“…Chlorinated dibenzofurans (C1-DBF's) are reported impurities in several types of chlorinated aromatic industrial chemicals produced in the United States and abroad, including PCB's (Bowes, MulvihiU, Simoneit, Burlingame & Risebrough, 1975;Nagayama, Kuratsune & Masuda, 1976;Miyata, Nakamura & Kashimoto, 1976), pentachlorophenols (Schwetz, Keeler & Gehring, 1974;Buser, 1975) and hexachlorobenzene (Villanueva, Jennings, Burse & Kimbrough, 1974). CI-DBF's are recognized environmental pollutants and are contaminants in foods (Department of Health, Education and Welfare, 1976;Firestone, 1973;Collins, Holmes & Wallen, 1972). Extremely high toxicity has been reported for the C1-DBF compound whose structure is reported here (Moore, Gupta & Vos, 1976;McKinney, Chae, Gupta, Moore & Goldstein, 1976).…”