on calcium which may lead to neurotoxicity. ortho-PCBs can disrupt thyroid hormone transport by binding to transthyretin. Alternative names Commercial PCB mixtures were marketed under the following names: Brazil Ascarel Czech Republic and Slovakia Delor France Phenoclor Pyralène (both used by Prodolec) Germany Clophen (used by Bayer) Italy Apirolio Fenclor Japan Kanechlor (used by Kanegafuchi) Santotherm (used by Mitsubishi) Pyroclor Former USSR Sovol Sovtol United Kingdom Aroclor xxxx (used by Monsanto Company) Askarel United States Aroclor xxxx (used by Monsanto Company) Asbestol Askarel Bakola131 Chlorextol – Allis-Chalmers trade name Hydol Inerteen (used by Westinghouse) Noflamol Pyranol/Pyrenol, Chlorinol (used in General Electric's oil-filled "chlorinol"-branded metal can capacitors. Utilized from the early 1960s to late 1970s in air conditioning units, Seeburg jukeboxes and Zenith televisions) Saf-T-Kuhl Therminol FR Series (Monsanto ceased production in 1971). Aroclor mixtures The only North American producer, Monsanto Company, marketed PCBs under the trade name Aroclor from 1930 to 1977. These were sold under trade names followed by a four-digit number. In general, the first two digits refer to the product series as designated by Monsanto (e.g. 1200 or 1100 series); the second two numbers indicate the percentage of chlorine by mass in the mixture. Thus, Aroclor 1260 is a 1200 series product and contains 60% chlorine by mass. It is a myth that the first two digits referred to the number of carbon atoms; the number of carbon atoms do not change in PCBs. The 1100 series was a crude PCB material which was distilled to create the 1200 series PCB product. The exception to the naming system is Aroclor 1016 which was produced by distilling 1242 to remove the highly chlorinated congeners to make a more biodegradable product. "1016" was given to this product during Monsanto's research stage for tracking purposes but the name stuck after it was commercialized. Different Aroclors were used at different times and for different applications. In electrical equipment manufacturing in the US, Aroclor 1260 and Aroclor 1254 were the main mixtures used before 1950; Aroclor 1242 was the main mixture used in the 1950s and 1960s until it was phased out in 1971 and replaced by Aroclor 1016. Production One estimate (2006) suggested that 1 million tonnes of PCBs had been produced. 40% of this material was thought to remain in use. Another estimate put the total global production of PCBs on the order of 1.5 million tonnes. The United States