Review and Analysis: Did the United States Transport, Off-Load and Use Commercial 2,4,5-T Herbicides with Unknown Amounts of Dioxin TCDD on Military Base Grounds in Panama Canal Zone between 1948 and 1999?

The 84 km Panama Canal connecting the Atlantic and Pacific oceans has historically been a strategic waterway for shipping and the location of United States (US) military bases. Since the construction of Lake Gatun reservoir, canal locks and navigation channel through the Isthmus of Panama tropical forests in the 1910s, chemicals, pesticides, and herbicides have been essential for controlling upland and wetland vegetation as well as managing mosquito-borne diseases. Chemicals and pesticides flowed into Lake Gatun via land surface runoff and subsurface drainage either attached to the sediment or in solution during the rainy season. Lake Gatun and the Panama Canal was the drinking water source for most of the civilian and military population living in the Panama Canal Zone. Between 1948 and 1999, US military base commanders had the ability to order, from the Federal Supply Catalog, commercially available herbicide 2,4,5-T with unknown amounts of dioxin TCDD for use on the military base grounds in the Panama Canal Zone. The herbicide 2,4,5-T was transported to Panama Canal Zone ports, including the ports Cristobal on the Caribbean and Balboa on the Pacific, and distributed to the US military bases in Panama by rail or truck. The US National Toxicology Program and the International Agency for the Research on Cancer listed dioxin and TCDD as known human carcinogens. Dioxins are endocrine disrupters and can cause certain chloracne, cancers, developmental and reproductive effects. In 1985, the United States government banned the manufacture of the herbicide 2,4,5-T, with unknown amounts of dioxin TCDD, after it was shown to cause cancer in animals. The objectives of this study are to determine: 1) the fate of dioxin TCDD, a contaminant in the herbicide 2,4,5-T, sprayed on the US military base vegetation in the Panama Canal Zone from 1948 to 1999, 2) the transport of dioxin TCDD rich sediment via soil erosion and overland flow into Lake Gatun and Panama Canal waterways and 3) the human health impacts of dioxin TCDD, a known carcinogen, on US military and Panamanian civilians exposed to dioxin TCDD in the Panama Canal Zone.

FORMATION MECHANISMS AND CONTROL STRATEGIES FOR DIOXINS IN INCINERATION PROCESS OF MUNICIPAL SOLID WASTES

Dioxins, which are of the most toxic materials on the earth, are principal emitted from waste incineration process. The molecular structures, toxicity parameters, such as toxicity equivalency factor, tolerable daily intake and physic-chemical properties of dioxins are briefly summarized. Three formation mechanisms of dioxins in waste incineration process, namely as de novo synthesis, mechanisms involving small organic molecular as precursors and homogenous gas phase reaction mechanism are alto reviewed. The influencing factors for dioxins formation during waste incineration process are also discussed. Three major methods for reducing dioxins emission from waste incineration process are discussed based upon the formation mechanisms and influencing factors. A new waste incineration process with low dioxins emission and low hydrogen chloride corrosion has been proposed based on multi- stage unit operation principal according to formation mechanisms of dioxins and potential production location in waste incinerators.

Influence of dioxin reduction on chemical composition of sintering exhaust gas with adding urea

With the addition of urea as an inhibitor, four groups of reducing dioxin emission experiments in sintering pot were conducted. The results show that, adding 0.05%, 0.1% and 0.5% （mass fraction） urea, the emission concentrations of dioxin are 0.287 0.258 and 0.217 ng-TEQ/m3, respectively. The dioxin emission rates drop substantially compared to 0.777 ng-TEQ/m3 flee of urea. With an increase of the urea content, the concentration of SO2 emission reduces sharply. （NH4）2SO4, formed by the reaction of SO2 and NH3, goes into the dust and part of NH3 is released before reaction with the emission of exhaust gas. The NO~ emission presents an increasing trend because the reaction of NH3 and 02 at high temperature produces NOx. Based on the consideration of factors such as the effect of reducing dioxin emission, and the chemical composition of exhaust gas, 0.05% is the optimum adding content of urea.

Correlations of PCBs, DIOXIN, and PBDE with TSH in Children's Blood in Areas of Computer E-waste Recycling

Objective To study correlations of polychlorinated biphenyls （PCBs）, DIOXIN, and polybrominated diphenyl ethers （PBDE） with thyroid stimulating hormone（TSH） in children, and assess the impact on children＇s health. Methods Three hundred and sixty nine children aged from 6 to 8, including 195 from Luqiao, the computer E‐waste recycling area, and 174 from Longyou, the control area, were selected for this investigation to elucidate the correlation of PCBs, DIOXIN, and PBDE with TSH in children’s blood samples. The children had a physical examination and their blood levels of PCBs, DIOXIN, PBDE, and TSH were detected after sample collection. Results In the E‐waste recycling area, the contents of PCBs, PBDE, DIOXIN, and TSH in the blood samples of children were 484.00±84.86 ng·g ‐1 lipid weight, 664.28±262.38 ng·g ‐1 lipid weight, 26.00±19.58 ng·g ‐1 lipid weight and 1.88±0.42 μIU/mL （serum） respectively, while in the control area, the PCBs, PBDE, DIOXIN, and TSH contents were 255.38±95 ng·g ‐1 lipid weight, 375.81±262.43 ng·g ‐1 lipid weight, 39.64±31.86 ng·g ‐1 lipid weight, and 3.31±1.04 μIU/mL respectively. Conclusion The health status of children in the control area are better than that in the contaminated area. Among children who are exposed to persistent organic pollutants, the pollutant content increases significantly in their serum, and the distribution of TSH levels in their bodies are also affected.

2,3,7,8-Tetrachlorodibenzo-p-dioxin Promotes Proliferation of Astrocyte Cells via the Akt/STAT3/Cyclin D1 Pathway

Objective The compound 2,3,7,8-tetrachlorodibenzo-p-dioxin(TCDD), a persistent organic pollutant, is harmful to the nervous system, but its effects on the brain are still unclear. This study aimed to investigate the effects of TCDD on astrocytes proliferation and underlying molecular mechanism. Methods The cell proliferation was measured by EdU-based proliferation assay and PI staining by flow cytometry. Protein expression levels were detected by Western blotting. Immunofluorescence, cytoplasmic and nuclear fractions separation were used to assess the distribution of signal transducer and activator of transcription 3(STAT3). Results C6 cells treated with 10 and 50 nmol/L TCDD for 24 h showed significant promotion of the proliferation of. The exposure to TCDD resulted in the upregulation in the expression levels of phosphorylated protein kinase B(p-Akt), phosphorylated STAT3, and cyclin D1 in a dose-and time-dependent manner. The inhibition of Akt expression with LY294002 or STAT3 expression with AG490 abolished the TCDD-induced cyclin D1 upregulation and cell proliferation. Furthermore, LY294002 suppressed the activation of STAT3. Finally, TCDD promoted the translocation of STAT3 from the cytoplasm to the nucleus, and LY294002 treatment blocked this effect. Conclusion TCDD exposure promotes the proliferation of astrocyte cells via the Akt/STAT3/cyclin D1 pathway, leading to astrogliosis.

Long-Term Fate of Agent Orange and Dioxin TCDD Contaminated Soils and Sediments in Vietnam Hotspots

The soils, tropical climate, and network of canals and rivers of southern Vietnam have created one of the most diverse tropical jungles and intensely cultivated landscapes of Southeast Asia. This paradise has a long history of numerous wars, foreign occupations, and most recently the Second Indochina War (aka the Vietnam War 1965-1972) which defoliated rain forests and ancient wetland mangroves and left behind contaminated soil and sediment hotspots. During this war, the United States (US) military sprayed 80 million liters of Agent Orange contaminated with the dioxin TCDD in a guerrilla war against communist insurgents. Agent Orange was a synthetic plant growth regulator comprised of equal amounts of two herbicides 2,4-dichloro phenoxyacetic acid C8H6Cl2O3 (2,4-D) and 2,4,5-trichlorophenoxyacetic acid C8H5Cl3O3 (2,4,5-T). TCDD, the dioxin, 2,3,7,8-tetrachlorodibenzodioxin (C12H4Cl4O2) was an unintended byproduct of the accelerated combustion process used in the manufacture of herbicides containing 2,4,5-T. Agent Orange has frequently been blamed for soil and sediment contamination and long-term human health problems;however, the true source of harm is the dioxin TCDD. Agent Orange has a short half-life of days and weeks after application to vegetation, and has not been found to persist, after 50 years, in the water or soils of southern Vietnam. However, the half-life of dioxin TCDD depends on where it is deposited and varies from 1 to 3 years on soil surfaces that have been fully exposed to sunlight, to as long as 20 to 50 years or more when buried in tropical subsoils, and more than 100 years in river and sea sediments. Dioxin TCDD was heavily concentrated in the US Air Force bases in Vietnam where the herbicides were stored, loaded on planes and helicopters for aerial spraying, and used extensively around military base perimeter fences as a security measure to prevent surprise attacks. Bien Hoa Air Force base, 40 km northeast of Ho Chi Minh City, continues to be one of the mega-hotspots where after 48 years the dioxin TCDD levels in fish and shrimp are still high and fishing is banned in ponds and lakes adjacent to the airbase. Although expensive, one of the most effective remediation to dioxin TCDD contaminated soils is incineration which is the recommended method of dioxin TCDD disposal.

Improvement of Chemically-activated Luciferase Gene Expression Bioassay for Detection of Dioxin-Iike Chemicals

Objective To improve the chemically-activated luciferase expression (CALUX)bioassay for detection of dioxin-like chemicals (DLCs) based on the toxicity mechanisms ofDLCs. Method A recombinant vector was constructed and used to transfect humanhepatoma (HepG2). The expression of this vector was 10-100 folds higher than that of pGL2used in previous experiments. The transfected cells showed aromatic hydrocarbon receptor(AhR)-meditated luciferase gene expression. The reliability of luciferase induction in thiscell line as a reporter of AhR-mediated toxicity was evaluated, the optimal detection timewas examined and a comparison was made by using the commonly used ethoxyresoufin-O-deethylase (EROD) activity induction assay. Result The results suggested that theluciferase activity in recombinant cells was peaked at about 4 h and then decreased to astable activity by 14 h after TCDD treatment. The detection limit of this cell line was0.11pmol/L, or 10-fold lower than in previous studies, with a linear range from 1 to 100pmol/L, related coefficient of 0.997, and the coefficient of variability (CV) of 15-30%.Conclusion The luciferase induction is 30-fold more sensitive than EROD induction, thedetection time is 68 h shorter and the detection procedure is also simpler.

Electronic Structure and Physical Characteristics of Dioxin Under External Electric Field

Dioxin is a highly toxic and caustic substance,which widely existed in the atmosphere,soil and water with tiny particles.Dioxin pollution has become a major problem that concerns the survival of mankind,which must be strictly controlled.The bond length,bond angle,energy,dipole moment,orbital energy level distribution of dioxin under the external field are investigated using DFT(density functional theory)on basis set level of B3LYP/6-31G(d,p).The results indicate that with the increase of the electric field,the length of one Carbon-Oxygen bond increases while another Carbon-Oxygen bond decreases.The energy gradually decreases with the electric field,while the change of the dipole moment has an opposite trend.In the infrared spectra,the vibration frequency decreases with the electric field increasing and shows an obvious red shift.Moreover,the ultraviolet-visible absorption spectra under different electric fields are analyzed with TD-DFT(time-dependent density functional theory)method.The wavelength of the strongest absorption peak increases and occurs red shift with the increase of the electric field.All the above results can provide reference for further research on the properties of dioxin under different external electric field.

Study on Catalytic Decomposition of Dioxins by Supported CeO_2-TiO_2-V_2O_5 Composite Catalyst

Loaded on the cordierite, the rare earth doped composite catalyst was prepared by sol-gel method combined with dipping technique. Taking Orthodichlorobenzene as model, the catalyst was used to remove the dioxins of the waste gas. The results showed that at 280 ℃ and gas space velocity being 8000 h-1, the orthodichlorobenzene could be removed effectivily by the prepared CeO-TiO2-V2O5 composite catalyst whose activity was remarkably enhanced by the doping of Ce, while the industrial side-stream test of dioxins from refuse incineration smoke indicated that the decomposition rate could reach above 93% under the same conditions.

Surface Electrostatic Potentials of Polychlorinated Dibenzo-p-dioxins and Their Applications in the Quantitative Structure-properties Relationships

Polychlorinated dibenzo-p-dioxins（PCDDs） are a group of important persistent organic pollutants.They are highly toxic and persistent in environment.In the present study,geometrical optimization and electrostatic potential calculations have been performed for 75 PCDD congeners and dibenzo-p-dioxin（DD） at the HF/6-31G＊ level of theory.A number of statistically based parameters have been extracted.Linear relationships between vapor pressures（logpL）,aqueous solubilities（logSw）,n-octanol/water partition coefficients（logKow） of PCDDs and structural descriptors have been established by stepwise linear regression analysis.The result shows that the quantities derived from the surface electrostatic potentials Vmin,Π,and Vs,av＋,together with Vmc（the molecular volume） and ELUMO（the energy of the lowest unoccupied molecular orbital） can be well used to express the quantitative structure-property relationships of PCDDs.Predictive capabilities of the models have also been demonstrated by leave-one-out cross-validation with the cross-validated correlation coefficient（Rcv） above 0.97.Based on these QSPR models,the predicted values have been presented for those PCDD congeners whose experimentally determined physicochemical properties are unavailable.

Comparative Study on Thermodynamic Properties and Stabilities of Polychloro-phenazines and Polychlorinated Dibenzo-p-dioxin

The thermodynamic properties and molecular volumes （Vm） of 76 polychlorophenazines （PCPZs） have been calculated at the B3LYP/6-31G^＊ level by using density functional theory. The isodesmic reactions were designed to calculate standard enthalpy of formation （△fH^θ） and standard free energy of formation （△fG^θ） of PCPZ congeners. According to the relative magnitude of their △fG^θ, the order of relative stability of PCPZ congeners was theoretically proposed. Comparing the results with those of polychlorinated dibenzo-p-dioxin （PCDD） isomers, it was found that S^θ, △fH^θ, △fG^θ, Vm and the order of relative stability of PCPZ congeners were quite similar to those of PCDDs.

Dioxins in the Food Chain: Contamination Fingerprint Analysis in Breeding Hens, Hatching Eggs and Broilers

While routine monitoring poultry meat was obtained from breeding hens, dioxins contaminations were detected in Portugal. Levels of 430.9 pg PCDD/F-WHO-TEQ/g1 were found, which are higher than the official limits legally allowed for this matrix (1.75 pg PCDD/F-WHO-TEQ/g). To identify the magnitude of the contaminations, 60 samples were collected from poultry farms and different matrices, namely: feed, water, wood shavings from the litters, muscle of the breeding hens, hatching eggs collected in the positive farm and muscle collected from broilers farms supplied by the positive breeding farm. The comparison of the dioxins congeners profiles showed that there was a coincidence of peaks of higher relative concentrations in the wood shavings, with the peaks of the highest relative concentration in the hatching eggs, especially the relative concentrations of the congeners 1,2,3,4,6,7,8-HpCDD and OCDD, which may be explained by the role of VLDLy in the delivery of triglycerides to the oocyte, where they will be used as the energy source for the developing embryo. The comparison of the dioxins congeners profiles of the breeding hens muscle with the poultry muscle, showed a coincidence of peaks of higher relative concentrations in the congeners 1,2,3,7,8-PeCDD, 1,2,3,6,7,8-HxCDD, 1,2,3,4,6,7,8-HpCDD and OCDD which may indicate a dechlorination pathway “in vivo”. Results allowed concluding that those wood shavings, improperly used as poultry litters, were certainly the source of contamination of the food chain.

Exposure to Dioxins and Furans at the Bormeh Kingtom Dumpsite in the Western Area of Sierra Leone

Humans and animals can be exposed to Dioxins and Furans through ingestion of fatty food, skin contact, and breathing contaminated air. Resulting health problems include skin disease, immune problems, and cancers. Managing the release of these chemicals is therefore important. The Stockholm Convention on Persistent Organic Pollutants requires parties to adopt measures that reduce sources of these chemicals. Sierra Leone developed its National Implementation Plan (NIP) in 2008, in compliance with this requirement. However, no known further steps have been taken, particularly at community level. In 2013, the UNDP’s GEF/SGP funded a pilot project to manage the release of Dioxins and Furans from two dumpsites in Freetown, Sierra Leone. This work was sponsored with funds from that project. The work sought to delineate the exposure of communities within and around the Bormeh-Kingtom dumpsite (Kingtom, Kolleh town, Ascension town, Crab town, and Congo town) to the chemicals. The study considered sources of exposure, relative quantities generated per year, and the routes of exposure. This exposure study is a first step in managing the release from those sources. Enumerators deployed at the dumpsite every day, 7:00 AM to 6:00 PM, for three months, quantifying and recording source materials. The amount of source materials dumped per day informed calculation of Dioxin/Furan releases in grams toxicity equivalence per year. The results revealed a release of 128.914 g TEQ/year in air and residue. This implies that the communities are at high risk of inhalation and dermal exposure. Livestock, mainly pigs, are also exposed as they feed on the waste deposited in the dumpsite. Humans in turn feed on the livestock, a recipe for biomagnification. The project team has been working on developing Best Management Practices to suppress the release of the chemicals.

卫生部关于禁止经销比利时等国受二恶英(Dioxin)污染食品的紧急通知

各省、自治区、直辖市卫生厅（局）：自１９９９年１月１５日以来，比利时、荷兰、法国、德国四国相继发生因饲料被二恶英（Ｄｉｏｘｉｎ）污染，导致畜禽类产品及乳制品含高浓度二恶英事件。据悉，上述国家的畜禽类及乳制品中除牛肉外，我国均已进口。二恶英属致癌物，...

Synergistic Effects of 2,3,7,8-Tetrachlorodibenzo-p-dioxin and N-nitrosodiethylamine on Cell Malignant Transformation

Objective The present paper aims to investigate the effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin （TCDD） and N-nitrosodiethylamine （DEN） on tumorigenesis and its potential mechanism. Methods The potentials of TCDD and DEN in separation or in combination to induce malignant transformation were tested in Balb/c 3T3 cells by using a cell transformation assay method. The possible mechanism of observed effects was studied further by adding α-naphthoflavone （α-NF）, a competitive binding agent of TCDD, to the Aryl hydrocarbon receptor （AhR） pathway. The mRNA expressions of Cyp1a1 and Cyp2a5 gene in Balb/c 3T3 cells treated by DEN and TCDD in separation or in combination with or without presence of α-NF were measured with fluorescence quantification RT-PCR technique. Results The cell transformation frequency （TF） was significantly higher in case of induction with TCDD in combination with DEN, as compared to that with either TCDD or DEN alone. These effects were not inhibited via α-NF. The mRNA expression levels of both Cyp1a1 and Cyp2a5 were enhanced by TCDD treatment alone, but this inducible effect was blocked in cells treated by TCDD and DEN in combination. Conclusion TCDD and DEN had a significant synergistic effect on tumorigenesis when they were used in combination. AhR pathway may not be the key mechanism of this synergistic effect. Thus, it is necessary to further test the potential mechanism involved in cancer development.

The 2008 Irish Dioxin Crisis:Prevention is better than Crisis Management

In Ireland, in 2008, pig feed manufactured from recycled human food became contaminated with dioxin and this led to a global recall of all Irish pork products produced from 1st September to 6th December 2008. This case study illustrates several points a) the food chain is only as secure as its weakest link, b) due to the complexity of the modern food chain, once pork is processed, precise traceability to a particular farm of origin is impossible, c) even with a single food agency, overseeing the policing of the food chain, things can go wrong, d) it demonstrated the benefits of having credible consumer protection agencies to undertake scientific risk assessment and communicate with the public, e) if risk management decisions are taken quickly, and communicated in an open and transparent manner to the public, adverse human health effects can be avoided and consumer confidence can maintained, f) in the EU the legal limit for dioxins in pork fat is 1 picogram per gram (10-12 ) and attempting to communicate the risks associated with this level of contamination plus the concepts of bioaccumulation and body burden and the need for continued exposure to result in adverse health effects is extremely challenging, g) there was a major economic impact and damage to the country's reputation as a food exporter and finally h) it illustrates that prevention is better that crisis management. Other countries can learn lessons from this incident that may prevent similar occurrences in their jurisdictions.

Pollution Status of Dioxins Persistent Organic Pollutants in Guangxi and Control Countermeasures

Production and pollution control situations of dioxins persistent organic pollutants in Guangxi were introduced.Pollution status of dioxins persistent organic pollutants in Guangxi was understood,and the existing problems in pollution control were analyzed,and finally pollution control countermeasures and suggestions were proposed.

Gas-particle partitioning of polychlorinated dibenzo-p-dioxins and dibenzofurans in the sintering process

The distribution of seventeen gaseous and particle-bound 2,3,7,8-substituted chlorinated PCDD/Fs in the flue gas of different windboxes of the sintering machine was analyzed. The influence of temperature change on the PCDD/Fs emission from the sintering process and the formation mechanism of PCDD/Fs were discussed. The result has shown that among the seventeen gaseous and particle-bound PCDD/Fs in the flue gas of different windboxes, furans occupied the major place. The proportion of the gaseous PCDD/Fs in most windboxes is from 40% to 60%. The change tendencies of the concentration of both the gaseous and particle-bound PCDD/Fs were similar, with a higher level at the end of the sintering bed. The PCDD/Fs concentration＇ s change tendency in the windbox was very consistent with the change of temperature of the flue gas in the windboxes. More than 60% PCDD/Fs of the total PCDD/Fs emission amount was emitted at the end of the sintering bed. Only this part of the waste gas accounted for 12% of the total waste gas volume.

Influence of hot air sintering on dioxin emission

Sintering pot tests with hot air were conducted. Air recovery from exhaust gas from the sintering plant. The effects was heated by using a resistance furnace to simulate heat of the process parameters, such as temperature of hot air, oxygen enrichment, coke consumption and bed depth, on quality of products, energy consumption and dioxin emission were investigated. Good results were obtained under the following conditions ： 200℃ hot air, no oxygen enrichment, lime with high CaO, thinner bed and addition of accelerant.

Investigation of Dioxin/Furans, PAHs and Heavy Metals in Sarcheshmeh Copper Complex Soil, Iran

Surface soil samples were collected from Sarcheshmeh Copper Smelter Plant and analyzed for 16 Polycyclic Aromatic Hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxin/furans (PCDD/Fs), and heavy metals to determine their concentrations, distributions, and probable sources of contamination. The mean concentrations of ΣPAHs, As, Pb, Zn, Se, Cd, and Cr in the soil samples were 878.8, 850, 2185, 2455, 21, and 24 mg/kg, respectively. Besides, their Toxic Equivalents (TEQs) were calculated. The samples generally displayed elevated concentrations of heavy metals when finding the toxic values of dioxin/furan compounds in comparison to the limit values for industrial uses. The background concentrations, molecular indices, and ring classes of the heavy metals indicated that their sources and those of PAHs were both geogenic and pyrolitic. The mean concentrations of total PAHs, PCDD/Fs, and heavy metals were compared with the reports from industrial areas throughout the world and the contamination rates at Sarcheshmeh Copper Plant were found to be moderate.