[Hallicrafters] More on polychlorinated biphenyls (PCB's)

[Barry L. Ornitz]

Old friend, Roy Morgan, K1LKY, asked:

> Barry, and others,
> 
> I *REALLY* appreciate any more or less hard facts posted on 
> this topic, particularly Barry's last post giving names of 
> the oils used in capacitors.
> 
> Though I have some capacitors at my place that almost 
> certainly contain PCB's, I am more interested in cleanup 
> methods than in disposal methods.  I assume that PCB's are 
> dangerous to the environment and would not just fling 
> old capacitors over the back fence.
> 
>   I am interested in guidance on the following points:
> 
> 1) If I find a capacitor or transformer or choke leaking, is 
> the leakage dangerous to me if I get the stuff on my hands?

Yes, you should avoid contact with the material.  It is hazardous.  
Read on for details.

> 2) Are PCB compounds dangerous only, or especially, if 
> burned?

PCB's are bad enough by themselves; they become even more 
hazardous if burned incompletely.  Incineration of PCB's 
requires a very high temperature incinerator, much higher than 
those used for municipal wastes.  In fact, the EPA requires 
periodic testing of PCB-rated incinerators to insure they are 
operating properly and to renew their permits.

Again, let me go into more detail as this post continues.

Bill Gerhold, K2WH, wrote:

> As an ex GE engineer, Pyranol is pure PCB about 65,000 ppm.

Pyranol 1467 was a mixture of chlorinated benzenes and 
biphenyls.  Pyranol 1476 was a mixture of isomeric 
pentachloro-biphenyls, and Pyranol 1478 was a mixture of 
isomeric trichlorobenzenes.  The mixtures containing the 
chlorinated benzenes were more common in transformer 
applications where lower viscosity was important.

Pyranol 1476 is considered "pure" PCB.  It has approximately 
54% chlorine on a weight basis.  Pure PCB would be one million 
parts per million, so I do not understand Bill's statement.

But this brings up an interesting point.  The Monsanto process 
for making PCB's started with biphenyl.  It is a little 
difficult to show the chemistry without the ability to show 
graphics so bear with me.  Biphenyl is a compound containing 
12 carbon atoms and 10 hydrogen atoms.  Its structure is two 
joined benzene rings.  The 10 hydrogen atoms attached to the 
two rings provide 10 sites for chlorination.  By using 
anhydrous chlorine, in the presence of iron filings or ferric 
chloride catalyst, these 10 sites were chlorinated (the 
hydrogen atoms were replaced by chlorine).  But the reaction 
was not particularly specific.  Instead of producing a pure 
product, a mixture of polychlorinated biphenyls were 
produced.  In addition, small quantities of byproducts such as 
chlorinated naphthalenes and chlorinated dibenzofurans were 
produced.  The presence of some of these byproducts is very 
important to the toxicology of the PCB mixture.

Each of these different compounds are called cogeners.  There 
are 209 of them.  They each have different chemical, physical, 
and toxicological properties.  Because of their chemical 
structure, which resembles 2,3,7,8-tetrachlorodibenzo-p-
dioxin, thirteen are considered to have "dioxin-like" 
toxicity.  The World Health Organization has assigned what 
they term Toxic Equivalency Factors to the PCB cogeners.  Many 
chlorinated dibenzofurans are also considered to have dioxin-
like toxicity.  By the way, the 3,3',4,4',5-
Pentachlorobiphenyl cogener has the highest TEF (0.1) and it 
is a common constituent of many industrial PCB mixtures.

The reactions were carried out until a chosen average chlorine 
concentration was produced.  The actual composition of each 
production batch was different.  For most commercial products 
Monsanto produced, there were typically 50 or more cogeners in 
each product.  The only generalizations that can be made are 
that the cogeners with a lower degree of chlorination are 
generally less persistent, more water soluble, and more 
flammable than PCBs with more chlorine atoms.  By less 
persistent, I mean that these compounds tend to degrade and be 
destroyed by oxidation when released to the environment.  
Sadly, the very reason PCB's were used - their stability and 
resistance to oxidation - mean that the compounds with higher 
degrees of chlorination stick around in the environment for a 
very long time.  For all practical purposes, they are here 
forever.

PCB's are poorly metabolized and they tend to accumulate 
in animal tissues or organs rich in lipids (fats).  
Unfortunately, compounds with a degree of chlorination above 
50% (like the pentachlorobiphenyls) are the worst offenders.  
PCB's can be found in human fat and plasma at detectable 
levels in almost all persons.  But the jury is still out on 
exactly what low levels are hazardous.  We know much more 
about the effects of exposure to high levels.

The known toxic effects of PCBs in humans exposed to high 
concentrations include an acne-like skin eruption (chloracne), 
brown pigmentation of the skin and nails, excessive eye 
discharge, swelling of eyelids, visual disturbances, 
distinctive hair follicles, systemic gastrointestinal 
symptoms, disturbance in liver function including jaundice, 
immune system damage, respiratory tract irritation, headaches, 
dizziness, depression, memory loss, fatigue, and impotence.  
Some of these symptoms lasted up to three years in some 
patients.  Infants born to mothers with high exposure often 
have decreased birth weight and skin coloration.

With prolonged exposure at low levels, investigators have 
reported liver damage, reproductive and development defects, 
and possibly cancer.

The cancer issue is a complex one and one with somewhat 
inconclusive results at present.  Laboratory animal 
experiments have shown many malignant, non-malignant, and 
reproductive effects.  The oncogenic (cancer causing) 
potential of PCB's has been shown to vary with exposure in 
laboratory animals.  Studies with laboratory rats fed with 
PCB-containing food for two years developed liver cancer.  
Studies on humans (and primates) have been less conclusive, 
although studies have shown that monkeys are affected at lower 
dosages than most other species.  Early research from a 1976 
study by Mobil Oil Corporation showed a possible association 
between occupational exposure to PCB's and cancer in humans.  
Yet later studies have concluded that the epidemiological data 
are not now adequate to confirm or negate the 
carcinogenic potential  of PCB's in humans.  We need more 
research to correlate the human and animal data.

Until more of this research is performed, the EPA finds no 
evidence to suggest that the animal data would not predict an 
oncogenic potential in humans.  Thus the Department of Health 
and Human Services (DHHS) has concluded that PCBs may 
reasonably be anticipated to be carcinogens, while the EPA and 
the International Agency for Research on Cancer (IARC) have 
determined that PCBs are probably carcinogenic to humans.

Quoting from the U. S. Department of Health and Human 
Services, November 2000 report on the toxicological profile 
for PCB's, the following paragraph is quite telling.

   "Carcinogenicity of PCBs in humans has been investigated 
   in retrospective occupational studies that evaluated 
   cancer mortality in workers exposed during capacitor 
   manufacturing and repairing, and in case-control studies 
   of the general population that examined associations 
   between cancer and serum or adipose tissue levels of PCBs 
   resulting from environmental exposures. Based on 
   indications of PCB-related cancer at several sites, 
   particularly the liver, biliary tract, intestines, and 
   skin (melanoma), the human studies provide suggestive 
   evidence that PCBs are carcinogenic. There is unequivocal
   evidence that PCBs are hepatocarcinogenic in animals."

My view on all of this is that until we learn otherwise, we 
should treat exposure to PCB's as exposure to potential 
carcinogens.  Taking extra precautions now will certainly do 
no harm, while ignoring them might cause problems in the 
future.

To go to Roy's second question, the EPA is very concerned 
about the toxicity of the chemicals produced when PCBs are 
involved in fire-related incidents. These chemicals include 
polychlorinated dibenzofurans (PCDFs) and polychlorinated 
dibenzo-p-dioxins (PCDDs), both of which are believed to be 
much more toxic than PCBs themselves.  The toxicological 
effects of these chemicals include embryotoxicity, 
teratogenicity (birth defects), reproductive effects, and 
oncogenicity (producing cancer).  So as I said above, treat 
PCB's with the utmost respect, and whatever you do, avoid 
exposure to anything involved with the combustion of PCB-
containing materials.

In an earlier post, I offered to provide my recommendations on 
cleaning radio equipment that might have leaking capacitors 
which may contain PCB's.  I had forgotten that Ed Sharpe, 
archivist at the Southwest Museum of Engineering, 
Communications, and Computation, has placed my previous 
document on this on the SMECC website.  Check out:

    http://www.smecc.org/haz-mat_in_military_comm_.htm

Following this procedure are two articles on electrolytic 
capacitors, information on why film resistors are superior to 
the old carbon composition units for restoring old radio gear, 
and finally an article on estimating the ratings of 
transformers.  Beware!  I like math...

Bill, K2WH, later wrote:

> I worked in GE's large transformer division for years (20+), 
> with men who worked up to their elbows in this stuff.  They 
> all have normal looking children and none of them came down 
> with cancer that I know of.
>
> The most debilitating effect these men suffered was mild 
> dermatitis.  This is because they didn't wear any protective 
> gear.  I believe the cancer scare came about through studies 
> with rats or some other animal.  The media got a hold of it 
> and the rest is history.  Our people were not eating the 
> PCB's - at least not deliberately!  One of the other reasons
> the stuff was banned is because it does not degrade 
> apparently at all over time.  That means if you spill some 
> of this stuff, it will basically remain intact as PCB 
> forever.
>
> As for myself, I could not touch the oil because of skin 
> sensitivity to it.  I would say it is "Some shade of Grey" 
> with current information.

Bill is certainly welcome to his own opinion, or that of 
GE, but I think the advice he gives makes PCB's seem far safer 
than they really are.  One interesting aspect of PCB exposure 
is that the offspring of animals (and people) tend to show 
more harmful effects of exposure than do the parents and some 
effects tend to skip a generation.  Considerable research has 
shown PCB exposure has marked effects on the endocrine systems 
of children born to exposed parents, especially the thyroid.  
The reproductive effects of PCB exposure on men seems to be 
far less than on women too.  Thus Bill's anecdotal evidence 
about fellow male co-workers may not give the whole story.

As I stated in my earlier post, there are literally thousands 
and thousands of documents on the subject.  Many are available 
online.  Just do a Google search and look at the number of 
hits.  I am by no means THE world's expert on PCB's, but I 
believe my training and experience in the chemical industry 
certainly give me more perspective than the average amateur 
radio operator.  Also let me add that 36 years ago, I too had 
my hands in PCB oil.  I have personal reasons to wish the 
hazards are small!  I wish I knew then what I know now...

So in summary, I consider leaking oil-filled capacitors to be 
a definite hazard.  The website I referenced gives my 
suggested procedure for cleaning up such a hazard with 
reasonable safety.  I hope my posts on this subject have been 
helpful in debunking some of the myths, or at least getting 
the readers to do more research on their own.

   73,  Dr. Barry L. Ornitz     WA4VZQ     ornitz at tricon.net
               Copyright 2003  B. L. Ornitz  
  Do not repost or place on a website without my permission.