In situ monitoring of the mutagenic effects of the gaseous emissions of a solid waste incinerator in metropolitan São Paulo, Brazil, using the Tradescantia stamen-hair assay

Genotoxicity of SPL (spent pot lining) as measured by Tradescantia bioassays

Spent Pot Liner (SPL) is a solid waste product generated in the process of aluminum production. Tradescantia micronuclei (Trad-MN) and stamen hair mutation (Trad-SHM) bioassays are very useful tests to assess genotoxicity of environmental pollutants. In the present study, we intended to investigate the genotoxicity of this waste with Tradescantia bioassays using leachates of SPL simulating the natural leachability of SPL in soil. The formation of micronuclei (MN) was found to be concentration dependent. MN frequency enhanced significantly with SPL treatment. In addition, SPL also appeared to increase the percentage of dyads and triads. Trad-SHM assay showed that SPL increases pink mutation events as SPL concentration increases. These results demonstrated that SPL is a cytogenotoxic agent that affects different genetic end-points (induction of micronuclei and point mutations) even at low concentration (2% and 3%).

[Spatial analysis of the health risks associated with solid waste incineration: a preliminary analysis]

OBJECTIVES

to examine if emissions from the Vergueiro solid waste incinerator are associated with an increased risk of cancer in the population in its vicinity.

METHODS

the area under influence of this incinerator was delimited by a 7 km radius from its geocoded centroid. Deaths of city residents in administrative districts inside this area due to cancer of lung, liver, larynx, non-Hodgkin's lymphoma in adults, leukemia, and all sites combined in children, in the 1998 to 2002 period, were selected and geocoded. The studied area was divided into 7 concentric rings delimited by a radius of 1 to 7 km from the incinerator. The analysis of the relationship between residential proximity to the incinerator and mortality due to cancer was based on the comparison of observed and expected cases, using the Stone test for decline in risk with distance from the incinerator.

RESULTS

the area studied comprised 1,599,532 inhabitants, of which 92,894 were children less than 5 years old and 634,993 were adults over 40 years old. No spatial gradient in risk was observed for any outcome in relation to distance from the incinerator.

CONCLUSION

although no excess risk for the selected cancers were observed, emissions of incinerators still operating and their possible health effects should be monitored. The study of the spatial distribution of health events in areas around point sources of air pollution can become a methodological option for surveillance activities.

Evaluation of mutagenic potential of contaminated atmosphere at Ibirapuera Park, São Paulo - SP, Brazil, using the Tradescantia stamen-hair assay

Trad-SHM assay was used to check mutagenic potential of atmospheric contamination at Ibirapuera Park, located in São Paulo city, Brazil, and variation of risk along the year, besides determining which Tradescantia clone, BNL 4430 or KU-20, better indicates risk. Thirty pots of both clones were exposed during one-year period (September, 2002-August, 2003). Twenty inflorescences were taken from each clone twice a month in the morning, in order to estimate the frequency of mutations in stamen hairs. Results were compared to air pollution and climatic data measured next to the exposure site. KU-20 showed stamen-hair mutations greater than BNL 4430. Greatest mutation rates in KU-20 were observed in condition of high monthly mean of NO(2) and average peak concentrations of NO during the day, indicating that mutagenic effects originated from vehicular pollution. Clone KU-20 revealed to be more appropriate for biomonitoring purposes at the Park.

Diesel emissions significantly influence composition and mutagenicity of ambient particles: a case study in São Paulo, Brazil

In 2003, a bus strike paralyzed the fleet of buses in Sao Paulo, Brazil during 3 days, from 6 to 8 of April, the complete interruption of services being achieved on the 7th. We evaluated the effect of the absence of this source of pollution on the composition, mutagenicity, and toxicity of the fine particulate material collected during this period. Particles were sampled in glass fiber filters on days 7 and 15 of April of 2003 (strike and nonstrike days, respectively), using a high-volume sampler. Trace element determinations (As, Br, Co, Cl, Fe, La, Mn, Sb, Sc, and Th) of particulate material samples were carried out by neutron activation analysis. Sulfur determination was done by X-ray fluorescence analysis. The ratio between nonstrike/strike concentrations of hydrocarbons associated with automotive emissions (benzene, toluene, ethyl-benzene, and xylenes; BTEX) was determined by gas chromatography/mass spectrometry. Mutagenesis of testing solutions was determined by means of the Tradescantia micronucleus assay in early tetrads of Tradescantia pallida. The inhibition of mitosis of the cells of the primary meristema of the root tips of Allium cepa was used as an index of the toxicity. Fine particle trace element contents were lower during the strike. The concentrations of sulfur and BTEX were 50% and 39.3% lower, respectively, on the strike day. A significant (P=0.038) reduction of micronuclei induced by fine particles sampled during the strike was observed. No effect of the strike on toxicity was detected. These results indicate that a program aiming to reduce emissions of the bus fleet in our town may impact positively the air quality by reducing the mutagenic potential of ambient particles.

Evaluation of the mutagenic potential of urban air pollution in São Paulo, Southeastern Brazil, using the Tradescantia stamen-hair assay

We used a short-term bioassay--the Tradescantia stamen-hair assay (TSH)--to evaluate the toxicity of ambient particles with an aerodynamic diameter less than 10 microm sampled in the metropolitan region of São Paulo, Brazil. Two exposure locations were selected: downtown São Paulo and Caucaia do Alto (mean PM10 levels of 64 and 14 microg/m3, respectively). The experiment was conducted July 11-August 15, 2002, and toxicity was assessed with the Tradescantia stamen-hair assay (TSH) employing clone KU-20 of Tradescantia. Four experimental groups were defined: inflorescences collected from plants cultivated in Caucaia, inflorescences collected from plants cultivated in São Paulo (to establish the baseline level of mutations in stamen hairs at both sites), inflorescences collected from plants cultivated in Caucaia and brought to São Paulo and maintained in chambers that received ambient air, and inflorescences collected from plants cultivated in Caucaia and brought to São Paulo and maintained in chambers that received air passed through a particle filter. The frequency of mutations observed in Caucaia was significantly lower than that in the remaining groups. Flower cuttings brought from Caucaia and receiving ambient air of São Paulo showed a rate of mutations similar to that of plants cultivated in São Paulo. Filtering particles from the air reduced the rate of mutation but not sufficiently to reach the level of that in Caucaia. The frequency of mutations observed in São Paulo was significantly associated with PM10 levels on the fifth day before the opening of the flowers (r = 0.47, p = 0.025). Our results indicate that urban particles play a significant role in the development of pollution-dependent mutations.

Urban air pollution induces micronuclei in peripheral erythrocytes of mice in vivo

In this study, we explored the role of chronic exposure to urban air pollution in causing DNA damage (micronuclei frequency in peripheral erythrocytes) in rodents in vivo. Mice (n=20) were exposed to the urban atmosphere of São Paulo for 120 days (February to June 1999) and compared to animals (n=20) maintained in the countryside (Atibaia) for the same period. Daily levels of inhalable particles (PM10), CO, NO(2), and SO(2), were available for São Paulo. Occasional measurements of CO and O(3) were made in Atibaia, showing negligible levels of pollution in the area. The frequency of micronuclei (repeated-measures ANOVA) increased with aging, the highest values obtained for the 90th day of experiment (P<0.001). The exposure to urban air pollution elicited a significant (P=0.016) increase of micronuclei frequency, with no significant interaction with time of study. Associations (Spearman's correlation) between pollution levels of the week that precede blood sampling and micronuclei counts were observed in São Paulo. The associations between micronuclei counts and air pollution were particularly strong for pollutants associated with automotive emissions, such as CO (P=0.037), NO(2) (P<0.001), and PM10 (P<0.001). Our results support the concept that urban levels of air pollution may cause somatic mutations.

Pollen mother cells of Tradescantia clone 4430 and Tradescantia pallida var. purpurea are equally sensitive to the clastogenic effects of X-rays

The Tradescantia micronucleus test is a sensitive bioassay for mutagenesis that may be employed both under field and laboratory conditions. This test has been standardized mostly on the basis of the results obtained with clone 4430. However, this clone is not well adapted to tropical weather, frequently showing problems with growth and flowering. In addition, it is attacked by parasites and insects, a fact that limits its use in field studies aiming at the biomonitoring of air pollution. In the city of São Paulo, Tradescantia pallida (Rose) Hunt. var. purpurea Boom is widely distributed as an ornamental plant in gardens and along roadsides and streets, mostly because of its natural resistance and its easy propagation. In this report, we present dose-response curves indicating that the sensitivity of T. pallida and clone 4430 to X-radiation (1, 10, 25 and 50 cGy) is similar. The results confirm our previous suggestion that T. pallida represents a good alternative for in situ mutagenesis testing in tropical regions, especially biomonitoring studies in which the exposure conditions may not be fully controllable.