Polychlorinated Dibenzofurans Congeners Research Articles

PCDD/F levels in plasma of a belgian population before and after the 1999 belgian PCB/DIOXIN incident

We evaluated the impact of the 1999 Belgian dioxin incident on the blood plasma polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) levels among 232 Belgian blood donors (74% men, mean age 47 years). The Red Cross made plasma samples from before the incident of these donors available. A second plasma sample was collected during the second half of 2000. The sum of the 17 PCDD/F congeners was significantly lower in 2000 compared to 1998 (417 pg/g fat versus 445 pg/g fat, respectively). This could be completely attributed to the significant decrease of OctaCDD (301 pg/g fat in 2000 versus 277 pg/g fat in 1998). Moreover a slight but significant decrease was observed for 2,3,7,8-TetraCDF and for 1,2,3,4,6,7,8-HeptaCDF. 1,2,3,7,8-PentaCDF and 2,3,4,7,8-PentaCDF however showed a slight but significant increase (respective levels in 1998 were 0.004 and 14.5 pg/g fat compared to 0.006 and 17.9 pg/g fat in 2000). Given their significantly higher presence in incident related food samples this increase can be attributed to the food contamination episode. However, the total toxicity remained unchanged (22.9 in 1998 versus 23.1 pg WHO-TEQ/g fat, p>0.05). Moreover the observed congener profiles and the total PCDD/F levels were similar to those of other European non-occupationally exposed populations. In conclusion, the 1999 PCB/dioxin incident was traceable in the plasma profiles (rise of the two specific PCDF congeners), but comparison of the results for both years indicates that the changes were too small to cause an adverse public health effect.

Concentrations of polychlorinated dibenzo- p-dioxins, polychlorinated dibenzofurans, and non- ortho and mono- ortho polychlorinated biphenyls in blood of Yusho patients

We measured the concentrations of polychlorinated dibenzo- p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), non- ortho polychlorinated biphenyls (non- ortho PCBs) and mono- ortho polychlorinated biphenyls (mono- ortho PCBs) in blood collected from 279 Yusho patients living in Japan, 92 Yusho-suspected persons living in Japan and 127 normal controls living in Fukuoka Prefecture, and compared among the groups in terms the concentrations of these compounds. The total toxic equivalents (TEQ) concentrations of PCDDs, PCDFs, non- ortho PCBs, and mono- ortho PCBs in the bloods of Yusho patients and Yusho-suspected persons were 161.4 and 51.2 pg TEQ/g lipid, respectively and were about 3.5 and 1.1 times higher than those of normal controls, respectively. Although the TEQ concentrations of PCDDs, non- ortho PCBs, and mono- ortho PCBs among Yusho patients, Yusho-suspected persons and normal controls were nearly the same, the PCDFs levels of Yusho patients were significantly higher than those of Yusho-suspected persons and about 10.3 times higher than those of normal controls. In Yusho patients, PCDFs contributed about 65% to the total TEQ concentration. Among the PCDFs congeners for Yusho patients, the concentration of 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) was about 11.3 times higher than that of normal controls. These findings indicated that Yusho patients even now, more than 34 years after the outbreak of Yusho, have much higher blood levels of 2,3,4,7,8-PeCDF in general than do unaffected persons.

POLYCHLORINATED NAPHTHALENE (PCN) AND DIBENZOFURAN (PCDF) CONGENER PATTERNS FROM PHENOL PRECURSORS IN THERMAL PROCESS: [II] EXPERIMENTAL RESULTS FROM DICHLOROPHENOLS (DCPs)

Polychlorinated naphthalenes (PCNs) formed along with dibenzo-p-dioxin and dibenzofuran products in the slow combustion of dichlorophenols (DCPs) at were identified. Each DCP reactant produced a unique set of PCN products. Major PCN congeners observed in the experiments were consistent with products predicted from a mechanism involving an intermediate formed by ortho-ortho carbon coupling of phenoxy radicals; polychlorinated dibenzofurans (PCDFs) are formed from the same interemediate. Tautomerization of the intermediate and elimination produces PCDFs; alternatively, CO elimination to form dihydrofulvalene and fusion produces naphthalenes. Only trace amounts of tetrachloronaphthalene congeners were formed, suggesting that the preferred PCN formation pathways from chlorinated phenols involve loss of chlorine. 3,4-DCP produced the largest yields of PCDF and PCN products with two or more chlorine substituents. 2,6-DCP did not produce tri- or tetra-chlorinated PCDF or PCN congeners. It did produce 1,8-DCN, however, which could not be explained.

Organic pollutants in wild ducks from New York state: I. Interspecies differences in concentrations and congener profiles of PCBs and PCDDs/PCDFs

Wild ducks of three species, common mergansers ( Mergus merganser americanus), gadwalls ( Anas streptera), and mallards ( Anas platyrhynchos), were collected near industrial sites in the Massena, NY area of the St. Lawrence River (SLR) in 1988/89 and 1994. Additional samples were collected in 1994 near a former polychlorinated biphenyl (PCB) capacitor plant at Fort Edward, NY (a mallard and two wood ducks ( Aix sponsa)), and at control sites (common mergansers, mallards and wood ducks). On a lipid basis, PCB concentrations in liver tissue from the 1994 collection ranged from 0.1 μg/g in a control wood duck to 676 μg/g in a common merganser from the SLR area. However, the highest total polychlorinated dibenzofuran (PCDF) concentrations were found in liver and fat tissues of gadwalls and mallards collected near the SLR industrial sites (2.8–12 ng/g lipid). These two species bioaccumulated non-2,3,7,8-substituted PCDFs in addition to 2,3,7,8-PCDF isomers, whereas common mergansers preferentially bioaccumulated 2,3,7,8-substituted PCDFs. The mergansers from the SLR sites were the only specimens contaminated with polychlorinated dibenzo- p-dioxins (PCDDs), which were all 2,3,7,8-substituted. The PCB and PCDF congener patterns in the duck tissues appear to have been influenced by both sampling location and species trophic level.

Distribution of PCDDs and PCDFs in Soils Collected from the Denver Front Range - Principal Components Analysis of Diffuse Dioxin Sources (10 pp)

The Rocky Mountain Arsenal (RMA) is a U.S. Army facility located northeast of Denver, Colorado that has been listed on the National Priorities List (NPL). It is currently being re-mediated under the authority of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) and the Superfund Amendments and Reauthorization Act of 1986 (SARA). As part of the remediation activities at RMA, indications were found that a source of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) had existed on the RMA. As a result, investigations were undertaken to assess the possible nature and extent of any potential sources of PCDDs and PCDFs on the RMA site. In addition, other studies were conducted that examined PCDD/PCDF contamination in the Denver area. The goal of these studies was to examine nature and extent of PCDD/PCDF contamination both on the RMA as well as in the surrounding Denver area. The intent of this study was to characterize sources of dioxins (PCDDs) and dibenzofurans (PCDFs) at low environmental concentrations which might have originated from diffuse sources in the Denver Colorado area and in particular, the Rocky Mountain Arsenal (RMA) using Principal Component Analysis (PCA). Over 200 soil samples were collected from the RMA and the Denver area. From the RMA, soil was collected as part of three studies that included a (1) random site-wide sampling of the RMA, (2) soils from the Western Tier Parcel (WTP), and (3) soils from Historic Use areas. Denver area soil samples were collected from five different land use categories: Residential, Agricultural, Open Space, Commercial, and Industrial. PCA was conducted on concentrations of 17 2,3,7,8-substituted PCDD and PCDF congeners in 220 soil samples collected from the RMA and the Denver Front Range region. PCA demonstrated the presence of possible minor sources of dioxins on the RMA. Current remediation efforts on RMA will result in the removal of these sources. Samples from the RMA were identified by the presence of a congener profile containing higher chlorinated PCDFs while the Denver Front Range areas were characterized by the presence of higher chlorinated PCDD congeners. The presence of a PCDF signature for the RMA samples does not necessarily indicate a major source of these contaminants on-site. Indeed, the relatively diffuse nature of the sample clusters would argue strongly against the presence of a single large source. Instead, the predominance of the PCDF congeners probably indicates the mixed industrial activities that took place on and near the site. PCA results indicate that PCDD/PCDF profiles in soils collected from the RMA differed from those collected from the outlying Denver areas but that a major source of these contaminants was not present. Rather, the diffuse nature of sample clusters from the PCA indicated that the congener profile of RMA samples was most likely a result of the mixed industrial activities that historically have taken place on and near the site. PCA also indicated that many of the 'open area' (peripheral site-wide) RMA soils samples did not differ from Denver are reference congener profiles. This finding was also true for samples collected from the WTP that were essentially indistinguishable from Off-RMA reference samples. In addition, total TEQ concentrations in soils collected from WTP were similar to those measured in soils collected from the Denver Front Range areas indicating that lack of a major source of PCDD/PCDF within the WTP zones of the RMA. Analytical as well as statistical results of the soil congener data indicate that the WTP soils are indistinguishable from soils collected from non-industrial areas in the Denver area. This finding would support the recent 'de-listing' of the WTP from the other RMA areas and its transfer to other authorities in the Denver area.

Is phenol condensation one of the major pathways in the formation of polychlorinated dibenzofurans in municipal waste incinerators?: Model prediction vs. field observation

The role of phenol condensation pathways in the formation of polychlorinated dibenzofurans (PCDF) in a municipal waste incinerator was assessed by comparing predicted PCDF homologue and isomer patterns with those obtained from the incinerator. A two-phenol condensation model, dependent only on the distribution of phenols, was used to predict the distributions of PCDF congeners in the incinerator. Complete distributions of phenols and PCDF congeners were obtained from the incinerator. To quantify the degree of agreement between obtained isomer distributions and those predicted by the model, R-squared values from linear correlations were calculated for the dichlorinated- through hexachlorinated-isomers. They ranged from 0.001 to 0.1. Agreement between obtained and predicted PCDF isomers was very poor for all homologues, suggesting that phenol condensation pathways are unlikely to be the primary route in the formation of PCDF in the incinerator. However, dibenzofuran (DF) is likely to be produced from a condensation of two phenols. This paper shows the use of PCDF homologue and isomer patterns calculated by the two-phenol condensation model for testing PCDF formation mechanism attribution in a municipal waste incinerator.

Adipose levels of dioxins and risk of breast cancer

Our objective was to evaluate the breast cancer risk associated with body burden levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). We conducted a hospital-based case-control study among 79 women diagnosed with invasive breast cancer and 52 controls diagnosed with benign breast conditions. We collected breast adipose tissue and analyzed it for all 17 2,3,7,8-substitituted PCDD/PCDFs. We used unconditional logistic regression to calculate age- and race-adjusted exposure-specific odds ratios (ORs) and 95% confidence intervals (CI) for each individual PCDD/PCDF congener as well as for the summary measures (I-TEQ, Adj-TEQ). Dioxin levels were consistent with reports from other small, contemporary studies of body burdens in the U.S. None of the odds ratios for any of the congeners or summary measures differed significantly from one. Especially for the PCDF congeners, point estimates tended to be below one. One notable exception was octachlorodibenzo-p-dioxin (OCDD), for which the odds ratio for the second and third tertiles appeared modestly elevated (OR = 1.22, 95% CI: 0.47:3.16 and OR = 1.62, 95% CI: 0.64:4.12, respectively), though the test for trend was not significant (p = 0.36). Breast cancer risk was not associated with adipose levels of PCDD/PCDFs. More study is suggested among women of color who may have higher body burden levels of these compounds.

Follow-up survey of dioxin concentrations in the blood of Yusho patients in 2002-2003.

We measured the concentrations of polychlorinated dizenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and non-ortho-coplanar polychlorinated biphenyls (Co-PCBs) in blood collected from 279 Yusho patients and 92 Yusho-suspected persons living in Japan in 2002, 269 Yusho patients and 74 Yusho-suspected persons living in Japan in 2003 and 128 normal controls living in Fukuoka Prefecture, and compared with the concentrations of these compounds among the groups. The total TEQ concentrations of PCDDs, PCDFs, and Co-PCBs in the blood of Yusho patients were 3.6 times and 3.3 times higher than those in the normal controls in 2002 and 2003, respectively. In the case of Yusho-suspected persons, the concentrations were 1.1 times and 1.0 times higher in 2002 and 2003, respectively. Among the TEQ concentrations of PCDDs, PCDFs, and Co-PCBs, the concentrations of PCDFs in the blood of Yusho patients were 10.3 times and 9.4 times higher than those of the normal controls in 2002 and 2003, respectively, whereas the concentrations of PCDDs and Co-PCBs in blood were identical in Yusho patients, Yusho-suspected persons and normal controls. Yusho patients indicated the highest concentrations ratio of PCDFs to the total TEQ concentrations. Moreover, of the PCDFs congeners for Yusho patients, the concentrations of 2,3,4,7,8-PeCDF were about 11.0 times and 10.1 times higher in 2002 and 2003 than those in normal controls. These results indicated that Yusho patients have a much higher concentration of 2,3,4,7,8-PeCDF in their blood than do unaffected persons even though over 34 years have passed since the outbreak of Yusho.

Quantitative structure–property relationship study of GC retention indices for PCDFs by DFT and relative position of chlorine substitution

The structural property and thermodynamic parameters of 136 polychlorinated dibenzofurans (PCDFs) were obtained by fully optimized calculation at B3LYP/6-31G* level, and the free energy and standard heat of formation of these compounds were consequently obtained by designing isodemic reactions. The dependency of these parameters on the number and position of chlorine substitutions were further discussed. The specific structural and thermodynamic parameters were consequently taken as chemical descriptors to get theoretical model I for predicting the gas chromatographic retention indices (RI) of PCDF congeners ( R 2=0.993 and SD=23.7 and q 2=0.986), in which the maximum relative error of RI for PCDFs is 2.75%. On the other hand, the number and relative position of chlorine substitutions were also used as theoretical descriptors, and the corresponding RI prediction model II ( R 2=0.997, SD=15.1 and q 2=0.997) for PCDFs was thus achieved. With maximum error of only 1.42% in predicting RI, it was surprisingly found that model II is simple and has high precision and predictive power. Finally validation for two models was carried out and the result showed the models developed in the present study are both reliable.

Rapid Bioassay for the Determination of Dioxins and Dioxin-like PCDFs and PCBs in Meat and Animal Feeds

Over the past several years, the numerous contamination incidents have raised concerns over the presence of halogenated aromatic hydrocarbons, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and related chemicals in foods and feeds. Here we applied a sensitive recombinant mouse hepatoma cell (H1L1.1c2) bioassay for the determination of dioxins and dioxin-like polychlorinated dibenzofurans (PCDFs) and biphenyls (PCBs) in meat and animal feeds. These cells responded to TCDD-like chemicals with dose-dependent induction of firefly luciferase activity, and the minimal detection limit of TCDD in the cell was 16 fg. Induction equivalency factors determined for pure TCDD-like polychlorinated dibenzo-p-dioxins (PCDDs), PCDFs, and PCBs in the bioassay were well-correlated with the World Health Organization's toxic equivalency factors. To determine the applicability of the bioassay system to detect those compounds presence in meat and feed samples, cell bioassays for 17 TCDD-like PCDDs and PCDFs congeners-spiked lipid extracted from beef or animal feed were performed. Mean recoveries of TCDD-like chlorinated PCDDs and PCDFs congeners from spiked beef or feed fat ranged from 61.2 to 122.3%. Within-laboratory coefficients of variation for analysis as index of precision were lower than 5.2%, and the calculated limits of detection and quantitation were 0.33 and 1 pg toxicity equivalency quantity (TEQ)/0.5 g fat, respectively. Correlation between bioassay- and high-resolution gas chromatography-mass spectrometry (HR-GC-MS)-determined TEQs for 10 meat samples was 0.85, with 1.2 times higher in bioassay than HR-GC-MS. The correlation between bioassay- and HR-GC-MS-determined TEQs in 10 animal feed products was 0.81, with 2.1 times higher in bioassay than HR-GC-MS. Overall, these results demonstrated that the recombinant cell bioassay can be used for the rapid detection and quantitation of PCDDs and dioxin-like PCDFs and PCBs in meats and animal feeds.

Levels and toxicokinetic behaviors of PCDD, PCDF, and coplanar PCB congeners in common cormorants from Lake Biwa, Japan.

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (Co-PCBs) were determined in the liver and pectoral muscle of common cormorants (Phalacrocorax carbo) collected from Lake Biwa, Japan. To clarify the toxicokinetic behaviors and potential toxicities of these chemicals, the present study addresses life-stage- and tissue-specific accumulation of the congeners. Total 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalents (TEQs) were in the range of 360 to 50,000 pg/g lipid weight in the liver and 310 to 12,000 pg/g lipid weight in the pectoral muscle. Among congeners, for which toxic equivalency factors were assigned, PCB126, 2,3,4,7,8-P5CDF, and 1,2,3,7,8-P5CDD made a greater contribution to total TEQs in the liver. Hepatic concentrations of T4- to H6CDDs, P5- and H6CDFs, and Co-PCBs (except PCB77) significantly increased with growth of cormorants, leading to life-stage-related compositional changes. The concentration ratios of liver to pectoral muscle revealed preferential accumulation of higher chlorinated congeners in hepatic tissue. For most congeners, concentration ratios significantly increased with an increase in hepatic total TEQs, suggesting their concentration-dependent hepatic sequestration. These results imply the presence of hepatic binding protein(s) such as cytochrome P450, inducible by these chemicals, which mayfunction as a binding species different from aryl hydrocarbon receptor. On the basis of these results, we conclude that the toxicokinetic behavior of each congener is life-stage-, tissue-, and concentration-dependent. TEQs in wildlife populations exposed to multiple congeners with varying concentrations should be used with caution for risk assessment, even within a species.

Prediction of polychlorinated dibenzofuran congener distribution from gas-phase phenol condensation pathways

A model for predicting the distribution of dibenzofuran and polychlorinated dibenzofuran (PCDF) congeners from a distribution of phenols was developed. The model is based on a simplified chemical mechanism. Relative rate constants and reaction order with respect to phenol precursors were derived from experimental results using single phenols and equal molar mixtures of up to four phenols. For validation, experiments were performed at three temperatures using a distribution of phenol and 19 chlorinated phenols as measured in municipal waste incinerator exhaust gas. Comparison of experimental measurements and model predictions for PCDF isomer distributions and homologue pattern shows agreement within measurement uncertainty. The R-squared correlation coefficient exceeds 0.9 for all PCDF isomer distributions and the distribution of PCDF homologues. These results demonstrate that the distribution of dibenzofuran and the 135 PCDF congeners from gas-phase condensation of phenol and chlorinated phenols can be predicted from measurement of the distribution of phenol and the 19 chlorinated phenol congeners.

Seaweed accelerates the excretion of dioxin stored in rats.

To prevent health problems of humans exposed to dioxin, it is important to enhance the fecal excretion of dioxin stored in the body. The effects of seaweed such as wakame, hiziki, and kombu on the gastrointestinal absorption and reabsorption of 17 types of polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) congeners was investigated in Wistar rats. Rats were fed 4 g of the basal diet or a seaweed diet containing PCDD and PCDF standard solution [233 ng of toxic equivalents (TEQ)/kg of body weight] once during the experiment period. In the group fed the 10% wakame diet, the levels of fecal excretion of PCDD and PCDF congeners were higher (p < 0.01) from days 1 to 5 by 2.8-fold for 2,3,7,8-TCDD, by 4.0-fold for 1,2,3,7,8-pentaCDD, by 3.4-fold for 1,2,3,4,7,8-hexaCDD, by 3.2-fold for 1,2,3,6,7,8-hexaCDD, by 2.5-fold for 1,2,3,7,8,9-hexaCDD, by 1.7-fold for 1,2,3,4,6,7,8-heptaCDD, by 1.1-fold for 1,2,3,4,6,7,8,9-octaCDD, by 3.0-fold for 2,3,7,8-tetraCDF, by 3.7-fold for 1,2,3,7,8-pentaCDF, by 3.7-fold for 2,3,4,7,8-pentaCDF, by 3.2-fold for 1,2,3,4,7,8-hexaCDF, by 3.0-fold for 1,2,3,6,7,8-hexaCDF, by 3.2-fold for 1,2,3,7,8,9-hexaCDF, by 2.9-fold for 2,3,4,6,7,8-hexaCDF, by 1.6-fold for 1,2,3,4,6,7,8-heptaCDF, by 2.2-fold for 1,2,3,4,7,8,9-heptaCDF, and by 1.2-fold for 1,2,3,4,6,7,8,9-octaCDF than those of the basal group, respectively. Rats were fed 4 g of the basal diet containing PCDD and PCDF standard solution (2991 ng of TEQ/kg of body weight) once on day 1 and then place on the basal diet for 7 days. After 1 week, the rats were fed either the basal diet or seaweed diet from days 8 to 35. In the group fed the 10% wakame diet, the levels of fecal excretion of PCDD and PCDF congeners were higher (p < 0.01 or p < 0.05) during the period from days 8 to 35 by 1.7-fold for 2,3,7,8-TCDD, by 1.8-fold for 1,2,3,7,8-pentaCDD, by 2.0-fold for 1,2,3,4,7,8-hexaCDD, by 1.9-fold for 1,2,3,6,7,8-hexaCDD, by 1.6-fold for 1,2,3,7,8,9-hexaCDD, by 1.5-fold for 1,2,3,4,6,7,8-heptaCDD, by 2.0-fold for 2,3,4,7,8-pentaCDF, by 2.1-fold for 1,2,3,4,7,8-hexaCDF, by 1.9-fold for 1,2,3,6,7,8-hexaCDF, by 1.7-fold for 2,3,4,6,7,8-hexaCDF, by 1.5-fold for 1,2,3,4,6,7,8-heptaCDF, and by 1.9-fold for 1,2,3,4,7,8,9-heptaCDF than those of the basal group, respectively. These findings suggest that the administration of seaweed such as wakame is efficient in preventing the absorption and reabsorption of dioxin from the gastrointestinal tract and might be useful in treatment of humans exposed to dioxin.

Relative potencies of polychlorinated dibenzo‐p‐dioxin, dibenzofuran, and biphenyl congeners to induce cytochrome P4501A mRNA in a zebrafish liver cell line

Induction of cytochrome P4501A (CYP1A) mRNA by polychlorinated dibenzo-p-dioxin (PCDD), polychlorinated dibenzofuran (PCDF), and polychlorinated biphenyl (PCB) congeners was measured in a zebrafish liver (ZF-L) cell line. The ZF-L cells were far less sensitive to PCDD, PCDF, and PCB congeners than were other fish cell lines. The 2,3,7,8-PCDDs, 2,3,7,8-PCDFs, and PCB 126 caused dose-related induction. All other PCBs tested, including other coplanar as well as ortho-substituted congeners, were ineffective at inducing CYP1A. The potency of each congener that gave a response, relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin, was determined. The ZF-L cell-derived relative potency values (REPs) are similar to other in vitro REPs in that the ZF-L cell-derived REPs are generally higher than those derived from in vivo models. Furthermore, the ZF-L cell-derived REPs are generally within fivefold of REPs determined in a variety of rainbow trout systems when the same endpoint in the same tissue are compared. Analysis of these data indicates that REPs based on molecular and biochemical responses in sensitive and insensitive species are similar, but overestimate relative in vivo toxicity in the rainbow trout. The ZF-L cell-derived REPs expand the database of REPs, providing additional information that will be useful in quantifying the uncertainty associated with applying consensus fish-specific toxic equivalency factors in ecological risk assessment.

Chlorophyll Derived from Chlorella Inhibits Dioxin Absorption from the Gastrointestinal Tract and Accelerates Dioxin Excretion in Rats

We investigated the effects of chlorophyll derived from Chlorella on gastrointestinal absorption of seven types of polychlorinated dibenzo-p-dioxin (PCDD) and 10 types of polychlorinated dibenzofuran (PCDF) in Wistar rats. Twenty-eight rats were randomly distributed into seven groups (n = 4). After overnight food deprivation, rats were given 4 g of the basal diet or 4 g of the chlorophyll diet containing 0.01-0.5% chlorophyll one time on day 1; each diet also contained 0.2 mL PCDD and PCDF standard solutions. The amounts of fecal excretion of PCDD and PCDF congeners from days 1 to 5 in the group fed 0.01% chlorophyll were 64.8% for 1,2,3,7,8-pentaCDD, 78.6% for 1,2,3,4,7,8-hexaCDD, 73.5% for 1,2,3,6,7,8-hexaCDD, 58.5% for 1,2,3,7,8,9-hexaCDD, 33.3% for 1,2,3,4,6,7,8-heptaCDD, 85.7% for 1,2,3,7,8-pentaCDF, 77.3% for 2,3,4,7,8-pentaCDF, 88.6% for 1,2,3,4,7,8-hexaCDF, 78.0% for 1,2,3,6,7,8-hexaCDF, 62.5% for 1,2,3,7,8,9-hexaCDF, 84.1% for 2,3,4,6,7,8-hexaCDF, 41.7% for 1,2,3,4,6,7,8-heptaCDF, and 40.0% for 1,2,3,4,6,7,8-heptaCDF greater (p &lt; 0.01) than those of the control group, respectively. The fecal excretion of PCDD and PCDF congeners was remarkably increased along with the increasing dietary chlorophyll. The amounts of PCDD and PCDF congeners in rats on day 5 administered dioxin mixtures were lower in the 0.01% chlorophyll group than in the control group, ranging from 3.5 to 50.0% for PCDD congeners and from 3.7 to 41.7% lower for PCDF congeners, except for 2,3,7,8-tetrachlorodibenzofuran. The amount of PCDD and PCDF congeners in rats was remarkably decreased along with the increasing dietary chlorophyll. These findings suggest that chlorophyll is effective for preventing dioxin absorption via foods.

Chlorophyll derived from Chlorella inhibits dioxin absorption from the gastrointestinal tract and accelerates dioxin excretion in rats.

We investigated the effects of chlorophyll derived from Chlorella on gastrointestinal absorption of seven types of polychlorinated dibenzo-p-dioxin (PCDD) and 10 types of polychlorinated dibenzofuran (PCDF) in Wistar rats. Twenty-eight rats were randomly distributed into seven groups (n = 4). After overnight food deprivation, rats were given 4 g of the basal diet or 4 g of the chlorophyll diet containing 0.01-0.5% chlorophyll one time on day 1; each diet also contained 0.2 mL PCDD and PCDF standard solutions. The amounts of fecal excretion of PCDD and PCDF congeners from days 1 to 5 in the group fed 0.01% chlorophyll were 64.8% for 1,2,3,7,8-pentaCDD, 78.6% for 1,2,3,4,7,8-hexaCDD, 73.5% for 1,2,3,6,7,8-hexaCDD, 58.5% for 1,2,3,7,8,9-hexaCDD, 33.3% for 1,2,3,4,6,7,8-heptaCDD, 85.7% for 1,2,3,7,8-pentaCDF, 77.3% for 2,3,4,7,8-pentaCDF, 88.6% for 1,2,3,4,7,8-hexaCDF, 78.0% for 1,2,3,6,7,8-hexaCDF, 62.5% for 1,2,3,7,8,9-hexaCDF, 84.1% for 2,3,4,6,7,8-hexaCDF, 41.7% for 1,2,3,4,6,7,8-heptaCDF, and 40.0% for 1,2,3,4,6,7,8-heptaCDF greater (p < 0.01) than those of the control group, respectively. The fecal excretion of PCDD and PCDF congeners was remarkably increased along with the increasing dietary chlorophyll. The amounts of PCDD and PCDF congeners in rats on day 5 administered dioxin mixtures were lower in the 0.01% chlorophyll group than in the control group, ranging from 3.5 to 50.0% for PCDD congeners and from 3.7 to 41.7% lower for PCDF congeners, except for 2,3,7,8-tetrachlorodibenzofuran. The amount of PCDD and PCDF congeners in rats was remarkably decreased along with the increasing dietary chlorophyll. These findings suggest that chlorophyll is effective for preventing dioxin absorption via foods.

Polychlorinated dioxins and furans in sediments at a site colonized byDreissenain western lake Ontario, Canada

AbstractPotential impacts ofDreissenaon polychlorinated dibenzo‐p‐dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) levels in sediment were investigated by comparing PCDD/PCDF levels in colonized sediment with levels in sediment in the same area that was not colonized but that was exposed to similar environmental conditions. Levels of PCDDs/PCDFs were also determined inDreissenatissues. The particle size distribution of colonized sediment was characterized by silt‐size material with peak abundance in the range of 7.5 to 20 μm, whereas noncolonized sediment was coarser in nature (30–60 μm). Total organic carbon (TOC) and concentrations of the PCDD/PCDF congener groups and individual 2,3,7,8‐substituted isomers were greater in colonized sediment. A trend was observed toward decreasing concentrations of PCDF congener groups with increased chlorine substitution in mussel tissues in contrast to increasing concentrations of PCDF congener groups with increased chlorination in sediments. The trend in the PCDD congener group profile in mussel tissues appeared more similar to the profile in sediments. Areal estimates of toxicity equivalents (TEQ) inDreissenabiomass at Port Dalhousie, Ontario, Canada (approx. 1,300 pg/m2) were about 0.9% of the TEQ in the top 3 cm of sediment (approx. 135,000 pg/m2). Differences in particle size distribution and PCDD/PCDF levels between colonized and noncolonized sediment suggest thatDreissenamay influence chemical and physical properties of sediment they colonize.

Chlorella Accelerates Dioxin Excretion in Rats

We investigated the effects of Chlorella on fecal excretion of polychlorinated dibenzo-p-dioxin (PCDD) congeners and polychlorinated dibenzofuran (PCDF) congeners in Wistar rats administered the rice oil that caused Yusho disease, as a substitute for purified dioxin. The rats were fed 4 g of a control diet or a 10% Chlorella diet containing 0.2 mL of the rice oil once during the 5-d experimental period. The amounts of PCDD and PCDF congeners excreted in feces from d 1 to 5 in the group fed 10% Chlorella were 0.2–11.3 and 0.3–12.8 times greater (P < 0.05), respectively, than those of the control group. We then investigated the fecal excretion of PCDD and PCDF congeners from d 8 to 35 in rats administered 0.5 mL of the rice oil. Rats consumed the basal diet for 1 wk. After 1 wk, they consumed either the basal diet or the 10% Chorella diet. The fecal excretions of PCDD and PCDF congeners in the group fed 10% Chlorella were 0.3–3.4 and 0.5–2.5 times greater (most, P < 0.05), respectively, than those of the control group. Thus, the fecal excretions of PCDD and PCDF congeners were greater in rats fed Chlorella. These findings suggest that the administration of Chlorella may be useful in preventing gastrointestinal absorption and for promoting the excretion of dioxin already absorbed into tissues. Moreover, these findings suggest that Chlorella might be useful in the treatment of humans exposed to dioxin.

Polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran congener profiles in fish, crayfish, and sediment collected near a wood treating facility and a bleached kraft pulp mill.

Polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran congener profiles in fish, crayfish, and sediment collected near a wood treating facility and a bleached kraft pulp mill.

Sex ratio after exposure to dioxinlike chemicals in Taiwan

Between 1977 and 1984, 48 girls but only 26 boys were born to parents exposed to 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD, or dioxin) in Seveso, Italy. The 1976 industrial accident at Seveso produced the highest documented community exposures to TCDD, and the period 1976–83 represents about one half-life of TCDD in adult human beings. Although TCDD is perhaps the most toxic and carcinogenic synthetic chemical known, has hormonal agonist/antagonist properties, and alters hormone metabolism, how it might have led to such a large departure from the expected sex ratio at birth of about 49 girls to 51 boys is unknown. Polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans (PCDFs) are also persistent and are toxicologically similar to (although less potent than) TCDD. They can occupy the Ah receptor, which is thought to mediate the toxic effects of TCDD. In two instances in Asia, thousands of people consumed cooking oil contaminated with PCBs and PCDFs, ingesting gram quantities of PCBs and milligram quantities of PCDFs. The two major PCDFs congeners (p=0·07). In the regression analysis, the multiple correlation square did not increase when PCB-TEqs were added into the model after I-TEqs. The high frequency of hypomineralised dental defects among normal children may be a sign of exposure to PCDD/Fs. Since the dental hard tissues do not undergo remodelling, defects that occurred in infancy can be diagnosed even after many years. Also, because defects are seen after exposure to very low concentrations, they may be the best available indicator of dioxin exposure.