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.HISTORICAL OVERVIEW: 2.A.5-T. ^cL?>i!-?, jiO'r* ^>.; y';r^8T* 4 r,v? o s o a j Chloracne 8 2,5,7,8-TCDD ' 1930s -- Chloracne, a dermatitis characterized by blackheads similar to teen-age acne but often more severe, was noted among workers dealing with chlorinated aromatic hydrocarbons (chloracnegens). 1941 -- 2,4-D and 2,4,5-T first synthesized. 1944 -- 2,4-D and 2,4,5-T reported as herbicides and marketed by Amchem Products. 1947 -- Effectiveness of 2,4,5-T and derivatives against woody plants resistant to 2,4-D established by Dow. 1948 -- 2,4,5-T registered for control of weeds on rangelands, fence rows and rights of way. 1949 -- Explosion in Monsanto's 2,4,5-trichlorophenol (TCP) unit at Nitro, W.Va. exposed 250 workers to reaction mass causing 122 cases of chloracne, some very severe. TCP is intermediate in 2,4,5-T manufacture. 1950 -- Presence of a "highly toxic impurity" in production of TCP recognized by Dow. 1957 -- 2,3,7,8-TCDD first implicated as causative agent of chloracne associated with TCP production. (Kimmig and Schultz, Germany) 1962 -- U.S. military began spraying 2,4,5-T formulations in Vietnam to take away foliage cover from the enemy. C04412 HISTORICAL OVERVIEW (CONT'D.) 1965 - 2,3,7,8-TCDD recognized by Dow as causative agent of chloracne in TCP wastes, Alerted health authorities and other U.S. 2,4,5-T manufacturers. Shared analytical techniques. 1970 - 2,3,7,8-TCDD's teratogenicity and fetotoxicity first reported in animals. U.S. military stopped spraying Agent Orange in Vietnam. U.S. Dept, of Agriculture suspended uses of 2,4,5-T. 1973 - Vietnamese study linked liver cancer, abortions,, and birth defects to Agent Orange spraying. 1976 - Explosion at ICMESA chemical plant in Seveso, Italy released heavy concentration of 2,3,7,8-TCDD in densely populated area. Workers (156) and residents (37,000) exposed. More than 500 treated for presumed toxic symptoms; 134 cases of chloracne. Mortality rate normal to date. Event received worldwide publicity through news media. 1978 - Dow announced chlorinated dioxins found in particulate matter in air emissions from various commercial and domestic combustion processes. 1979 - Suit filed by Vietnam veterans against five U.S. chemical companies that produced Agent Orange. Companies, in turn, filed third party action against U.S. government for its negligent misuse of the chemical 1982 - Times Beach DIOXIN Chemical Nomenclature: Dioxin = Dibenzo--dioxin 82 73 Media: Dioxin = 2v3,7,8-Tetrachlorodibenzo-&-dioxin = 2,3,7,8-TCDD -t - # I CHLORINATED DIOXINS (CDDs) cix cix 75 CDDs 22 TCDDs 2,3,7,8-TCDD - most toxic isomer to the male guinea Pig CCDs 10 to 20 times more toxic than chlorinated dibenzofurans in the rabbit ear test Cix Clx STRUCTURE AND PHYSICAL PROPERTIES OF 2,3,7,8-TCDD ci Cl ci Cl Physical State: Molecular Weight: Melting Point, C.: Decomposition Point, C.: Solubility: White, crystalline solid 322 303-305 980-1000 Water = 2 x 10~8 g./L Benzene = 0.57 g./L .o-Di chlorobenzene = 1.4 g./L SOURCES AND FORMATION OF DIOXINS Formed during manufacture of chlorophenols intermediates in synthesis of pesticides. Thus contaminants in chlorophenol derived pesticides. Pyrolysis (<750C) of chlorophenols or chlorophenol derived pesticides. Formed in a wide variety of commercial and domestic combustion processes. -* r REQUIREMENTS FOR DIOXIN FORMATION Precursor must contain an o-substituted benzene ring with one of the substituents being an oxygen atom attached directly to the ring. R The two substituents must be able to react with each other to form another compound. The reaction is favored by basic conditions (e.g., sodium hydroxide) and temperatures of 180-400C. Presence of a metal catalyst (e.g. copper or iron powder) promotes the reaction. MANUFACTURE OF 2 5 - T Step 1 + 4 Cl2 Benzene Chlorine Cl Cl Cl Cl TCB (1,2,4,5-Tetrachlorobenzene) 4 HC1 Hydrogen chloride Step 2 Cl + 2 NaOH + 2 CH3OH Sodium Methanol Cl hydroxide ONa + CH3OCH3 Dimethyl ether + NaCl + NaTCP Sodium (Sodium 2,4,5- chloride trichlorophenate) 2 H 20 Water Step 3 Cl ONa Cl Cl + ClCH2 C00Na -----;> + NaMCA (Sodium monochloro- acetate) Na 2,4,5-T (Sodium 2,4,5-trichlorophenoxyacetate) NaCl ^ H2SOi+ ---- > Sulfuric acid 2,4,5-T (2,4,5-Trichlorophenoxy- acetic acid) Na2SOi+ Sodium sulfate FORMATION OF 2,5,7,8-TCDD AS SIDE REACTION IN MANUFACTURE OF Nq TCP NaTCP "Predioxin" sodium salt NaCl Sodium chloride Y Cl ci 2,3,7,3-TCDD NaCl MANUFACTURE OF PENTA AND SANTQBRITF OH Phenol + 5 Cl2 Chlorine OH NaOH Sodium hydroxide Cl + Cl Penta (Pentachlorophenol) 5 HCl Hydrogen chloride Cl + h 2o Cl Water Santobrite FORMATION OF CHLORINATED DIBENZO-E-DIOXINS AND CHLORINATED DIBENZOFURANS AS SIDE REACTIONS IN MANUFACTURE OF PENTA Octachlorodibenzo-dioxin 1 ,2 ,3 ,4 ,5, 7 ,*8 Heptachloro-6 -hydroxy dibenzofuran z' METHODS OF DESTRUCTION OF CHLORINATED DIOXINS Incineration at temperatures of 1000 to 1500 in industrial incinerators. Future: molten salt combustion or microwave plasma destruction. Degraded quickly by sunlight or artificial ultraviolet light (photolysis). Chemical destruction by ozonolysis, chlorinolysis, catalytic wet oxidation (Zimpro process), and catalytic dechlorination processes. Biological destruction by new genetic engineered bacteria may hold future promise. CHEMISTRY OF INCINERATION OF 2,5,7,8-TCDD 2,3,7>8-TCDD Oxygen Hydrogen from organic donor 12 co2 + 2 h 2o + 4 HCl Carbon dioxide Water Hydrogen chloride CHEMISTRY OF PHOTOLYSIS OF 2,3,7,8-TCDD 2j 3j 7 j8-JCDD Hydrogen from organic donor Dioxin + 4 HC1 Hydrogen chloride 2-Hydroxydiphenyl oxide Polymer III. HISTORICAL OVERVIEW; PHENOXY HERBICIDES & CHLORACNE REFERENCE: "The Science of 2,4,5-T and Associated Phenoxy Herbicides", R. W. Bovey and A. L. Young/ Wiley, New York, 19801 1930's Chloracne, a dermatitis characterized by comedones (blackheads) similar to teen-age acne but often more severe, was noted among workers dealing with chlorinated aromatic (benzene-derived) hydrocarbon materials. Components which cause chloracne are termed "chloracnegens". 1941 2,4-D and 2,4,5-T first synthesized. 1942 Cell elongation in plants by 2,4-D a concentrations first established. 1944 Effectiveness and selectivity of 2,< broad-leaf weeds in lawns and the f established grasses was established 1947 Effectiveness of 2,4,5-T and deriva plants resistant to 2,4-D established. 1950 Presence of "a highly toxic impurity" in production of TCP recognized by Dow. ' 1957 TCDD first implicated as causative agent for chloracne (Kimmig and Schultz, Germany). 1964 Dow tecognized waste oils from TCP caused chloracne. 1965 TCDD recognized by Dow as causative agent for chloracne in TCP wastes. Alerted health authorities and other 2,4,5-T manufacturers. Shared analytical techniques. 1966 Dow able to lower TCDD content of 2,4,5-T to less than 1 ppm. r ii Rev. 1 - 11/5/82 ATTORKR Vf03X attorke-c u n i ffiiv. C06949