Dioxin and dioxin-like PCB impurities in some Japanese agrochemical formulations

The profile and amount of dioxin impurity in agrochemicals were studied thr ough detailed analysis of historic Japanese formulations. The chemicals ana lyzed include pentachlorophenol (PCP), 2,4,6-trichlorophenyl-4 ' -nitrophen yl ether (chloronitrofen, CNP), 2,4-dichlorophenyl-4 ' -nitrophenyl ether ( nitrofen, NIP), tetrachloro-iso-phthalonitrile (chlorothalonil, TPN), 2-met hyl-4-chloro-phenoxyacetic acid (MCP) and 2,4-dichlorophenoxyacetic acid (2 ,4-D), Among the six, two herbicides, PCP and CNP, produced during the 1960 s and 1970s, contained very high concentrations of PCDD/DFs and TEQ. Others contained relatively low concentrations of PCDD/DFs. Dioxin-like PCB conce ntrations in all chemicals studied were low and their contributions to TEQ were negligible. The total dioxin emissions from the use of agrochemicals i n Japan during the past 40 years (1955-1995) were estimated to be about a f ew hundred thousand kg of PCDD/DFs and 250 kg of WHO-TEQ from PCP and 190 x 10(3) kg of PCDD/DFs and 440 kg of WHO-TEQ from CNP. The major dioxin cong eners present in PCP formulations were highly chlorinated PCDD/ DFs that ca n be formed by the coupling of PCP and/or 2,3,4,6-tetrachlorophenol, and th ose in the CNP formulations were tetra- to hexa-chlorinated PCDD/DFs that c an be formed from 2,4,6-trichlorophenol and/or 2,3,4,6-tetrachlorophenol. ( C) 2001 Elsevier Science Ltd. All rights reserved.