2,3,5,6-tetrachlorophenol acts at the sites of adenosine triphosphate production and decreases or blocks it without blocking the electron transport chain. Thus the poison uncouples phosphorylation from oxidation. Free energy from the electron transport chain then converts to more body heat. As body temp rises, heat-dissipating mechanisms are overcome and metabolism is speeded. More adenosine diphosphate and other substrates accumulate, and these substrates stimulate the electron transport chain further. The electron transport chain responds by using up more and more available oxygen (increasing oxygen demand) in an effort to produce adenosine triphosphate, but much of the free energy generated is liberated as still more body heat. Oxygen demand quickly overcomes oxygen supply, and energy reserves become depleted (1).
Metabolism
2,3,5,6-Tetrachlorophenol is rapidly absorbed and excreted following occupational exposure, which involves both the inhalation and dermal routes. Sulfation and glucuronidation are the main metabolic pathways of 2,3,5,6-tetrachlorophenol. Studies suggest rapid absorption after dermal application. 2,3,5,6-Tetrachlorophenol is excreted as tetrachloro-p-hydroquinone, and partly unchanged (3).
Not directly listed by IARC, but related polychlorophenols are discussed, and combined exposures to polychlorophenols or to their sodium salts are classified as possibly carcinogenic to humans (Group 2B). (2)
Dermal exposure can cause corrosive skin damage (3).
Symptoms
Dust has been found irritating to the nose and throat. Skin or eye contact can cause irritation of the exposed surface. Clinical signs preceding death for all tetrachlorophenol isomers included initial hyperactivity followed by hypoactivity, neuromuscular weakness, and convulsions. Headache can also result from exposure to 2,3,5,6-tetrachlorophenol (3).
Treatment
In case of oral exposure, dilution may enhance absorption of phenol, and should be avoided; charcoal may be administered. If methemoglobinemia occurs, administer 1 to 2 mg/kg of 1% methylene blue slowly IV in symptomatic patients. Additional doses may be required. if hypotensin occurs, infuse 10 to 20 mL/kg isotonic fluid. If hypotension persists, administer dopamine or norepinephrine. Following inhalation exposure, move patient to fresh air. Monitor for respiratory distress, and 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. Irrigate exposed eyes with copious amounts of room temperature water for at least 15 minutes following eye exposure. Following dermal exposure, remove phenol with undiluted polyethylene glycol 300 to 400 or isopropyl alcohol prior to washing, if readily available. Wash exposed areas twice or for at least 10 minutes with large quantities of soapy water. Water alone may be harmful. (4)
