Toxicity Profiles

RAGs A Format for Pentachlorophenol - CAS Number 87865

Pentachlorophenol is a manufactured organic chemical not found naturally in the environment. Pure pentachlorophenol occurs as a colorless or white powder with a crystalline structure that has a sharp chemical odor when hot, but very little smell at room temperature. Pentachlorophenol was previously used as a biocide and wood preservative and was one of the most heavily used pesticides in the United States. Now, only certified applicators can purchase and use pentachlorophenol. It is still used in industry as a wood preservative for power line poles, railroad ties, cross arms, and fence posts. It is no longer found in wood preserving solutions or insecticides and herbicides that can be purchased for home and garden use. Commercial pentachlorophenol preparations contain 85 to 99% pentachlorophenol and various other phenol impurities as well as dioxins and furans. The presence of these impurities makes the assessment of toxicity difficult.

Pentachlorophenol is readily absorbed following oral or inhalation exposure and is widely and rapidly distributed throughout the body. Human fatalities and toxic effects including tachycardia, jaundice, and other hematologic alterations have been reported for acute and subchronic occupational inhalation exposures to pentachlorophenol. Short-term exposures to large amounts of pentachlorophenol or long-term exposure to low levels can harm the liver, kidneys, blood, lungs, nervous system, immune system, and digestive tract. Researchers have seen similar effects in animals. Impurities in commercial pentachlorophenol may cause many, but not all, of its harmful effects. Direct contact with pentachlorophenol can irritate the skin, eyes, and mouth, particularly when it is a hot vapor.

Based upon increased risk of cancer, specifically in the livers and adrenal glands of mice, pentachlorophenol is classified by the EPA as a probable human carcinogen (Weight of Evidence Category B2). There is no good evidence that pentachlorophenol causes cancer in humans.

The following is a presentation of the toxicity information associated with Pentachlorophenol.

Noncarcinogenic Health Effects

• The Oral Chronic Reference Dose is 3.00E-02 (mg/kg-day).
• The Oral Chronic Reference Dose has a modifying factor of 1.
• The Oral Chronic Reference Dose has an uncertainty factor of 100.
• The Oral Chronic Reference Dose is based on the Schwetz et al. study from 1978.
• The Oral Chronic Reference Dose study target organs are liver and kidney.
• The Oral Chronic Reference Dose study critical effect is pathology.
• The overall confidence in the Oral Chronic Reference Dose is medium.
• The Dermal Chronic Reference Dose is 3.00E-02 (mg/kg-day).
• The Dermal Chronic Reference Dose is based on a gastrointestinal absorption factor of 1.0000.

Carcinogenic Health Effects

• The Oral Slope Factor is 1.20E-01 (mg/kg-day)^-1.
• The Oral Slope Factor study target organ is liver.
• The Oral Slope Factor study cancer type is carcinoma/adenoma.
• The Oral Slope Factor is based on the NTP study from 1989.
• The Dermal Slope Factor is 1.20E-01 (mg/kg-day)^-1.
• The Dermal Slope Factor is based on a gastrointestinal absorption factor of 1.0000.