Article

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

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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.

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... It was not until the mid-1980s that Vietnamese Scientists began inviting and working with scientists from the international community. For scientists from Western countries, arranging visits, traveling throughout Vietnam, and collecting specimens for dioxin and furan analyses were at times daunting tasks [Schecter, Ryan, and Constable 1986]. Agent Orange and its associated dioxin contaminant have been topics of interest at each of the past 26 international conferences on " ...
... Eight presentations were presented by Vietnamese scientists and collaborating colleagues in the special session on " Observations in Man " [Masuda 1986]. Since 1986, there have been an increasing number of manuscripts published both as extended abstracts in the DIOXIN Symposium Series, and as full papers, initially in Chemosphere (a non-peer reviewed journal), on the presence of TCDD in river sediment, food, and human tissue [Schecter, Ryan, and Constable 1986; Schecter, Etizer, and Hites 1989; Yang 2002]. Many of these studies associated the dioxin contaminant with health effects in Vietnamese civilians [Lang 1986; Phiet et al 1989; Phuong et al 1990; Dai et al 1990]. ...
Book
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For almost four decades, controversy has surrounded the tactical use of herbicides in Southeast Asia by the United States military. Few environmental or occupational health issues have received the sustained international attention that has been focused on Agent Orange, the major tactical herbicide deployed in Southern Vietnam. With the opening and establishment of normal relations between the United States and the Socialist Republic of Vietnam in 1995, the time has come for a thorough re-examination of the military use of Agent Orange and other "tactical herbicides" in Southern Vietnam, and the subsequent actions that have been taking place since their use in Vietnam. The United States Department of Defense has had the major role in all military operations involving the use of tactical herbicides, including that of Agent Orange. This included the Department's purchase, shipment and tactical use of herbicides in Vietnam, its role in the disposition of Agent Orange after Vietnam, its role in conducting long-term epidemiological investigations of the men of Operation RANCH HAND, and its sponsorship of ecological and environmental fate studies. This book was commissioned by The Office of the Deputy Under Secretary of Defense (Installations and Environment) with the intent of providing documentation of the knowledge on the history, use, disposition and environmental fate of Agent Orange and its associated dioxin. © Springer Science+Business Media, LLC 2009. All rights reserved.
... 2, 3, 7, 8-TCDD is the most toxic congener and is an unavoidable by-product in the synthesis of various organochlorine chemicals. This compound was the main contaminant found in 2, 4, 5-trichloracetic acid (2, 4, 5-T), the so-called ''Agent Orange'', widely disseminated as a defoliant in the Vietnam War (Schecter et al. 1986), and was also the main contaminant in the Seveso contamination incident (Eskenazi et al. 2001). Adverse effects induced by PCDD/F exposure include dermal toxicity, immunotoxicity, reproductive deficits, teratogenicity, endocrine toxicity, and carcinogenicity/tumor promotion. ...
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... The goals of the study focus on assessing the human body burdens of dioxins [the 29 PCDD, PCDF, and polychlorinated biphenyl (PCB) congeners with dioxin-like activity (Van den Berg et al. 1998] and the factors that predict those body burdens. Other instances of environmental exposures to dioxins have resulted in increased body burdens of these compounds: residents of Seveso, Italy, who were exposed by a release from a trichloro phenol reactor in 1976 (Bertazzi et al. 2001;Landi et al. 1998); the Ranch Hand cohort (Akhtar et al. 2004) and Vietnamese civilians (Baughman and Meselson 1973;Dwernychuk et al. 2002;Schecter et al. 1986Schecter et al. , 2003 exposed to Agent Orange during the Vietnam era; and victims of the Yusho (Masuda 2003;Rappe et al. 1978) and Yucheng (Guo and Yu 2003) rice oil poisoning incidents in 1968 and 1979, respectively. These studies have documented the occurrence of chloracne among heavily exposed subjects and have suggested excess cancer incidence, diabetes, and other endocrine-related health effects. ...
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The University of Michigan Dioxin Exposure Study (UMDES) was undertaken in response to concerns that the discharge of dioxin-like compounds from the Dow Chemical Company facilities in Midland, Michigan, resulted in contamination of soils in the Tittabawassee River floodplain and areas of the city of Midland, leading to an increase in residents' body burdens of polychlorinated dibenzodioxins and polychlorinated dibenzofurans. The UMDES is a hypothesis-driven study designed to answer important questions about human exposure to dioxins in the environment of Midland, where the Dow Chemical Company has operated for > 100 years, and in neighboring Saginaw, Michigan. In addition, the UMDES includes a referent population from an area of Michigan in which there are no unusual sources of dioxin exposure and from which inferences regarding the general Michigan population can be derived. A central goal of the study is to determine which factors explain variation in serum dioxin levels and to quantify how much variation each factor explains. In this article we describe the study design and methods for a large population-based study of dioxin contamination and its relationship to blood dioxin levels. The study collected questionnaire, blood, dust, and soil samples on 731 people. This study provides a foundation for understanding the exposure pathways by which dioxins in soils, sediments, fish and game, and homegrown produce lead to increased body burdens of these compounds.
... Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (PCBs), collectively referred to as dioxin-like compounds or dioxins, are of concern because they are toxic, persist in the environment, have the potential for accumulation in the food chain, and are detected at low concentrations in virtually all humans [U.S. Environmental Protection Agency (EPA) 2003a(EPA) , 2003b(EPA) , 2003c. A number of environmental exposure incidents have resulted in increased body burdens of dioxins, including the release of 2,3,7,8-tetrachloro dibenzo-p-dioxin (TCDD) from a reactor accident in Seveso, Italy, in 1976 (Bertazzi et al. 2001;Landi et al. 1998); exposure to Agent Orange from the Vietnam conflict among the Ranch Hands cohort (Akhtar et al. 2004) and Vietnamese civilians (Baughman and Meselson 1973;Dwernychuk et al. 2002;Schecter et al. 1986Schecter et al. , 2003; and victims of the Yusho (Masuda 2003;Rappe et al. 1978) and Yucheng (Guo and Yu 2003) rice oil poisoning incidents in 1968 and 1979, respectively. These studies have documented increased body burdens of dioxins among exposed populations but have provided limited data regarding the potential exposure pathways by which the dioxin releases have reached the human population. ...
Article
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We conducted a population-based human exposure study in response to concerns among the population of Midland and Saginaw counties, Michigan, that discharges by the Dow Chemical Company of dioxin-like compounds into the nearby river and air had led to an increase in residents' body burdens of polychlorinated dibenzofurans (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs), here collectively referred to as "dioxins." We sought to identify factors that explained variation in serum dioxin concentrations among the residents of Midland and Saginaw counties. Exposures to dioxins in soil, river sediments, household dust, historic emissions, and contaminated fish and game were of primary interest. We studied 946 people in four populations in the contaminated area and in a referent population, by interview and by collection of serum, household dust, and residential soil. Linear regression was used to identify factors associated with serum dioxins. Demographic factors explained a large proportion of variation in serum dioxin concentrations. Historic exposures before 1980, including living in the Midland/Saginaw area, hunting and fishing in the contaminated areas, and working at Dow, contributed to serum dioxin levels. Exposures since 1980 in Midland and Saginaw counties contributed little to serum dioxins. This study provides valuable insights into the relationships between serum dioxins and environmental factors, age, sex, body mass index, smoking, and breast-feeding. These factors together explain a substantial proportion of the variation in serum dioxin concentrations in the general population. Historic exposures to environmental contamination appeared to be of greater importance than recent exposures for dioxins.
... 5,6 Also, TCDD levels in pooled adipose tissue from Hanoi of former North Vietnamese soldiers reached as high as 8.1 ppt, compared with 1.4 ppt in the general population pool from Hanoi in North Vietnam. 6 Moreover, other PCDD/F congeners in adipose tissues 7 and sediment samples 8 were also found to be higher in the South than in the North, which suggested that part of this difference may be due to atmospheric deposition generated by combustion sources. ...
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Chapter
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In the present study, conducted in 1991 and 1992, fifty Vietnam veterans from Michigan volunteered to have their blood analyzed for chlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs). Seventeen of these veterans also contributed semen which was analyzed in three composite samples. Six of fifty Michigan veterans exhibited elevated TCDD blood levels ranging from 20.4 to 131 parts per trillion (ppt). The remaining forty-four had TCDD levels ranging from not detected to 8.3 ppt, with a mean level of 4.1 ppt lipid. Semen TCDD levels ranged from 0.00178 to 0.0034 ppt wet weight in the three composite samples. The veterans had total coplanar, mono- and di-ortho PCBs blood lipid levels ranging from 49,900 to 628,000 ppt, lipid. The PCB levels in these fifty veterans do not reflect exposure in Vietnam but do indicate that total dioxin-like toxicity in Americans, including Vietnam veterans, is greater than that from dioxins and dibenzofurans alone.
Article
This work extends our previous work on levels of PCDD/Fs in human milk. In this paper, three countries are presented, the Federal Republic of Germany for reference purposes, pooled specimens from Los Angeles California and Binghamton, New York, widely separate cities in the United States, and various locations in the north and south of Vietnam, from 1980s specimens. Milk from the 2 US cities contain almost identical levels of the detectible PCDD/Fs, whereas in the north of Vietnam, a less industrial area, markedly lower PCDD/Fs levels were found. 2,3,4,7,8-PnCDF was markedly higher in Germany than the USA, although other values were similar. German specimens had higher PCDD/Fs levels than the USA, however, and higher toxic equivalents. Vietnamese milk specimens from the south have lower TCDD values now than they did in the 1970s when Agent Orange spraying occurred, when TCDD levels were, in some cases, markedly elevated.
Article
The elimination constants and half lives of 1,2,3,7,8-, 2,3,4,7,8-PnCDF and 1,2,3,6,7,8-HxCDF were determined in the liver of female Sprague Dawley rats. The possible pharmacokinetic interaction between these PCDFs was studied
Article
Samples of adipose tissue from 45 occupationally exposed employees of a chemical plant and - as controls - from 21 persons resident in Hamburg, Germany have been analysed for PCDDs and PCDFs by HRGC-HRMS. For TCDD and some other compounds, the results include the highest concentrations ever found in humans. Correlations between chloracne and dioxin levels are discussed.
Article
IntroductionAbsorption/Bioavailability Following ExposureDistributionMetabolism and ExcretionPhysiologically Based Pharmacokinetic ModelsPharmacokinetics in Special PopulationsReferences
Article
An estimated 23% of deaths worldwide are attributed to environmental causes. Moreover, environmental factors have a substantial adverse effect on children's health, contributing to an estimated 36% of childhood mortality. Due to the tremendous impact environment toxicants have on public health globally, it is important to understand their exposure sources, biological mechanisms of disease, and health impacts. This chapter provides an overview of the top 10, highest ranking environmental contaminants of concern as identified by the Agency for Toxic Substances and Disease Registry, four priority air pollutants, and seven contaminants of emerging concern. For each contaminant, or class of contaminants, the routes of exposure and health effects are described. Environmental contaminants are predicted to continue to substantially affect human health all over the world, rendering the study of environmental contaminants crucial to public health interventions.
Article
During the past decade a considerable amount of data has been generated concerning polychlorinated dibenzodioxin (PCDD) and polychlorinated dibenzofuran (PCDF) levels in humans from many geographical locations. To organize these data in a useful fashion for environmental purposes and for consideration of human toxicity, selected portions of our data are presented in a somewhat atypical fashion, by percentage contribution of individual congeners to total PCDD/Fs in human tissue, and to the total dioxin equivalents(TEq). This is done to better characterize congener contributions from environmental contamination in various geographical regions at this time and health-related levels. To present the findings in a global perspective, data from widely different locations are presented including the United States, Germany, Vietnam, the former Soviet Union, Thailand, Cambodia, China, South Africa, and Guam.
Article
Adipose TCDD levels were generally nondetectable at 2 pg/g in the North of Viet Nam and severalfold higher in the South than in the U.S. Soil movement may account for the geographic distribution of levels.
Article
Persistent organic pollutants (POPs) are man-made chemicals that have an intrinsic resistance to natural degradation processes, and are therefore environmentally persistent. The introduction of POPs into the environment from anthropogenic activities has resulted in their widespread dispersal and accumulation in soils and water bodies, as well as human and ecological food chains where they are known to induce toxic effects. Due to their ubiquity in the environment and lipophilic properties, there is mounting concern over the potential risks of human exposure to POPs. This has led to the establishment of a worldwide research program to determine prevailing levels of POPs in the population and investigate the health risks associated with background exposure. This paper reviews the state of knowledge regarding residual levels of POPs in human adipose tissue worldwide, and provides preliminary data on the levels of key POPs in female adipose tissues collected in Singapore. Organochlorine pesticides (OCPs) were found to be comparable to levels reported for Poland in 2001, with a mean of 0.98μgg−1 (or 0.84μgg−1 on a lipid weight basis). For total polychlorinated biphenyl (PCB) congeners, the mean concentration of 34ngg−1 (lipid weight basis) is lower than values reported from Japan in 1980 and Belgium in 2000. Polybrominated diphenyl ethers (PBDEs) are present at similar levels to Belgium in 2000, at 3.7 (or 4.7ngg−1 lipid weight basis).
Article
We have analyzed 19 samples of human adipose tissue obtained from general population of Madrid (Spain), determining the levels of tetra- to octachlorinated dibenzo-p-dioxins and -furans. We found that PCDD are present in higher concentrations than PCDFs, with the levels for PCDDs increasing by about two orders of magnitude with chlorination, from tetra- to octa-. The distribution of PCDFs among groups of congeners was more uniform than that of PCDDs. The concentration of penta-, hexa- and hepta-congeners was usually below 70 pg/g. Levels and patterns of PCDDs and PCDFs in Spanish adipose tissues were similar to those found in other industrialized countries.
Article
The analysis of Hector's dolphin for PCDDs and PCDFs has been undertaken to provide data on the levels of these contaminants in New Zealand's coastal waters and thereby information on the extent of their distribution throughout the global environment. Using isomer specific methodology the blubber of 6 dolphin samples from the South Island of New Zealand have been found to contain unexpected amounts of 2,3,7,8-TCDD, 2,3,7,8-TCDF, 1,2,3,7,8-PeCDD and 2,3,4,7,8-PeCDF with only minor amounts of other 2,3,7,8-chlorinated isomers. No non 2,3,7,8-substituted isomers were detected. For both male and female dolphins the overall congener distributions are similar, and mirror that reported for other aquatic biota.
Article
Sediment samples were collected from three Vietnamese rivers between 1985 to 1986. A previous analysis of those samples revealed a presence of most PCDD/Fs, but 2,3,7,8-TCDD was not found in the samples when HRGC/MS and negative ion chemical ionization techniques were used. Those sediment samples were reanalyzed for 2,3,7,8-TCDD and -TCDF by using HRGC/HRMS. A concentration of 213 ppt of 2,3,7,8-TCDD was detected. This may be evidence for the movement of Agent Orange 2,3,7,8-TCDD from contaminated areas into rivers.
Article
Twenty-seven individual and ten pooled human adipose tissue specimens, collected from persons from the south and north of Vietnam, respectively, were analyzed for 2,3,7,8-TCDD and 2,3,7,8-TCDF. The results show a mean value of 19 ppt TCDD and 7 ppt TCDF in the samples from persons in the South, and non-detected TCDD and TCDF in the samples from persons from the North. Differences in 2,3,7,8-TCDD body burdens continue to be substantiated in the populations of the south and north of Vietnam.
Article
Chlorinated dioxins and dibenzofurans have been reported in breast milk specimens from a number of countries in recent years. The values reported here extend the number of countries throughout the world from which human milk PCDD/F data is being reported. In general, higher levels of PCDD/Fs are found in industrial areas than in non industrial areas. DDT and its metabolite, DDE, are found in higher levels in milk from Thailand and Vietnam. PCB contamination is highest in milk from Germany, followed by the USA, with Thailand and Vietnam specimens presenting still lower values.
Chapter
Toxic chemical exposure assessment in humans has been approached in a variety of ways. Environmental measurements, such as of air levels in a workplace, have been used to estimate exposure. For example, useful indirect estimates of exposure have been calculated from the amount of time spent in a workplace known to be contaminated with asbestos. Packs of cigarettes smoked per day for a given number of years has been used to estimate dose of the carcinogens from cigarette smoke. Direct measurement of chemical levels in blood or other tissues is a more recent approach. The latter presupposes some knowledge of the metabolism of the compound of concern as well as a good exposure history. In recent years, it has become possible to measure, in a sensitive and specific fashion, the highly toxic, lipid-soluble, synthetic polychlorinated dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) in human tissue. This chapter will primarily review our own work in developing and using human tissue measurement to document exposure to the halogenated dioxins and structurally related compounds, including the chlorinated dibenzofurans and PCBs.
Article
This study examined whether the concentrations of chlorinated dibenzo-p-dioxins and dibenzofurans in human milk and their subsequent intake by the nursing infant may exceed the recommended intake values currently employed by the United States Environmental Protection Agency and the United States Public Health Services Centers for Disease Control. Data was utilized from populations known historically and by isomer-specific analysis of adipose tissue and milk samples to have different levels of exposure to these contaminants. These included northern and southern Vietnam, and the United States. Based on a number of assumptions, these calculations suggested that some nursing infants present in southern Vietnam during and shortly after herbicide spraying, may have consumed, and are continuing to consume, amounts of these contaminants that are greater than currently recommended intake values. Although concentrations of these compounds in samples from the United States are lower, they are still near or greater than the recommended amounts. Analysis of data from northern Vietnam indicate that nursing infants here are exposed to amounts of TCDD equivalents that are below employed standards. However, interpretation of these numbers varies considerably depending on whether the standard from the EPA or CDC is chosen; the latter value for allowable intake being approximately 100-fold higher than the former. Further study is needed to determine if there is any real short- or long-term clinical risk to the nursing infants in these populations.
Article
Between 1984 and 1988, eight hospitalized surgical patients living in different provinces in the south of Vietnam were interviewed to estimate potential exposure to Agent Orange during the Second Indochina War and their adipose tissue polychlorinated dibenzodioxin and dibenzofuran (PCDD/F) levels were measured. Seven out of eight specimens had detectable 2,3,7,8-TCDD levels ranging from 3.2 to 56.7 ppt in a lipid basis with a mean of 25.2 ppt. Previous findings from northern Vietnamese patients not exposed to Agent Orange showed non detectable levels of TCDD. The relatively high level of 2,3,7,8-TCDD as compared to total PCDDs and PCDFs in fat tissue suggests its source is at least partially from Agent Orange. The medical diagnoses for the three patients with the highest levels of 2,3,7,8-TCDD in their adipose tissue were: primary carcinoma of the liver (56.7 ppt), adenoma of the prostate (55.9 ppt), and adenocarcinoma of the stomach (28.9 ppt). A causal relationship between dioxin levels and illness is neither implied nor proven in this paper consisting of case reports from a pilot study which is not epidemiologic in nature. Clinical history of potential exposure to a herbicide thought to be Agent Orange was in some instances correlated with elevated levels of 2,3,7,8-TCDD in adipose tissue specimens.
Article
A large population exists in the south of Vietnam potentially exposed to 2,3,7,8-TCDD, a contaminant of 2,4,5-T herbicide used in Agent Orange and Purple during wartime (1962–1971). Over 170 kilograms of 2,3,7,8-TCDD in the herbicide was sprayed over 10% of the south of Vietnam (1). In 1984 and 1985, adipose tissues were taken from 9 patients at the Obstetrics and Gynecological Hospital in the south of Vietnam and polychlorinated dibenzodioxins and dibenzofurans were measured. Medical, reproductive, nursing and history of exposure to herbicides were recorded. Eight of nine patients had detectable levels of 2,3,7,8-TCDD ranging from 4 to 103 ppt with a mean of 23 ppt, 3 to 4 fold higher than in industrial countries. Total PCDD/F levels, 442 to 4708 ppt, mean 2606 ppt, are 2 fold higher than in industrial countries. In some cases there is correlation between TCDD level and a history of herbicide exposure. A nursing history is sometimes associated with relatively lower TCDD levels. Determination of 2,3,7,8-TCDD levels in adipose tissues of potentially exposed persons is useful for establishing relative body burden and quantitative dioxin body burden classification of cases and controls for future epidemiologic research assessing cancer and reproductive outcomes, or for clinical studies.
Article
In order to search the source of polychlorinated dibenzo‐p‐dioxins (PCDDs) and dibenzofurans (PCDFs) in blue mussel in Osaka bay, sediments from Osaka bay and from rivers running near an urban municipal incinerator were analysed for PCDDs, PCDFs and PCBs. The river and estuary sediments were all found to be contaminated with PCDDs at average levels of 9.8 and 12ppb on the dry basis, PCDFs of 7.8 and 5.1 ppb, and PCBs of 1600 and 1300ppb, respectively. The two sediments contained similar profiles of specific isomers and congeners of PCDDs and PCDFs with each other. In addition, there was observed positive close correlations between PCDD and PCDF levels in the two specimens as well as fly ash from urban municipal incinerators. These allow the conclusion that the main source of the two chemicals in Osaka bay is fly ash from waste incineration.
Article
Molecular and biochemical evidence support Aryl hydrocarbon (Ah) receptor‐mediated mechanism for most of the known toxic effects of dioxins. However, this approach does not consider modification of toxic responses due to the simultaneous presence of other congeners with comparable affinities for the Ah receptor. In this paper we describe (a) the biochemical rationale for a competitive binding of TCDD and other congeners for the Ah receptor, and (b) the elements of a competitive binding model to estimate the formation of an Ah receptor‐TCDD complex in the presence of other competing ligands. The model is based on the relative mass balance, and binding affinities of congeners to the Ah receptors, from rat liver cytosolic preparations. Using the model, a quantitative biochemical parameter for the formation of the total receptor bound to TCDD, defined as “Competitive Binding Ratio” (f), was calculated for adipose tissue dioxin‐residue data from human populations. Using Monte Carlo methods, we calculated the cumulative probability of the distribution of Ah receptor bound to TCDD as a fraction of total bound receptors.
Chapter
Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are two classes of structurally and toxicologically similar persistent environmental contaminants. These compounds are formed as by-products in various chemical and combustion processes and are now global environmental contaminants. The environmental persistence and lipophilic properties of these compounds have led to effective transport of these chemicals into the food chain with pronounced accumulation at higher trophic levels, including humans. As a result, there is concern regarding possible adverse effects of these contaminants on human health and the environment.
Article
Infant mortality in the first year of life was found to be higher in two herbicide sprayed villages between 1966 and 1986 than in an unsprayed village. The effect has diminished with time.
Article
PCDDs and PCDFs were determined in samples of human milk collected in 1973 and 1985 in the south of Vietnam and the levels compared to samples taken in 1970 and present day North American samples. In the Vietnam samples from the three time periods between one-half and two-thirds were positive for 2,3,7,8-TCDD. Average levels of the positives on a lipid basis, declined from about 484 ppt in 1970, to 121 ppt in 1973 and then to 12 ppt in 1985. The latter value is higher but similar to the value of about 5 ppt presently found in North American human milk and much higher than that found in samples from the north of Vietnam where Agent Orange was not used. The average body burden of 2,3,7,8-TCDD in the nursing mothers from 1970 and 1973 has been estimated to be 3.6 and 0.98 micrograms, respectively. Such an accumulation is near the value calculated by us to produce chloracne and other symptoms in some industrial workers.
Article
Full-text available
A subset of workers was followed after exposure to polychlorinated biphenyls (PCBs), dioxins, and furans in an occupational medicine clinic setting. Patterns of PCBs found in adipose tissue resembled the pattern seen when soot from the incident or Aroclor 1254 was examined by GC-MS. Adipose tissue also revealed levels of hepta- and octachlorinated furans and dioxins as high as 8400 ppt in one repeatedly exposed worker. Control fat from patients with no known exposure to furans or dioxins was usually in the several hundred parts per trillion range for these isomers, but slightly over 2000 ppt in one sample. Electron microscopic analysis of liver biopsies from three patients who developed mild elevations of hepatic enzymes in their serum revealed morphologic alterations in some ways similar to those seen in animals after feeding experiments with PCBs, dioxins or the Binghamton State Office Building soot. These include pleomorphic mitochondria, giant mitochondria, prominent dense mitochondrial granules, cristae parallel to the long axis of the mitochondria and crystalline structure within same mitochondria as well as lipid droplets in liver cells and slightly dilated smooth endoplasmic reticulum.
Article
Full-text available
A procedure has been developed for the reliable detection of TCDD in animal tissues down to levels approaching 1 ppt. It makes use of chemical cleanup, preparative gas liquid chromatography, and analysis by time averaged high resolution mass spectroscopy. A limited number of fish and crustacean samples was collected in South Vietnam in 1970 near areas heavily exposed to the herbicide 2,4,5-T. TCDD was detected in these samples at levels ranging from 18 to 810 ppt. TCDD was not detected in a sample of Cape Cod butterfish used as a control. These results suggest that TCDD may have accumulated to biologically significant levels in food chains in some areas of South Vietnam exposed to herbicide spraying.
Article
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has been detected at levels ranging from 20 to 173 parts per trillion in adipose tissue from three Vietnam veterans who were "heavily exposed" to Herbicide Orange. Some tissue samples from other Vietnam veterans and from controls also contained 2,3,7,8-TCDD at levels below 20 parts per trillion.
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Schecter, A., Tiernan, T., Taylor, M., Van Ness, G., Garrett, J., Wagel, D., Gitlitz, G., Bogdasarian, M.: Biological markers after exposure to polychlorinated dibenzo-p-dioxins, dibenzofurans, biphenyls and biphenylenes. Part I: Findings using fat biopsies to esti-mate exposure. In: Chlorinated Dioxins and Dibenzofurans in the Total Environment, Part II, Eds., Keith, L., Choudhary, G., and Rappe, C., Butterworth Publishers, Stoneham, Massachusetts, Ann Arbor Science, pp. 215-245, 1985.
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Patient fat biopsies for chemical analysis and liver biopsies for ultrastructural characterization after exposure to polychlorinated dioxins, furans and PCBs
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