PCBs AND ASSOCIATED AROMATICS 879
there sufficient data to observe any possible trends which
may exist between PCDF formation and temperature/load/
dissolved oxygen conditions. It can only be surmised that
the onset of a hot-spot which is severe enough to cause deg-
radation of cellulosic or Class A dielectric insulation would
result in the failure of the equipment in a time which would
be too short to allow the formation of PCDFs.
An EPRI report on the degradation of PCBs under elec-
trical discharge has shown that PCDFs are not formed.^46 ThePCB components of Yusho oils were primarily tetra- and
pentaCBs with lesser quantities of tri-, hexa- and hepta-
CBs and small quantities of octa- and nonCBs. In contrast
to the predominance of tetra- and pentaCBs in the rice oil,
Yusho patients showed predominantly hexa- and hepta-CBs
in their blood which indicates that a selective metabolism of
the lower CBs had occurred over a period of about 7 years.
This is a very significant finding when considering the rela-
tive toxicity of different PCB formulations. In the case of
Aroclor 1016, for example, the predominant components are
mono- and di-CBs with 0.1% of hexa-CBs. Aroclor 1016,
therefore, would not be expected to bioaccumulate to the
same extent as a PCB mixture containing a larger percentage
of chlorine such as Aroclor 1254.
PCDFs appear to have a different distribution in the body
from that of PCBs. There tends to be accumulation in the liver.
About forty PCDF congeners have been identified in Yusho
oil but, of these, only 10 were found above the detection
limits in the blood of patients. Two tetra-, two penta- and
two hexa-CDFs were identified.^47 The distribution of PCQs
among blood, liver and adipose tissue of Yusho patients has
been found to be similar to that of PCBs although the rate of
elimination of PCQs appears to be similar to, or even a little
faster than that of PCBs.^48TABLE 16
Percent distribution of symptoms of Yusho reported by 189 patients examined before October 31, 1968Symptoms Males N 89 Females N 100Dark brown pigmentation of nails 83.1 75.0
Distinctive hair follicles 64.0 56.0
Increased sweating at palms 50.6 55.0
Acne-like skin eruptions 87.6 82.0
Red plaques on limbs 20.2 16.0
Itching 42.7 52.0
Pigmentation of skin 75.3 72.0
Swelling of limbs 20.2 41.0
Stiffened soles in feet and palms of hands 24.7 29.0
Pigmented mucous membrane 56.2 47.0
Increased eye discharge 88.8 83.0
Hyperemia of conjunctiva 70.8 71.0
Transient visual disturbance 56.2 55.0
Jaundice 11.2 11.0
Swelling of upper eyelids 71.9 74.0
Feeling of weakness 58.4 52.0
Numbness in limbs 32.6 39.0
Fever 16.9 19.0
Hearing difficulties 18.0 19.0
Spasm of limbs 7.9 8.0
Headache 30.3 39.0
Vomiting 23.6 28.0
Diarrhea 19.1 17.0Source: Kuratsune et al. , 1972.TABLE 17
The increase in PCDF concentration in service aged Kanechlor 400
heat exchanger fluids is greater even than the increase found in high
temperature catalyzed fluidsIn Service
Age (yr.)Temperature
(°C) PCBs (ppm)PCQs*
(ppm)PCDFs
(ppm)14 180–270 968,400 31,000 510
3 200–220 999,000 690 277
0 ‡ 999,800 209 33
* PCB polychlorinated quaterphenyl.
‡ not used.C016_003_r03.indd 879C016_003_r03.indd 879 11/18/2005 1:12:32 PM11/18/2005 1:12:32 PM