Ionic mechanisms underlying cardiac toxicity of the organochloride solvent trichloromethane

Chlordecone reduces hyperpolarization-activated-current (Ih) conductance in honeybee

The pacemaker channel (HCN) is responsible for electrical activity in a wide range of excitable cells, including those of invertebrates. Using Xenopus oocytes and HEK cell, we show here that HCN-channel from Apis mellifera is activated by hyperpolarization, modulated by cAMP, and blocked by cesium. Its PNa/PK relative permeability is 1:3, and its unitary conductance is 1.5 pS, which is similar to that of the mammalian HCN2 channel. Moreover, bee h-current is blocked by high concentrations of ZD7288, and organochlorine pesticide chlordecone reduces Ih amplitude in a dose-dependent manner (IC50 value was 9.37 µM) and diminishes HCN conductance, while preserving voltage dependence. In contrast, Deltamethrin exhibits no discernible impact. Molecular docking of Chlordecone in a homology model of bee HCN generated by AlphaFold3 suggests a binding site located at the end of the S6 helix that could explain the conductance inhibition caused by Chlordecone.

Utilizing perhalopyridine-based alkynes as suitable precursors for the synthesis of novel poly(1,2,3-triazolyl)-substituted perhalopyridines

A novel series of poly(1,2,3-triazolyl)-substituted perhalopyridines 5a-f were successfully synthesized from the click reaction of the terminal alkynes (drived from the nucleophilic substitution reactions of PFP 1a and PCP 1b with excess amounts of propargyl alcohol) with aryl azides 4a-c under ultrasonic irradiation. Likewise, the sonication of reaction mixtures containing pyridyl cores 3, alkyl bromides 6a,b, and NaN3 under one-pot conditions afforded their respective aliphatic 1,2,3-triazoles 7a-d in yields ranging from 71% to 83%. We next developed an effective method for the regioselective preparation of 2,3,4,5-tetrachloro-6-(prop-2-yn-1-yloxy)pyridine 3c through SNAr reaction of PCP with propargyl alcohol without the utilization of any catalyst. It was then used to fabricate several ((1,2,3-triazol-4-yl)methoxy)-3,4,5,6-tetrachloropyridines 8a-c under the reaction conditions. Finally, the Pd(PPh3)4-catalyzed SMC reaction of tris-triazoles 5b,e with arylboronic acids 9a-c offered a practical method for the synthesis of biaryl-embedded poly(1,2,3-triazoles) 10a-f in good yields.

1,1-Difluoroethane Hydrocarbon Cardiomyopathy

1,1-Difluoroethane (DFE) cardiomyopathy results from the direct inhalation of toxic halogenated hydrocarbons. We present a case series of acute DFE cardiomyopathy illustrating the typical presentation of severe DFE cardiomyopathy along with a detailed description of its mechanism of injury. (Level of Difficulty: Advanced.).

Assessment of Methylene Chloride-Related Fatalities in the United States, 1980-2018

Importance

Methylene chloride is a halogenated organic solvent widely used in paint strippers, cleaners, adhesives, and sealants. Despite label warnings and occupational standards, methylene chloride-related fatalities continue to occur in the United States.

Objective

To identify and analyze methylene chloride-related fatalities in the US.

Design, Setting, and Participants

For this case series, we conducted systematic searches of sources, including PubMed and government databases, for unintentional fatalities in the US that were associated with exposure to methylene chloride or products containing methylene chloride between 1980 and 2018. We reviewed all available information, including inspection reports, autopsy reports, and medical records; data analyses were conducted from August 2018 to August 2020. Cases were categorized as those occurring in the home (consumer deaths) or at work (occupational deaths).

Exposures

Methylene chloride or products containing methylene chloride.

Main Outcomes and Measures

To determine characteristics of the methylene chloride-related fatalities, we recorded demographic information; the setting; circumstances, including information on safety measures used, if available; and products used. Where medical records were available, we recorded toxicology results and autopsy findings. We also obtained data about nonfatal methylene chloride cases from the American Association of Poison Control Centers.

Results

From 1980 to 2018, 85 methylene chloride-related fatalities were identified in the US, including 74 (87%) in occupational settings; of those who died, 75 (94%) were men, and for the 70 cases with available information, the median (interquartile range) age of the decedents was 31 (24-46) years. Paint strippers were the most common products involved in methylene chloride-related fatalities (n = 60). The proportion of occupational fatalities related to paint stripping increased from 22 (55%) before 2000 to 30 (88%) after 2000. Similarly, occupational fatalities associated with bathtub or paint stripping in bathrooms increased from 2 (5%) before 2000 to 21 (62%) after 2000. From 1985 to 2017, the American Association of Poison Control Centers documented 37 201 nonfatal methylene chloride cases, with a decrease in the annual number of cases starting in the late 1990s.

Conclusions and Relevance

Results of this case series demonstrated that despite regulations to address the toxic effects of methylene chloride use for consumers and workers, there are continuing fatalities in the US, particularly in occupational settings. Prevention of fatalities associated with methylene chloride exposure should emphasize the use of safer substitutes, rather than hazard warnings or reliance on personal protective equipment.

Solvent-based paint and varnish removers: a focused toxicologic review of existing and alternative constituents

Paint and varnish removers constitute a major potential source of organic solvent exposure to contractors and home improvement enthusiasts. Unfortunately, the leading paint remover formulations have traditionally contained, as major ingredients, chemicals classified as probable human carcinogens (eg, methylene chloride) or reproductive toxicants (eg, N-methylpyrrolidone). In addition, because of its unique toxicology (ie, hepatic conversion to carbon monoxide compounding generic solvent narcosis and arrythmogenesis), high volatility, and rigorous requirements for personal protective equipment, methylene chloride exposures from paint removers have been linked to numerous deaths involving both occupational and consumer usage. The aim of this review is to summarize the known toxicology of solvent-based paint remover constituents (including those found in substitute formulations) in order to provide health risk information to regulators, chemical formulators, and end-users of this class of products, and to highlight any data gaps that may exist.

Chloroform is a potent activator of cardiac and neuronal Kir3 channels

Chloroform has been used over decades in anesthesia before it was replaced by other volatile anesthetics like halothane or sevoflurane. Some of the reasons were inadmissible side effects of chloroform like bradycardia or neural illness. In the present study, we identified members of the G protein-activated inwardly rectifying potassium channel family (Kir3) expressed in Xenopus oocytes as potential common molecular targets for both the neural and cardiac effects of chloroform. Millimolar concentration currents representing a 1:10000 dilution of commercially available chloroform were used in laboratories that augment neuronal Kir3.1/3.2 currents as well as cardiac Kir3.1/3.4. This effect was selective and only observed in currents from Kir3 subunits but not in currents from Kir2 subunits. Augmentation of atrial Kir3.1/3.4 currents leads to an effective drop of the heart rate and a reduction in contraction force in isolated mouse atria.

Electrocardiographic changes and exposure to solvents

Background

Occupational exposures can cause cardiovascular disorders. Some exposures may be harmful, and exposures to chemicals such as metal welding fumes, gases, and pesticides, and stress related to physical and occupational hazard, which results in cardiovascular disorders such as arrhythmia, could be prevented. The objective of this study was to determine the electrocardiographic changes in occupational exposure to organic solvents.

Methods

It was a historical cohort study and was carried out on workers of industries. The study was carried out with flexible interview, physical examination, checklist for obtaining clinical history, and electrophysiology test. Group 1 included the workers in the production line of solvent and paint, group 2 included administrative personnel, and group 3 included workers from other industries who did not have solvent exposure. A number of participants in group 1, group 2, and group 3 were 500, 498, and 501, respectively. Electrocardiographic changes were recorded in health issues.

Results

The frequency of arrhythmia, P wave, and QRS complex changes were highest in group 1. The risk of arrhythmia was 1.15 (1.08‐1.49), P wave change was 1.02 (1.01‐2.28) which was significant and considered as highest risk,, and QRS complex change was highest in group 1, whose relative risk was 1.53 (1.46‐1.61). ST segment and T wave changes (depression or elevation) were highest in group 1 and had no significant differences (P < .05).

Conclusion

Working in solvent industry is a risk of developing arrhythmia. Exposure to chemical especially solvent agents mostly affects the cardiovascular system and is effective on electrocardiography, which must be prevented.

Degradation of Trichloromethane by the Combination of UV Irradiation and Peroxymonosulfate

Trichloromethane (TCM) is a harmful halogenated organic compound usually used in the industry and a typical disinfection by-product in the water treatment with the use of chorine as disinfectant. The degradation of TCM by peroxymonosulfate combined with UV irradiation at λ= 254 nm (UV/PMS) was investigated. Results showed that TCM was efficiently degraded by UV/PMS and about 80% of TCM was decomposed when the concentration of PMS was 0.5mM. Radical-scavenging experimental results indicated that both HO• and SO4•- might contribute to the degradation of TCM. However, HO• might first be captured by PMS to form SO5•- and then partly decomposed into SO4•-, which might react with TCM. The increased concentration of PMS led to the increased removal efficiency of TCM. Whilst, the efficiency was little affected by initial concentration of TCM, indicating that there might be competition reaction with TCM degradation for radicals.