Table 1. Levels of PCDDs in commercial chlorinated phenols, and levels 

 of 2,3,7,8-TCDD in 2,4,5-T acid and ester formulations (Hardell 1983). 



Formulation 



Geographic 

 locale 

 (year) 



Concentration, in mg/kg (ppm) 

 PCDDs 2,3,7,8-TCDD 



2,4,5-T Acid 

 2,4,5-T Ester 

 2,4,5-T Ester 

 2,4,5-T Ester 

 2,4,5-T Acid 

 2,4,5-T Acid 

 Agent Orange 

 Agent Orange 



2,4,6-trichlorophenol 



2,4,6-trichlorophenol 



2,3,4,6-tetrachlorophenol 



Pentachlorophenol 



Pentachlorophenol 



Sweden (1952) 

 Sweden (I960) 

 Finland (1962) 

 Finland (1967) 

 USA (1964) 

 USA (1969) 

 USA (-) 

 USA (-) 



Sweden (-) 

 USA (-) 

 England (-) 

 USA (-) 

 Germany (-) 



3.0 



0.3 



12.0 



1,900-2,625 



6.8 



1.10 



0.40 



0.95 



0.22 



4.8 



6.0 



0.12 



5.1 



soluble in organic solvents, and will decompose on exposure to UV light, 

 including sunlight (NIOSH 1984), or to hydroxyl compounds (Josephson 1983). 

 The isomer 2,3,7,8-TCDD is a colorless crystalline solid at room temperature 

 and decomposes when heated at greater than 700 C (Table 2). 



Data on 

 incorporated 

 are bioavail 

 litter have 

 of indi vidua 

 as closely 

 and 1,2,4,7, 

 activity and 

 2,3,7 and 

 toxic PCDD i 

 ODD, 1,2,3,7 



the biovai lability of PCDDs are scarce. It is 



into wood as a result of chlorophenol (prese 

 able. Swine and poultry using chlorophenol -trea 

 been found to be contaminated with PCDDs (NRCC 1 

 1 PCDD isomers can vary by a factor of 1,000 to 



related as 2,3,7,8-TCDD and 1,2,3,8- TCDD or 1 

 8-penta CDD (Rappe 1984). Isomers with the h 



acute toxicity have 4 to 6 chlorine atoms, and 

 8) positions substituted with chlorine. On th 

 somers are 2,3,7,8-TCDD, 1,2, 3, 7, 8-penta CDD, 

 ,8,9-hexa CDD, and 1,2,3,4,7,8-hexa CDD (Rappe 1 



known that PCDDs 

 rvative) treatment 

 ted wooden pens or 

 981). Toxicities 

 10,000 for isomers 

 ,2, 3, 7, 8-penta CDD 

 ighest biological 

 all lateral (i.e., 

 is basis, the most 

 1,2,3,6,7,8-hexa 

 984). 



Although PCDDs are highly persistent, volatilization and photolysis are 

 major removal processes (NRCC 1981). In soils, 2,3,7,8-TCDD undergoes 

 photolysis rapidly on the surface in a few hours, but more deeply buried 

 2,3,7,8-TCDD could have a chemical half-time greater than 10 years (NRCC 

 1981). Microbial degradation of 2,3,7,8-TCDD in soils is slow, with 

 biological half-times estimated at 1.0 to 1.5 years (Ramel 1978). However, 

 2,3,7,8-TCDD was detected in northwestern Florida from samples of soils. 



