Encyclopedia of Environmental Science and Engineering, Volume I and II

898 PCBs AND ASSOCIATED AROMATICS

distribution since there was a positive correlation between the

dioxin level and age. Sielken’s correlation for the St. Louis

population was

log e [TCDD]  1.02  0.023  age; r  0.72.

The observation might be partially explained by persons

ingesting a contaminated diet but does not support an ini-

tially high exposure of the population to contaminated moth-

er’s milk. Schecter et al.^79 have compared the results from

several workers on the concentrations of PCDDs and PCDFs

in human milk derived from north and south Vietnam and

the United States. They then went on to calculate the 2,3,7,8-

TCDD equivalents contained in the milk and to derive the

ratio between the first year intake and the recommended

intake values. The data showed that in south Vietnam, and

a small percentage of the population in the US are exposed

to 2,3,7,8-TCDD concentrations in mothers milk which are

sometimes very much greater than the limits set by both

the USEPA and the United States Public Health Services

Centers for Disease Control (USCDC). The calculations are

extended in Table 31 to include the data reported by Ogaki

et al.^80 on Japanese foodstuffs.

Table 32 shows the estimated daily intake of total

2,3,7,8-TCDD equivalents by nursing infants in South and

North Vietnam, Japan and the United States. It has been

assumed that an average consumption of milk is 800 mL/day

and that the body is 10 Kg. The “Acceptable Daily Intake”

or ADI value for the ingestion of 2,3,7,8-TCDD set by the

EPA for an assumed 70 year lifespan is 1 pg/Kg/d. Adults

are assumed to be 55 Kg for Vietnamese residents and 70 Kg

for North Americans.

The data in Table 31 were used to calculate 2,3,7,8-

TCDD equivalents in Table 32. The daily intake of a nursing

baby was derived on the assumption that an average of 800

mL of milk were consumed per day. The first year intake

is then 365 times the daily intake corrected for an assumed

body weight of 10 Kg. It is further assumed that there is no

further ingestion or excretion of PCDDs/PCDFs during the

70 year lifespan of the individual. Under such a condition,

TABLE 29

There is a strong correlation between the observed ratios of PCDDs

and PCDFs in tissues in northern Japan with the ratios found in foods

Tissue (T 4 )t (P 5 )t (H 6 )t (H 7 )t (O 8 )t

Lung 0.2 1.2 1.5 1.4 0.02

Liver 0.3 1.2 3.9 1.1 0.01

Kidney 0.7 0.8 1.8 0.5 —

Adipose 0.5 0.5 0.8 1.1 0.05

(T 4 ) i  ratio of T 4 isomers in the daily food intake

(T 4 ) t  (T 4 CDDs/T 4 CDFs) t  ratio of T 4 isomers in tissue.

TABLE 30

TCDD equivalents of different PCDD/PCDF congeners

Congeners USEPA Swiss Danish German Eadon

2,3,7,8-TCDD 11111

1,2,3,7,7-P 5 CDD 0.5 0.1 0.1 0.1 1

1,2,3,4,7,8-H 6 CDD 0.04 0.1 0.1 0.1 0.033

1,2,3,6,7,8-H 6 CDD 0.04 0.1 0.1 0.1 0.033

1,2,3,7,8,9-H 6 CDD 0.04 0.1 0.1 0.1 —

1,2,3,4,6,7,8-H 7 CDD 0.001 0.01 0.01 0.01 —

O 8 CDD — — — 0.001 —

2,3,7,8-TCDF 0.1 0.1 0.1 0.1 0.33

2,3,4,7,8-P 5 CDF 0.1 0.1 0.2 0.1 0.33

1,2,3,4,7,8-H 6 CDF 0.01 0.1 0.1 0.1 0.02

1,2,3,6,7,8-H 6 CDF 0.01 0.1 0.1 0.1 0.02

2,3,4,6,7,8-H 6 CDF 0.01 0.1 0.1 0.1 0.02

1,2,3,4,6,7,8-H 7 CDF 0.001 0.01 0.01 —

O 8 CDF — — — 0.001 —

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