benzofurans and 1-2-3-7-8-pentachlorodibenzofuran

The concentrations of immunoglobulins (IgA, IgD, IgG, IgM) and of several cytokines were measured in the plasma of volunteers with clearly, but moderately, increased body burdens of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF), using monoclonal antibodies and an enzyme-linked immuno-sorbant assay. Two groups of workers with different body burdens of PCDD/PCDF were studied: (trial I) persons with mainly 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and (trial II) persons with mainly penta- and hexachlorinated dibenzofurans (P5CDF/H6CDF) in their blood fat. Including the reference group, 158 volunteers were investigated. A slight but statistically significant decrease was observed in the plasma concentration of IgG1 in persons exposed to TCDD, but not in persons exposed to P5CDF/H6CDF. When the data of both groups were pooled and a multi-regression analysis against international TCDD toxicity equivalencies (I-TEq, NATO/CCMS) was performed, taking several confounding factors into account, no influence of the dioxin exposure could be revealed. There were no changes in the plasma concentrations of the other immunoglobulins studied. In the same volunteers, no deviation from the reference range was found for the concentrations of the cytokines: IL-1alpha, IL-1beta, IL-6 and TNFalpha in blood plasma.

Topics: Adult; Aged; Benzofurans; Body Burden; Cytokines; Female; Humans; Immune System; Immunoglobulin G; Male; Middle Aged; Occupational Exposure; Polychlorinated Dibenzodioxins; Receptors, Cell Surface

It usuallytakes a few weeks to analyze dioxin concentrations and dioxin-TEQ (toxicity equivalency quantity) in fluegases from municipal solid waste (MSW) incinerators by a standard method provided by Japanese industrial standard (JIS 0311). To reduce the required time for analysis, we have developed a new on-line measuring system for furans homologues. This system is composed of a sensitive and robust vacuum ultraviolet (VUV) single-photon ionization (SPI) ion trap (IT) time-of-flight mass spectrometer (VUV-SPI-IT-TOFMS) and automatic sampling/concentrating process. In this work, pentachloro-dibenzofuran (P5CDF) was selected as an index homologue in chlorinated dibenzo-p-dioxin/ furan homologues (DXNs) because its concentration and I-TEF (international toxicity equivalency factor), which are 2,3,4,7,8-P5CDF is 0.5 and 1,2,3,7,8-P5CDF is 0.05, are high and the concentration correlates closely with the total amount of dioxin-TEQ. The lowest detectable limit, 1 pg (0.001 ng-TEQ/m3 N) was demonstrated by laboratory tests. This system underwent a field test at several actual MSW plants and the tests revealed the following: (a) This system is applicable for dioxin-TEQ evaluation from actual MSW incinerators. (b) It can continuously monitor P5CDF in a fluegas for 7 months. (c) The frequency of the measurements is once every 2-6 h, depending on the concentration of P5-CDF.

Topics: Benzofurans; Calibration; Incineration; Mass Spectrometry; Online Systems; Waste Products

Polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs) are toxic environmental contaminants which have the potential to accumulate in human tissues. In order to examine the potential for systemic exposure following dermal exposure, the absorption, distribution, and elimination of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF), 1,2,3,7,8-pentachlorodibenzofuran (1PeCDF), and 2,3,4,7,8-pentachlorodibenzofuran (4PeCDF) were evaluated in male F344 rats. TCDD (0.00015, 0.001, 0.01, 0.1, 0.5, and 1.0 mumol/kg) and the three PCDFs (0.1, 0.5, and 1.0 mumol/kg) were applied to a preclipped region on the back of the rat and covered with a perforated cap. The rats were held in individual metabolism cages for 3 days. In animals administered 0.1 mumol/kg, the absorption of TCDF was greater than that of 4PeCDF, 1PeCDF, and TCDD. Relative absorption (percentage of administered dose) declined with increasing dose while the absolute absorption (microgram/kg) increased nonlinearly with dose. Absorption of TCDF at 0.1 mumol/kg was 48% of the administered dose which was significantly greater than that of the other compounds. At this dose, absorption of 4PeCDF was greater than that of TCDD. Absorption at the higher doses was similar for all four compounds. Maximum relative absorption of TCDD (approximately 40% of the administered dose) was obtained at 0.001 and 0.00015 mumol/kg. Major tissue depots for these four chemicals included liver, adipose, skin, and muscle tissue; however, the liver:fat ratio for 4PeCDF was approximately fourfold higher than that for the other three compounds. When normalized to 100% of dose absorbed, the distribution of 4PeCDF-derived radioactivity in liver and adipose tissue was similar to that previously observed after oral and iv administration. In animals administered 0.1 mumol TCDF or 1PeCDF/kg, 56 and 32% of the respective absorbed dose was excreted as polar metabolites within 3 days. Very little of the absorbed dose of either TCDD (approximately 10%) or 4PeCDF (approximately 2%) was eliminated. Results indicate that the dermal absorption of these compounds is incomplete and that systemic toxicity following acute dermal exposure to levels found in the environment is unlikely.

Topics: Administration, Cutaneous; Animals; Benzofurans; Dioxins; Dose-Response Relationship, Drug; Environmental Pollutants; Feces; Industrial Waste; Male; Polychlorinated Dibenzodioxins; Polymers; Rats; Rats, Inbred F344; Skin Absorption; Tissue Distribution

1,2,3,7,8-Pentachlorodibenzofuran (1PeCDF) is one of several toxic polychlorinated dibenzofurans (PCDFs) which are ubiquitous environmental contaminants. Related in structure and toxicity to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), PCDFs have been detected in municipal and industrial effluents, PCB mixtures, and in a variety of antiseptics and preservative solutions. The objective of this study was to evaluate the distribution and elimination of 1PeCDF in the rat and to compare these parameters with that of 2,3,4,7,8-pentachlorodibenzofuran (4PeCDF) and 2,3,7,8-tetrachlorodibenzofuran (TCDF). After iv administration of 0.1 mumol [3H]1PeCDF/kg, 1PeCDF was rapidly cleared from the blood and distributed to the liver, muscle, skin, and adipose tissue in a manner similar to that for other dibenzofurans. The initial pool sizes of 1PeCDF-derived radioactivity in the liver, muscle, skin, and adipose tissue were 43,35,10, and 7% of the administered dose, respectively. In all cases, loss of radioactivity from these tissues could be described by exponential decay and the initial half-lives for these tissues were 1.36, 0.03, 13, and 1 day, respectively. After redistribution from the muscle, skin, and adipose tissues to the liver, 1PeCDF was metabolized to a polar metabolite(s) and excreted from the body via the bile into the feces. No parent compound was detected in the bile and fecal excretion was the major route of elimination. Most of the radioactivity in the urine was excreted within the first day, after which less than 0.5% of the dose/day was detected. More than half of the administered dose was excreted in the urine and feces within 2 days. The whole-body half-life of related compounds is 4PeCDF much greater than 1PeCDF greater than or equal to TCDF. Therefore, persistence appears to be inversely related to the metabolism of these compounds and metabolism is inhibited by chlorine-substituted carbon atoms adjacent to the oxygen atom in the dibenzofuran ring.

Topics: Animals; Benzofurans; Bile; Environmental Pollutants; Feces; Lethal Dose 50; Male; Rats; Rats, Inbred F344; Structure-Activity Relationship; Tissue Distribution