Expositionsabschätzung: Human-Biomonitoring vs. Modellrechnungen

Exposure assessment represents an important and integral part of the assessment of health risks associated with the human exposure to toxic substances in soil and other environmental media. In recent times model calculations are widely used to assess the doses of toxic substances which have been incorporated into the human body via different routes of exposure. The present paper discusses the possibilities and limitations of such model calculations with regard to exposure and risk assessment. A critical point is that the results largely depend on the basic assumptions introduced into the model calculations. Moreover, the results refer to a more or less typical scenario of exposure, although they do not allow any conclusion with regard to individual exposure levels. In contrast, the use of biomarkers of exposure (human biological monitoring) represents a methodological approach to estimate individual exposure levels of subjects exposed to toxic substances in a given situation. In practice, the identification of persons at risk and the exclusion of individual health risks can only be based on human biological monitoring studies. Exposure assessment based on theoretical calculations and exposure assessment based on biomarkers of exposure and effects should be regarded as complementary approaches in exposure and risk assessment.     

Clearance of atrazine in soil describing xenobiotic behavior

The primary aim of this study was to evaluate the “clearance concept” as a tool for describing the behavior of xenobiotic movement into and through soils. As an example, degradation of 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) with the formation of metabolites 2-chloro-6-isopropylamino-s-triazine (desethylatrazine) and 2-chloro-4-ethylamino-s-triazine (desisopropylatrazine) was investigated. Atrazine was sprayed post-emergently in doses of 0.125 or 0.5 g active ingredient/m² each on four test plots. Soil type was a sandy-loam, on which corn (Zea mays L.) was cultivated. Soil samples were taken as cores of 0.2 m depth 0, 1, 2, 4, 8, 12, 16 and 20 weeks after application of atrazine, and analyzed by HPLC. Soil concentrations of atrazine were highly correlated (r=0.993, p< 0.001) between the two applications of 0.125 g/m² and 0.5 g/m². Up to 50% of the atrazine was measured as metabolites during the whole vegetation period. Clearance of atrazine from soil was calculated as the total load of atrazine divided by the area under the soil atrazine concentration time curve. Soil atrazine clearance was calculated as 5.13 +/? SD 1.10 and 5.17 +/? SD 1.02 liter of soil per day for doses of 0.125 g/m² and 0.5 g/m², respectively (from a “soil unit” of 1 × 1 × 0.2 meter). The clearance concept might be a tool for risk assessment of xenobiotics.     

Estimation of mercury content in tailings of the gold mine area of Poconé, Mato Grosso,Brazil

As in many other parts of the world, gold is produced in the surface mining region of Poconé, Mato Grosso, Brazil, using mercury. The goal of this investigation was to estimate the amount of mercury in certain tailings and to determine the area of the land that has been contaminated by the gold mining operations. Mercury concentrations from 2 to 495 ng/g (dw) were determined in the tailing materials. It was observed that only isolated sites were acting as central points of contamination. Using digital Landsat satellite data (The-matic Mapper) and aerial photos, the sites degraded by the mining were classified, and their total area was estimated to be 12.3 km² in the region of Poconé. It was estimated, that 4.9 km² were occupied by the contaminated tailings. The mean height of the pile slags was determined to be 4.5 m. From the experimentally calculated average density of the material in the tailings, 2.01 g/cm³, the total mercury content in the piles of tailings was estimated to be 1600 ± 350 kg.     

Chemikaliensicherheit

Ohne Zusammenfassung     

Bestimmung von Tier- und Pflanzenarten auf einer Sonderabfalldeponie

Pr?ambel Ziel und Absicht  Zur Entwicklung eines Bewusstseins für die Artenvielfalt in unserer Umwelt hat die Zeitschrift GEO 1999 den ‚Tag der Artenvielfalt’ ausgerufen. Seitdem finden jedes Jahr europaweit Feldforschungsaktionen statt. Für Bayer Industry Services ist die Artenbestimmung auf der Sonderabfalldeponie in Bürrig eine Gelegenheit zu zeigen, dass sich Umweltschutz und fachgerechte Deponierung von Sonderabf?llen nicht widersprechen. Methoden  Die Teilnehmer am ‚Tag der Artenvielfalt’ bestimmen selbst, welches Gel:ande sie untersuchen wollen. Innerhalb eines Tages im Juli werden die dort vorkommenden Tier- und Pflanzenarten bestimmt und an GEO gemeldet. Ergebnisse und Schlussfolgerungen  Innerhalb eines Nachmittages wurden 47 Pflanzen-, 25 Vogel- und 7 weitere Tierarten bestimmt. Das Interesse der Teilnehmer an der Naturbeobachtung wurde durch die Aktion gef?rdert. Weitere Termine zur Bestimmung der Artenvielfalt wurden vereinbart. Empfehlung und Ausblick  Zur genauen Beobachtung eines definierten Naturraumes ist die Begehung zu unterschiedlichen Jahreszeiten sinnvoll. Bei Schulklassen müssen die Exkursionen mit dem Lehrplan abgestimmt werden.     

Influence of Inversion Layers on the Distribution of Air Pollutants in Urban Areas

The air quality in urban areas is on the one hand determined by the intensity of emissions. On the other hand atmospheric dispersion and chemical transformation conditions as well as topographic location have great influence on the ambient air concentrations. Within, this study the correlation between pollutant concentrations and the dynamics of atmospheric barrier and mixing layers has been experimentally investigated by tethered balloon soundings.The most important barrier layer is the surface inversion. During clear sky it develops in the late afternoon and is dissolved by warm air from the heated ground in the morning. Emitted pollutants are kept beneath this inversion. But, at the same time, the component ozone is depleted below and stored above the layer within the so called `ozone reservoir layer'. During night elevated mountain sites are decoupled from the ground conditions and stay within this reservoir without a remarkable nocturnal decrease of ozone concentration. The regularly observed ground level ozone increase in the morning hours is firstly caused by down mixing from the reservoir. The conditions and dynamics are illustratively depicted by vertical profiles of the different components and diagrams of temperature and concentration isopleths over the height and the experiment time lasting over five days.     

Detection of Human Enteric Viruses in Freshwater from European Countries

The transmission of water-borne pathogens typically occurs by a faecal–oral route, through inhalation of aerosols, or by direct or indirect contact with contaminated water. Previous molecular-based studies have identified viral particles of zoonotic and human nature in surface waters. Contaminated water can lead to human health issues, and the development of rapid methods for the detection of pathogenic microorganisms is a valuable tool for the prevention of their spread. The aims of this work were to determine the presence and identity of representative human pathogenic enteric viruses in water samples from six European countries by quantitative polymerase chain reaction (q-PCR) and to develop two quantitative PCR methods for Adenovirus 41 and Mammalian Orthoreoviruses. A 2-year survey showed that Norovirus, Mammalian Orthoreovirus and Adenoviruses were the most frequently identified enteric viruses in the sampled surface waters. Although it was not possible to establish viability and infectivity of the viruses considered, the detectable presence of pathogenic viruses may represent a potential risk for human health. The methodology developed may aid in rapid detection of these pathogens for monitoring quality of surface waters.