THIOUREA LEACHING OF GOLD FROM A CALCINE OF GOLD-BEARING ARSENICAL PYRITE CONCENTRATE

The thiourea leaching of gold from the calcine of gold-bearing arsenical pyrite concentrate of Kangjiawan mine was studied.The effects of the leaching time,the concentrations of thiourea,hydrochloric acid and initial ferric ion on the leaching recovery of gold were investigated,and a regressive model has been established,which showed that the concentrations of thiourea and hydrochloric acid were the most important factors,leaching time the second,and concentration of the initial ferric ion the least・Under the optimal conditions,that is,temperature 50℃,the ratio of liquid to solid 4:1,thiourea 12g/L,hydrochloric acid 1 mol/L,and initial ferric ion 1 g/L,the leaching recoveries of gold and silver were more than 81%and 73%,respectively.The increase of silver recovery and the reduction of thiourea consumption could be attained when sodium sulphite was added.

Thiolated arsenicals in arsenic metabolism: Occurrence,formation, and biological implications

Arsenic（As） is a notoriously toxic pollutant of health concern worldwide with potential risk of cancer induction, but meanwhile it is used as medicines for the treatment of different conditions including hematological cancers. Arsenic can undergo extensive metabolism in biological systems, and both toxicological and therapeutic effects of arsenic compounds are closely related to their metabolism. Recent studies have identified methylated thioarsenicals as a new class of arsenic metabolites in biological systems after exposure of inorganic and organic arsenicals, including arsenite, dimethylarsinic acid（DMAV）, dimethylarsinous glutathione（DMAIIIGS）, and arsenosugars. The increasing detection of thiolated arsenicals,including monomethylmonothioarsonic acid（MMMTAV）, dimethylmonothioarsinic acid（DMMTAV） and its glutathione conjugate（DMMTAVGS）, and dimethyldithioarsinic acid（DMDTAV） suggests that thioarsenicals may be important metabolites and play important roles in arsenic toxicity and therapeutic effects. Here we summarized the reported occurrence of thioarsenicals in biological systems, the possible formation pathways of thioarsenicals, and their toxicity, and discussed the biological implications of thioarsenicals on arsenic metabolism, toxicity, and therapeutic effects.

Feasibility Evaluation of Using Biochar-based Permeable Reactive Barrier for the Remediation of Mercury and Arsenic Composite Polluted Water Bodies

This study employed a modified biochar material to construct a permeable reactive barrier(PRB)for the treatment of water bodies polluted with mercury and arsenic.The experimental results demonstrated that the addition of goethite-modified biochar significantly enhanced the remediation efficiency of As(III),achieving a maximum removal rate of 100%.Conversely,pure biochar exhibited high efficiency in the removal of Hg(II),with a maximum removal rate approaching 100%.Furthermore,the pH level of the water significantly influenced the adsorption efficiency of heavy metal ions,with the optimal removal performance observed at a pH of 6.0.The PRB system demonstrated excellent removal rates under low concentrations of heavy metals.However,as the concentration increased,the remediation efficiency exhibited a slight decrease.In summary,the findings of this study provide compelling evidence for the use of modified biochar in the construction of PRBs for the remediation of mercury and arsenic-polluted water bodies.Furthermore,the study reveals the mechanism by which pH and heavy metal concentration influence remediation efficiency.

Distribution and Contamination of Arsenic in Fish, Gastropods and Bivalves in the Aby and Tendo Lagoons in East of Ivory Coast

Lagoons are ecosystems for biodiversity and the livelihoods of coastal communities. The main objective of the study was to analyze the variability of arsenic concentrations in gastropods and bivalves in the Aby and Tendo lagoons, taking into account spatial, seasonal and hydrological variations. The study was carried out in four stages spread over two successive hydroclimatic cycles, including two seasons during the rainy season and two more during the dry season. The samples were taken in two areas of the Aby and Tendo lagoons. Arsenic levels were measured by ICP-MS. The results showed that mean arsenic concentrations in the muscles of organisms in Aby Lagoon ranged from 0.01 to 1.26 μg As/g, with a mean and median of 0.17 and 0.06 μg As/g, respectively. Fish had the highest levels of arsenic, followed by crustaceans, while molluscs and plants had lower and comparable concentrations of As. Arsenic concentrations in tilapia and jawbones varied significantly between sites and seasons, with higher concentrations at Tendo and during the rainy season. Arsenic concentrations in gastropods and bivalves were significantly higher than those of other species, with averages of 0.74 and 1.03 mg As/kg, respectively.

Roles of Aqueous Extract of Marigold on Arsenic-Induced Oxidative Damage in Pancreatic Islet β-Cells

Roles of Marigold extracts (ME) on arsenic trioxide (ATO)-induced oxidative damage to pancreatic β-cells need to be further elucidated. In this study, NIT-1 cells were treated with different concentrations of and/or ATO, following by the cell viability was detected by CCK8 assay. Then, intracellular reactive oxygen species (ROS) levels, lipid peroxide (MDA) contents and superoxide dismutase (SOD) activity were measured with a fluorescence probe method and colorimetric assay, respectively. The apoptosis rate and morphology was detected and observed with hoechst 33,258 staining assay. The mRNA levels and protein expressions of nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) were measured by real-time fluorescence quantitative polymerase chain reaction and protein immunoblotting assay, respectively. Our results indicated that Co-treatment with ME and ATO exacerbated the cell viability decreasing reduced by ATO, while the addition of ME after ATO treatment effectively promote the recovery of ATO reduced survival rates. The ATO group increased apoptosis (P P β-cells by modulating the activation of the Nrf2 signaling pathway.

Role of complex organic arsenicals in food in aggregate exposure to arsenic

For much of the world＇s population, food is the major source of exposure to arsenic.Exposure to this non-essential metalloid at relatively low levels may be linked to a wide range of adverse health effects. Thus, evaluating foods as sources of exposure to arsenic is important in assessing risk and developing strategies that protect public health. Although most emphasis has been placed on inorganic arsenic as human carcinogen and toxicant, an array of arsenic-containing species are found in plants and animals used as foods. Here,we 2evaluate the contribution of complex organic arsenicals（arsenosugars, arsenolipids,and trimethylarsonium compounds） that are found in foods and consider their origins,metabolism, and potential toxicity. Commonalities in the metabolism of arsenosugars and arsenolipids lead to the production of di-methylated arsenicals which are known to exert many toxic effects. Evaluating foods as sources of exposure to these complex organic arsenicals and understanding the formation of reactive metabolites may be critical in assessing their contribution to aggregate exposure to arsenic.

Mechanism of Learning and Memory Impairment in Rats Exposed to Arsenic and/or Fluoride Based on Microbiome and Metabolome

Objective Arsenic(As) and fluoride(F) are two of the most common elements contaminating groundwater resources. A growing number of studies have found that As and F can cause neurotoxicity in infants and children, leading to cognitive, learning, and memory impairments. However, early biomarkers of learning and memory impairment induced by As and/or F remain unclear. In the present study, the mechanisms by which As and/or F cause learning memory impairment are explored at the multi-omics level(microbiome and metabolome).Methods We stablished an SD rats model exposed to arsenic and/or fluoride from intrauterine to adult period.Results Arsenic and/fluoride exposed groups showed reduced neurobehavioral performance and lesions in the hippocampal CA1 region. 16S rRNA gene sequencing revealed that As and/or F exposure significantly altered the composition and diversity of the gut microbiome, featuring the Lachnospiraceae_NK4A136_group, Ruminococcus_1, Prevotellaceae_NK3B31_group, [Eubacterium]_xylanophilum_group. Metabolome analysis showed that As and/or F-induced learning and memory impairment may be related to tryptophan, lipoic acid, glutamate, gamma-aminobutyric acidergic(GABAergic) synapse, and arachidonic acid(AA) metabolism. The gut microbiota, metabolites, and learning memory indicators were significantly correlated.Conclusion Learning memory impairment triggered by As and/or F exposure may be mediated by different gut microbes and their associated metabolites.

Hesperidin attenuates arsenic trioxide-induced cardiac toxicity in rats

Objective:To explore the cardioprotective effect of hesperidin against arsenic trioxide-induced cardiac toxicity in rats.Methods:Cardiac toxicity was induced by oral administration of 4 mg/kg arsenic trioxide for 30 days.Hematological,biochemical,electrocardiography,echocardiography,and histopathological examinations were performed.Results:Hesperidin decreased the neutrophil-to-lymphocyte ratio,calcium,creatine kinase-myoglobin binding,lactate dehydrogenase,IL-6,and lipid peroxidation,as well as increased sodium and potassium concentration and superoxide dismutase and catalase activity in arsenic trioxide-intoxicated rats.Moreover,it reduced peak systolic velocity and end-diastolic velocity while increasing heart rate.Arsenic trioxide-induced histopathological damage to cardiac tissue was prominently alleviated by hesperidin treatment.Conclusions:Hesperidin attenuates arsenic trioxide-induced cardiac toxicity in rats.Therefore,it can be further explored as a cardioprotective agent.

Arsenic removal from acidic industrial wastewater by ultrasonic activated phosphorus pentasulfide

Arsenic is one of the main harmful elements in industrial wastewater.How to remove arsenic has always been one of the research hotspots in academic circles.In the process of arsenic removal by traditional sulfuration,the use of traditional sulfurizing agent will introduce new metal cations,which will affect the recycling of acid.In this study,phosphorus pentasulfide (P_(2)S_(5)) was used as sulfurizing agent,which hydrolyzed to produce H_(3)PO_(4) and H_(2)S without introducing new metal cations.The effect of ultrasound on arsenic removal by P_(2)S_(5) was studied.Under the action of ultrasound,the utilization of P_(2)S_(5) was improved and the reaction time was shortened.The effects of S/As molar ratio and reaction time on arsenic removal rate were investigated under ultrasonic conditions.Ultrasonic enhanced heat and mass transfer so that the arsenic removal rate of 94.5%could be achieved under the conditions of S/As molar ratio of 2.1:1 and reaction time of 20 min.In the first 60 min,under the same S/As molar ratio and reaction time,the ultrasonic hydrolysis efficiency of P_(2)S_(5) was higher.This is because P_(2)S_(5) forms ([(P_(2)S_(4))])^(2+)under the ultrasonic action,and the structure is damaged,which is easier to be hydrolyzed.In addition,the precipitation after arsenic removal was characterized and analyzed by X-ray diffraction,scanning electron microscope-energy dispersive spectrometer,X-ray fluorescence spectrometer and X-ray photoelectron spectroscopy.Our research avoids the introduction of metal cations in the arsenic removal process,and shortens the reaction time.

铜冶炼过程中的砷反应行为及其处理技术的回顾

砷作为五大有毒元素之一,其对生物体和生态环境的健康威胁已引起公众的广泛关注。有色金属冶炼,特别是铜冶炼,是砷的重要人为来源,应被列为重点关注对象。因此,明确砷在铜冶炼过程中的行为,对铜冶炼企业的正常生产和环境保护具有重要意义。本工作简要介绍了冶炼用工业铜矿物和铜矿中砷的赋存形式,以及铜冶炼工艺的演变。此外,还分析了砷在有代表性的铜冶炼过程中的挥发、转化和分布行为,明确了其流向和富集规律。研究了其他矿物成分(Cu、Pb、Zn、Fe、Ca、Si)与砷在冶炼副产品(铜渣和烟尘)形成过程中的相互作用,阐明了砷污染物的形成机制。最后,分析了冶炼烟气、烟尘和铜渣中砷的控制技术,提出了未来通过将砷污染物转化为金属砷来回收砷的可能策略。

Plant-derived natural compounds in the treatment of arsenic-induced toxicity

Arsenic toxicity,imposed mainly by arsenic-contaminated groundwater,is considered a critical threat to global communal health,as there is no specific and proven conventional therapy for chronic arsenic toxicity,i.e.,arsenicosis,which is an insidious global public health menace affecting 50 countries.Alternative options should,therefore,be explored for the mitigation of arsenicosis.Literature survey reveals several natural compounds from plants possess significant protective efficacy against arsenic toxicity in chiefly preclinical and few clinical investigations.The studies on the ameliorative effects of plant-derived natural compounds against arsenic toxicity published in the last 25 years are collated.Forty-eight plant-based natural compounds possess alleviative effects on experimental arsenic-induced toxicity in animals,six of which have been reported to be clinically effective in humans.A potential nutraceutical or therapeutic candidate against arsenicosis for humans may thus be developed with the help of recent advancements in research in this area,along with the currently available treatments.

CD71-mediated liposomal arsenic-nickel complex combined with all-trans retinoic acid for the efficacy of acute promyelocytic leukemia

Clinically,arsenic trioxide(ATO)was applied to the treatment of acute promyelocytic leukemia(APL)as a reliable and effective frontline drug.However,the administration regimen of AsⅢwas limited due to its fast clearance,short therapeutic window and toxicity as well.Based on CD71 overexpressed on APL cells,in present study,a transferrin(Tf)-modified liposome(LP)was established firstly to encapsulate AsⅢin arsenic-nickel complex by nickel acetate gradient method.The AsⅢ-loaded liposomes(AsLP)exhibited the feature of acid-sensitive release in vitro.Tf-modified AsLP(Tf-AsLP)were specifically taken up by APL cells and the acidic intracellular environment triggered liposome to release AsⅢwhich stimulated reactive oxygen species level and caspase-3 activity.Tf-AsLP prolonged half-life of AsⅢin blood circulation,lowered systemic toxicity,and promoted apoptosis and induced cell differentiation at lesion site in vivo.Considering that ATO combined with RA is usually applied as the first choice in clinic for APL treatment to improve the therapeutic effect,accordingly,a Tf-modified RA liposome(Tf-RALP)was designed to reduce the severe side effects of free RA and assist Tf-AsLP for better efficacy.As expected,the tumor inhibition rate of Tf-AsLP was improved significantly with the combination of Tf-RALP on subcutaneous tumor model.Furthermore,APL orthotopic NOD/SCID mice model was established by 60CO irradiation and HL-60 cells intravenously injection.The effect of co-administration(Tf-AsLP+Tf-RALP)was also confirmed to conspicuous decrease the number of leukemia cells in the circulatory system and prolong the survival time of APL mice by promoting the APL cells’apoptosis and differentiation in peripheral blood and bone marrow.Collectively,Tf-modified acid-sensitive AsLP could greatly reduce the systemic toxicity of free drug.Moreover,Tf-AsLP combined with Tf-RALP could achieve better efficacy.Thus,transferrinmodified AsⅢliposome would be a novel clinical strategy to improve patient compliance,with promising translation prospects.

Ammonium Metavanadate Fabricated by Selective Precipitation of Impurity Chemicals on Inorganic Flocculants

High purity ammonium metavanadate(NH_(4)VO_(3))is the most vital chemical to produce V2O5,VO2,VN alloy,VFe alloy and VOSO4,which have some prospective applications for high strength steel,smart window,infrared detector and imaging,large scale energy storage system.NH_(4)VO_(3)is usually produced by spontaneous crystallization from the aqueous solution due to its sharp dependence of solubility on the temperature.However,hazardous chemicals in industrial effluent,include phosphorate,silicate and arsenate,causing severe damage to the environment.In this work,these impurities are selectively precipitated onto inorganic flocculants,while the vanadate dissolved in an aqueous solution keeps almost undisturbed.Therefore,high purity NH_(4)VO_(3)is produced by the crystallization from the purified solution.By screening various flocculants and precipitating parameters,polyaluminum sulfate with an optimal amount of 50 g/L,is demonstrated to selectively remove phosphorate,silicate and arsenate,corresponding to the removing efficiency of 93.39%,97.11%and 88.31%,respectively.NH_(4)VO_(3)from the purified solution holds a purity of 99.21%,in comparison with 98.33%in the product from the crude solution.This purifying technology cannot only produce NH_(4)VO_(3)with high added value,but also reduce the environmental pollution of waste liquid.

Source,migration,distribution,toxicological effects and remediation technologies of arsenic in groundwater in China

Groundwater with high arsenic(As) content seriously threatens human life and health. Drinking high-As groundwater for a long time will lead to various pathological changes such as skin cancer, liver cancer,and kidney cancer. High-As groundwater has become one of the most serious environmental geological problems in China and even internationally. This paper aims to systematically summarize the sources,migration, distribution, toxicological effects, and treatment techniques of As in natural groundwater in China based on a large number of literature surveys. High-As groundwater in China is mainly distributed in the inland basins in arid and semi-arid environments and the alluvial and lacustrine aquifers in river deltas in humid environments, which are in neutral to weakly alkaline and strongly reducing environments.The content of As in groundwater varies widely, and As(Ⅲ) is the main form. The main mechanism of the formation of high-As groundwater in China is the reduced dissolution of Fe and Mn oxides under the action of organic matter and primary microorganisms, alkaline environment, intense evaporation and concentration, long-term water-rock interaction, and slow groundwater velocity, which promote the continuous migration and enrichment of As in groundwater. There are obvious differences in the toxicity of different forms of As. The toxic of As(Ⅲ) is far more than As(V), which is considered to be more toxic than methyl arsenate(MMA) and dimethyl arsenate(DMA). Inorganic As entering the body is metabolized through a combination of methylation(detoxification) and reduction(activation) and catalyzed by a series of methyltransferases and reductases. At present, remediation methods for high-As groundwater mainly include ion exchange technology, membrane filtration technology, biological treatment technology, nanocomposite adsorption technology, electrochemical technology, and so on. All the above remediation methods still have certain limitations, and it is urgent to develop treatment materials and technical means with stronger As removal performance and sustainability. With the joint efforts of scientists and governments of various countries in the future, this worldwide problem of drinking-water As poisoning will be solved as soon as possible. This paper systematically summarizes and discusses the hot research results of natural high-As groundwater, which could provide a reference for the related research of high-As groundwater in China and even the world.

Preparation of Biomanganese Oxide-biochar Composite and Its Remediation of Arsenic Contamination

[Objectives]To prepare biomanganese oxide/biochar composite(BMO-BC)and examine its remediation performance on arsenic contamination.[Methods]The BMO-BC was prepared by cultivating Pseudomonas putida MnB1 in the presence of Mn 2+and biochar.[Results]The initial concentration of Mn 2+in the culture system had no significant effect on the growth rate and domestication cycle of Pseudomonas putida MnB1.The results of SEM-EDS and XRD analysis confirm that the adsorbent prepared in this experiment was a composite of biomanganese oxide and biochar particles.The results of arsenic pollution removal test in simulated environment showed that the in-situ formed BMO-BC composite had certain removal effect on As(III)and the presence of biochar particles and manganese dioxide in the reaction system and the manganese oxidation ability of microbial strain MnB1 affect its remediation performance to As(III).[Conclusions]When the initial concentration is in the range of 0-10.0 mg/L,the isothermal adsorption data of BMO-BC on As(III)conforms to the Langmuir model.

Use of Agent Purple, Agent Orange and Agent Blue on Royal Thai Air Force Base Perimeters in Thailand during the Vietnam War

Seven Royal Thai Air Force bases in Thailand were used by the United States Air Force (USAF) during the Vietnam War as staging hubs for operations in Laos and Cambodia. Five bases in Thailand, including Nakhon Phanom (NKP), Ubon, Korat, U-Tapao and Udorn endured sniper fire interdiction, perimeter penetration, and sapper (combat engineer) attacks. Nam Phong, an eighth Royal Thai Air Force base was used by the United States Marine Corps air operations starting in 1972. US Military personnel stationed throughout Thailand were also attacked by Communists insurgents. Two herbicides, Agent Purple and Agent Orange containing 2, 4, 5-T contaminated with dioxin (TCDD—2, 3, 7, 8 tetrachlorodibenzodioxin) and a third herbicide, the arsenic-based Agent Blue, were routinely received at these Thailand airbases in support of air missions and to keep airbases and perimeter fences clear of vegetation. Udorn Royal Thai Air Force (RTAF) base, established in the 1950s was consistently a target of enemy attacks during this period. The Thai government allowed the United States to use five bases, covertly, and two other Thai bases, openly, due to concerns that the civil war inside Laos might spread into Thailand. The US Air Force began, in 1961, to provide the air defense of Thailand and to fly reconnaissance flights over Laos. Under the United States and Thailand’s “gentleman’s agreement”, the bases used by the USAF were considered RTAF bases under the command of Thai officers. The USAF at Udorn was under the command of the United States Pacific Air Forces (PACAF) Thirteenth Air Force and was used to temporarily store and distribute Agent Purple, Agent Orange and Agent Blue to Laos’s airfields for spraying of the Ho Chi Minh Trail. Thai air police controlled access to the bases using sentry dogs, observation towers, and machine gun emplacements. The USAF Security police assisted the Thai air police in base defense. In this study, we document the use of Agent Orange, Agent Purple and Agent Blue on Royal Thai Air Force base perimeters and grounds during the Vietnam War, potential active-duty service personnel exposure to these toxic herbicides and health impacts of the contaminant dioxin TCDD and arsenic on U.S. Vietnam Era Veterans and Vietnam Veterans. This documentation is important evidence in the “assumption of exposure” for health claims to the US Veterans Administration (VA) by veterans that served in Thailand between 1962 and 1976.

United States Secret War in Laos: Long-Term Environmental and Human Health Impacts of the Use of Chemical Weapons

In 1959, the United States Central Intelligence Agency (CIA) operation, against the Pathet Lao insurgences and Viet Mien military troops and supply route, began. The Ho Chi Minh Trail was developed after the North Vietnam government and military decided to reunify South and North Vietnam. The People’s Army of Vietnam (PAVN) then connected the old trails leading from North Vietnam panhandle southward into eastern Laos, Cambodia and South Vietnam. Starting from Hanoi, the primary trail turned southwest into Laos and eastern Cambodia before branching into South Vietnam. Beginning in 1960s, the volume of traffic on the network of trails expanded significantly, but it still took more than a month’s march, by foot and bicycle, to travel from North to South Vietnam. Ho Chi Minh Trail traffic was impacted by repeatedly by Royal Laotian Air Force (RLAF), which was supported by US Air Force tactical herbicide spraying (Operation Ranch Hand program), and US Air Force bombing runs. By the late 1960s, the trail was improved and could accommodate heavy trucks in some sections and was used to supply the annual needs of over one hundred thousand regular PAVN troops active in South Vietnam. By 1974, the trail was a well-marked series of jungle roads (some of them paved) with underground support facilities such as hospitals, fuel-storage tanks, and supply caches with weapons. The Ho Chi Minh Trail was the major supply route for PAVN forces that overran Republic of Vietnam (RV) forces in 1975 and unified Vietnam. The primary objective of this paper is to determine the environmental and human health impacts of RLAF and US Air Force secret spraying of tactical herbicides on Ho Chi Minh Trail in Laos.

Assessment of Soil Contamination and Human Health Risk around an Industrial Gold Mine in Côte d’Ivoire: The Case of Arsenic

The Tongon mine generates millions of tons of waste rock and tailings, which are stored in landfills in the vicinity of the mine. These tailings contain arsenic. The risk of soil contamination in this area is evident. This study assesses the arsenic contamination of soils around the mine and the health risks to the local population. Soil samples were taken from plastic bags and other materials used as working tools. Arsenic concentrations were determined by inductively coupled plasma mass spectroscopy, after the soil samples had been concentrated and digested. Metal contamination indices were used to assess the degree of soil contamination. The results obtained indicate that soils in the industrial zone of the Tongon gold mine have very high average concentrations, well above the world average for uncontaminated soils of 6 mg/kg arsenic. Geoaccumulation index values range from 1.28 to 3.40. These values highlight severe arsenic soil contamination. The human health risk assessment revealed that exposure risks are well above the critical limit of 1 and are, in descending order, children > adult women > adult men. These results indicate an ecological risk, requiring environmental monitoring, underpinned by the development of an effective remediation strategy to reduce local pollution and contamination.

Review and Analysis: Fate of Arsenic Applied to Canal Shipping Lane Vegetation and United States Military Base Grounds in the Panama Canal Zone

The opening of the Panama Canal in 1913 increased the availability of internationally traded goods and transformed ocean-shipping by shortening travel time between the Atlantic Ocean and Pacific Ocean. The canal sparked the growth of port authorities and increased ship tonnage on both coasts of Panama. Since the construction of the Panama Canal, in the 1910s, pesticides, herbicides and chemicals, including arsenic, have been essential for controlling wetland vegetation, including hyacinth, which blocked rivers, lakes, and the canal as well as managing mosquitoes. Pesticides and chemicals flowed into Lake Gatun (reservoir) either attached to sediment or in solution during the monsoon season. Lake Gatun was the drinking water source for most of the people living in the Panama Canal Zone. The United States military base commanders had the ability to order and use cacodylic acid (arsenic based) from the Naval Depot Supply Federal and Stock Catalog and the later Federal Supply Catalog on the military base grounds in the Panama Canal Zone. Cacodylic acid was shipped to Panama Canal Zone ports, including Balboa and Cristobal, and distributed to the military bases by rail or truck. The objective of this study is to determine the fate of arsenic: 1) applied between 1914 and 1935 to Panama Canal shipping lane hyacinth and other wetland vegetation and 2) cacodylic acid (arsenic) sprayed from 1948 to 1999 on the US military base grounds in the Panama Canal Zone.

Agent Blue: A Secret Military and Environmental Chemical Weapon Used for Food Denial in South Vietnam during the Vietnam Civil War (1962-1965)

During the last 60 years, the southern Vietnam environment and Vietnamese living in the Mekong Delta have bio-accumulated arsenic from natural and anthropic (Vietnam Civil War (1962-1965)) sources via their drinking water (groundwater from tube wells) and food supply leading to an increasing risk of chronic poisoning over time. A synthesis and analysis of publications and records is presented to document the Republic of Vietnam (RV), the official name of the South Vietnam Government, and United States (US) militaries contribution to arsenic levels and toxic spikes in the Vietnam Mekong Delta groundwater. During the Vietnam Civil War, Agent Blue, in powder form, was shipped to Port Saigon, via the Saigon River, and transported to the Tan Son Nhut Air Force base during the Vietnam Civil War. After the official start of the American-Vietnam War (1965-1973) the tactical herbicides were re-routed to Bien Hoa Air Force base (1965 to 1971). Approximately 3.2 million liters of Agent Blue (468,008 kg As) was sprayed or dumped by the RV military with the assistance and support of the Central Intelligence (CIA), US Army and US Navy, during the 1962-1965 Khai Huang (Hamlet) Program. A portion of an additional 4.6 million liters of Agent Blue (664,392 kg of As) was sprayed between 1962 and 1965 by the US Air Force as part of Operation Ranch Hand and prior to the official start of the American-Vietnam War in August 1964. Operation Rand Hand began in 1962 and ended in 1971. The Institute of Medicine estimated a total of 7.8 million liters (1,132,400 kg As) of Agent Blue was applied to southern Vietnam landscape from 1962 to 1971. This total includes both the 1962 to 1965 RV Khai Huang program with the assistance of the CIA, US Army and US Navy, and the total Agent Blue applied by US Air Force Operation Ranch Hand from 1962 to 1971. The primary objective of this study was to document how Agent Blue, the arsenic-based herbicide, became a secret US military and environmental chemical weapon used by the RV and US militaries in southern Vietnam during the Vietnam Civil War years (1962-1965). This assessment found that the anthropic arsenic, including Agent Blue, added a toxic burden to the Mekong Delta soils, surface water, groundwater, drinking water, food supply, and human health. However, there are missing details regarding political decisions and a full accounting of the geographic locations sprayed and amount of Agent Blue used. Vietnam War Archives have paper correspondence and RV herbicide spray records that shed greater light on this period. These records are over 50 years old and need to be electronically scanned, stored, and made available for additional historical analyses.