896 PCBs AND ASSOCIATED AROMATICS
been developed. In addition to Eadon’s model,^73 derived
from data on soot samples taken from the Binghamton
state office building fire, there are also models proposed
by Danish and Swiss groups as well as the USEPA^74. A re-
examination of the USEPA model was presented by J.R.
Olsen et al.^75
Table 30 shows the “TCDD Equivalent” factors used in
different models. The TCDD equivalents of a mixture of
isomers can be calculated by multiplying the amount of
each isomer with its TCDD equivalent from Table 30 and
then summing the individual isomer contributions to the
mixture.
Samples of human breast milk taken from areas in
Vietnam which were sprayed with Agent Orange have
shown markedly increased 2,3,7,8-TCDD levels even 10–15
years after cessation of the contamination. Some of the iso-
mers of PCDDs and PCDFs found in the mother’s milk wereindicative of other contamination sources such as pentachlo-
rophenol wood and paper preservative as well as, possibly,
incineration products. The importance of such studies can be
considered in terms of health risks to infants.
Schecter et al.^76 have observed that the body burden of
2,3,7,8-TCDD alone in nursing mothers from the south of
Vietnam in 1973 was close to the adverse effect level calcu-
lated to cause chloracne in occupationally exposed workers
based upon the “tolerable daily intake” of 30 pg/Kg of body
weight over a 70 year lifetime, nursing infants in both North
America and South Vietnam ingest more than a lifetime dose
of PCDD/F in their first year.^77
The levels of 2,3,7,8-TCDD in human adipose tissue in
North America have been reported for populations in St. Louis,
Atlanta, Utah and in Canada by R.L. Sielken.^78 He pointed
out that the random level of 2,3,7,8-TCDD in human tissue
is more likely to have a lognormal distribution than a normalTABLE 26
The distribution of PCDDs and PCDFs in northern Japanese foods and human tissues (ppt)T 4 CDDs P 5 CDDs H 6 CDDs H 7 CDDs O 8 CDDsSample T 4 CDFs P 5 CDFs H 6 CDFs H 7 CDFs O 8 CDFsTuna 1674/311 1227/459 1259/300 901/t t/t
Flatfish t/N.D. 3120/66 1626/379 1101/t t/t
Mackerel t/27 1413/218 926/113 1051/697 N D./t
Chicken 1171/55 1509/634 539/323 1006/t t/t
Egg 282/14 164/N.D. 326/103 N.D./124 N.D./1256
Milk N.D./36 121/43 86/119 N.D./136 N.D./167
Pork 714/159 N.D./361 N.D./250 N.D./416 N.D./68Rice t/118 208/80 171/54 N.D./508 N.D./222
Flour t/69 56/67 59/61 15/112 N.D./113
Potato N.D./19 17/12 15/122 t/53 N.D./14
Peanuts N.D./227 204/102 88/29 50/470 N.D./181
Soybeans 11/104 16/281 t/62 26/219 N.D./213
Miso N.D./N.D. 18/1662 14/326 21/241 13/23Spinach 36/20 26/36 30/40 18/85 t/131
Radish N.D./35 13/28 t/36 t/51 N.D./t
Mushroom t/t 16/t 14/t t/t t/48
Carrot t/32 38/84 40/27 20/123 t/66Apple N.D./18 28/234 21/38 11/453 t/tLung 1272/143 890/530 635/495 241/487 144/272
Liver 891/150 822/508 342/717 188/298 190/263
Kidney 441/184 1387/519 403/394 394/266 59/t
Adipose tissue 492/129 1658/434 1096/434 301/483 70/356t trace, < 10 ppt, N.D. not detected.C016_003_r03.indd 896C016_003_r03.indd 896 11/18/2005 1:12:37 PM11/18/2005 1:12:37 PM