Polychlorinated biphenyls (PCBs) were manufactured worldwide for various technical applications. Because of their chemical stability, PCBs made excellent coolants and insulating fluids for transformers and capacitors. Other applications included carbonless paper, paints, hydraulic fluids, plasticizers, plastic additives and flame retardants. It is estimated that more than 1.5 million tons of PCBs were produced worldwide.
The toxicity of PCBs was documented in medical cases as early as the 1920s and 30s. Factory workers involved in the manufacture of PCBs exhibited adverse health effects such as severe skin diseases.
In 1968, the first case was reported in Japan with over 1200 patients, many of them children. The cause of this illness was the contamination of rice oil with industrial PCBs. The victims’ average amount of PCBs ingested was estimated at two grams. By 1973, 22 of the 1200 victims had died, 41% from malignant tumors, indicating a possible link to PCB ingestion.
In 2001, PCBs were added to the list of Persistent Organic Pollutants by the Stockholm Convention.
Their high-persistence and ubiquitous distribution through past use, disposal and leakages have resulted in global contamination of soils, air, rivers and other waterways that will affect our food and water supplies for years to come.
Although PCB concentrations in the environment are slowly decreasing, but a low-level human exposure to PCBs through diet and inhalation of contaminated indoor air remains a concern. Numerous studies have linked PCBs, even at low levels, to toxic effects such as endocrine disruption, neurotoxicity, immunotoxicity and carcinogenesis.