chemical information


Chemical Class:

Polychlorinated biphenyl (PCB)

Chemical SubClass


Manufacturing/Use Status

banned for use/manufacture in the U.S.

Found in these people:

Anonymous Adult 1, Kathy Fowler, Sara Corbett

Found in these locations:

Rockville, MD; NY, USA

Exposure routes:

Banned industrial insulators and lubricants. Residual environmental contamination results in continued exposures.


Laboratory animals. In animal studies, PCBs cause a wide variety of effects including liver and thyroid tumors; kidney, gastrointestinal, immune, urinary tract, and reproductive toxicity; altered lipid and carbohydrate metabolism; nail and nail bed changes; reduced fertility and birth defects. Specific birth defects include reproductive tract and skeletal abnormalities. PCBs are endocrine disruptors because they alter thyroid and adrenal hormone levels and function. PCBs cause significant neurotoxicity, including decreased exploratory behavior, learning, spatial and non-spatial discrimination, auditory deficits and altered levels of brain neurotransmitters (dopamine and serotonin) (ATSDR 2000b).

Humans. The effects of PCBs have been studied in humans who were exposed through diet, work, and industrial accidents. PCBs are reasonably anticipated to be human carcinogen (NTP 2002). They are associated with skin, liver, biliary tract, and intestinal cancers. Other effects of PCBs include respiratory effects, gastrointestinal damage (nausea, vomiting, abdominal pain), eye irritation, increased susceptibility to infection, and hypothyroidism (ATSDR 2000b, Persky, et al. 2001). Other possible health effects associated with PCB exposure are menstrual irregularities and decreased fertility in women. Inconsistent associations have been noted with non-Hodgkin's lymphoma, breast cancer, cardiovascular disease, sperm and fertility in males, low birth weight and head circumference (ATSDR 2000b). PCB exposure in the womb or during lactation is also associated with decreased IQ and impaired psychomotor development, decreased immune function, altered liver enzyme and lipid levels, and skin disease (chloracne) (ATSDR 2000b).


Polychlorinated biphenyls, or PCBs, are toxic, persistent, bioaccumulative, and lipophilic ("fat-loving"). This means that PCBs build up and are stored in fatty tissues and fluids, such as breast milk, and can be passed on to fetuses and infants during pregnancy and lactation. In humans PCBs are linked to increased rates of a number of cancers, including malignant melanoma; non-Hodgkin's lymphoma; and brain, liver, and lung cancer. PCB poisonings in humans have caused fetal and infant death, birth defects, and brain damage in children exposed in the womb. PCBs are known to interfere with hormonal processes. In 1976, the manufacture of PCBs was banned in the United States because of concern for human health impacts, but are still widely found in the general population of the U.S.

In humans, PCBs are associated with skin lesions, thyroid disruption, and altered menstrual cycling, as well as damage to the nervous, immune, and cardiovascular systems. PCB exposure in the womb or during lactation is also associated with decreased IQ and impaired psychomotor development, decreased immune function and skin disease (chloracne) (ATSDR 2000b). The National Toxicology Program considers several PCB mixtures to be "reasonably anticipated" human carcinogens (NTP 2002). Likewise, EPA considers PCBs to be "probable" human carcinogens (EPA 2002b).

In laboratory animals, PCBs are known to cause cancer and damage to the reproductive, endocrine, immune, and nervous systems. In addition, PCBs damage the kidney and gastrointestinal tract, and cause birth defects.

PCB-126 has been found in 5 of the 35 people tested in EWG/Commonweal studies.

Top health concerns for PCB-126 (References)

health concern or target organ weight of evidence
Brain and nervous systemunknown
Immune system (including sensitization and allergies)limited

Results for PCB-126

in blood serum (lipid weight)

Showing results from EWG/Commonweal Study #1, industrial chemicals and pesticides in adults, EWG/Commonweal Study #4, industrial chemicals and pesticides in cord blood, EWG Study #3, industrial chemicals and pesticides in adults, Pollution in Minority Newborns, EWG Study #8, chemicals in mother and 2 children, San Francisco Reporter

EWG/Commonweal results

  • geometric mean: 0.00533 ng/g (lipid weight) in blood serum
  • found in 5 of 35 people in the group
0 ng/g (lipid weight) in blood serum 0.0442

PCB-126 results

Detailed toxicity classifications (References)

classification governing entity/references
Nervous system toxicity - weight of evidence unknown/unassessedATSDR (2000). Toxicological profile for polychlorinated biphenyls (PCBs): Health effects chapter.
Limited evidence in humans - immune system toxicityATSDR (2000). Toxicological profile for polychlorinated biphenyls (PCBs): Health effects chapter.