1,2-Dichlorobenzene (1,2-DCB), or ortho-dichlorobenzene, is an organic compound with the formula C6H4Cl2. This colourless liquid is poorly soluble in water but miscible with most organic solvents. 1,2-Dichlorobenzene contains two chlorine atoms connected to one benzene molecule. Most of the 1,2-DCB released into the environment is present as a vapor. 1,2-DCB can burn, but they do not burn easily. (4, 5)
belongs to the class of organic compounds known as dichlorobenzenes. Dichlorobenzenes are compounds containing a benzene with exactly two chlorine atoms attached to it.
1,2-DCB was found to covalently bind to DNA, RNA, and proteins of liver, kidney, lung, and stomach. (4)
Metabolism
After absorption, 1,2-DCB ist distributed in blood, the urinary bladder, kidney, fat, and liver. The initial step in the metabolism of 1,2-DCB is metabolism by cytochrome P-450 isozymes, mainly P4502E1, to an active epoxide. This epoxide can either react directly with cellular components, be conjugated to glutathione or glucuronic acid, or be hydrolyzed to form 2,3-dichlorophenol or 3,4-dichlorophenol. The dichlorophenol metabolites can be further metabolized by conjugation with glutathione, glucuronic acid, or sulfate, or further oxidized to catechols. An additional oxidation to form dichlorohydroquinone metabolites has also been proposed. Microsomal studies have implicated cytochrome P-450, and particularly P4502E1, as a major component of 1,2-DCB metabolism, resulting in the formation of dichlorophenols, dichlorocatechols, and dichlorohydroquinones. 1,2-DCB is eliminated primarily in the urine as metabolites rather than as the parent compound. (4)
3, not classifiable as to its carcinogenicity to humans. (3)
Uses/Sources
Exposure may result from breathing contaminated air, drinking contaminated water or eating contaminated food, and skin contact. (4)
Minimum Risk Level
Acute Oral: 0.7 mg/kg/day (Rat and Mouse) (2)
Intermediate Oral: 0.6 mg/kg/day (Rat and Mouse) (2)
Chronic Oral: 0.3 mg/kg/day (Rat and Mouse) (2)
Health Effects
Inhaling the vapor or dusts of 1,2-DCB at very high concentrations could be very irritating to eyes and nose and cause burning and tearing of the eyes, coughing, difficult breathing, and an upset stomach. Ingestion of 1,2-DCB can cause effects in the kidneys and blood, and that 1,3-DCB caused thyroid and pituitary effects. (4)
Symptoms
Cough, drowsiness, sore throat and unconsciousness can result from inhalation. Burning sensation, diarrhoea, nausea and vomiting can follow ingestion. In case of dermal or eye exposure, redness and pain of the exposed surface can occur. Moreover, skin exposure can cause skin dryness. (6)
Treatment
Following oral exposure, administer charcoal as a slurry; administer oxygen to all cyanotic or symptomatic patients. In case of methemoglobinemia, administer 1 to 2 mg/kg of 1% methylene blue slowly IV in symptomatic patients; also consider adjunctive therapy. In case of inhalation exposure, move patient to fresh air; monitor for respiratory distress. If cough or difficulty breathing develops, evaluate for respiratory tract irritation, bronchitis, or pneumonitis. Administer oxygen and assist ventilation as required. Treat bronchospasm with inhaled beta2 agonist and oral or parenteral corticosteroids. Following eye exposure, irrigate exposed eyes with copious amounts of room temperature water for at least 15 minutes. Following dermal exposure, skin should be thoroughly washed with soap and water; contaminated clothing and shoes should be discarded. Administer 100 percent humidified supplemental oxygen with assisted ventilation as required. Treat for methemoglobinemia and sequelae. Signs and symptoms of methemoglobinemia may be delayed. (7)
