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PCB warning label on a power transformer known to contain PCBs. Polychlorinated biphenyls (PCBs) are organochlorine compounds with the formula C 12 H 10−x Cl x; they were once widely used in the manufacture of carbonless copy paper, as heat transfer fluids, and as dielectric and coolant fluids for electrical equipment. [2]
Diagram of deodorization tower The PCB that was used as the heating medium leaked from the pipes and mixed into the rice bran oil. Yushō disease (油症, lit. ' oil symptoms ') was a mass poisoning by polychlorinated biphenyls (PCBs) which occurred in northern Kyūshū, Japan, in 1968.
A mixture of polychlorinated biphenyls contaminated with dioxins was accidentally added to animal food. The early signs of poisoning were already noticed in February 1999, but the source and extent of contamination were only discovered in May 1999. It appeared that more than 2500 farms could have been supplied with this contaminated food.
There are 209 PCB compounds. Analogously to PCDDs at least two lateral chlorines in each ring in positions 3,4, and/or 5 are needed for dioxin-like activity. Because the AH receptor requires a planar (flat) structure, only PCB congeners that can rotate freely along the C—C axis between the rings can attach the receptor.
Yushō disease; mass poisoning resulting from rice bran oil contaminated with polychlorinated biphenyls in Kyūshū killed more than 500. 1971, Iraq. Iraq poison grain disaster: A mass poisoning by grain treated with a methylmercury fungicide which was imported to the country as seed and never intended for human consumption. According to ...
1968 – Yushō disease; mass poisoning resulting from rice bran oil contaminated with polychlorinated biphenyls in Kyūshū, Japan; 1971 – 1971 Iraq poison grain disaster: 100 to 400 died of mercury poisoning by eating seeds intended for planting and treated with mercury as a fungicide. [16] [17]
In May 1999, there was a dioxin crisis in Belgium: quantities of polychlorinated biphenyls with dioxin-like toxicity had entered the food chain through contaminated animal feed. 7,000,000 chickens and 60,000 pigs had to be slaughtered. This scandal was followed by a landslide change in government in the elections one month later.
Exposure to the coplanar stereoisomer 3,3',4,4',5,5'-hexabromobiphenyl (but not the non-coplanar stereoisomer) in genetically susceptible mice is known to cause immunotoxicity and disorders related to the central nervous system, and even at doses as low as 2.5 mg/kg, excess neonatal fatalities are observed (LD 50 is from 5–10 mg/kg). [1]