The Hidden Radioactive Danger of Mantle Lamps

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PHOTO: MOTHER EARTH NEWS STAFF
Although most people are unaware of the problem, the mantles in such lamps are actually radioactive . . . possibly enough so to threaten the health of folks who depend on them.

The lantern–long a standby source of light–may pose a health threat due to radioactive danger from mantle lamps. (See the mantle lamp photos in the image gallery.)

The warm yellow glow of an open-flame kerosene lamp is
comforting and–under the right
circumstances–even romantic, but almost anyone who’s
tried to read by the light of one of the standard wick-type
lanterns fully appreciates the usefulness of the mantle
lamp. When the mantle (a small cylindrical hood,
which–when placed over a flame–becomes white
hot and gives off very bright light) was incorporated into
the design of gas, kerosene, and oil lamps about 100 years
ago, the light intensity of such devices jumped from about
15 watts to nearly 60. With this refinement, folks were
significantly more able to continue their daytime
activities after darkness fell than they’d ever been
before!

Today, many campers and residents of non-electrified areas
(as well as individuals who have chosen to do without
electricity) rely on light provided by mantle lamps for
reading, sewing, and other close work . . . and they’ve
been pretty danged grateful for that eye-saving
illumination, too. However, although most people are
unaware of the hidden radioactive danger of mantle lamps. The mantles in such lamps are
actually radioactive . . . possibly enough so to threaten
the health of folks who depend on them.

The mantles used on modern lanterns acquire their
radioactive properties during the manufacturing process.
First, the fabric that will eventually form the small rayon
mesh pouches is dipped into a solution of thorium and
cerium nitrates. The nitrates are then precipitated into
the cloth with ammonia, and–after it’s
dried–the mantle is coated with nitrocellulose, which
fixes the ammonia salts and improves the pre-burning
capability of the material. Occasionally, a manufacturer
will also add a small amount of beryllium to give the ash
(the residue that’s left behind after the lantern’s
nitrocellulose-assisted initial burn) greater strength.
However, it’s the thorium in the mantle that incandesces
and gives off the functional white light.

Unfortunately, that same element is radioactive. It
is–to be more precise–an
alpha-particle-emitting radioisotope which has a decay
series of ten radiodaughters (a “daughter” is an element
that is an immediately produced by-product of the
disintegration of a radioactive element). The first
radiodaughter is radium 228, a betaemitter which–in
time–produces subsequent alpha-emitting
radiodaughters.

The difference between alpha and beta particles is an
important one for lantern users to understand. Both types
of emissions are referred to as short-range radiation:
Alpha particles are large and slow-moving, and can easily be
stopped by such a barrier as a piece of paper or the glass
chimney of a lantern . . . while beta particles are smaller
and faster, and can penetrate body tissue. Either type can
pose a health risk to the body if its emitters (in this
particular case, thorium and radium) are inhaled or
ingested . . . with the alpha particle being the more
dangerous.

Inside the body, you see, “alphas” often travel a distance
equal only to a cell’s diameter, concentrating their effect
in one tiny location. Therefore, alpha energy can overwhelm
a cell’s chemistry, possibly targeting the stricken spot
for a future cancer, or altering the cells genetic matter. [EDITOR’S NOTE: Refer to the Medical Self-Care column “Are
Cigarettes Radioactive?” (issue 74) for a discussion of
the health effects of low-level radiation. To order back
issues, turn to page 48 of this issue.]

The manufacturers of lanterns and mantles (Coleman and
Aladdin are the largest of such firms) are well aware of
thorium’s radioactive properties, since they must be
licensed by the Nuclear Regulatory Commission to possess
and process the material and, furthermore, are required to
label bulk shipments of the mantles as “radioactive” during
transport. However, the companies have rejected any
suggestion that they put warning labels on individual
mantle packages, maintaining that the level of
radiotoxicity is “insignificant”.

The industry position is based, in part, on a 1979 study by
Milo Voss–a health physicist from Ames,
Iowa–which characterized the alpha-emitting nature of
thorium as relatively harmless unless the particles are
ingested or inhaled. Even if the risk is that limited,
though, there’s a strong likelihood that an unsuspecting
individual could breathe in airborne radioactivity, without
being aware of it, while lighting a mantle.

Consumer Action on Mantle Lamps

Until recently, only a few people were informed of the
health risks posed by mantle lamps. Some mention of the
issue had been made in several California newspapers, but
no widespread attention had been drawn to the problem.

In fact, if it hadn’t been for Walter Wagner, a health
physicist employed by the Veterans Administration Medical
Center in San Francisco, the entire matter might have
escaped large-scale public notice. As it happened, though,
Wagner toured the Rancho Seco nuclear power plant near
Sacramento, California in October 1980 . . .
and–during his visit–a health physicist
employed there pulled out a lantern mantle. The man never
explained why he was carrying that small cloth pocket at a
nuclear electricity-generating plant, but–in
retrospect–Wagner suspects that the physicist may
have been trying to point out that nuclear plant employees
aren’t the only ones exposing the public to radioactivity.

At any rate, what struck Wagner about the incident was that
the mantle registered on the scintillation counter he’d
brought along on the tour. He was surprised, because
thorium is an alpha-emitter, and most such particles should
have been stopped by the packaging. Reflecting on it later,
Wagner decided that the counter was not registering thorium
at all, but–instead–indicating the presence of
some of its decay elements . . . so he bought a mantle to
experiment with.

After confirming his theory, Walt contacted the Coleman
Company in March 1981 to ask the firm to put warnings on
mantle packages. When that effort proved unsuccessful,
Wagner filed a $300 million class action suit, in November
1981, against the Coleman Company and other manufacturers
of mantles . . . which seeks to return reputed damages to
mantle purchasers and to require the companies to begin
using warning labels on their products.

Thorium and Health Risks

By way of a little background, the thorium (Th-232) that’s
used in lanterns is a fertile nuclide, which can actually
be bred into uranium 233 (U-233), a fissionable isotope
suitable for nuclear weapons or reactors. (In fact, thorium
itself has been used in reactors on an experimental basis
and supposedly could have been bred into weapons-grade
U-233 at the Osirak nuclear power plant located near
Baghdad, Iraq, which was destroyed by the Israelis on June
7, 1981.)

In a home or tent, the main danger in mantle use arises
from thorium’s first radiodaughter, radium 228 (Ra-228).
Radium is a “bone seeker” . . . which means that it is
biochemically analogous to calcium, and that the body will
substitute it for calcium during periods of bone growth.
Thus, the radiumladen fumes from lamp mantles present an
obvious hazard to children who may be close by. Likewise,
pregnant women and their unborn babies–could be
endangered, since Ra-228 (and Ra-224), which can be inhaled
and ingested by the mother, readily crosses the placental
barrier and can be absorbed by the fetus. Similarly, a
nursing mother who inhales volatized radium would pass some
of it along to her infant.

Taking Precautions

While the chief sources of danger are the
alpha-particle-emitting daughters of Ra-228, Wagner says
that “significant” beta radiation can strike the body when
a mantle is placed close to the skin. If it’s carried in a
shirt pocket, for instance, the breast and lung tissue will
absorb radiation . . . and if it’s put in a pants pocket, a
man’s testicles would be exposed to some low-level
radiation (though the actual risk involved in either case
is, at present, subject to debate). Wagner cautions that a
mantle–even when it’s new and still inside its
packaging–should never be placed in pockets, and
children should never be allowed to touch or play with the
devices.

The Physicist further advises that the initial pre-burning,
and all subsequent lighting, of mantles be performed in an
open area with adequate air circulation . . . and that only
after 15 to 20 minutes of burning should a mantle lamp be
brought into a closed environment. What’s more, Wagner
notes that the thorium is in place even after the mantle
has been burning. You see, one of the reasons manufacturers
use thorium is that it has a very high melting point.
Therefore, a mantle will continue to emit alpha radiation
during use, with most of these particles being stopped by
the glass chimney. On the other hand, once the mantle is
lighted, most of the radium will boil off in the first 15
to 20 minutes, and the mantle won’t emit further beta
radiation until several days later . . . when Ra-224 is
produced by the decaying thorium.

Wagner suggests that if you light your lamp once a day, it
should be vented to the outdoors. If the lantern is used
continuously, however, venting is probably not necessary,
as the air change in the room should be adequate.

Users of mantle lamps should especially avoid breathing in
the particulate ash or getting any ash in their food.
(“Thorium ash is very bad to inhale,” Walter says, “as it
simply sits in the lungs for months to years, and when it
eventually gets into the blood, it goes directly to the
bone, where–again–it stays for years.”)

It’s impossible, of course, to avoid some exposure while
changing the mantles . . . however, since that procedure
normally requires only a few minutes, the total risk is
small (less than one chance in a million of a resulting
cancer). By contrast, leaving a mantle in a pocket for
hours at a time increases the risk of cancer considerably
(up to one chance in 10,000).

When it comes time to dispose of a mantle, Wagner suggests
that the ashes not be deposited on a compost heap or tilled
into garden soil, where the radiotoxicity could become part
of the food chain. Rather, it’s better to put the old
mantle with trash that will be going to a landfill or other
dump.

Given all the facts, why haven’t mantle manufacturers
admitted the hazard of thorium? That’s a question Walt
hopes to have answered when the suit comes to trial.
(Following two postponements, a hearing is scheduled–
as of this writing–for September or October of this
year.) Coleman has called Wagner’s allegations
“preposterous” and charged that his conclusions are more
“emotional than scientific”.

In return, Wagner’s suit claims that 1,000 persons have
already suffered cancer or birth defects through improper
use of the mantles . . . that 1,000 more will be stricken
as a result of past exposure . . . and that manufacturers
have been negligent by failing to warn users and to advise
them of safety precautions that might have lessened or
prevented injury.

Perhaps the welcome white light for nighttime reading isn’t
as necessary–or as benign–as we thought.

EDITOR’S NOTE: Walter Wagner, the radiation physicist who
initiated the mantle suit against the Coleman Company and
others, is the discoverer of the first piece of substantial
evidence of the existence of magnetic monopoles, subatomic
particles previously thought to exist but sought after for
many years without success. Wagner’s breakthrough occurred
in 1975, while he was working on a physics experiment at
the University of California at Berkeley.

NOTE: All readings were taken with the Radiation Alert
Monitor 4 detector from a measuring distance of 1/8 inch.
All readings were averaged during a 30-second exposure
time. The Coleman 220 was taken on a camping trip during
the three-day test interval, during which it was burned
outdoors for about 36 hours . . . while the Coleman 5114
remained unlighted back in the laboratory. It’s interesting
to note that there’s quite a difference between the
three-day readings for the two lamps, both of which are
equipped with a pair of mantles.


What’s Hot . . . And What’s Not

When MOTHER’S staffers decided to test lantern mantles far
radiation while checking out Mary Anderson’s story, we
asked Walter Wagner for some tips on exactly what we should
be looking for. He said that–with the right
equipment–we should be able to record radioactivity
emanating from the mantles at several stages . . . in the
package, out of the package, during the preburn phase, and
several days later when the thorium coating produces radium
as a decay product.

Thus informed, we turned to the folks at Solar
Electronics–a group connected with The Farm in
Summertown, Tennessee–for advice about how to monitor
the mantles. They furnished us with a Solar
Electronics-made instrument–the Radiation Alert
Monitor 4–which turned out to be a small, hand-held
radiation detector that’s sensitive to a broad spectrum of
ionizing radiation . .. including alpha and beta particles,
gamma rays, and X-rays.

Next, we gathered up several lanterns that used the suspect
mantles and performed an informal experiment to check for
radioactivity. Admittedly, our research was by no means
controlled (for instance, one of the staffers borrowed a
lantern for a weekend camping expedition during the rest,
and thereby inadvertently provided some information on an
in-use mantle) . none of us is trained in radiation
detection . . . and our facilities are not equipped to
measure–or control–the temperature at which
each lantern burns.

However, despite such limitations, we were able to obtain
the results Walt Wagner told us we would: The lantern
mantles are radioactive . . . and this radioactivity
persists because the thorium is producing a radioactive
chain of decay products. Thus, the figures in the chart on
the preceding page are useful for comparing the
radioactivity of several types of mantles employed in a
variety of lanterns.

Perhaps the main point of MOM’S little test, though, was
that it awakened us to the prevalence of sources of
low-level radiation. It’s only recently that medical
journals and other health forums have started discussing a
possible link between
lower-than-previously-assumed-dangerous levels of radiation
and cancer. The big question, of course, is what dosage of
low-level radiation places a human being at risk. This may
never be adequately answered (and there may well be no
“safe” dosage).

When we were talking to Dan Sythe at The Farm and mentioned
the results of our mantle experiment, he pointed out that
some people wear or carry watches that emit more radiation
than a lantern mantle . . . many old timepieces and clocks
were painted with radium to illuminate the dials (other
substances are used today). Household radiation sources
also include smoke detectors, old kitchen timers, and
static eliminators (devices used to reduce static on film
and records).

Still another source is old pottery or crockery that’s
decorated with red or orange glaze (the coloring can
contain uranium). The orange plate pictured on a previous
page–shown registering 0.5 milliroentgens (mR) per
hour of radiation–belongs to a staff member . . .
it’s among a set of 1940’s-vintage Fiesta ware that she was
given by her grandmother.

And while we were exploring sources of radiation, we
recalled recent warnings concerning the health risk of
radon . . . a radioactive gas that’s naturally present in
nearly all rocks and soil, as well as in building materials
such as brick or concrete. It appears that radon is more
concentrated in airtight, energy-efficient structures than
in others for at least two reasons: These buildings
frequently rely on rock, brick, or concrete for heat sinks
. . . and–because care is taken to minimize hear
leakage–the air in such houses isn’t changed very
often. Therefore, more radon is produced and allowed to
accumulate in the efficient dwellings.

We were interested enough, therefore, to check MOM’S
house–the earth-bermed, hybrid solar structure at the
Eco-Village–to determine whether it produces
higher-than-normal levels of radiation. The structure
didn’t budge the detector’s needle, though . . . but then,
the house is located in–and largely built of
materials from–a relatively old geographic region
where naturally occurring levels of radiation are not as
high as in some other parts of the United States.

In short, using the detector helped awaken us to the fact
that low-level radiation is fairly prevalent . . . often in
common, readily available consumer items. And as an
outgrowth of their cooperation with MOTHER on this story,
the folks at Solar Electronics have decided to make two
types of instruments available to readers who might want to
do some testing in their own homes or workplaces.

The Radiation Alert Monitor 4 has a meter that directly
reads in milliroentgens (mR) per hour . . . plus a count
light and “beeper” function. Three meter ranges allow
detection of radiation levels up to 50 mR/hour, or up to
5,000 times natural background levels. Essentially, the
instrument is a mini-Geiger counter for making precise
measurements. A Radiation Alert Monitor 4 costs $150, plus
$5.00 for shipping charges.

Another detector that some of you might find interesting is
the Radiation Alert-Mini. This is a small
instrument–which can be clipped in a shirt pocket or
on a belt–designed to alert a person who is exposed
to radioactivity by sounding an alarm. While there’s no
meter, the device does have a three-level alarm system of
flashing LED’s (light-emitting diodes) and audible tones.

According to Mr. Sythe, the Radiation AlertMini would
provide good insurance for someone who might be exposed to
radioactivity during the course of his or her work, or who
lives in a “risk” area (perhaps close to a nuclear power
plant) and would like to know about it if radiation levels
were suddenly to surge. The Radiation Alert-Minis are
available for $199 each (a unit customarily sells for
$249.50, but Solar Electronics is discounting the device
for MOTHER-readers only), plus $5.00 for shipping.

These radiation detectors can be ordered, far the prices
mentioned above, from Solar Electronics, Dept. TMEN, Summertown, Tennessee. If you’d like to
obtain more information about either device, simply write
(please enclose a dollar or two to help defray mailing
expenses) and request brochures. Or you might want to
inquire about discounts on bulk orders (Solar Electronics
has recently supplied a number of Radiation Alert-Minis to
companies whose employees may be exposed to excessive
radiation levels).