Document YD1rbDGYy0zJgw7MpRp1GoGDV

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, 004412 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,A,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; 13A 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 coranercial 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 = Dlbenzo-jj-dloxin e2 73 Media: Dioxin = 2,3,7,8-Tetrachlorodibenzo-p-dioxin = 2,3,7,8-TCDD CHLORINATED DIOXINS (CDDs) c ix 75 CDDS 22 TCDDs 2,3,7,8-TCDD - most toxic isomer to the male guinea Dig CCDs 10 to 20 times more toxic than chlorinated dlbenzofurans In the rabbit ear test Clx 0  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 fi-Dichlorobenzene = l.z* 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. fr ~ 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. 0-- R X The two substituents must be able to react with each other to form another compound. ,,ONa h 3c Na'jO 2 NaCl The reaction is favored by basic conditions (e.g., sodium hydroxide) and temperatures of 18(M00C. Presence of a metal catalyst (e.g., copper or iron powder) promotes the reaction. o MANUFACTURE OF 2,4,5-T Step 1 Step 2 Step 3 + 4 Cl2 Benzene Chlorine Cl Cl Cl TCB (1,2,4,5-Tetrachlorobenzene) 4 HC1 Hydrogen chloride Cl Cl + 2 NaOH + 2 CH3 OH Sodium Methanol Cl hydroxide 170C ONa + CH3 OCH3 Dimethyl ether + NaCl + Sodium (Sodium 2,4,5- chloride trichlorophenate) 2 H20 Water Cl ONa Cl + ClCH2 C00Na -- NaMCA (Sodium monochloro- acetate) Cl OCH2COONa + Cl Cl Na 2,4,5-T (Sodium 2,4,5-trichlorophenoxyacetate) NaCl Step 4 Cl 0CH2 C00Na + % H2S0it Cl Cl Sulfuric acid Cl -a Cl 0CH2 C00H + 2,4,5-T (2,4,5-Trichlorophenoxy- acetic acid) 5 Na2 SOit Sodium sulfate FORMATION OF 2,5,7,8-TCDD AS SIDE REACTION IN MANUFACTURE OF Nq TCP NaTCP Na "Predioxin" sodium salt NaCl Sodium chloride 2,3,7,3-TCDD NaCl MANUFACTURE OF PENTA AND SANTOBRITE OH Phenol + 5 Cl2 OH Cl JL Cl 60-190C Y^lY ---- * JL 1 + Chlorine ci Penta (Pentachlorophenol) 5 HCl Hydrogen chloride OH Cl Cl VCl"r t ^C1 Cl + NaOH 70-90C Sodium hydroxide ONa Cl Cl VCl" ^C1 Cl Santobrite h 2o Water FORMATION OF CHLORINATED DIBENZO-^-DIOXINS AND CHLORINATED DIBENZOFURANS AS SIDE REACTIONS IN MANUFACTURE OF PENTA Oc tachlorodibenz o-dioxin l,2f3 t4,5,7;8Heptachloro-6 -hydroxy dibenzofuran 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 + 12 02 + 4 [H] 1000-1500C Oxygen Hydrogen from organic donor 12 C02 + 2 H20 Carbon dioxide Water 4 HCl Hydrogen chloride CHEMISTRY OF PHOTOLYSIS OF 2,3,7,8-TCDD 2,3,7,8-TCDD + 8 [H ] hv > Hydrogen from organic donor + 4 HC1 Hydrogen chloride + 2 [H] 2-Hydroxydiphenyl oxide Polymer III. HISTORICAL OVERVIEWS PHENQXY 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 at low concentrations first established. 1944 Effectiveness and selectivity of 2,4-D for removal of broad-leaf weeds in lawns and the field without harming established grasses was established. 1947 Effectiveness of 2,4,5-T and derivatives against woody 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 recognized 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. Rev. 1 - 11/5/82 C06949