Fidelis Selenka

Mobilization of PAH and PCB from contaminated soil using a digestive tract model

Environmental contaminants are mainly incorporated by ingestion. In general only those contaminants mobilized by the digestive juices are available for absorption in the digestive tract, while pollutants still fixed to indigestible particles leave the body without any effect. To evaluate the different health risks arising from the ingestion of individual types of polluted soil or other materials, we developed an in vitro test system which simulates the transition of pollutants from contaminated materials into digestive juices by means of a standardized artificial gastro-intestinal model. The test system simulates the influence of the acidic environment of the stomach (gastric model) followed by the neutral or slightly alkaline environment of the small intestine (gastro-intestinal model). Investigations on small amounts of polluted soil, sewage sludge, asphalt, metal scrap and blast sand showed that the mobilization of polycyclic aromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB) by artificial gastric juice reaches 3% up to 22% of the pollutant concentration introduced into the test system. Elutions of the contaminated materials under gastric and subsequently under intestinal conditions with bile concentrations of 3 g/l resulted in PAH- and PCB-mobilizations in the range of 5% up to 40%. The degree of mobilization depends considerably on supplementary food material added to the test system. Lyophilized milk increased the fraction of mobilized PAH and PCB to 40%-85%. Application of the test system on 22 different contaminated soils showed that the mobilization of PAH under gastro-intestinal conditions with the addition of lyophilized milk ranged from 7% up to 95%, and the mobilization of PCB ranged from 32% up to 83%. This indicates that the test system can be a useful tool for evaluating the individual health risks arising from polluted soil or other materials.

Decrease of PCDD/F levels in human blood from Germany over the past ten years (1989-1998)

744 whole blood samples of normal subjects from Germany collected in 1989-1998 have been analyzed for polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) by capillary gas chromatography/high resolution mass spectrometry. Over the examined time period a continuous decrease of the PCDD/F concentrations in human blood was observed. The mean levels found were 43.7 pg I-TEq/g (lipid basis) in 1989 and 20.7 pg I-TEq/g (lipid basis) in 1996/98 [median: 42.2 and 19.4]. The reduction to about the half was found for most congeners. Each one-year subset of the collective and the entire collective shows a positive correlation of the PCDD/F blood levels with age for most of the congeners, the sum values and the calculated toxicity equivalents. For statistical evaluation a multiplicative model was used: Concentration = A x Age(B). The correlation is mostly pronounced for lower chlorinated PCDD and for 2,3,4,7,8-PentaCDF. The PCDD/F concentrations in human blood in relation to the year of examination and the age of the subjects can be described by a linear model: I-TEq [pg/g (lipid basis)] = 6176 - 3.097 x Year + 0.6482 x Age or by a multiplicative model: I-TEq [pg/g(lipid basis)] = 10(89.08-0.04415 x Year + 0.008468 x Age).

Four Years of Experience with Silver-Copper Ionization for Control of Legionella in a German University Hospital Hot Water Plumbing System

Silver-copper ionization was used for controlling Legionella distribution in a German university hospital hot water plumbing system for 4 years. In the beginning, silver concentrations were not allowed to exceed 10 microg/L because of drinking water regulation limits in Germany. Water samples were monitored for Legionella counts, temperature, and silver and copper concentrations. A significant (P<.001) 3.8-log reduction of Legionella counts, from 40, 000 cfu/L to 7 cfu/L, was found during the first year with silver-copper ionization. Nevertheless, the long-term efficacy of silver concentrations <10 ,++microg/L was not sufficient. Legionella counts increased to 10,000 cfu/L during the third year. During the fourth year, we studied the influence of higher silver concentrations on Legionella distribution. With an average silver level of 30 microg/L, only a 1.3-log reduction in Legionella, to 500 cfu/L, was achieved. The effect was not significant (P=.071); therefore, it must be considered that Legionella developed a tolerance to silver ions.

Human fecal PCDD/F-excretion exceeds the dietary intake

A mass balance of human dietary PCDD/F-intake and fecal PCDD/F-excretion was carried out. The participants of the study were seven male and seven female adults between the ages of 24 to 64 years, living in North Rhine-Westphalia, Germany. The PCDD/F-intake was measured using the duplicate method. Sampling time of each food duplicate covered three days. The fecal PCDD/F-excretion was measured by collecting the feces which corresponded to the food duplicates. The mean daily dietary PCDD/F-intake was 49 pg I-TEq/d (range: 23-96 pg I-TEq/d) and therewith lower than that estimated in the past. The mean daily fecal PCDD/F-excretion was 98 pg I-TEq/d (40-200 pg I-TEq/d). This is twice the amount of the PCDD/F-intake. The fecal excretion of OCDD was especially higher than the dietary intake (mean: 7 fold, range: 1.2-21 fold). The differences between PCDD/F-intake and PCDD/F-excretion may be caused by a reduction of the body burden as a consequence of decreasing PCDD/F-intake. Other explanations were additional sources of exposure to PCDD/F or de novo formation of PCDD/F in the human body.

Impact of silver and copper on the survival of amoebae and ciliated protozoa in vitro

The efficacy of 1:10 silver/copper combinations for inactivation of Hartmannella vermiformis amoebas and the ciliated protozoan Tetrahymena pyriformis in vitro was studied. Tetrahymena and Hartmannella/isolate 19 were inactivated for 2 log steps by 100 + 1000 micrograms/l Ag + Cu. Hartmannella/isolate 21 was more resistant. 500 + 5000 micrograms/l produced only a 0.6 log reduction. The investigations clearly showed that levels within the limit of the German drinking water regulation (10 + 100 micrograms/l Ag + Cu) could not inactivate these protozoas in vitro.

Myeloperoxidase-catalyzed formation of PCDD/F from chlorophenols

Chlorophenols (CP) are transformed in vitro to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) by a biochemical-catalyzed oxidation. This is shown for 2,4,5-tri-, 2,3,4,6-tetra-and pentachlorophenol with myeloperoxidase recovered from human leucocytes in the presence of hydrogen peroxide. The yield, the reaction, and the PCDD/F-pattern found depend on the CP. The formation rates are in the micromol-per-mol range for all substrates. The experiments confirm the suspicion that a biochemical formation of PCDD/F from precursors such as CPs can take place in the human body and that this metabolic pathway may lead to a higher inner exposure with PCDD/F than is now assumed.

Levels of PCDD/PCDF in blood fat as indices of the PCDD/PCDF body burden in humans

The levels of PCDD/F in blood fat are similar to those in body fat and in milk fat of lactating women. Therefore, the levels of PCDD/F in blood fat can be used as an index of the individual PCDD/F body burden in humans. In order to evaluate the PCDD/F background exposure levels of the German population, blood samples collected from 95 subjects (age 12-82 years) living in a rural area of North-West Germany were analysed for PCDD/F. The median 2,3,7,8-TCDD toxicity equivalents (TE) were 40.8 pg I-TE/g blood fat and the 95th percentile was 82.1 pg I-TE/g blood fat. The TE levels in blood fat show a marked increase with age, which reflects the pronounced accumulation of PCDD/F in the human body throughout the entire lifetime. Considering single congeners, significant differences in the age-related increase were noted. Using age-specific reference values derived from this study the levels of PCDD/F in blood fat of individuals environmentally exposed to PCDD/F under different circumstances were evaluated.

Peroxidase-catalyzed in vitro formation of polychlorinated dibenzo-p-dioxins and dibenzofurans from chlorophenols.

Chlorophenols (CP) are transformed in vitro to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) by a peroxidase-catalyzed oxidation. This is shown for 2,4,5-tri-, 2,3,4,6-tetra- and pentachlorophenol with plant horseradish peroxidase and with myeloperoxidase recovered from human leukocytes, each in the presence of hydrogen peroxide. The yield, the reaction and the PCDD/F-pattern found are dependent on the CP. The amounts of PCDD/F formed within 4 or 24 h are in the micromol/mol-range for all substrates and both peroxidases. The experiments suggest that biochemical formation of PCDD/F from precursors such as CPs can take place in the human body and that this metabolic pathway may lead to a higher inner exposure to PCDD/F than up to now assumed based on intake data for PCDD/F.

Teil 3: PCDD/F im Blutfett ausgewählter Personen

ZusammenfassungIm Zusammenhang mit der im Jahre 1991 aufgedeckten hohen Belastung der Rückstandshalden und des Umfeldes einer früheren Kupferhütte in Marsberg (Nordrhein-Westfalen) mit polychlorierten Dibenzo-p-dioxinen und Dibenzofuranen (PCDD/F) wurden die Konzentrationen dieser Schadstoffe im Blut von 56 ausgewählten Probanden aus Marsberg untersucht. Es handelte sich dabei um direkte Anwohner der Halden bzw. der früheren Kupferhütte und um Personen, die in besonderer Weise mit Haldenmaterial in Kontakt gekommen waren. Parallel dazu wurde eine gleichgroße Gruppe von alters- (±3 Jahre) und geschlechtsgleichen Personen aus dem Kreis Steinfurt (Münsterland, Nordrhein-Westfalen) untersucht.Die Belastung der Marsberger Probanden betrug im Mittel 28,5 pg BGA-TE/g Blutfett (52,7 pg NATO/CCMS-TE/g Blutfett), die des Steinfurter Kollektivs 23,9 pg BGA-TE/g Blutfett (44,4 pg NATO/CCMS-TE/g Blutfett) (Medianwerte: Kollektiv Marsberg: 24,4 pg BGA-TE/g Blutfett (43,2 pg NATO/CCMS-TE/g Blutfett), Kollektiv Steinfurt: 23,4 pg BGA-TE/g Blutfett (43,0 pg NATO/CCMS-TE/g Blutfett). Die Konzentrations-Spannweiten betrugen 11,3–103 pg BGA-TE/g Blutfett (22,1–231 pg NATO/CCMS-TE/g Blutfett) [Marsberg] bzw. 9,1–48,9 pg BGA-TE/g Blutfett (16,9–98 pg NATO/CCMS-TE/g Blutfett) [Steinfurt]. Die in Relation zu dem Steinfurter Kollektiv im Mittel höheren TE-Blutfettgehalte der Marsberger Probanden waren vornehmlich durch erhöhte Penta- und HexaCDF-Konzentrationen bedingt. Es ist zu vermuten, daß diese bei mehreren Probanden erkennbaren Auffälligkeiten des Kongenerenmusters durch Aufnahme von PCDD/F aus dem belasteten Haldenmaterial bzw. Boden zustande gekommen sind. Eine eindeutige Klärung dieser Frage ist aufgrund der vorliegenden Untersuchungsergebnisse nicht möglich.AbstractThis study was designed to assess the degree of exposure to PCDD/F in 56 selected persons living in the vicinity of a former copper smelter located in Marsberg, Germany. The copper smelter was in operation until 1945. In 1991, high levels of PCDD/F were found particularly in materials from the slag dumps (10 000 – 100 000 ng TE/kg).The levels of PCDD/F in blood fat were used as parameters for individual PCDD/F exposure.Since only limited reference data for PCDD/F in human blood were available, blood samples of a reference group were analyzed in the same way. The criteria were collected from a group matched for sex, age (±3 years) and body mass.The median NATO/CCMS-Toxicity equivalency values (NATO/CCMS-TE-values) of the Marsberg group (43,2 pg NATO/CCMS-TE/g blood fat) and the reference group (43,0 pg NATO/CCMS-TE/g blood fat) were similar, whereas the arithmetic mean of the Marsberg group (52,7 pg NATO/CCMS-TE/g blood fat) was higher than that of the reference group (44,4 pg NATO/CCMS-TE/g blood fat). The frequency distribution of the individual TE-values of the Marsberg group was slightly shifted toward higher values. The individuals of the Marsberg group had significantly higher levels of PentaCDF, HexaCDF and HeptaCDF on average than the individuals of the reference group.On the basis of TE-values, the majority of the individuals from Marsberg did not have an increased body burden of PCDD/F. However, some individuals could be identified with TE-values exceeding background levels ranging up to 231 pg NATO/CCMS-TE/g blood fat. Although it must be assumed that the unusual congener pattern found in many of the test subjects is a result of ingestion of contaminated slag material or soil, the findings of this study could not verify this fact.

Gas-chromatographic determination of trace amounts of vinyl chloride in water and air after derivatization to 1,2=dibromochloroethane

SummaryA quantitative method for the determination of trace amounts of vinyl chloride in water and air is presented. Analysis of water is performed by stripping it with 250 ml/min helium from a 1-l sample at 20°C for 30 min to transfer the vinyl chloride into the gas phase. The vinyl chloride is concentrated on an ice-cooled adsorption tube, which is filled with 550 mg of silica gel and 300 mg of activated charcoal. Air samples are taken by drawing a known volume directly through the ice-cooled adsorption tube. The tubes are eluted with carbon disulfide and the vinyl chloride is derivatizised with bromine water to form 1,2-dibromochloroethane. The derivative is determined by capillary gas chromatography with an electron capture detector. The method was tested using water samples over a range from 0.4 ng/l to 1.25 μg/l. The detection limits are 0.4 ng/l for 1-l water samples or 50 ng/m3 for 7.5 l air.