Martin van den Berg

Presence of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in fish-eating birds and fish from The Netherlands

In the period 1980 to 1982, nineteen CormorantsPhalacrocorax carbo, three Grey HeronsArdea cinerea and one Great Crested GrebePodiceps crisatus were collected in The Netherlands. The livers of these fish-eating birdspecies were analyzed for polychlorinated dibenzo-p-dioxins and dibenzofurans.Only congeners with a 2,3,7,8-chlorine substitution pattern were found in the livers. Major components were 2,3,4,7,8-pentachlorodibenzofuran and 1,2,3,6,7,8-hexachlorodibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin and 1,2,3,7,8-pentachlorodibenzo-p-dioxin were also present. Six pooled samples of the EelAnguilla anguilla, showed the same congeneric pattern of chemicals as found in these bird species. In the Eel, 2,3,4,7,8-pentachlorodibenzofuran and 1,2,3,6,7,8-hexachlorodibenzo-p-dioxin were generally present in the 1 to 5 ng/kg range. Since the Eel is the Cormorants 2 major food, this indicates strong bioaccumulation for both congeners in the liver of the Cormorant.Significant correlations were found between the various congeners retained in the liver of the Cormorant. It is proposed that this is a result of a continous exposure to a relatively stable background mixture, probably originating from fish consumption. Based on the congeneric patterns found in the Cormorant, polychlorinated biphenyls and pentachlorophenol are suggested as major contaminating sources for this species. Based on the results from the Cormorants, an open one compartment model was applied to estimate concentrations of 2,3,4,7,8-PnCDF in the Eel. These calculations were in good agreement with the actual measurements found in the Eels.

The presence of PCDDs and PCDFs in human breast milk from the Netherlands

Abstract Sixteen individual and two pooled human milk samples were analyzed for PCDDs and PCDFs. All detected PCDD and PCDF congeners had a 2,3,7,8-chlorine substitution pattern. The PCDDs and PCDFs were associated with the lipid fraction of the milk. Major components were 2,3,4,7,8-PnCDF (0.2 – 2.6 ppt), 1,2,3,6,7,8-HxCDD (0.2 – 5.7 ppt), 1,2,3,4,6,7,8-HpCDD (1.3 – 19.1) and OCDD (1.7 – 37.8 ppt), with concentrations on total milk basis. Minor components were 1,2,3,7,8-PnCDD, 1,2,3,7,8,9- and 1,2,3,4,7,8- HxCDD (⩽ 1 ppt). Qualitatively and quantitatively the milk samples from the Netherlands strongly resemble those from Sweden and West-Germany. A linear relationship was found between some congeners. This correlation was highest for congeners having an equal number of chlorine atoms or those with a difference of one chlorine atom. By using a one compartment open model for multiple doses, a maximum liver concentration of approximately 200 ppt 2,3,4,7,8-PnCDF in the neonate was calculated after six months.

Discourse grammar and verb phrase anaphora

We argue that an adequate treatment of verb phrase anaphora (VPA) must depart in two major respects from the standard approaches. First of all, VP anaphors cannot be resolved by simply identifying the anaphoric VP with an antecedent VP. The resolution process must establish a syntactic/semantic parallelism between larger units (clauses or discourse constituent units) that the VPs occur in. Secondly, discourse structure has a significant influence on the reference possibilities of VPA. This influence must be accounted for.We propose a treatment which meets these requirements. It builds on a discourse grammar which characterizes discourse cohesion by means of a syntactic/semantic matching procedure which recognizes parallel structures in discourse. It turns out that this independently motivated procedure yields the resolution of VPA as a side effect.

Bioavailability of PCDDs and PCDFs adsorbed on fly ash in rat, guinea pig and Syrian golden hamster

In the environment PCDDs and PCDFs often occur in an adsorbed state in soil, sediment or combustion residues. Detailed information about physical, chemical and biological properties is available only for 2,3,7,8-TCDD and to a lesser extent for 2,3,7,8-TCDF. Information about the bioavailability of PCDDs and PCDFs in the adsorbed state is also very limited. The authors have reported earlier about the bioavailability of these compounds from fly ash in the rat. In this paper they report the bioavailability of these compounds from fly ash of a municipal incinerator in three animal species, during a one to three month feeding study.

Thermal Degradation of Polychlorinated Dibenzo-p-dioxins and Polychlorinated Dibenzofurans on Fly Ash from a Municipal Incinerator

Abstract Heating fly ash from a municipal incinerator under oxygen deficient conditions in the temperature range from 200 to 470°C caused dechlorination of the PCDDs and PCDFs present in the matrix. The isomeric and congeneric composition of PCDDs and PCDFs was qualitatively and quantitatively determined by using GC/MS analysis. TCDD, TCDF, PnCDD and PnCDF concentrations increased in the temperature range from 200 to 370°C followed by a decrease at higher temperatures. The higher chlorinated compounds showed no distinct concentration maximum and

Bio-availability of PCDDs and PCDFs on fly ash after semi-chronic oral ingestion by the rat

Abstract Groups of rats ( n = 5) were fed a diet containing 2.5% RCl pre-treated fly ash from the electrostatic precipator of a municipal incinerator during 34, 59 and 99 days. Livers were analysed for 2,3,4,7,8-pentachlorodibensofuran and higher chlorinated dibenso(p)dioxins (PCDDs) and dibensofurans (PCDFs). All isomers retained in the liver had a 2,3,7,8-chlorine substitution pattern. Total group dose varied between 0.2 and is μg for each individual retained compound. Retention in the liver was highest for 2,3,4,7,8-PnCDF, being 14% of the dose for the group killod on day 99. The other isomers detected in the livers had a retention generally below 10%. The 2,3,7,8-substituted hexa- and hepta- chlorinated PCDDs and PCDFs were retained in the liver in constant relative concentrations throughout the experiment, which closely approached a linear relationship to the administered dose.

Bioavailability of PCDDs and PCDFs on fly ash after semi-chronic oral ingestion by guinea pig and syrian golden hamster

Abstract Groups of guinea pigs and syrian golden hamster ( n = 5) were fed 2.5% HCL pre-treated fly ash from the electrostatic precipitator of a municipal incinerator during one, two and three months, respectively, in the diet. The livers were analyzed for tetra-, penta- and hexa-chlorinated dibenzo(p)dioxins (PCDDs) and dibenzofurans (PCDFs). In the livers of the hamsters 2,3,7,8-substituted PCDDs and PCDFs were the major isomers retained. In the livers of the guinea pigs 2,3,7,8 substituted PCDDs and PCDF congeners were retained, but also a number of otherwise substituted PCDFs. These other PCDF congeners included some having a 2,3,6,7 or alternate chlorine substitution pattern. Those congeners retained in the livers were generally below 5% of the group dose. The PCDF congener which had the highest retention in the livers of guinea pig was 1,2,3,7,8-PnCDF, 11.3% after 95 days. In the livers of the hamsters highest retention was found for 2,3,4,7,8-PnCDF, 8.4% after 95 days. For most 2,3,7,8-substituted PCDDs and PCDFs the retention in the livers of the guinea pigs and hamsters was not significantly different during the whole period, which could indicate a bioconcentration approaching a linear relationship to the administered dose. Constant relative concentrations in the livers were found for the 2,3,7,8- substituted penta- and hexa-chlorinated PCDDs and PCDFs in both species during the three time periods.

Some pharmacokinetic aspects of PCDDs and PCDFs in mammals after administration of a fly ash extract from a municipal incinerator

Abstract Fly ash extracts were fed to male hamster (single dose), male rat (single dose and multiple dose), pregnant and lactating female rat (multiple dose). The retention of four isomers, 2,3,7,8-TCDD, 2,3,7,8-TCDF, 1,2,3,7,8-PnCDD and 2,3,4,7,8-PnCDF, was studied in the liver of the adults, foetuses and liver of the sucklings. Liver retention was structure dependent and different for both species. Transportation of the isomers via the mother milk was 50–100 times more effective than via the placenta. After a single intravenous dose of fly ash extract to male rats the elimination of these four isomers was studied in the liver, during a period of 10 days. Elimination rates for 2,3,7,8-TCDD, 1,2,3,7,8-PnCDD and 2,3,4,7,8-PnCDF were in the same range. Pharmacokinetic calculations were done on both tetra congeners, to obtain information about the validity of the published K e values in the multiple dose experiments with male rats. For 2,3,7,8-TCDF the K e value was applicable, but for 2,3,7,8-TCDD the validity of the K e could not be determined.

Retention of PCDDS and PCDFS in the liver of the rat and hamster after oral administration of a municipal incinerator fly ash extract

A single dose of an extract from 16 and 5 grams fly ash was administered orally to male rats and hamsters. In the rat 1,2,3,7,8‐PnCDD had the highest retention (41%) in the liver. The congener with the highest retention in the liver of the hamster was 2,3,4,7,8‐PnCDF (70.9%). In two oral multiple dose experiments with rats, highest liver retentions were found for 1,2,3,7,8‐PnCDD (51.7%) and 1,2,3,6,7,8‐HxCDD (59.8%). With the exception of 2,3,4,6,7‐PnCDF, all PCDDs and PCDFs retained in the liver of rat and hamster had a 2,3,7,8 chlorine substitution pattern. In both types of experiments with rats the retention of 2,3,7,8‐TCDF in the liver was very low, 1.1–2.8% of the total dose. In the liver of the hamster retention of 2,3,7,8‐TCDF was almost equal to that of 2,3,7,8‐TCDD, indicating that the hamster is probably metabolizing 2,3,7,8‐TCDF Jess efficiently than the rat. In all experiments 1,2,3,7,8‐PnCDD and 2,3,4,7,8‐PnCDF were retained in the liver more efficiently than 2,3,7,8‐TCDD. Based on first orde...

Vehicle-dependent bioavailability of polychlorinated dibenzo-p-dioxins (PCDDs) and -dibenzofurans (PCDFs) in the rat

Abstract PCDDs and PCDFs were administered as fly ash (500 mg) or fly ash extract to male Wistar rats. The extract was administered orally and intravenously by using arachidis oil and miglyol 812 as oily vehicles. Liver retentions were determined after 48 hours as a degree of bioavailability. In all experiments only the 2,3,7,8-substituted congeners, with the exception of 2,3,4,6,7-PnCDF, were detected in the liver. The dose was 10 to 40 ng for each congener. The lowest bioavailability was found in the experiments with crude or hydrochloric acid pretreated fly ash. Liver retentions were comparable for both experiments with fly ash (0.4 – 3.8%) and were approximately 10 times higher in the oral experiments with oily vehicles. Miglyol 812 produced slightly lower liver retentions compared with arachidis oil. Intravenous dosage with miglyol 812 resulted in liver retentions twice as high as oral administration with this vehicle.