[A case of oral chloropicrin poisoning].

Chloropicrin is a commonly used pesticide in agricultural production. The clinical manifestations of oral poisoning patients are complex, and the lesions involve multiple organs. At present, the specific pathogenic mechanism of such poisoning is not clear, and the treatment experience is insufficient, so there are certain difficulties in clinical diagnosis, treatment and treatment. In this paper, the data of a patient with oral chloropicrin poisoning treated in Yidu Central Hospital of Weifang City in April 2023 were summarized. The patient was admitted to our hospital for treatment in time, and his condition improved after Hemopurification, methylene blue reduction, organ support, infection prevention as well as other symptomatic support. Oral chlorophenol can cause lung damage, skin and mucous membrane damage, and may have certain effects on the nervous system and kidney. Early intervention, especially blood purification, is effective.

Far-UVC 222 nm Treatment: Effects of Nitrate/Nitrite on Disinfection Byproduct Formation Potential.

Irradiation at far ultraviolet C (far-UVC) 222 nm by krypton chloride (KrCl*) excilamps can enhance microbial disinfection and micropollutant photolysis/oxidation. However, nitrate/nitrite, which absorbs strongly at 222 nm, may affect the formation of disinfection byproducts (DBPs). Herein, we evaluated model organic matter and real water samples and observed a substantial increase in the formation potential for trichloronitromethane (chloropicrin) (TCNM-FP), a nitrogenous DBP, by nitrate or nitrite after irradiation at 222 nm. At a disinfection dose of 100 mJ·cm-2, TCNM-FP of humic acids and fulvic acids increased from ∼0.4 to 25 and 43 µg·L-1, respectively, by the presence of 10 mg-N·L-1 nitrate. For the effect of nitrate concentration, the TCNM-FP peak was observed at 5-10 mg-N·L-1. Stronger fluence caused a greater increase of TCNM-FP. Similarly, the increase of TCNM-FP was also observed for wastewater and drinking water samples containing nitrate. Pretreatment using ozonation and coagulation, flocculation, and filtration or the addition of H2O2 can effectively control TCNM-FP. The formation potential of other DBPs was minorly affected by irradiation at 222 nm regardless of whether nitrate/nitrite was present. Overall, far-UVC 222 nm treatment poses the risk of increasing TCNM-FP of waters containing nitrate or nitrite at environmentally relevant concentrations and the mitigation strategies merit further research.

Soil microeukaryotic communities and phosphorus-cycling microorganisms respond to chloropicrin fumigation and azoxystrobin application.

Fumigants and fungicides are effective at controlling soil-borne pathogens but might also adversely affect soil beneficial microbes, such as soil phosphorus (P) solubilizing microbes, further altering nutrient cycling processes. Therefore, this study investigated the effects of the fumigant chloropicrin (CP) and the fungicide azoxystrobin (AZO) on soil microeukaryotes and P-cycling related soil bacteria through a greenhouse experiment. Soil microeukaryotic communities and bacterial communities containing two phosphomonoesterase encoding genes (phoC and phoD) were analysed using high-throughput sequencing methods. Results showed that, when applied at the field recommended application dosage, the fungicide AZO had no significant influence on the community structure of soil microeukaryotes and phoD-containing bacteria. However, in CP-fumigated soils, the soil microeukaryotic community composition changed from fungi-dominated to protist-dominated. CP fumigation significantly decreased the total phoC/phoD gene copy number but increased the relative abundance of some phoC/phoD-containing bacteria (such as Sinorhizobium and Streptomyces), which are significantly positively correlated to available P compositions in soil. The structural equation model (SEM) confirmed that CP fumigation could affect soil available P content directly by altering phoC-/phoD-containing bacteria, or indirectly by affecting phoC/phoD gene abundance and acid/alkaline phosphatases activity in soil. The inconsistent changes in phoC/phoD-containing bacteria, phoC/phoD gene number, and the phosphomonoesterase activities indicated that enzyme secretion may not be the only way for P solubilizing soil microorganisms to regulate P availability after soil fumigation. The outcome of this study can provide theoretical support for the design of soil beneficial microorganism recovery strategies and the regulation of phosphate fertilizer after soil fumigation.

Simulation of chloropicrin emissions in response to soil conditions and applicator practices.

HYDRUS 2D was used to simulate chloropicrin (CP) emissions across a range of expected application and environmental conditions present within California, where CP is widely used in the pre-plant treatment of soils for high-value specialty crops. Simulations were developed based on field calibration work and physicochemical parameters from literature with additional consideration of application rate-dependent degradation and applicator practices including application depth, application mode, and tarp material. Model output was compared to the distribution of indirect whole-field flux estimates derived from field monitoring studies using measures of maximum 8-h, maximum 24-h, and cumulative emissions due to their relevance to public health. We observed a strong linear relationship (R2 ≥ 0.80, p < 0.001) between HYDRUS-simulated and field-based maximum flux estimates and no evidence of statistical difference depending on the estimation source for maximum 24-h flux. A linear relationship of similar strength (R2 = 0.82, p < 0.001) was observed between simulated and field-based cumulative emission estimates, although mean HYDRUS estimates were lower than field-estimated values for some high-emission application methods. Analysis of simulation output demonstrated large differences in CP emissions in response to application method and a non-linear increase in CP emissions with increasing application rate, with considerable interaction between application variables including application depth, tarp types, and field layout. The findings generally support the use of simulated CP emission estimates as a tool to address gaps in field-based flux estimates, particularly where characterization of short-term peak emissions is needed.

Chloropicrin induced ocular injury: Biomarkers, potential mechanisms, and treatments.

Ocular tissue, especially the cornea, is overly sensitive to chemical exposures. The availability and adoption of chemical threat agent chloropicrin (CP) is growing in the United States as a pesticide and fumigant; thereby increasing the risk of its use in warfare, terrorist attacks and non-intentional exposure. Exposure to CP results in immediate ocular, respiratory, and dermal injury; however, we lack knowledge on its mechanism of toxicity as well as of its breakdown products like chlorine and phosgene, and effective therapies are elusive. Herein, we have reviewed the recent findings on exposure route, toxicity and likely mechanisms of CP induced ocular toxicity based on other vesicating chemical warfare agents that cause ocular injury. We have focused on the implication of their toxicity and mechanistic outcomes in the ocular tissue, especially the cornea, which could be useful in the development of broad-spectrum effective therapeutic options. We have discussed on the potential countermeasures, overall hallmarks and challenges involved in studying ocular injuries from chemical threat agent exposures. Finally, we reviewed useful available technologies and methods that can assist in the identification of effective medical countermeasures for chemical threat agents related ocular injuries.

Mechanisms by which chloropicrin fumigation promotes soil potassium conversion and absorption.

Fumigation of soil using chloropicrin has been proven to significantly affect soil nutrient cycling, but the mechanism by which soil potassium conversion and plant uptake is promoted remains unclear. In this study, we conducted a fumigation experiment to investigate the effects of chloropicrin soil fumigation on the conversion of soil potassium post-fumigation (days 7-70), and its mechanisms, tomatos were planted in fumigated and non-fumigated soils to enable further comparisons. Results showed that the content of rapidly available potassium and available potassium decreased by 16-24% and 17-23% at day 28 respectively, when tomato was planted in chloropicrin-fumigated soils compared to the non-fumigated soils. The potassium content of tomato planted in fumigated soil was significantly higher than that planted in non-fumigated soil (30.3 vs. 21.9 mg g-1 dry weight). Chloropicrin fumigation resulted in a significant change in the soil bacterial and fungal community structures, and trigged a long-term (at least 70-day) decrease in microbial diversity. Network analysis showed that chloropicrin soil fumigation changed microbial co-occurrence patterns by decreasing bacterial total links, nodes, and average degree, and increasing fungal total links, nodes, and average degree. Chloropicrin fumigation caused significant changes in the relative abundance of Bacillus species, which are involved in potassium dissolution. Structural equation model (SEM) suggested that fumigation with chloropicrin enhanced the contribution of soil potassium to tomato growth and reduced the contribution of bacterial communities. Together, the results of our study help in understanding the crop yield enhancement mechanism of soil fumigation.

Response of soil phosphatase activity and soil phosphorus fractions to the application of chloropicrin and azoxystrobin in ginger cultivation.

BACKGROUND: Soil fumigation can change soil nutrient cycling processes by affecting soil beneficial microorganisms, which is a key issue for soil fertility. However, the effect of combined application of fumigant and fungicide on soil phosphorus (P) availability remains largely unclear. We investigated the effects of the fumigant chloropicrin (CP) and the fungicide azoxystrobin (AZO) on soil phosphatase activity and soil P fractions in ginger production using a 28-week pot experiment with six treatments: control (CK), a single application of AZO (AZO1), double applications of AZO (AZO2), CP-fumigated soil without AZO (CP), CP combined with AZO1 (CP + AZO1) and CP combined with AZO2 (CP + AZO2). RESULTS: AZO application alone significantly increased the soil labile P fractions (Resin-P + NaHCO3 -Pi + NaOH-Pi) at 9 weeks after planting (WAP) but decreased the soil phosphatase activity at 28 WAP. CP fumigation significantly reduced the soil phosphatase activity but increased the proportions of soil labile P fractions (Resin-P + NaHCO3 -Pi + NaHCO3 -Po) to total P (TP) by 9.0-15.5% throughout the experiment. The combined application of CP and AZO had a synergistic effect on soil phosphatase activity and soil P fractions compared with a single application. CONCLUSION: Although AZO application and CP fumigation can increase soil available P in the short term, they might negatively affect soil fertility in the long run by inhibiting soil phosphatase activity. Soil microbial activities, especially microorganisms related to P cycling, may be responsible for the variations in soil P availability, but further research is needed. © 2023 Society of Chemical Industry.

Chloramination of Nitromethane: Incomplete Chlorination and Unexpected Substitution Reaction.

Ozone is commonly used as a predisinfectant in potable water reuse treatment trains. Nitromethane was recently found as a ubiquitous ozone byproduct in wastewater, and the key intermediate toward chloropicrin during subsequent secondary disinfection of ozonated wastewater effluent with chlorine. However, many utilities have switched from free chlorine to chloramines as a secondary disinfectant. The reaction mechanism and kinetics of nitromethane transformation by chloramines, unlike those for free chlorine, are unknown. In this work, the kinetics, mechanism, and products of nitromethane chloramination were studied. The expected principal product was chloropicrin, because chloramines are commonly assumed to react similarly to, although more slowly than, free chlorine. Different molar yields of chloropicrin were observed under acidic, neutral, and basic conditions, and surprisingly, transformation products other than chloropicrin were found. Monochloronitromethane and dichloronitromethane were detected at basic pH, and the mass balance was initially poor at neutral pH. Much of the missing mass was later attributed to nitrate formation, from a newly identified pathway involving monochloramine reacting as a nucleophile rather than a halogenating agent, through a presumed SN2 mechanism. The study indicates that nitromethane chloramination, unlike chlorination, is likely to produce a range of products, whose speciation is a function of pH and reaction time.

Ocular injury progression and cornea histopathology from chloropicrin vapor exposure: Relevant clinical biomarkers in mice.

Ocular tissue is highly sensitive to chemical exposures. Chloropicrin (CP), a choking agent employed during World War I and currently a popular pesticide and fumigating agent, is a potential chemical threat agent. Accidental, occupational, or intentional exposure to CP results in severe ocular injury, especially to the cornea; however, studies on ocular injury progression and underlying mechanisms in a relevant in vivo animal model are lacking. This has impaired the development of effective therapies to treat the acute and long-term ocular toxicity of CP. To study the in vivo clinical and biological effects of CP ocular exposure, we tested different CP exposure doses and durations in mice. These exposures will aid in the study of acute ocular injury and its progression as well as identify a moderate dose to develop a relevant rodent ocular injury model with CP. The left eyes of male BALB/c mice were exposed to CP (20% CP for 0.5 or 1 min or 10% CP for 1 min) using a vapor cap, with the right eyes serving as controls. Injury progression was evaluated for 25 days post-exposure. CP-exposure caused a significant corneal ulceration and eyelid swelling which resolved by day 14 post exposure. In addition, CP-exposure caused significant corneal opacity and neovascularization. Development of hydrops (severe corneal edema with corneal bullae) and hyphema (blood accumulation in the anterior chamber) was observed as advanced CP effects. Mice were euthanized at day 25 post-CP-exposure, and the eyes were harvested to further study the corneal injury. Histopathological analyses showed a significant CP-induced decrease in corneal epithelial thickness and increased stromal thickness with more pronounced damage, including stromal fibrosis, edema, neovascularization, trapped epithelial cells, anterior and posterior synechiae, and infiltration of inflammatory cells. Loss of the corneal endothelial cells and Descemet's membrane could be associated with the CP-induced corneal edema and hydrops which could lead to long term term pathological conditions. Although exposure to 20% CP for 1 min caused more eyelid swelling, ulceration, and hyphema, similar effects were observed with all CP exposures. These novel findings following CP ocular exposure in a mouse model outline the corneal histopathologic changes that associate with the continuing ocular clinical effects. The data are useful in designing further studies to identify and correlate the clinical and biological markers of CP ocular injury progression with acute and long-term toxic effects on cornea and other ocular tissues. We take a crucial step towards CP ocular injury model development and in pathophysiological studies to identify molecular targets for therapeutic interventions.

Considerations for the optimization of in vitro models of chloropicrin toxicity.

Chloropicrin (CP) is a common agricultural fumigant historically used as a chemical warfare agent and is a concern for potential use in warfare and terrorist applications. Our inability to effectively treat CP-induced injuries makes it essential to better understand CP toxicity. We set out to elucidate variables that must be understood to achieve optimal exposure conditions for in vitro investigations given that such models are important for the study of CP injury and potential therapeutics. To this end, we evaluated the effects of volatility, cell seeding density, and serum concentration of cell culture medium on CP toxicity in an immortalized human corneal epithelial cell line. We found that even with very dilute solutions, CP remained highly volatile, so much so that a 0.0019% CP solution resulted in 90% cell death at time 0, but was nearly nontoxic 45 min later. Not surprisingly, the CP-induced IL-8 response was shown to vary with cell viability in this experiment. After exposure with 0.00115% CP, cells that were 12% confluent experienced over 40% more cell death than cells exposed at 87% confluency. Exposure with the same CP dose in medium containing concentrations of fetal bovine serum (FBS) ranging from 0.1% to 15% exhibited a 17% difference in cell viability. Given that chemical toxicity can be significantly influenced by volatility, cell density, and serum content of cell culture medium, these phenomena should be explored during the development and optimization of toxicant exposure models.