John J. Ryan

Gas chromatographic separations of all 136 tetra- to octapolychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans on nine different stationary phases

All 49 polychlorinated dibenzo-p-dioxins and 87 polychlorinated dibenzofurans containing 4 to 8 chlorines have been synthesized and purified as individual compounds in quantitative amounts. These standards have been chromatographed on a series of nine fused-silica capillary gas chromatography (GC) columns containing silicone stationary phases of diverse polarity (100% methyl, 5% phenyl methyl, 50% phenyl methyl, 50% methyl trifluoropropyl, 50%, 75%, 90% and 100% cyanopropyl and liquid crystalline smectic). The data, expressed in a series of GC chromatograms and in tables of relative retention times, are the most comprehensive to date with regard to individual congeners and variety of stationary phases and provide a confirmation of much earlier work. The information shows that all 136 compounds, including the biologically important 2,3,7,8-substituted congeners, can be separated from each other mostly with two stationary phases. However, possible variation in GC conditions and stationary phases necessitates assessment of the resolution of near eluting isomers. Comparisons and contrasts to previously published reports have also been noted.

Chlorinated dibenzo-p-dioxins and chlorinated dibenzofurans in Canadian human adipose tissue

Abstract Seventy-two samples of human adipose tissue were analysed for tetra- to octa- chlorinated dibenzo-p-dioxins and -furans. The tissues taken at autopsy from three different time periods mostly from across Canada showed the presence of only 2,3,7,8-chlorine substituted dioxins and furans. The dioxin levels were highest and increased on additional chlorination from tetra- to octa- with 2,3,7,8-tetra dioxin averaging between 5 and 10 parts per trillion (ppt), octa-dioxin averaging between 600 and 800 ppt and intermediate levels for the penta-, hexa-, and hepta- dioxins. The furan levels were found to be lower but more uniform showing average values of 17, 17, and 33 ppt for the penta-, hexa-, and hepta- congeners, respectively. The pattern shown by the tissue extracts on gas chromatography was distinctive for human adipose and indicated pentachlorophenol as the source of the higher chlorinated dioxins. The concentrations of both dioxins and furans in these tissues were 2 to 3 orders of magnitude lower than those known to cause adverse effects in humans.

Elimination of polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) from human blood in the Yusho and Yu-Cheng rice oil poisonings

The pharmacokinetics of polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in humans was studied by monitoring the blood concentrations of individuals who ingested a contaminated rice oil in Japan (yusho) in 1968 and in Taiwan (yu-cheng) in 1979. Sixteen yusho patients were followed from 1982 to 1990 and three yu-cheng individuals from 1980 to 1989. From the three yucheng patients, blood lipid values for the two persistent toxic congeners, 2,3,4,7,8-pentachlorodibenzofuran (PnCDF) and 1,2,3,4,7,8-hexachlorodibenzofuran (HxCDF), varied from 50 μg/kg at first sampling to about 1 μg/kg at last sampling corresponding to half-lives for elimination (t1/2) of 2-21/2 years. The blood lipid values for the same PCDF congeners in yusho patients varied from 5 μg/kg down to 0.1 μg/kg. The calculated t1/2 were more variable with median values closer to 10 years. Planar PCBs #126 and #169 were present at lower concentrations than the PCDFs. For seven of the other PCB congeners, half-lives for elimination in the yu-cheng individuals varied from 1.2 up to 4.6 yr depending on the degree of chlorination. For the yusho patients, the elimination for the PCBs was longer. These results show that clearance of the toxic PCDFs and PCBs in humans is non-linear with faster elimination at higher exposure followed by slower decreases as background levels are approached. Such a clearance pattern can best be explained by a two compartment liver and fat pharmacokinetic model.

Tissue distribution of dioxins and furans in humans from the general population

Abstract The distribution of tetra- to octa-chlorinated dibenzo-p-dioxins and-furans in the human body was studied in two autopsy subjects from the general population. Analysis of tissues was carried out by extraction, acid defatting, chromatography, and measurement by gas chromatography (GC) — mass spectrometry (MS). Many 2,3,7,8-chlorine substituted dioxins and furans in the same relative proportion were detected in all five tissues examined. On a whole weight basis, levels of dioxins and furans descended in order: abdominal and subcutaneous fat, liver, muscle and kidney. On a lipid basis, the levels were similar for all tissues.

Chlorinated dibenzo-p-dioxin and dibenzofuran levels in human adipose tissue and milk samples from the north and south of Vietnam

Abstract Although 2,3,7,8-TCDD has been found to be extremely toxic to a variety of laboratory aminals, human epidemiology studies, where exposure to 2,3,7,8-TCDD has been less well characterized than in animal toxicologic studies, have been less conclusive in characterizing the extent of toxicity. In order to determine whether the newly refined techniques of human adipose tissue biopsy including isomer specific and sensitive measurement of PCDDs and PCDFs might be able to assist in finding populations within the same country with high and low levels of dioxins, adipose tissue samples were taken and levels analyzed from the north and south of Vietnam. It seemed reasonable, based on previous work, that high levels of 2,3,7,8-TCDD might still be found in adipose tissue in selected patients living in areas sprayed with Agent Orange and other 2,3,7,8-TCDD containing herbicides, and that lower levels should be found in patients not exposed to 2,3,7,8-TCDD from herbicides or other sources, such as persons who had always resided in the north of Vietnam. Of 9 specimens from patients hospitalized in Hanoi who had never been south, none had detectable adipose tissue levels of 2,3,7,8-TCDD at a detection limit of 2 or 3 ppt on a wet weight basis. Of 15 specimens from Ho Chi Minh City hospitalized patients the mean of positive specimens (12 of 15) was 28 on a lipid basis. The mean of the positive values from the south is about 2 to 3 times higher than found in the North American Continent control patients where the mean is about 6–10 ppt and much higher than in the north of Vietnam. In the northern specimens, the levels were non-detectable with a sensitivity of between 2 and 3 ppt. Other PCDD and PCDF isomers not found in Agent Orange, the penta- through octachlorinated dibenzo-dioxins and dibenzofurans, were similar in isomer type and quantity in the south of Vietnam to what we previously reported in North America. Adipose tissue from the north of Vietnam contained the lowest levels of four through eight chlorinated dioxins and furans thus far reported. The initial data suggests that populations exist in the south of Vietnam with elevated levels of 2,3,7,8-TCDD at the present time, fourteen years after the last known 2,3,7,8-TCDD (Agent Orange) application, superimposed on a preexisting body burden of dioxins and dibenzofurans from sources other than Agent Orange such as technical grade pentachlorophenol or products of incineration contaminated with higher chlorinated PCDDs or PCDFs. In light of the recent finding that unexpected levels of PCDDs and PCDFs exist in the general adult population of industrialized countries, ca. 1,000 to 1,200 ppt, wet weight of total dioxin and furan isomers in adipose tissues, it seems reasonable that the extent of human toxicity of dioxins may be more readily characterized in Vietnam than in industrialized countries. Because 2,3,7,8-TCDD was applied in 1962–1970, although not yet cleaned up, the levels of 2,3,7,8-TCDD in the environment, the food chain, and in humans, would be expected to decrease with time. Therefore, if studies are not initiated in a timely fashion, the opportunity to better characterize the extent of the toxicity of TCDD to humans as well as the persistence of TCDD in the environment in Vietnam may be lost.

Variation of dioxins and furans in human tissues

Abstract A number of chlorinated dibenzo-p-dioxins (PCDDs) and chlorinated dibenzofurans (PCDFs) occur in human adipose tissue at levels from 5 pg/g for 2, 3, 7, 8-TCDD to approximately 1000 pg/g for octachlorodibenzo-p-dioxin (OCDD). The variation of these compounds in tissues has been studied with respect to age, sex, tissue type, and country. A sampling of 46 adipose tissues from Canada in 1976 has shown a positive correlation of 2,3,7,8-TCDD level of detectable samples with age but not sex. This relationship is supported by the analysis for the first time of tissue from a 6 month old infant and the demonstration of little or no measurable levels of PCDDs/PCDFs. Three additional tissue types, pancreas, brain, and testis, from two autopsies were assayed for PCDDs/PCDFs for the first time but little or none were found even though the first two tissues had up to 10% lipid. A small sampling of adipose tissue from the general population in Japan in 1984 contained generally the same types and concentrations of PCDDs/PCDFs as are found in tissues from other industrialized countries.

HUMAN BODY BURDEN OF POLYCHLORINATED DIBENZOFURANS ASSOCIATED WITH TOXICITY BASED ON THE YUSHO AND YUCHENG INCIDENTS

The polychlorinated dibenzofurans (PCDFs) are one group of man-made toxicants for which reasonably extensive data exist relevant to dose-response relationships in humans. Examination of contaminated food oil consumption from the yusho (Japan) poisoning incident indicates the mean uptake or body burden of 2, 3, 4, 7, 8-pentachlorodibenzofuran (PnCDF) equivalents (PEQ) associated with nausea and anorexia to be 4.4 micrograms/kg body wt and that associated with chloracne to be 5.9 micrograms/kg. For the yucheng (Taiwan) poisoning incident, blood measurements for chloracne show a similar body burden of 4.0 micrograms/kg. The latter value is toxicologically equivalent to a 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalent (TEQ) body burden of 2.0 micrograms/kg body wt or about 150 micrograms for an adult person. This corresponds to an adipose tissue level of about 10 micrograms/kg fat, and is comparable to that known to cause chloracne in rhesus monkeys. These body burdens on a TEQ basis are more than 200 times higher than the average current levels of PCDDs/PCDFs found in North American populations and are the first to relate human body burdens of PCDFs with a known effect and to compare them to animal data. Since the effects reported may not be the most sensitive indicator of human toxicity, lower body burdens could be associated with more subtle toxicological events.

Partitioning of 2,3,7,8-chlorinated dibenzo-p-dioxins and dibenzofurans between adipose tissue and plasma lipid of 20 Massachusetts Vietnam veterans

Abstract This paper compares each currently measurable chlorinated dioxin and dibenzofuran congener in fat and blood from 20 human volunteers who are U.S. Vietnam veterans. Our findings confirm previous studies in that 2,3,7,8-TCDD levels in blood and fat tissue are similar, on a lipid basis. However, of other congeners compared, we have found significant differences for some in the levels present in blood to the corresponding levels in fat. The associations between the amount of congener detected in blood and fat for most congeners showed highly significant correlation coefficients.

2,3,7,8-tetrachlorodibenzo-p-dioxin and related dioxins and furans in snapping turtle () tissues from the upper St. Lawrence River

Abstract Fat and liver samples from three snapping turtles ( Chelydra serpentina ) from the upper St. Lawrence River were analysed for tetra- up to octa-chlorinated dibenzo-p-dioxins (PCDDs) and chlorinated dibenzofurans (PCDFs) by two gas chromatography - mass spectrometry techniques and by a bioassay. The tissues contained only 2,3,7,8-chlorine substituted PCDDs and PCDFs with high levels occurring for 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD). On a wet weight basis, fat levels of 2,3,7,8-TCDD were 4 to 7 times higher than liver levels with up to 500 pg/g present in turtle fat. One fat sample also contained over 3 ng/g of 2,3,4,7,8-pentachlorodibenzofuran (PnCDF) suggestive of a PCB source of contamination. The TCDD levels in the turtles are consistent with the consumption of a fish diet containing about 20 pg/g 2,3,7,8-TCDD, a level currently found in eel samples from the same region. Comparison of this limited snapping turtle data with that of other aquatic species from the same and different bodies of water suggest that the Niagara River via Lake Ontario could be a possible source of contamination of 2,3,7,8-TCDD for the St. Lawrence River. The results also show that turtles are excellent monitors for PCDD and PCDF contamination. Human consumption of turtle tissue samples containing the highest levels of 2,3,7,8-TCDD and PCDFs so far detected in wildlife samples may constitute a hazard.

High-performance liquid chromatography in the analysis of chorinated dibenzodioxins and dibenzofurans in chicken liver and wood shaving samples

Abstract High-performance liquid chromatography (HPLC) has been used to cleanup chicken liver and wood shaving samples for their subsequent analysis by mass spectrometry (MS). With a reversed-phase system and discrete fraction collection, hexa-, hepta-, octachlorodibenzodioxin and octachlorodibenzofuran have been detected in wood shavings and chicken livers to a lower level of 25 pg/g. With the use of HPLC as a cleanup tool, the MS determination both on the probe and by gas chromatography-MS resulted in an improved peak shape and a stronger more accurate signal for the dioxins and furans.