Phosgene oxime: a highly toxic urticant and emerging chemical threat

Dermal Exposure to Vesicating Nettle Agent Phosgene Oxime: Clinically Relevant Biomarkers and Skin Injury Progression in Murine Models

Phosgene oxime (CX), categorized as a vesicating chemical threat agent, causes effects that resemble an urticant or nettle agent. CX is an emerging potential threat agent that can be deployed alone or with other chemical threat agents to enhance their toxic effects. Studies on CX-induced skin toxicity, injury progression, and related biomarkers are largely unknown. To study the physiologic changes, skin clinical lesions and their progression, skin exposure of SKH-1 and C57BL/6 mice was carried out with vapor from 10 μl CX for 0.5-minute or 1.0-minute durations using a designed exposure system for consistent CX vapor exposure. One-minute exposure caused sharp (SKH-1) or sustained (C57BL/6) decrease in respiratory and heart rate, leading to mortality in both mouse strains. Both exposures caused immediate blanching, erythema with erythematous ring (wheel) and edema, and an increase in skin bifold thickness. Necrosis was also observed in the 0.5-minute CX exposure group. Both mouse strains showed comparative skin clinical lesions upon CX exposure; however, skin bifold thickness and erythema remained elevated up to 14 days postexposure in SKH-1 mice but not in C57BL/6 mice. Our data suggest that CX causes immediate changes in the physiologic parameters and gross skin lesions resembling urticaria, which could involve mast cell activation and intense systemic toxicity. This novel study recorded and compared the progression of skin injury to establish clinical biomarkers of CX dermal exposure in both the sexes of two murine strains relevant for skin and systemic injury studies and therapeutic target identification. SIGNIFICANCE STATEMENT: Phosgene oxime (CX), categorized as a vesicating agent, is considered as a potent chemical weapon and is of high military and terrorist threat interest since it produces rapid onset of severe injury as an urticant. However, biomarkers of clinical relevance related to its toxicity and injury progression are not studied. Data from this study provide useful clinical markers of CX skin toxicity in mouse models using a reliable CX exposure system for future mechanistic and efficacy studies.

Recent advances in fluorescent and colorimetric chemosensors for the detection of chemical warfare agents: a legacy of the 21st century

Chemical warfare agents (CWAs) are among the most prominent threats to the human population, our peace, and social stability. Therefore, their detection and quantification are of utmost importance to ensure the security and protection of mankind. In recent years, significant developments have been made in supramolecular chemistry, analytical chemistry, and molecular sensors, which have improved our capability to detect CWAs. Fluorescent and colorimetric chemosensors are attractive tools that allow the selective, sensitive, cheap, portable, and real-time analysis of the potential presence of CWAs, where suitable combinations of selective recognition and transduction can be integrated. In this review, we provide a detailed discussion on recently reported molecular sensors with a specific focus on the sensing of each class of CWAs such as nerve agents, blister agents, blood agents, and other toxicants. We will also discuss the current technology used by military forces, and these discussions will include the type of instrumentation and established protocols. Finally, we will conclude this review with our outlook on the limitations and challenges in the area and summarize the potential of promising avenues for this field.

Supporting discovery and development of medical countermeasures for chemical injury to eye and skin

Vesicants, from vesica (Latin for blister), can cause local and systemic toxicity. They include the chemotherapy drug nitrogen mustard and chemical warfare agents sulfur mustard, Lewisite, and phosgene oxime. These agents are commonly released in vapor form and consequently, eyes and skin are the most vulnerable. The ocular and cutaneous injuries can be acute, subacute, or chronic, and can predispose casualties to secondary deleterious effects. Underlying these broad organ responses are shared and tissue-specific cellular and molecular biological cascades that attempt to counteract such chemical injuries. Depending on the severity of the chemical insult, biological responses often lead to inadequate wound healing and result in long-term pathology instead. Exposure to other toxic industrial chemicals such as acrolein, chloropicrin, and hydrogen fluoride, can also cause prominent eye and skin damage. There are currently no FDA-approved drugs to counteract these injuries. Hence, the possibility of a mass casualty emergency involving these chemicals is a major public health concern. Recognizing this critical challenge, the United States Department of Health and Human Services (HHS) is committed to the development of medical countermeasures to advance national health and medical preparedness against these highly toxic chemicals. Here, we provide an overview of various HHS funding and scientific opportunities available in this space, emphasizing parallels between eye and skin response to chemical injury. We also discuss a main limitation of existing data and suggest ways to overcome it.

A hybrid model based on fuzzy VIKOR and the classical optimal search to detect illegal chemical warehouses

The use of chemical weapons has turned into an increasing risk for the world. In this study, a hybrid approach on the basis of fuzzy VIKOR and the optimal search model to cope with an important case study called the detection of illegal chemical warehouses is introduced. It is obvious that such illegal activities are accomplished under high secret considerations. Therefore, we have several types of ambiguity and uncertainty in this problem. First, fuzzy VIKOR is used to prioritize the suspicious warehouses based on time and cost of a search under fuzzy environment. Also the probability of existence of chemical agents in each warehouse (Pi) and the probability of detection (αi) in case materials exist in warehouse, are estimated. Next, the output of VIKOR i.e., Q is assumed as an input of optimal search model and optimal strategy for searching is achieved by solving a stochastic dynamic programming. According to this hybrid approach, we start from the location that has the maximum value of αiPiQi. Although we get benefits of fuzzy logic, VIKOR, and classical optimal search, the suggested method is easy to understand and straightforward to utilize in real-world problems. Also this model can enhance the robust nature of hybrid approach and reduces its sensitivity to the change of weights.

Construction of a ratiometric phosgene probe by chromophore formation from auxochrome

A new fluorescent probe for ratiometric detection of phosgene is reported. This probe was constructed with classic 1,8-naphthalimide and 2-(2-aminophenyl)benzimidazole by Ullmann coupling reaction. After exposure to phosgene, yellow fluorescence weakened while blue fluorescence enhanced significantly. There was a ratiometric response between 542 nm and 490 nm. The detection limit (LOD) was 6.7 nM and the response time was within 200 s in CHCl₃. Meaningfully, a new chromophore, benzo [4,5]imidazo[1,2-c]quinazolin-6(5H)-one, was formed after 2-(2-aminophenyl)benzimidazole unit reacted with phosgene, and the ratiometric response was achieved by two chromophores in which the mechanism was confirmed by ¹H NMR spectra, HRMS and theoretical calculation. Furthermore, test papers and nanofibers were fabricated with the probe, which could sensitive detection of phosgene within 10 min and 1 min respectively.