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Pentachlorophenol (penchloro, penta, PCP, others) is a chlorinated aromatic hydrocarbon that has been used as a pesticide to preserve wood products from insect and fungal damage (eg, power line poles). Since 1984, its use in the United States has been restricted to industrial purposes by certified applicators. It is a ubiquitous environmental contaminant detectable in the general population. It appears to be an endocrine and immune disrupter. It is a probable carcinogen (EPA). It is formed as a by-product during water disinfection with chlorinated oxidants. Moreover, it was noted that children living in the areas of pentachlorobenzene and hexachlorobenzene emissions had elevated pentachlorophenol serum and urine concentrations.

Dinitrophenols (dinosam, DNOC, DNP, and analogs) have been used as insecticides, herbicides, fungicides, and chemical intermediaries and are used in some explosives, dyes, and photographic chemicals. Dinitrophenol has also been taken orally for weight reduction. The use of dinitrophenol as a pesticide or as a weight-reducing agent is banned in the United States, although the chemical appears to be available over the Internet.


  1. Pentachlorophenol and dinitrophenols uncouple oxidative phosphorylation in the mitochondria. Substrates are metabolized, but the energy produced is dissipated as heat instead of producing adenosine triphosphate (ATP). The basal metabolic rate increases, placing increased demands on the cardiorespiratory system. Excess lactic acid results from anaerobic glycolysis.

  2. Dinitrophenols may oxidize hemoglobin to methemoglobin.

  3. In animal studies, pentachlorophenol is mutagenic, teratogenic, and carcinogenic. DNP is mutagenic, teratogenic, and may be weakly carcinogenic.


These agents are readily absorbed through the skin, lungs, and GI tract.

  1. Inhalation. The air level of pentachlorophenol considered immediately dangerous to life or health (IDLH) is 2.5 mg/m3. The ACGIH-recommended workplace air exposure limit (TLV-TWA) is 0.5 mg/m3 as an 8-hour time-weighted average.

  2. Skin. This is the main route associated with accidental poisoning. An epidemic of intoxication occurred in a neonatal nursery after diapers were inadvertently washed in 23% sodium pentachlorophenate.

  3. Ingestion. The minimum lethal oral dose of pentachlorophenol for humans is not known, but death occurred after ingestion of 2 g. Ingestion of 1–3 g of dinitrophenol in an adult is considered lethal.


The toxic manifestations of pentachlorophenol and dinitrophenol are nearly identical. Profuse sweating, fever, tachypnea, and tachycardia are universally reported in serious poisonings and can manifest as early as 3.5 hours after intentional overdose.

  1. Acute exposure causes irritation of the skin, eyes, and upper respiratory tract. Systemic absorption may cause headache, vomiting, weakness, and lethargy. Profound sweating, hyperthermia, tachycardia, tachypnea, convulsions, and coma are associated with severe or fatal poisonings. Pulmonary edema, intravascular hemolysis, pancreatitis, jaundice, and acute renal failure have been reported. Death usually is caused by cardiovascular collapse or hyperthermia. After death, an extremely rapid onset of rigor mortis is reported frequently. ...

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