Toward a Time Trend Analysis of Dioxin Emissions and Exposure

Old agrochemical samples were analyzed for their dioxin impurities. Some herbicides were contaminated with 2,3,7,8-chlorine-substituted dioxin congeners. Using these new data as well as impurity and emission data reported in the literature, the time trends for dioxin emissions from the use of chlorinated aromatic compounds and some incineration activities have been estimated. The results indicate that dioxin emission was high during 1960s and 1970s and then decreased in terms of both amount of dioxin (PCDD/Fs) and toxic equivalent (TEQ). Herbicides were the major sources in the high emission period. After the mid-1980s, incineration sources became major. The order of importance in terms of total dioxin emission into the environment during the past 40 years is estimated to be chloronitrofen (CNP) > pentachlorophenol (PCP) > municipal solid waste incineration (MSWI) ≅ industrial waste incineration (IWI) in terms of PCDD/Fs and PCP > CNP > PCB > MSWI ≅ IWI in terms of I-TEQ.