|
 Carbon
tetrachloride (CCl4) was a common cleaning agent used
commercially through about the early 1950s when it began receiving
a lot of bad press due to a linkage to severe kidney damage from
exposure even in vapor form. I notice that Mac mentions having read
an article about the potential danger of 'carbon-tet' in an edition
of
Radio & Television News, not coincidentally the publication
where the "Mac's Radio Service Shop" series appears. He also mentions
a publication called
International Projectionist (see thumbnail at left),
which included instructions for cleaning movie film with carbon
tetrachloride, and had a warning about health risks. Dry cleaners
were big users, as were industrial production facilities because
of its exceptional degreasing properties.
Lots of cleaning agents have come and gone over the years. Back
in the early 1980s while working for Westinghouse Oceanic Division
in Annapolis, Maryland, we routinely used methyl ethyl chloride
(MEK) to clean flux off PC boards and for removing lacquer coatings
from components and markings. Sometime around 1984-85 or so it was
withdrawn from use due to having been placed on the suspected carcinogen
list. Today and for the last two decades, I have been buying
MEK at Home Depot and using it for cleaning parts prior to painting,
so evidently a government panel somewhere has decided it is not
as dangerous as originally thought.
Mac's Radio Service Shop: Carbon-Tet Can Kill
By John T. Frye
"Hey, Barney," Mac's muffled voice came from behind the closed
door of the chassis-cleaning closet, "step outside and see if you
can smell any carbon-tet fumes at this exhaust-fan port."
The apprentice technician of Mac's Radio Service Shop went out
into the alley and sniffed cautiously at the strong current of air
being pushed out by the fan. "Sure can," he called; "where's it
coming from?"
"Come on back in here and see," Mac invited.
When Barney opened the door of the cleaning closet, he immediately
noticed some changes. For one thing, a sort of metal funnel was
mounted with its large opening pointing directly toward the exhaust
fan and only a couple of inches away from it. From the smaller end
of the funnel a piece of down-spouting went down along the wall
and terminated in a ninety-degree elbow that rested on the floor.
In front of the open mouth of this elbow was a piece of gauze that
had been soaked in carbon tetrachloride. Replying to the boy's questioning
look Mac explained:
"Carbon-tet fumes are five times as heavy as air; so I cooked
up this arrangement to pull them right off the floor without interfering
too much with the sucking out of dust from the top of the room.
That fact that you could detect the carbon-tet vapor outside while
I could smell none of it in here shows that the system is working."
"And that's good?"
"I'll say it's good. Just recently I've had my eyes opened to
just how dangerous breathing carbon-tet fumes can be; and when I
think of how carelessly we have been using the stuff in the past,
I feel like a man who has just found out that the make-shift poker
he has been using to stir the fire is really a stick of dynamite."
"How did you get hep to all this?"
"I had a little 'hint' published in Radio & Television
News" that involved the use of the cleaning fluid. That brought
me a letter from an instructor at the Coast Guard Institute asking
if I was aware of the very real danger that lurked in the improper
use of the chemical - a danger that he had seen demonstrated very
tragically. Naturally, I asked him for more information; and at
the same time I wrote to the American Medical Association and to
one of the country's largest manufacturers of carbon-tetrachloride
for their opinions. I also mentioned what I was doing to Dick Rider,
the operator down at the State Theater, and he promptly came up
with some back issues of a trade magazine called "International
Projectionist" that discussed the use of the cleaning agent in the
operating booth. From all these sources came warnings that say substantially
the same thing: carbon-tetrachloride can and will cause serious
illness and death if proper precautions are not observed in its
use."
"I've noticed that bottles of the stuff always carry warning
labels saying you should not breathe the vapor," Barney mused; "but
I never paid much attention to them. How does it get you?"
"It can do serious harm if the vapor is inhaled, if it is taken
internally, if it is splashed into the eyes, or even if it is permitted
to come into contact with the skin."
"Sounds like a lot of stuff to me," Barney said skeptically.
"While I've never tried drinking it or splashed it into my eyes,
I've inhaled a lot of vapor and have had it all over my hands lots
of times, and I'm still kicking."
"You've been mighty lucky," Mac said. "One thing that has helped
is that you have usually used the carbon-tet in here with the exhaust
fan going, and that has kept the vapor concentration down. However,
it does not take a heavy concentration to be dangerous. Doctors
used to think that anything under 100 parts per million was safe,
but now they think it is desirable to keep the vapor below 50 parts
per million. You can get an idea of just how little this is when
I tell you that a normal nose just begins to detect the odor at
79 parts per million."
"Maybe some people can take more of it than others can."
"That's quite true. In one case I read about, four men were working
together using carbon-tet for cleaning purposes. The next day one
of the men developed symptoms of carbon-tetrachloride poisoning.
Three days later, since he was still not feeling well, he entered
a hospital. Ten days later, in spite of proper medical care, he
died. None of the other three men showed any ill ef-fects."
"Then poisoning doesn't always show up right away," Barney observed.
"That's one of the treacherous things about it," Mac replied. "It
is not unusual for symptoms to show up from two to eight days after
exposure, and because of this the connection between the poisoning
and the use of the chemical is often overlooked. But to get back
to the subject of the varying reaction of people to carbon-tet,
it has been discovered that certain groups of people are especially
susceptible to poisoning. These groups include fat people, undernourished
people, alcohol addicts, and people who suffer from diabetes, liver
or kidney diseases, jaundice, pulmonary and heart disease, or peptic
ulcers."
"So alcohol and carbon-tet don't mix, eh?" Barney said thoughtfully.
"Boss, you had better clean the sets this afternoon. Mom hasn't
noticed it yet, but her sweet cider is beginning to taste more interesting
every day now, and I hit it up pretty hard after dinner. I know
you wouldn't want me to take any chances."
"Well, you have already had a whiff of the vapor; so let's see
if you have any of the typical symptoms of vapor-poisoning," Mac
said with a grin. "The symptoms depend somewhat upon the concentration
of the vapor and the duration of the exposure; but in general they
are a feeling of fullness in the head, mental confusion, and headache;
and then this is followed by nausea, stupor, and loss of consciousness.
In severe cases there may be trouble with the vision and the coughing
up of bloody mucus. If the person is not removed to a safe area
promptly, death may occur because the person simply stops breathing."
"Suppose you should topple over while you were using the stuff
here at the bench. What ought I to do?"
"Drag me outside into the fresh air. If I quit breathing, administer
artificial respiration at once and keep at it until I start to breathe
naturally again. Keep me lying down and warm. After I regain consciousness,
you can give me some hot tea or coffee to drink. Of course, a doctor
should be summoned at the first opportunity and the treatment turned
over to him."
"Is there anything I should be careful not to do?"
"Yes; never give alcohol, fats, oils, or epinephrine to a person
who has been exposed to carbon tetrachloride."
"What's the best thing to do if you accidentally get some of
it in your eyes?"
"Wash them at once with large quantities of water for a period
of at least fifteen minutes."
"What would you do for a person who accidentally drank some of
the liquid ?"
"That would be particularly dangerous, for
drinking only 3 or 4 cc of carbon-tetrachloride may cause death.
The first thing to do is to cause vomiting by making the victim
drink a glass of lukewarm salty or soapy water. This unpleasant
but necessary procedure should be repeated at least three times
to insure that all poison possible is removed from the stomach.
Then a teaspoon of Epsom salts in water can be given. That is about
all the layman can do outside of seeing to it that the victim is
placed in the hands of a competent doctor as quickly as possible."
"What does it hurt to get carbon-tet on the skin?"
"For one thing it washes away the natural oil of the skin and
results in redness, roughness, and chapping. This, in turn, impairs
the skin's ability to keep out germs and microbes, and infection
is likely to develop. It is especially important to keep the chemical
away from cuts and burned areas on the skin, for, while it has not
been definitely established, there is some evidence that the poison
may be absorbed into the system through such places. Finally, some
individuals display an allergy to the cleaning agent.
"If you do get some of it on the skin," Mac continued, "you should
immediately wash with a mild soap and warm water. Then an ointment
containing petrolatum or lanolin should be applied.
"You know, you're beginning to scare me," Barney admitted.
"You should be scared," Mac said emphatically. "Carbon-tet fumes
are said to be more poisonous than chloroform. If the poisoning
does not cause immediate death, it may result in permanent damage
to the liver, kidneys, heart, adrenal glands, lungs, or digestive
and nervous systems. There is an added danger when carbon tetrachloride
is exposed to an open flame or intense heat, for then it decomposes
and forms the deadly phosgene gas of warfare."
"What kind of safety rules would you recommend ?"
"Always keep carbon tetrachloride in tightly-stoppered bottles
and keep the stoppers in those bottles except when you are actually
extracting some of the liquid. Never use the chemical except out
of doors or in a well-ventilated place, preferably one with down-draft
ventilation. Never allow pads or cloths soaked with the liquid to
lie around, but place them outside as soon as you are through with
them. Take precautions to prevent getting the cleaner in your eyes.
Avoid having the skin in contact with it for a prolonged length
of time, such as would occur when carbon tetrachloride-soaked gloves
are worn. Never place carbon-tet on an open flame or a hot surface.
And, of course, never keep it in a medicine cabinet or with any
other bottles whose contents are taken internally."
"Whew!" Barney gasped. "In view of all that, maybe it would be
better just to quit using it altogether."
"Not at all," Mac denied. "Gasoline is dangerous, too, but that
does not cause us to give up our automobiles and go back to the
horse and buggy. Carbon-tet does a lot of jobs around a radio shop
better than any other chemical agent. It is an excellent dry-cleaning
fluid, metal degreaser, and rubber solvent. You can't beat it for
cleaning turntable rims, wire and tape recorder heads, tuning condenser
wip-ing contacts, or volume controls. It evaporates quickly and
leaves practically no residue. Many manufacturers of turntables,
recorders, TV tuners, etc., recommend its use; and there is no reason
why their recommendations should not be followed; but just remember
to observe common sense precautions when you are using it."
"I'll remember, Boss," Barney promised. "From now on, while I've
got the cork out of that carbon-tet bottle, I'm only going to breathe
out!"
Posted February 4, 2016
Mac's Radio Service Shop Episodes on RF Cafe
This series of instructive
technodrama™
stories was the brainchild of none other than John T. Frye, creator of the
Carl and Jerry series that ran in
Popular Electronics for many years. "Mac's Radio Service Shop" began life
in April 1948 in Radio News
magazine (which later became Radio & Television News, then
Electronics
World), and changed its name to simply "Mac's Service Shop" until the final
episode was published in a 1977
Popular Electronics magazine. "Mac" is electronics repair shop owner Mac
McGregor, and Barney Jameson his his eager, if not somewhat naive, technician assistant.
"Lessons" are taught in story format with dialogs between Mac and Barney.
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