Civilian exposure to chlorine gas: A systematic review

Chlorine-Induced Toxicity on Murine Cornea: Exploring the Potential Therapeutic Role of Antioxidants

Chlorine (Cl2) exposure poses a significant risk to ocular health, with the cornea being particularly susceptible to its corrosive effects. Antioxidants, known for their ability to neutralize reactive oxygen species (ROS) and alleviate oxidative stress, were explored as potential therapeutic agents to counteract chlorine-induced damage. In vitro experiments using human corneal epithelial cells showed decreased cell viability by chlorine-induced ROS production, which was reversed by antioxidant incubation. The mitochondrial membrane potential decreased due to both low and high doses of Cl2 exposure; however, it was recovered through antioxidants. The wound scratch assay showed that antioxidants mitigated impaired wound healing after Cl2 exposure. In vivo and ex vivo, after Cl2 exposure, increased corneal fluorescein staining indicates damaged corneal epithelial and stromal layers of mice cornea. Likewise, Cl2 exposure in human ex vivo corneas led to corneal injury characterized by epithelial fluorescein staining and epithelial erosion. However, antioxidants protected Cl2-induced damage. These results highlight the effects of Cl2 on corneal cells using in vitro, ex vivo, and in vivo models while also underscoring the potential of antioxidants, such as vitamin A, vitamin C, resveratrol, and melatonin, as protective agents against acute chlorine toxicity-induced corneal injury. Further investigation is needed to confirm the antioxidants' capacity to alleviate oxidative stress and enhance the corneal healing process.

Successful treatment of 1 patient with chlorine-induced ARDS using awake self-prone positioning and nasal high-flow oxygen: A case report

RATIONALE

Accidents involving chlorinated compounds in the context of cleaning are not uncommon. However, improving the treatment success rate for acute respiratory distress syndrome (ARDS) patients caused by chlorine gas presents significant challenges.

PATIENT CONCERNS

A 28-year-old female was admitted to the intensive care unit after accidental inhalation of chlorine gas resulting in ARDS.

DIAGNOSES

The patient was diagnosed with ARDS attributed to chlorine gas exposure.

INTERVENTIONS

The intervention involved utilizing a combination of awake self-prone positioning (ASPP) and high-flow nasal oxygen therapy for treatment.

OUTCOMES

After continuous ASPP and high-flow nasal oxygen therapy, the patient quickly recovered and was transferred out of the intensive care unit on the 6th day without any adverse events.

LESSONS

ASPP combined with high-flow nasal oxygen therapy can improve patients' hypoxemia, prevent the need for intubation, avoid rapid deterioration of the condition, reduce treatment complexity, and lower mortality rate.

Ophthalmic Manifestations of Chlorine Gas Exposure: What Do We Know So Far?

Chlorine gas is a hazardous substance that can cause severe health effects when inhaled or exposed to the skin. It is an odorless, colorless gas in many industrial and manufacturing settings and conflict areas. While exposure to chlorine gas is generally limited to the workplace and public areas, there are instances in which people may be exposed to high levels of chlorine gas for a short period of time due to spills, mishaps on the road or railroads, or other tragedies. In addition to the general health effects of chlorine gas, this essay will focus on the effects of chlorine gas on the eyes. The eyes are particularly sensitive to chlorine gas, and exposure can cause various symptoms, ranging from mild irritation to severe damage. Symptoms of chlorine gas exposure to the eyes include redness, burning, tearing, and blurred vision. In more serious cases, exposure to chlorine gas can cause permanent damage to the eyes, including corneal ulcers, scarring, and blindness. It is important to be aware of the signs and symptoms of chlorine gas exposure and the potential long-term effects to take the necessary steps to protect oneself. In addition to the potential health effects, it is important to understand the properties of chlorine gas. Chlorine gas is heavier than air and tends to settle in low-lying areas. It is highly reactive and can react with other substances to form hazardous compounds. As such, it is important to be aware of the potential for chlorine gas to react with other environmental substances and accumulate in certain areas. Finally, it is important to understand the background of chlorine gas use in various conflict areas. Chlorine gas has been used as a chemical weapon for centuries, and its use in modern warfare has been documented in various conflicts. As such, it is important to be aware of the potential for chlorine gas to be used in war zones and to take the necessary precautions to protect oneself. In conclusion, chlorine gas is a hazardous substance that can cause severe health effects when inhaled or exposed to the skin. The eyes are particularly sensitive to chlorine gas, and exposure can cause various symptoms, ranging from mild irritation to severe damage. It is important to be aware of the signs and symptoms of chlorine gas exposure and the potential long-term effects to take the necessary steps to protect oneself. Additionally, it is important to understand chlorine gas's properties and its background use in various conflict areas.

Lung injury and oxidative stress induced by inhaled chlorine in mice is associated with proinflammatory activation of macrophages and altered bioenergetics

Chlorine (Cl2) gas is a highly toxic and oxidizing irritant that causes life-threatening lung injuries. Herein, we investigated the impact of Cl2-induced injury and oxidative stress on lung macrophage phenotype and function. Spontaneously breathing male C57BL/6J mice were exposed to air or Cl2 (300 ppm, 25 min) in a whole-body exposure chamber. Bronchoalveolar lavage (BAL) fluid and cells, and lung tissue were collected 24 h later and analyzed for markers of injury, oxidative stress and macrophage activation. Exposure of mice to Cl2 resulted in increases in numbers of BAL cells and levels of IgM, total protein, and fibrinogen, indicating alveolar epithelial barrier dysfunction and inflammation. BAL levels of inflammatory proteins including surfactant protein (SP)-D, soluble receptor for glycation end product (sRAGE) and matrix metalloproteinase (MMP)-9 were also increased. Cl2 inhalation resulted in upregulation of phospho-histone H2A.X, a marker of double-strand DNA breaks in the bronchiolar epithelium and alveolar cells; oxidative stress proteins, heme oxygenase (HO)-1 and catalase were also upregulated. Flow cytometric analysis of BAL cells revealed increases in proinflammatory macrophages following Cl2 exposure, whereas numbers of resident and antiinflammatory macrophages were not altered. This was associated with increases in numbers of macrophages expressing cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS), markers of proinflammatory activation, with no effect on mannose receptor (MR) or Ym-1 expression, markers of antiinflammatory activation. Metabolic analysis of lung cells showed increases in glycolytic activity following Cl2 exposure in line with proinflammatory macrophage activation. Mechanistic understanding of Cl2-induced injury will be useful in the identification of efficacious countermeasures for mitigating morbidity and mortality of this highly toxic gas.

Differential modulation of lung aquaporins among other pathophysiological markers in acute (Cl2 gas) and chronic (carbon nanoparticles, cigarette smoke) respiratory toxicity mouse models

Inhaled toxic chemicals and particulates are known to disrupt lung homeostasis causing pulmonary toxicity and tissue injury. However, biomarkers of such exposures and their underlying mechanisms are poorly understood, especially for emerging toxicants such as engineered nanoparticles and chemical threat agents such as chlorine gas (Cl₂). Aquaporins (AQPs), commonly referred to as water channels, are known to play roles in lung homeostasis and pathophysiology. However, little is known on their regulation in toxicant-induced lung injuries. Here, we compared four lung toxicity models namely, acute chemical exposure (Cl₂)-, chronic particulate exposure (carbon nanotubes/CNT)-, chronic chemical exposure (cigarette smoke extract/CSE)-, and a chronic co-exposure (CNT + CSE)- model, for modulation of lung aquaporins (AQPs 1, 3, 4, and 5) in relation to other pathophysiological endpoints. These included markers of compromised state of lung mucosal lining [mucin 5b (MUC5B) and surfactant protein A (SP-A)] and lung-blood barrier [protein content in bronchoalveolar lavage (BAL) fluid and, cell tight junction proteins occludin and zona-occludens]. The results showed toxicity model-specific regulation of AQPs measured in terms of mRNA abundance. A differential upregulation was observed for AQP1 in acute Cl₂ exposure model (14.71-fold; p = 0.002) and AQP3 in chronic CNT exposure model (3.83-fold; p = 0.044). In contrast, AQP4 was downregulated in chronic CSE model whereas AQP5 showed no significant change in any of the models. SP-A and MUC5B expression showed a decreasing pattern across all toxicity models except the acute Cl₂ toxicity model, which showed a highly significant upregulation of MUC5B (25.95-fold; p = 0.003). This was consistent with other significant pathophysiological changes observed in this acute model, particularly a compromised lung epithelial-endothelial barrier indicated by significantly increased protein infiltration and expression of tight junction proteins, and more severe histopathological (structural and immunological) changes. To our knowledge, this is the first report on lung AQPs as molecular targets of the study toxicants. The differentially regulated AQPs, AQP1 in acute Cl₂ exposure versus AQP3 in chronic CNT nanoparticle exposure, in conjunction with the corresponding differentially impacted pathophysiological endpoints (particularly MUC5B) could potentially serve as predictive markers of toxicant type-specific pulmonary injury and as candidates for future investigation for clinical intervention.

Chlorination in the pandemic times: The current state of the art for monitoring chlorine residual in water and chlorine exposure in air

During the COVID-19 pandemic, the use of chlorine-based disinfectants has surged due to their excellent performance and cost-effectiveness in intercepting the spread of the virus and bacteria in water and air. Many authorities have demanded strict chlorine dosage for disinfection to ensure sufficient chlorine residual for inactivating viruses and bacteria while not posing harmful effects to humans as well as the environment. Reliable chlorine sensing techniques have therefore become the keys to ensure a balance between chlorine disinfection efficiency and disinfection safety. Up to now, there is still a lack of comprehensive review that collates and appraises the recently available techniques from a practical point of view. In this work, we intend to present a detailed overview of the recent advances in monitoring chlorine in both dissolved and gaseous forms aiming to present valuable information in terms of method accuracy, sensitivity, stability, reliability, and applicability, which in turn guides future sensor development. Data on the analytical performance of different techniques and environmental impacts associated with the dominated chemical-based techniques are thus discussed. Finally, this study concludes with highlights of gaps in knowledge and trends for future chlorine sensing development. Due to the increasing use of chlorine in disinfection and chemical synthesis, we believe the information present in this review is a relevant and timely resource for the water treatment industry, healthcare sector, and environmental organizations.

Elucidation of in Vitro Chlorinated Tyrosine Adducts in Blood Plasma as Selective Biomarkers of Chlorine Exposure

Chlorine is a widely available industrial chemical and involved in a substantial number of cases of poisoning. It has also been used as a chemical warfare agent in military conflicts. To enable forensic verification, the persistent biomarkers 3-chlorotyrosine and 3,5-dichlorotyrosine in biomedical samples could be detected. An important shortfall of these biomarkers, however, is the relatively high incidence of elevated levels of chlorinated tyrosine residues in individuals with inflammatory diseases who have not been exposed to chlorine. Therefore, more reliable biomarkers are necessary to distinguish between endogenous formation and exogeneous exposure. The present study aims to develop a novel diagnostic tool for identifying site-specific chlorinated peptides as a more unambiguous indicator of exogeneous chlorine exposure. Human blood plasma was exposed in vitro to various chlorine concentrations, and the plasma proteins were subsequently digested by pronase, trypsin, or pepsin. After sample preparation, the digests were analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) and liquid chromatography high-resolution tandem mass spectrometry (LC-HRMS/MS). In line with other studies, low levels of 3-chlorotyrosine and 3,5-dichlorotyrosine were found in blank plasma samples in this study. Therefore, 50 site-specific biomarkers were identified, which could be used as more unambiguous biomarkers for chlorine exposure. Chlorination of the peptides TY*ETTLEK, Y*KPGQTVK, Y*QQKPGQAPR, HY*EGSTVPEK, and Y*LY*EIAR could already be detected at moderate in vitro chlorine exposure levels. In addition, the latter two peptides were found to have dichlorinated fragments. Especially, Y*LY*EIAR, with a distinct chlorination pattern in the MS spectra, could potentially be used to differentiate exogeneous exposure from endogenous causes as other studies reported that this part of human serum albumin is nitrated rather than chlorinated under physiological conditions. In conclusion, trypsin digestion combined with high-resolution MS analysis of chlorinated peptides could constitute a valuable technique for the forensic verification of exposure to chlorine.

Human chlorine gas exposition and its management - an umbrella review on human data

Even though exposure to chlorine gas has been quite frequent in the past few decades, no specific antidotes exist. This umbrella review aimed to investigate possible recommendations for treatment after a chlorine gas exposure. A published systematic review protocol that adapted the existing Navigation Guide methodology was used for including studies without comparator. Using PubMed, Web of Science, Google scholar for all potentially relevant systematic reviews, two authors independently included papers and extracted data. The risk of bias and quality of evidence was assessed by two independent review teams blinded to each other. A qualitative summary of the study findings was conducted for this overview. There were a total of 31 studies, from 4 systematic reviews, that met the inclusion criteria, comprising 3567 reported cases, with only two studies with comparators. Six studies reported pre-hospital management of patients after exposure to chlorine gas. With respect to the treatment, the most used were oxygen therapy, endotracheal intubation, β2-agonists, and corticosteroids. This review found a high quality of evidence for the effectiveness of pre-hospital management (i.e. exposure cessation) on survival at hospital discharge after exposure to chlorine gas. Oxygen administration was effective with moderate quality of evidence, as well as other types of treatment (e.g. β2, corticosteroids), but with a low level of evidence. This umbrella review highlighted the low level of evidence for existing treatments of chlorine gas poisoning. This project was supported by the French Pays de la Loire region and Angers Loire Métropole (TEC-TOP project). There is no award/grant number. The review protocol was registered on PROSPERO under the registration number CRD42021231524.

Autophagy in Extracellular Matrix and Wound Healing Modulation in the Cornea

Autophagy is a robust cellular mechanism for disposing of harmful molecules or recycling them to cells, which also regulates physiopathological processes in cornea. Dysregulated autophagy causes inefficient clearance of unwanted proteins and cellular debris, mitochondrial disorganization, defective inflammation, organ dysfunctions, cell death, and diseases. The cornea accounts for two-thirds of the refraction of light that occurs in the eyes, but is prone to trauma/injury and infection. The extracellular matrix (ECM) is a noncellular dynamic macromolecular network in corneal tissues comprised of collagens, proteoglycans, elastin, fibronectin, laminins, hyaluronan, and glycoproteins. The ECM undergoes remodeling by matrix-degrading enzymes and maintains corneal transparency. Autophagy plays an important role in the ECM and wound healing maintenance. Delayed/dysregulated autophagy impacts the ECM and wound healing, and can lead to corneal dysfunction. Stromal wound healing involves responses from the corneal epithelium, basement membrane, keratocytes, the ECM, and many cytokines and chemokines, including transforming growth factor beta-1 and platelet-derived growth factor. Mild corneal injuries self-repair, but greater injuries lead to corneal haze/scars/fibrosis and vision loss due to disruptions in the ECM, autophagy, and normal wound healing processes. Presently, the precise role of autophagy and ECM remodeling in corneal wound healing is elusive. This review discusses recent trends in autophagy and ECM modulation in the context of corneal wound healing and homeostasis.

Effects of Two Chlorine Gas Attacks on Hospital Admission and Clinical Outcomes in Kafr Zita, Syria

Background In 2014, Hama Governorate was exposed twice to chlorine gas, with 15 patients presenting to Kafr Zita Hospital in Northwest Syria. This study aimed to describe clinical manifestations of chlorine gas exposure to identify factors leading to facility admission and the need for ICU/intubation in conflict-affected areas with limited healthcare infrastructure. Methods We conducted a case-series study, using medical records of suspected chlorine-exposed patients presenting at Kafr Zita Hospital on either 11 April or 22 May 2014. Data on age, sex, initial clinical presentation, therapeutic management, and outcome were compared by hospital admission/non-admission and attack date. All patients provided verbal informed consent. Results Fifteen patients with signs of chlorine gas exposure had detailed medical records. The mean age was 25.7 years (range 2-59), eight were male (53%), and three (20%) were under age 16. At initial presentation, all experienced respiratory distress, due to severe airway inflammation confirmed by nonspecific pulmonary infiltrates on chest x-ray, and similar intestinal, neurological, dermatological, ophthalmological, and psychological signs and symptoms. Acute management consisted of oxygen and bronchodilators for all patients, hydrocortisone (93%), antiemetics (80%), and dexamethasone (13%). Seven (47%) made a rapid symptomatic recovery and were discharged the same day and eight (53%) were admitted for a median of two days (range 1-6 days), one of whom required intubation and later died. The only significant associations found were higher mean pulse rate (i.e. 138 versus 124; p=0.043) and body temperature (37.0 versus 36.5; p=0.019) among admitted patients compared to non-admitted. Conclusion Our results demonstrated that even in low-resource humanitarian settings the survival rate for chlorine gas exposed patients is fair. Despite the small sample, this study provides insight into the clinical presentation, management, and outcomes of weaponized chlorine gas exposure, though further research is required to understand any chronic consequences.

Acute chlorine poisoning caused by an accident at a swimming pool

Chlorine is an irritant gas that is widely used in water purification. Several previous reports had reported accidents of inhalation injuries at swimming pools. However, there have been limited data on the detection of on-site chlorine concentration. This study aims to report a chlorine leakage accident at a swimming pool caused by improper disinfection operations. Calculation using the gas diffusion simulation software showed that the on-site chlorine concentration was 221.45 ppm. When the accident occurred, there were 92 individuals at the swimming pool and the gym, among which 61 were referred to the emergency department of five different hospitals for feeling ill. Among them, 22 patients underwent chest high-resolution computed tomography scans in our hospital. According to the findings, 4 (18.2%) patients had peribronchitis, 3 (13.6%) had tracheobronchitis, 4 (18.2%) had pneumonia, 4 (18.2%) had interstitial pulmonary edema, and 3 (13.6%) had alveolar pulmonary edema. The symptoms of 22 patients who visited our hospital significantly improved after comprehensive treatment. Three months after the accident, 8 of 17 patients presented obstructive ventilation defects or small airway dysfunction. The accidental exposure to chlorine may induce acute poisoning with various respiratory injuries and prolonged lung dysfunction.

Development of an LC-MS/MS method for quantification of 3-chloro-L-tyrosine as a candidate marker of chlorine poisoning

A simple and sensitive liquid chromatography coupled with electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) method for the determination of 3-chloro-L-tyrosine (Cl-Tyr) was developed and validated. For sample preparation, 50 μL of the body fluids or tissue extracts were processed by protein precipitation followed by the derivatization with dansyl chloride. The calibration curve was linear over the concentration range of 2.0-200 ng/mL blood or 4.0-400 ng/g tissue. Our method allowed the reproducible and accurate quantification. That is, the intra- and inter-assay coefficients of variation were below 7.73 and 6.94%, respectively in both the blood and lung. We applied the developed method to the analysis of Cl-Tyr in the human autopsy samples, which were suspected of chlorine poisoning, and detected 55.2 ng/mL and 206.6 ng/g Cl-Tyr in left heart blood and lung, respectively. Furthermore, in more than 20 autopsy samples, which were obtained from other causes of death including burn, drowning, hanging, internal disease, trauma and drug poisoning, Cl-Tyr was almost not detected in their both body fluids and organ tissues. In conclusion, the data here reported demonstrate that the LC/ESI-MS/MS method allows the Cl-Tyr in the autopsy samples and that chlorine exposure strongly affects its level, providing a basis for novel identification tool of chlorine poisoning.

Forensic issues arising in the assessment of chlorine-related deaths in a domestic setting

A retrospective review of autopsy files at the Forensic Science South Australia, Australia, was undertaken over a 20-year period from January 2000 to December 2019 for all cases where chlorine had caused or contributed to death. Two cases were identified out of a total of 25,121 autopsies (0.008%): a 53-year-old man who committed suicide in a cellar with granulated chlorine, and a 49-year-old woman with asthma who died of acute bronchospasm due to exposure to chlorine gas while mixing swimming pool chemicals in her kitchen. Chlorine-related deaths are uncommon in domestic situations. However, the absence of biomarkers and non-specific findings at autopsy complicate the diagnosis, particularly as environmental levels are not stable. While accidents with cleaning agents or swimming pool reagents are the most common event in the literature in domestic settings (exclusive of industrial or transportation accidents), suicide may also very rarely occur. Individuals with asthma and chronic respiratory diseases are at higher risk of an adverse outcome upon exposure to chlorine gas, with inattention to proper storage conditions and handling protocols being additional risk factors.

Membrane-Based Portable Colorimetric Gaseous Chlorine Sensing Probe

Highly toxic chlorine gas imposes serious health risks in the workplace. The ability to on-site, real-time monitoring of instantaneous and time-weighted average (TWA) chlorine gas concentrations in a simple, sensitive, accurate, and reliable manner would be highly beneficial to improve workplace health and safety. Here, we propose and experimentally validate a gaseous chlorine detection principle based on a N,N-diethyl-p-phenylenediamine sulfate salt/Cl₂ colorimetric reaction-controlled membrane process to regulate the gaseous chlorine transport across a gas-permeable membrane that enables the establishment of a time-resolved analytical relationship to quantify chlorine concentration by multidata points with dramatically enhanced accuracy and reliability. A gas-permeable membrane-based portable colorimetric gaseous chlorine sensing probe (MCSP) was designed and fabricated. The MCSP embedded the proposed analytical principle that is capable of real-time continuous monitoring of the instantaneous and TWA chlorine gas concentrations within an analytical range of 0.009-2.058 mg L^-1 without the need for on-going calibration, which could be a useful analytical tool for managing the toxic chlorine gas-imposed health risks in workplaces.

Chemical warfare agent research in precision-cut tissue slices-a useful alternative approach

The use of chemical warfare agents (CWAs) in military conflicts and against civilians is a recurrent problem. Despite ongoing CWA research using in vitro or in vivo models, progress to elucidate mechanisms of toxicity and to develop effective therapies, decontamination procedures, and general countermeasures is still limited. Novel scientific approaches to address these questions are needed to expand perspectives on existing knowledge and gain new insights. To achieve this, the use of ex vivo techniques like precision-cut tissue slices (PCTSs) can be a valuable approach. Existing studies employing this economical and relatively easy to implement method show model suitability and comparability with the use of in vitro and in vivo models. In this article, we review research on CWAs in PCTSs to illustrate the advantages of the approach and to promote future applications.

Histone H4 aggravates inflammatory injury through TLR4 in chlorine gas-induced acute respiratory distress syndrome

Background

Chlorine gas (Cl₂) exposure remains a public health concern in household, occupational, and transportation accidents around the world. The death rate associated with acute respiratory distress syndrome (ARDS) caused by high concentrations of Cl₂ is very high, mainly because the pathogenesis of ARDS remains unclear. Histone H4 has been identified as an important endogenous pro-inflammatory molecule. The present study aimed to examine the pathogenic role of histone H4 in Cl₂-induced ARDS.

Methods

ARDS was induced by Cl₂ exposure in male C57BL/6 mice. Circulating histone H4, blood gas, pulmonary edema, endothelial activation, and neutrophil infiltration were measured during acute lung injury (ALI). Histone H4 or anti-H4 antibody was administered through the tail vein 1 h prior to Cl₂ exposure to study the pathogenic role of histone H4. Toll-like receptor 2 knock-out (Tlr2-KO) and Tlr4-KO mice were used in conjunction with blocking antibody against TLR1, TLR2, TLR4, or TLR6 to explore the mechanism involved in histone H4-mediated injury.

Results

Cl₂ exposure induced a concentration-dependent ALI. The levels of circulating histone H4 were positively correlated with Cl₂ concentrations. Pretreatment with intravenous histone H4 further aggravated lethality rate, blood gas, endothelial activation, and neutrophil infiltration, while anti-H4 antibody showed protective effects. Tlr4 deficiency improved lethality rate, blood gas, and pulmonary edema, and prevented endothelial and neutrophil activation caused by Cl₂ exposure. More importantly, Tlr4 gene deletion greatly diminished the effect of histone H4 or anti-H4 antibody observed in wild-type (WT) mice. The impact of Tlr2 on inflammatory injury was not significant. The role of TLRs was also validated by endothelial activation mediated by histone H4 in vitro.

Conclusions

Circulating histone H4 played a pro-inflammatory role in ARDS caused by Cl₂. TLR4 was closely involved in histone H4-mediated inflammatory injury. Therefore, intervention targeting histone H4 is potentially protective.

Determination of 3-chloro-l-tyrosine as a novel indicator of chlorine poisoning utilizing gas chromatography-mass spectrometric analysis

Chlorine gas exposure occurs in chemical warfare, industrial and household accidents. In forensic science, the generation of chlorine gas by mixing sodium hypochlorite detergent and strong acid detergent cannot be overlooked because of the possibility of suicide method (NaClO + 2HCl → NaCl + H₂O + Cl₂). Though typical autopsy findings are obtained in chlorine exposure, such as pulmonary edema, useful biomarkers don't exist. In this research, we developed an analytical method of 3-chloro-l-tyrosine (Cl-Tyr) in blood as a novel marker of chlorine poisoning utilizing gas chromatography-mass spectrometry (GC-MS). Cl-Tyr was purified using protein precipitation and cation-exchange solid phase extraction, derivatized by the silylation agent and subjected to GC-MS. The quantification range was 10-200 ng/mL and good reproducibility was obtained. We applied the developed method to analyze Cl-Tyr in autopsy sample, which is suspected of chlorine poisoning, and detected 59.7 ng/mL Cl-Tyr in left heart blood. To our knowledge, this is the first report of determination of the chlorinated biomolecule in the human autopsy sample from chlorine poisoning.

Five Decades of Global Chemical Terror Attacks: Data Analysis to Inform Training and Preparedness

BACKGROUND

Chemical weapons attacks during the recent conflict in Syria and Iraq highlight the need to better understand the changing epidemiology of chemical weapons use, especially among non-state actors. Public health professionals and policy-makers require this data to prioritize funding, training, chemical weapons preparedness, disaster response, and recovery. The purpose of this investigation is to provide descriptive data that can be used by policy-makers and public safety officials to better prepare for these potential attacks.

METHODS

A five-decade descriptive retrospective review of The Global Terrorism Database, maintained by the National Consortium for the Study of Terrorism and Responses to Terrorism, was conducted to understand trends in chemical agents, targets, and routes of exposure. We reviewed and analyzed data specific to these documented chemical attacks between 1970 and 2017.

RESULTS

383 terror attacks involved chemical weapons over the study period. A specific agent was named in 154 incidents, while 124 incidents could be classified into traditional chemical weapons categories (eg, vesicant, choking agents). A route of exposure was identified in 242 attacks, with the most common routes of exposure being dermal-mucosal and inhalational. Caustic agents were used in the highest portion of attacks (25%) where the route of exposure was known. Explosive devices were used in 21% of attacks to deliver these chemical agents. Of particular note, private citizens and educational facilities were targeted in 25% and 12% of attacks, respectively. The average number of attacks increased from 6 per year between 1970 and 2011 to 24.9 per year between 2011 and 2017 (coinciding with the start of the Syria conflict). The most commonly utilized chemicals were chlorine (26.0%), tear gas (20.8%), and cyanide (15.6%). Blood agent incidents declined from 32.6% before the September 11, 2001 attacks to 13.6% after 2001, while nerve agent attacks fell from 9.3% to 1.2%. In contrast, choking (namely chlorine) and vesicant (mustard) agent use increased from 7% to 48.1% and from 2.3% to 6.2% of attacks, respectively.

CONCLUSIONS

Chemical weapon use in global terrorism remains an increasingly common occurrence that requires better characterization. The average number of chemical terrorist attacks per year is increasing, with a large proportion resulting from the conflicts in Iraq and Syria. Choking (chlorine) and vesicant (mustard) agents have become the predominant chemical terror agent since 2001, with a decreased incidence of blood (cyanogenic) and nerve (sarin) agents. Future preparedness initiatives should focus on vulnerable targets such as private citizens and educational institutions. Improving blast injury response is essential, along with prioritizing disaster training focused on choking agents, vesicants, and caustics.

IoT-Enabled Gas Sensors: Technologies, Applications, and Opportunities

Ambient gas detection and measurement had become essential in diverse fields and applications, from preventing accidents, avoiding equipment malfunction, to air pollution warnings and granting the correct gas mixture to patients in hospitals. Gas leakage can reach large proportions, affecting entire neighborhoods or even cities, causing enormous environmental impacts. This paper elaborates on a deep review of the state of the art on gas-sensing technologies, analyzing the opportunities and main characteristics of the transducers, as well as towards their integration through the Internet of Things (IoT) paradigm. This should ease the information collecting and sharing processes, granting better experiences to users, and avoiding major losses and expenses. The most promising wireless-based solutions for ambient gas monitoring are analyzed and discussed, open research topics are identified, and lessons learned are shared to conclude the study.

Toxic effects of chlorine gas and potential treatments: a literature review

Chlorine gas is one of the highly produced chemicals in the USA and around the world. Chlorine gas has several uses in water purification, sanitation, and industrial applications; however, it is a toxic inhalation hazard agent. Inhalation of chlorine gas, based on the concentration and duration of the exposure, causes a spectrum of symptoms, including but not limited to lacrimation, rhinorrhea, bronchospasm, cough, dyspnea, acute lung injury, death, and survivors develop signs of pulmonary fibrosis and reactive airway disease. Despite the use of chlorine gas as a chemical warfare agent since World War I and its known potential as an industrial hazard, there is no specific antidote. The resurgence of the use of chlorine gas as a chemical warfare agent in recent years has brought speculation of its use as weapons of mass destruction. Therefore, developing antidotes for chlorine gas-induced lung injuries remains the need of the hour. While some of the pre-clinical studies have made substantial progress in the understanding of chlorine gas-induced pulmonary pathophysiology and identifying potential medical countermeasure(s), yet none of the drug candidates are approved by the U.S. Food and Drug Administration (FDA). In this review, we summarized pathophysiology of chlorine gas-induced pulmonary injuries, pre-clinical animal models, development of a pipeline of potential medical countermeasures under FDA animal rule, and future directions for the development of antidotes for chlorine gas-induced lung injuries.

Emergency management of chlorine gas exposure - a systematic review

INTRODUCTION

Chlorine exposure can lead to pulmonary obstruction, reactive airway dysfunction syndrome, acute respiratory distress syndrome and, rarely, death.

OBJECTIVE

We performed a systematic review of published animal and human data regarding the management of chlorine exposure.

METHODS

Three databases were searched from 2007 to 2017 using the following keywords "("chlorine gas" OR "chlorine-induced" OR" chlorine-exposed") AND ("therapy" OR "treatment" OR "post-exposure")". Forty-five relevant papers were found: 22 animal studies, 6 reviews, 19 case reports and 1 human randomized controlled study. General management: Once the casualty has been removed from the source of exposure and adequately decontaminated, chlorine-exposed patients should receive supportive care. Humidified oxygen: If dyspnea and hypoxemia are present, humidified oxygen should be administered. Inhaled bronchodilators: The use of nebulized or inhaled bronchodilators to counteract bronchoconstriction is standard therapy, and the combination of ipratropium bromide with beta₂-agonists effectively reversed bronchoconstriction, airway irritation and increased airway resistance in experimental studies. Inhaled sodium bicarbonate: In a randomized controlled trial, humidified oxygen, intravenous prednisolone and inhaled salbutamol were compared with nebulized sodium bicarbonate. The only additional benefit of sodium bicarbonate was to increase the forced expiratory volume in one second, 2 and 4 h after administration. Corticosteroids: Dexamethasone 100 mg/kg intraperitoneally (IP) reduced lung edema when given within 1 h of chlorine inhalation and when administered within 6 h significantly decreased (p < 0.01) the leukocyte count in the bronchoalveolar lavage (BAL). As corticosteroids were never given alone in clinical studies, it is impossible to assess whether they had an additional beneficial effect. Antioxidants: An ascorbic acid/deferoxamine combination (equivalent to 100 mg/kg and 15 mg/kg, respectively) was administered intramuscularly 1 h after chlorine exposure, then every 12 h up to 60 h, then as an aerosol, and produced a significant reduction (p < 0.05) in BAL leukocytes and a significant reduction (p < 0.007) in mortality at 72 h. The single clinical case reported was uninterpretable. Sodium nitrite: Sodium nitrite 10 mg/kg intramuscularly (IM), 30 min post-chlorine exposure in mice and rabbits significantly reduced (p < 0.01) the number of leukocytes and the protein concentration in BAL and completely reversed mortality in rabbits and decreased mortality by about 50% in mice. No clinical studies have reported the use of sodium nitrite. Dimethylthiourea: Dimethylthiourea 100 mg/kg IP significantly decreased (p < 0.05) lymphocytes and neutrophils in BAL fluid 24 h after chlorine exposure in experimental studies. No clinical studies have been undertaken. AEOL 10150: Administration of AEOL10150 5 mg/kg IP at 1 h and 9 h post-chlorine exposure reduced significantly the neutrophil (p < 0.001) and macrophage (p < 0.05) bronchoalveolar cell counts. Transient receptor potential vanilloid 4 (TRPV4): IM or IP TRPV4 reduced significantly (p < 0.001) bronchoalveolar neutrophil and macrophage counts to baseline at 24 h. No clinical studies have been performed. Reparixin and triptolide: In experimental studies, triptolide 100-1000 µg/kg IP 1 h post-exposure caused a significant decrease (p < 0.001) in bronchoalveolar neutrophils, whereas reparixin 15 mg/kg IP 1 h post-exposure produced no benefit. Rolipram: Nanoemulsion formulated rolipram administered intramuscularly returned airway resistance to baseline. Rolipram (40%)/poly(lactic-co-glycolic acid) (60%) 0.36 mg/mouse given intramuscularly 1 h post-exposure significantly reduced (p < 0.05) extravascular lung water by 20% at t + 6 h. Prophylactic antibiotics: Studies in patients have failed to demonstrate benefit. Sevoflurane: Sevoflurane has been used in one intubated patient in addition to beta₂-agonists. Although the peak inspiratory pressure was decreased after 60 min, the role of sevofluorine is not known.

CONCLUSIONS

Various therapies seem promising based on animal studies or case reports. However, these recommendations are based on low-level quality data. A systematic list of outcomes to monitor and improve may help to design optimal therapeutic protocols to manage chlorine-exposed patients.

Difficulties in interpretation when assessing prolonged and subacute exposure to the toxic effects of chlorine

The purpose of this study was a toxicological interpretation of exposure to chlorine with unusual course. Medical, clinical and court records, as well as reviews of the literature, served as the basis for this interpretation. The first case of poisoning concerns a 52-year-old man who for a short time (probably several hours), during the industrial cleaning of facilities with sodium hypochlorite, was exposed to chlorine in a presumed high concentration. The man was obese and suffered from hypertension and moderate atherosclerosis, and therefore could be more susceptible to the toxic effects of chlorine. After exposure no pulmonary edema or symptoms typical for acute respiratory distress syndrome were present. The second case concerns the chronic poisoning of a 56-year-old man who worked for eight years, 8 h a day, 5 days a week, in a room which was next to a chlorination room. In this chamber technical sodium hypochlorite was stored and dosed. In both cases, determining a cause and effect relationship between exposure to toxic and allergic agents in the form of active chlorine, and the onset of symptoms may be difficult. The findings described above in the first and second case are particularly important in cases of compensation claims and may have a completely different etiology than previously described in medical literature.