounds in urban airborne particulates sampled with the inhalable PM-10 high volume sampler in two different streets of Brescia, a heavily industrialized town in northern Italy, using the Tradescantia/micronucleus test and a bacterial mutagenicity test (Kado test, a more sensitive version of the Ames test). In addition, the Tradescantia/micronucleus test was used for in situ monitoring of gaseous pollutants in other urban areas of Brescia and in two car tunnels, one with heavy car traffic in Perugia, a town in central Italy, and one in Brescia with moderate traffic. The Tradescantia-micronucleus test carried out on extracts of airborne particulates gave positive results only for the sample collected in the traffic-congested street where also higher bacterial mutagenicity was found. The in situ monitoring of the urban areas with the Tradescantia/micronucleus test always gave negative results. Monitoring carried out in the two car tunnels showed a significant increase in micronuclei frequency only in flowers exposed in the smaller and more polluted tunnel.

Mutagens and carcinogens in size-classified air particulates of a Northern Italian town

This research was designed to examine the presence of mutagenic/carcinogenic compounds in urban airborne particulate matter in relation to particles aerodynamic size. Inhalable (< 10 microns) airborne particulate (PM-10) was collected at a low traffic site in an industrialized Northern Italian town, using a high volume sampler equipped with a cascade impactor for particles fractionation. The organic extracts of different fractions were examined for mutagenicity in Salmonella typhimurium strains TA98 and TA98/1,8-DNP6 using the microsuspension procedure, and for polycyclic aromatic hydrocarbons (PAHs) content by gas chromatography. Size fractionated particles were also analysed for heavy metals (Fe, Mn, Zn, Pb, Cu, Cd, Cr, Ni, V) using plasma spectrophotometry. The results of mutagenicity and chemical analyses indicate that, at the site investigated, inhalable particulate was largely made of fine (< 0.5 micron) particles, which accounted for most of PAHs and mutagenicity. A similar pattern of distribution was found for heavy metals, which were relatively more abundant in small (< 1.5 microns) particles compared to coarser ones.

Mutagenicity of extracts of lake drinking water treated with different disinfectants in bacterial and plant tests

Abstract Raw water and drinking water samples collected from five treatment plants supplied by a northern Italian lake in two periods of the year (summer and winter) were studied for their mutagenicity. The water samples were concentrated on silica C 18 cartridges and the adsorbates were tested at increasing doses with a bacterial short-term mutagenicity test (Ames test with Salmonella typhimurium TA98 and TA100 strains), which reveals the gene-mutation-inducing ability of pollutants, and with a plant genotoxicity bioassay ( Tradescantia /micronucleus test), which determines clastogenicity (chromosome-breaking ability). Raw water samples from all treatment plants were found to contain bacterial direct-acting mutagens detectable mainly with TA98 strain. The analyses of drinking water samples after water treatment showed some interesting results: TA98 mutagenicity was reduced when ozone was used together with chlorine dioxide, but TA100 mutagenicity was increased, though only in the summer sample; mutagenicity detectable with both strains was always reduced after chlorine dioxide disinfection; on the contrary, in all treatment plants using NaClO TA98 mutagenicity of winter samples increased. Raw lake water induced a high number of micronuclei in the Tradescantia /micronucleus test, showing a strong clastogenicity. This activity was higher in the NaClO-treated samples, and lower with the other disinfectants. Therefore, disinfection of lake water with ozone and/or chlorine dioxide seems to be a suitable alternative to the use of NaClO for controlling the formation of nonvolatile mutagens. The concentration method coupled with the two mutagenicity tests was found to be a simple, rapid and relatively inexpensive system for monitoring treatment plants and studying the influence of different disinfection systems on water mutagenicity.

Mutagenicity and clastogenicity of gas stove emissions in bacterial and plant tests

The aim of this research was to study the gaseous and particulate emissions of genotoxic substances during cooking with two types of methane stoves (a new one and an old one). The particulates were sampled both with a cascade impactor air sampler and an impinger with ice trap and analyzed by two bacterial mutagenicity tests (Ames and Kado tests) and by HPLC for polycyclic aromatic hydrocarbons (PAH). Gaseous emissions were studied in situ using the Ames test, a clastogenicity plant test (Tradescantia‐micronucleus test), and in an automated system for chemical analyses. Clear indirect mutagenicity was found only with the Kado test (TA98‐S9) in extracts of particulates emitted from the old methane stove and collected with the impinger. Similar mutagenicity (TA98+S9) was also found for the finest fraction of particulates (<0.5 um) collected from both stoves. Gaseous emissions of both stoves caused clastogenicity in the in situ experiments with the Tradescantia‐micronucleus test. The physico‐chemical analyses of the emissions showed also the presence of very fine particulates and trace amounts of PAH. The exposure of these genotoxins could be particularly important for occupationally exposed individuals in homes and businesses and for susceptible subjects living indoors for long periods (infants, children, the sick, and the elderly). Environ. Mol. Mutagen. 31:402–408, 1998.