Toxicity Profiles

RAGs A Format for Aroclor^® 1260 - CAS Number 11096825

Aroclor^® 1260 is a colorless, liquid polychlorinated biphenyl (PCB) mixture containing approximately 38% C₁₂H₄Cl₆, 41% C₁₂H₃Cl₇, 8% C₁₂H₂Cl₈, and 12% C₁₂H₅Cl₅ with an average chlorine content of 60%. PCBs are inert, thermally and physically stable, and have dielectric properties. They have been used in closed systems such as heat transfer liquids, hydraulic fluids and lubricants, and in open systems such as plasticizers, surface coatings, inks, adhesives, pesticide extenders, and for microencapsulation of dyes for carbonless duplicating papers. In the environment, the behavior of PCB mixtures is directly correlated to the degree of chlorination. Aroclor^® is strongly sorbed to soil and remains immobile when leached with water; however, the mixture is highly mobile in the presence of organic solvents. PCBs are resistant to chemical degradation by oxidation or hydrolysis. PCBs have high bioconcentration factors, and tend to accumulate in the fat of fish, birds, mammals, and humans. In humans, relatively greater amounts of PCBs have also been identified in skin, liver, and breast milk.

PCBs are absorbed after oral, inhalation, or dermal exposure and are stored in adipose tissue. Accidental human poisonings and data from occupational exposure to PCBs suggest initial dermal and mucosal disturbances followed by systemic effects that may manifest themselves several years post-exposure. Initial effects are enlargement and hypersecretion of the Meibomian gland of the eye, swelling of the eyelids, pigmentation of the fingernails and mucous membranes, fatigue, and nausea. These effects were followed by hyperkeratosis, darkening of the skin, acneform eruptions, edema of the arms and legs, neurological symptoms, such as headache and limb numbness, and liver disturbance. Hepatotoxicity is a prominent effect of PCBs, including Aroclor^® 1260, that has been well characterized. Effects include hepatic microsomal enzyme induction, increased serum levels of liver-related enzymes (indicative of hepatocellular damage), liver enlargement, lipid deposition, fibrosis, and necrosis.

Data are suggestive but not conclusive concerning the carcinogenicity of PCBs in humans. However, hepatocellular carcinomas in three strains of rats and two strains of mice have led the EPA to classify PCBs as group B2, probable human carcinogen.

The following is a presentation of the toxicity information associated with Aroclor-1260:

• The Oral Slope Factor is for exposure to soil or food is 2.00E+00 (mg/kg-day)-1.
• The Oral Slope Factor is for exposure to water is 4.00E-01 (mg/kg-day)-1.

• The Inhalation Unit Risk for exposure to soil or food is 5.7E-01 (mg/m3)-1.
• The Inhalation Unit Risk for exposure to water is 1.0E-01 (mg/m3)-1.

• The Dermal Slope Factor for exposure to soil or food is 2.22E+00 (mg/kg-day)-1.
• The Dermal Slope Factor for exposure to water is 4.44E-01 (mg/kg-day)-1.
• The Dermal Slope Factors are based on a gastrointestinal absorption factor of 0.9000.