Polychlorinated Biphenyls (PCBs):PCBs are listed as "reasonably anticipated to be human carcinogens" in the Fourteenth Report on Carcinogens published by the National Toxicology Program because there is limited evidence of a relationship between exposure to PCBs and cancer in humans. Long-term exposure to PCBs may have serious effects on the liver, immune system, endocrine system, reproductive system, and thyroid hormone levels, which in turn may affect normal growth and development. Exposure may damage the nervous system, causing headaches, numbness, weakness, and tingling in the arms and legs; it may also cause learning deficits and changes in activity. Short-term exposure to PCBs can irritate and burn the eyes, lungs, nose, and throat. It can cause coughing, difficulty breathing, nausea, vomiting, weight loss, depression, fatigue, sweating at the palms, jaundice, headache, dizziness, nervousness, muscle and joint pain, discoloration of fingernails, arthritis, and stomach pain. In women, short-term exposure can cause irregular menstrual cycles. Skin contact with PCBs may cause an acne-like skin rash, which can last for years.