is used in the manufacture of the herbicide 2,4,5-trichlorophenoxyacetic acid 

 (2,4,5-T), and other trichlorophenoxy acids, and the germicide 

 hexachlorophene. There is general agreement that 2,3,7,8-TCDD is exceedingly 

 stable, readily incorporated into aquatic and terrestrial ecosystems, 

 extraordinarily persistent, and virtually impossible to destroy. 

 PCDD-contaminated phenoxy herbicides are not the only sources of 2,3,7,8-TCDD, 

 others include polychlorinated biphenyls and pentachlorophenols. The other 74 

 isomers enter the biosphere from a variety of sources (NRCC 1981). The fate 

 and effects of PCDDs--with special reference to 2,3,7,8-TCDD and its role in 

 poisonings of humans, aquatic organisms, wildlife, livestock, poultry, and its 

 contamination of vegetation, soils, and sediments--have been extensively 

 reviewed (Blair 1973; Cattebeni et al. 1978; Ramel 1978; Nicholson and Moore 

 1979; NRCC 1981; Hay 1982; Kociba and Schwetz 1982a, b; Choudhary et al . 1983 

 Josephson 1983; Long et al . 1983; Stolzenburg and Sullivan 1983; NIOSH 1984 

 Nriagu and Simmons 1984; Rappe 1984; Webb 1984; Kamrin and Rodgers 1985 

 Stalling et al . 1985a, b; Young and Cockerham 1985). 



This account summarizes available data on ecological and toxicological 

 aspects of PCDDs in the environment, with special reference to fish, wildlife, 

 and their diets. In addition, it reviews and provides recommendations for the 

 protection of sensitive species of wildlife and aquatic biota. This report is 

 part of a continuing series of synoptic reviews prepared in response to 

 requests for information from Resource Contaminant Specialists of the U.S. 

 Fish and Wildlife Service. 



