Comparison of different digestive tract models for estimating bioaccessibility of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) from red slag 'Kieselrot'.

'Kieselrot' (red slag), a highly PCDD/F-contaminated leaching residue from a copper production process, has been used as surface layer for more than 1,000 sports fields, playgrounds and pavements in Germany and neighbouring countries. Children can ingest this material directly by hand-to-mouth activities or soil-pica behaviour. Furthermore secondary contamination of farm land or kitchen gardens by drift of red slag dust may lead to an enrichment of PCDD/F within the food-chain. PCDD/F can be mobilized from contaminated materials by digestive juices and thus become bioaccessible for intestinal absorption. Two different digestive tract models were used to estimate the bioaccessibility of PCDD/F from red slag and to study the influence of food material on the mobilization of the contaminants. The bioaccessibility of PCDD/F from red slag depends on the charge of red slag material used, the bile content of the intestinal juice and on the presence of lipophilic foodstuffs. A low bioaccessibility of less than 5% was found when using a digestive tract model with a low bile content and in absence of food material. The bioaccessibility was estimated to be more than 60% when using a model with a higher bile content and in the presence of whole milk powder. A low bioaccessibility of PCDD/F from red slag in general--as assumed until now and mentioned in legal provision--was not confirmed by our study. Considering observations for the different homologue groups it is obvious that bioaccessibility is the first of several important steps to estimate human health risks arising from contaminated materials. In case red slag contaminated with PCDD/F their absorption rate in the digestive tract and/or metabolism might be at least just like important.

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.

Decrease of PCDD/F levels in human blood--trend analysis for the German population, 1991-1996.

More than 500 whole blood samples of normal subjects from Germany collected in 1991-1996 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 about 42.7 pg I-TEq/g (lipid basis) in 1991 and 20.7 pg I-TEq/g (liquid basis) in 1996 [median: 40.8 and 19.2]. A reduction to about half was found for most congeners. Each 1-year subset of 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 in blood = A x ageB. The correlation is mostly pronounced for lower chlorinated PCDD and for 2,3,4,7,8-PentaCDF.

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.

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.

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.

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.

Comparison of free-living amoebae in hot water systems of hospitals with isolates from moist sanitary areas by identifying genera and determining temperature tolerance.

Legionella-contaminated hot water systems and moist sanitary areas in six hospitals were sampled for amoebae by following a standardized collection protocol. Genus identifications and temperature tolerance determinations were made. Amoebae identified as Hartmannella vermiformis (65%), Echinamoebae spp. (15%), Saccamoebae spp. (12%), and Vahlkampfia spp. (9%) were detected in 29 of 56 (52%) hot water samples. Twenty-three of 49 (47%) swabs obtained from moist areas were amoeba positive. The following genera were identified: Acanthamoeba (22%), Naegleria (22%), Vahlkampfia (20%), Hartmannella (15%), and Vanella (7%). The temperature tolerance of amoebae from hot water systems was strikingly different from that of amoebae from moist areas. At 44 degrees C on agar, 59% of amoebic isolates sampled from hot water systems showed growth. The corresponding value for isolates from moist areas was only 17%. Six Acanthamoeba isolates from the moist areas were considered potential pathogens. Four Hartmannella and two Saccamoeba isolates from hot water could be cultured at 53 degrees C.

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.

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.

[Effect of silver and copper ions on survival of Legionella pneumophila in tap water]. / Einfluss von Silber- und Kupfer-Ionen auf das Uberleben von Legionella pneumophila in Leitungswasser.

In vitro studies were performed to give information about the required metal concentrations in decontaminating Legionella-loaded warm water systems with the electrochemical generation of Ag+ and Cu2+ ions. The influence of Ag and Cu ions, as single compounds and in combination, on the survival of Legionella pneumophila (serogroup 6) was determined in tap water at 45 degrees C. Marked differences were detected in the action of these metals. Ag produced a much stronger inhibition than Cu. No additive effect was demonstrated when using Ag/Cu-combinations in the ratio of 1:10. In this case only the Ag-induced inhibition was detected. After 1 h of incubation at 45 degrees C a concentration of 80 + 800 micrograms/L Ag + Cu was needed to produce the maximal inhibitory effect (a 5 log decrease). An identical effect was seen after exposure to 20 + 200 micrograms/L Ag + Cu in the long-term action (24 h of incubation). The minimum inhibitory concentration after long-term incubation was 5 + 50 micrograms/L Ag + Cu. These metal concentrations produced a 1 log reduction. The in vitro results are discussed under consideration of earlier investigations after metering Ag and Cu into a Legionella-loaded water system and generated the following conclusions: In the beginning highly contaminated water systems at 45 degrees C need concentrations between 40 and 80 micrograms/L Ag + 400 to 800 micrograms/L Cu to kill Legionellas. After effective reduction of Legionella concentration of at least some logarithmic powers a slow constant maintenance concentration of 5 to 20 micrograms/L Ag + 50 to 200 micrograms/L Cu could be applied. At 22 degrees C the in vitro inactivation response is much lower. On the other hand in warm water systems with temperatures of 50 to 60 degrees C lower metal concentrations are sufficient.

Gas chromatographic determination of trace amounts of vinyl chloride and dichloroethenes in landfill-gas.

A method for the determination of vinyl chloride (VC) and dichloroethenes (DCE) in gas samples is presented. The analytes are preconcentrated from a gas-volume of up to 20 l on an adsorption tube filled with 1.0 g of a carbon molecular sieve at a flow rate of 80 l/h and are subsequently desorbed with carbon disulfide. Vinyl bromide is added as internal standard to the extract. The analytes are determined as their 1,2-dibromo-derivatives by capillary gas chromatography with electron capture detection. The detection limits have been found to be 82 ng/m(3) = 32 ppt (VC), 190 ng/m(3) = 48 ppt (1,1-DCE) and 96 ng/m(3) = 24 ppt (cis-/trans-1,2-DCE). The method has been used for the quantification of the anaerobic microbial degradation of tetra- (PCE) and trichloroethene (TCE) to dichloroethenes and vinyl chloride in landfill sites. The substances have been analyzed in landfill-gas as well as in gaseous emissions from the landfill surface. The mean emission rates of tetrachloroethene, trichloroethene and vinyl chloride from the landfill surface into the ambient air are about 0.5 microg/(m(2) x h).

[Dioxin level of small volume gardeners in Duisburg]. / Untersuchungen zur Dioxinbelastung von Kleingärtnern aus Duisburg.

The PCDD/F levels were determined in the venous blood of 21 allotment gardeners in Duisburg (Germany). Soil analyses had shown elevated levels of PCDD/F in garden soil (range 16.4-77.6 ng I-TE/kg). Vegetable plants also had elevated levels of PCDD/F, mainly due to airborne contamination. The highest levels were found in kale (2.6-65.6 ng I-TE/kg d.w.) and endive (1.7-28.5 ng I-TE/kg d. w.). The study population consisted of 5 females and 16 males (mean age 57 years; range 43-67 years), who had been cultivating their allotment gardens for an average of 20 years (range 7-36 years). About 50% of their total vegetable consumption and 30% of their fruit consumption were from their own gardens. The mean 2.3.7.8-TCDD toxicity equivalents (TE) of PCDD/F in blood fat were 44.3 pg I-TE/g fat (range 29.2-81.1 pg I-TE/g fat). Compared to reference data these values are within the range of background PCDD/F-levels in the German population. The concentrations in individual gardeners as well as the congener pattern were not different from those of normal subjects. The present study shows that increased levels of PCDD/F in garden soil and garden products do not have a significant effect on the PCDD/F burden in gardeners, even if they consume homegrown vegetables and fruits from their own allotment gardens for many years in succession.

[Digoxin content in blood lipids of children, athletes, sports ground attendants and residents after content with dioxin-containing surface slag (Kieselrot)]. / Dioxingehalte im Blutfett von Kindern, Sportlern, Platzwarten und Anwohnern nach Kontakt mit dioxinhaltigen Tennenflächen (Kieselrot).

In 1991 it was discovered, that a large number of sporting grounds and playgrounds in Germany were covered with a waste slag material from a former copper smelter located at Marsberg, Germany. This material was found to contain high levels of PCDD/F ranging up to 100,000 TE/kg. The objective of the present study was to assess whether subjects sporting on such grounds had elevated levels of PCDD/F in blood. PCDD/F in blood fat was used as an indicator of the PCDD/F body burden. Additionally, six children and seven residents of a contaminated sporting and playground were examined. Generally, the levels of PCDD/F in blood fat were in the range of background levels in all subjects. Taking into account the effect of age, slightly elevated blood levels of PCDD/F were detected in children. The results show that the bioavailability of PCDD/F in the slag material is very low. However, from the preventive point of view children who might ingest slag material by hand-to-mouth-activities, should not play on such contaminated playgrounds.

[Volatile organochlorine compounds in human tissue]. / Leichtflüchtige Organochlorverbindungen im menschlichen Gewebe.

Between November 1978 and June 1979 a total of 150 tissue sample (subcutaneous adipose tissue, perinephric fat, liver, lung and muscle tissue) from 30 autopsy cases were examined for their content of volatile organic chlorinated compounds. The ages of the deceased ranged from 29 to 82 years, whereas the majority was 60-70 years old and most were male. Volatile organic chlorinated compounds are detected in all tissue samples investigated. The compounds chloroform, 1,1,1-trichloroethane, carbon tetrachloride, trichloroethylene and tetrachloroethylene are always found. The mean values vary between 2 and 25 micrograms/kg wet tissue. The values increase from carbon tetrachloride over 1,1,1-trichloroethane, trichloroethylene and tetrachloroethylene to chloroform. With the exception of 1,1,1-trichloroethane much lower values are found in the liver, lung and muscle tissues than in the fatty tissues. The mean value of chloroform detected in subcutaneous adipose tissue amounted to 23,4 micrograms/kg wet tissue, in perinephric fat 24.8 micrograms/kg, in liver tissue 10.8 micrograms/kg, in lung tissue 9.9 micrograms/kg and in muscle tissue 10.0 micrograms/kg. Maximum values are 10 to 20 times higher. The chloroform content of the tissues increase with age and reach a maximum between 50 and 70 years of age. This increase is not influenced by the fat content of the tissues.

[Effect of pesticides on the release of histamine, chemotactic factors and leukotrienes from rat mast cells and human basophils]. / Einfluss von Pestiziden auf die Freisetzung von Histamin, chemotaktischen Faktoren und Leukotrienen aus Rattenmastzellen und menschlichen Basophilen.

The influence of pesticides on mediator release from rat peritoneal mast cells and human basophiles was studied. Mediators from mast cells and basophils are important factors in allergic and inflammatory reactions. Release of histamine from rat mast cells and human basophils is demonstrated by stimulation with dieldrin, DDT, heptachlor, heptachlorepoxid and biphenyl. This pesticide-induced histamine secretion is dose-dependent and requires Ca2+. In contrast, incubation with gamma-HCH, HCB and carbaryl produces no significant histamine release. Additive histamine secretion results from simultaneous stimulation of rat mast cells with pesticides and anaphylatoxin C5a. Further, secretion of eosinophil and neutrophil chemotactic factors from rat mast cells is induced during incubation with dieldrin, biphenyl and heptachlorepoxid. It is also demonstrated that pesticides can stimulate the generation of lipidmediators. Biphenyl, gamma-HCH, heptachlor, heptachlorepoxid, DDT and dieldrin cause the release of leukotriene C4 from rat mast cells. The possible role of these in vitro results is discussed.

[A method for detection of volatile organic halogenated compounds in human and animal tissues (author's transl)]. / Eine methode zum Nachweis flüchtiger Organohalogen-verbindungen in menschlichen und tierischen Geweben.

A method is described which is suitable for detecting volatile halogenated hydrocarbons boiling from 60 degrees to 150 degrees C in human and animal tissues. Fried tissue samples of 10 grams are homogenized with Na2SO4. Stripped by nitrogen in an 80 degrees C water bath the compounds are sorbed on XAD-2 columns and desorbed by pentane. The pentane extract can directly be analyzed without further clean up, either by gas-liquid chromatography or by microcoulometry. Limits of detection achieved were between 6.2 X 10(-9) g/kg for carbon tetrachloride and 49 X 10(-9) g/kg for 1,1,2-trichloroethane. The recovery in human tissue is 87% as mean value.