AndyB wrote:
Chuck Harris wrote:
....
We have several of those folks here on the group, and they have
related their
personal experience.


Thats a bit like the "My grandad smoked 80 a day all his life and lived
to a 101" chestnut. Is this proof that smoking doesn't give you cancer
or that the cancer statistics are wrong?

Smoking and cancer are a funny (as in peculiar) example to pull out as a
comparison to PCB exposure. First, the anti smoking groups pretend that
no one ever got lung cancer without smoking. The truth is more like as
many people get it with smoking as get it without. The cancer connection
is difficult. The heart disease and emphasema associations are much easier
to prove... and I am not now, nor have I ever been a smoker.

Second, smoking is a great act of self deception. People who smoke go out
of their way to become heavily exposed to tobacco smoke. It doesn't seem
to me that it would be all that common for people to intentionally ingest
PCB's.

Being in the presence of PCB is not the same as being exposed to PCB, or
ingesting PCB.

Personal experience or anecdotal evidence means very little when dealing
with long term toxicity (unless the illness is specifically associated
with a given exposure, like asbestos and mesothilioma). It is medical
statistics of a large, controled group that shed any truth to a matter
such as this. Unfortunately, these are hard to come by because of the
long term nature of PCB toxicity in a society literally bathed in
chemical contaminants and highly mobile.

There a couple of ways of looking at that. The one I tend towards is
the connection can't be found because it doesn't actually exist for such
small levels of exposure.

Even closely monitored exposures, like the Seveso incident in Italy are
inconclusive (I once spoke to the head of toxicology for the UKs
Chemical Response Unit who reckoned that no-one found any ill effect
from that incident, but she was defending a hazardous waste site at the
time.)

Again, this is probably because the connection doesn't exist for small
levels of exposure.

....


The World Health Organisation place a TDI of 1-4 picograms (a picogram
being a *trillionth* of a gram) on Dioxin-like PCB's.

Dioxin and PCB's aren't the same thing. The WHO TDI is a limit for *ingested*
amounts of PCB on a *continual* (eg. daily) basis, not an extremely
infrequent, accidental skin exposure to a very small quantity (such as might
happen if one touches a leaky PCB coated capacitor). You cannot legitimately
infer that because PCB has a 1-4 picogram TDI, that occasional skin
exposure to a 1-4 picogram sample is harmful.

No one is suggesting that the PCB be intentionally ingested over a long term.
And no one is suggesting that you make a habit of exposing yourself to PCB.

We are all going to die of something. And yet with all of our exposure to
toxic chemical coctails, heavy metals, and radiation, quality of life, and
life expectancy continues to rise...(even accounting for the extreme lack
of childhood deaths due to the success of vaccines on the usual childhood
diseases.)

Reasoned caution is good, but hysteria isn't all that useful in cases like
this.

-Chuck