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

Abstract

There have been many fatal occupational accidents of skin exposure to monochloroacetic acid (MCA). However, there have been no reports of dermatological findings and the lethal consequences have not yet been demonstrated. Therefore, harmful local and systemic effects were investigated after dermal exposure to MCA. A 0.5 mL aliquot of MCA solution (40% w/w) was applied to the abdominal skin of ten 10-week-old male SD rats under anesthesia. The exposure area (25 x 25 mm2) was 1.6% of the total surface area. The dose of MCA per area was 34.1 mg/cm2. Saline was similarly administered to 10 control rats. Histopathological findings after 10 min were observed by light microscopy. Blood samples were collected by exsanguinations from the carotid arteries after 4 h. Skin samples were collected 10 min after the initial exposure. Histological findings showed severe degeneration of collagen bundles in the epidermis and subcutaneous tissues. P(CO2), HCO(3)-, TCO2, BE and glucose levels were decreased in the MCA group. AST, m-AST, ALT, BUN, Cr, NH3, lactic acid, pyruvic acid, RBC, Hb, Hct, total protein and albumin were increased in the MCA group. The burn was determined to be a third-degree burn on the basis of the histopathological findings. The severe toxicity was probably a consequence of the rapid permeability. Biochemical parameters were a consequence of hepatocellular injuries, renal dysfunction, dysglyconeogenesis and dysfunction of ammonia metabolism. MCA reportedly enters the TCA cycle and inhibits aconitase. MCA metabolites also inhibit pyruvate carboxylase in the gluconeogenesis pathway. Therefore, the important serum biochemical abnormalities such as hypoglycemia and lactic acidosis should be monitored to find the acute systemic disorders.