Systemic effects and skin injury after experimental dermal exposure to monochloroacetic acid

Skin burns from monochloroacetic acid leak in a chemical plant: a case report

The patient, a 45-year-old male chemical factory worker, was burned by monochloroacetic acid discharged from a ruptured pipe. The patient was merely flushed with water and did not leave the workplace immediately. As a result, he suffered local burn symptoms, which gradually worsened. Two and a half hours after the accident, he developed symptoms of systemic poisoning, such as lethargy and dyspnoea. After a thorough debridement of the wound surface and subsequent skin grafting combined with early glucocorticoid therapy and haemofiltration, a satisfactory result was achieved, and the patient eventually recovered. With the widespread use of monochloroacetic acid in China, incidents of poisoning with this chemical are becoming increasingly common, with more than 100 cases reported in the past ten years in China alone.

Therapeutic applications of dichloroacetate and the role of glutathione transferase zeta-1

Dichloroacetate (DCA) has several therapeutic applications based on its pharmacological property of inhibiting pyruvate dehydrogenase kinase. DCA has been used to treat inherited mitochondrial disorders that result in lactic acidosis, as well as pulmonary hypertension and several different solid tumors, the latter through its ability to reverse the Warburg effect in cancer cells and restore aerobic glycolysis. The main clinically limiting toxicity is reversible peripheral neuropathy. Although administration of high doses to rodents can result in liver cancer, there is no evidence that DCA is a human carcinogen. In all studied species, including humans, DCA has the interesting property of inhibiting its own metabolism upon repeat dosing, resulting in alteration of its pharmacokinetics. The first step in DCA metabolism is conversion to glyoxylate catalyzed by glutathione transferase zeta 1 (GSTZ1), for which DCA is a mechanism-based inactivator. The rate of GSTZ1 inactivation by DCA is influenced by age, GSTZ1 haplotype and cellular concentrations of chloride. The effect of DCA on its own metabolism complicates the selection of an effective dose with minimal side effects.

Lethal acute lung injury and hypoglycemia after subcutaneous administration of monochloroacetic acid

Hypoglycemia is suspected in the acute lethal toxicity induced by cutaneous exposure to monochloroacetic acid (MCA). Although it has been shown that hepato-renal dysfunction is involved, the mechanism and the target organs that directly affect mortality remain to be determined. We suspected respiratory failure as a main cause of death in some reported cases. We investigated dose-response effects, hypoglycemia, and lung injury in rats exposed to MCA. Serum glucose, blood gases, and parameters of alveolar injury in bronchoalveolar lavage fluid (BALF) were analysed 2 and 4 h after subcutaneous administration of MCA (108, 135 or 163 mg/kg). Apparent pulmonary injury and hypoglycemia were not identified 2 h after administration, but lactate dehydrogenase (LDH) and total cells in BALF were dose-dependently increased; and severe hypoglycemia was identified 4 h after administration. Blood gas analysis showed remarkable alveolar gas dysfunction as exchange in the 163 mg/kg group. Thus, hypoglycemia and lung injury appear to cause death in response to MCA exposure.

Transports of acetate and haloacetate in Burkholderia species MBA4 are operated by distinct systems

Background

Acetate is a commonly used substrate for biosynthesis while monochloroacetate is a structurally similar compound but toxic and inhibits cell metabolism by blocking the citric acid cycle. In Burkholderia species MBA4 haloacetate was utilized as a carbon and energy source for growth. The degradation of haloacid was mediated by the production of an inducible dehalogenase. Recent studies have identified the presence of a concomitantly induced haloacetate-uptake activity in MBA4. This uptake activity has also been found to transport acetate. Since acetate transporters are commonly found in bacteria it is likely that haloacetate was transported by such a system in MBA4.

Results

The haloacetate-uptake activity of MBA4 was found to be induced by monochloroacetate (MCA) and monobromoacetate (MBA). While the acetate-uptake activity was also induced by MCA and MBA, other alkanoates: acetate, propionate and 2-monochloropropionate (2MCPA) were also inducers. Competing solute analysis showed that acetate and propionate interrupted the acetate- and MCA- induced acetate-uptake activities. While MCA, MBA, 2MCPA, and butyrate have no effect on acetate uptake they could significantly quenched the MCA-induced MCA-uptake activity. Transmembrane electrochemical potential was shown to be a driving force for both acetate- and MCA- transport systems.

Conclusions

Here we showed that acetate- and MCA- uptake in Burkholderia species MBA4 are two transport systems that have different induction patterns and substrate specificities. It is envisaged that the shapes and the three dimensional structures of the solutes determine their recognition or exclusion by the two transport systems.

Chloroacetic acid induced neuronal cells death through oxidative stress-mediated p38-MAPK activation pathway regulated mitochondria-dependent apoptotic signals

Chloroacetic acid (CA), a toxic chlorinated analog of acetic acid, is widely used in chemical industries as an herbicide, detergent, and disinfectant, and chemical intermediates that are formed during the synthesis of various products. In addition, CA has been found as a by-product of chlorination disinfection of drinking water. However, there is little known about neurotoxic injuries of CA on the mammalian, the toxic effects and molecular mechanisms of CA-induced neuronal cell injury are mostly unknown. In this study, we examined the cytotoxicity of CA on cultured Neuro-2a cells and investigated the possible mechanisms of CA-induced neurotoxicity. Treatment of Neuro-2a cells with CA significantly reduced the number of viable cells (in a dose-dependent manner with a range from 0.1 to 3mM), increased the generation of ROS, and reduced the intracellular levels of glutathione depletion. CA also increased the number of sub-G1 hypodiploid cells; increased mitochondrial dysfunction (loss of MMP, cytochrome c release, and accompanied by Bcl-2 and Mcl-1 down-regulation and Bax up-regulation), and activated the caspase cascades activations, which displayed features of mitochondria-dependent apoptosis pathway. These CA-induced apoptosis-related signals were markedly prevented by the antioxidant N-acetylcysteine (NAC). Moreover, CA activated the JNK and p38-MAPK pathways, but did not that ERK1/2 pathway, in treated Neuro-2a cells. Pretreatment with NAC and specific p38-MAPK inhibitor (SB203580), but not JNK inhibitor (SP600125) effectively abrogated the phosphorylation of p38-MAPK and attenuated the apoptotic signals (including: decrease in cytotoxicity, caspase-3/-7 activation, the cytosolic cytochrome c release, and the reversed alteration of Bcl-2 and Bax mRNA) in CA-treated Neuro-2a cells. Taken together, these data suggest that oxidative stress-induced p38-MAPK activated pathway-regulated mitochondria-dependent apoptosis plays an important role in CA-caused neuronal cell death.

Superficial Burns Secondary to Misuse of Acetic Acid Solution

Topical use of acetic acid solutions is one of the treatments for human papillomavirus infections, although the disease can spontaneously resolve. Over-the-counter availability of acetic acid solutions for medical use presents a potential hazard for misuse. Here we present an example of accidental use. A 13-year-old boy was wounded as a result of using an acetic acid solution for cosmetic purposes. Superficial burns on the left side of his face were managed with topical wound care, and minimal scar formation occurred.

Iatrogenic Full-Thickness Chemical Burns from Monochloracetic Acid

A case of iatrogenic full-thickness chemical burns from monochloroacetic acid (MCA) crystal application is described, followed by a brief review of the relevant literature and discussion of both local and systemic problems that may be encountered with absorption of this chemical. We believe this to be the first reported case of full-thickness burns in association with MCA. The degree of injury and systemic side effects encountered as a procedure complication highlights the importance of using this chemical with care in any clinical setting. In addition, an apparent predilection of MCA for the germinal matrix as found in this case may further complicate reconstructive options for associated injuries.