infectant other than iodine. Usually water will
need to be filtered--four hours is a long wait.
A bottle of tetraglycine hydroperiodide tablets
or saturated aqueous iodine is much smaller
than this device and far cheaper.
STERI-PEN ULTRAVIOLET WATER DISINFECTION
A new product recently released by Hy-
dro-Photon, Inc., called Steri-Pen, disinfects
water with ultraviolet light. Time (magazine)
thought enough of this device to list it among
their "Inventions of the Year" for 2001.
The manufacturer states that in studies
carried out at the University of Maine, Uni-
versity of Arizona, University of North Caro-
lina, and Oregon Health Sciences University,
this product was demonstrated to eliminate
viruses, bacteria, and protozoa well enough to
meet the EPA Guide Standard and Protocol
for Testing Microbiological Water Purifiers.
(It destroyed in excess of 99.9999% of bacte-
ria, 99.99% of viruses, and 99.9% of proto-
zoa.)
The reports on the tests at these four insti-
tutions can be downloaded from Hydro-
Photon's website (www.hydrophoton.com).
They sound convincing. Among the organ-
isms against which this device was effective
were cryptosporidia and giardia.
The device is seven inches long and about
one-and-a-half inches on each side. It weighs
six to eight ounces with batteries, depend-
ing on the battery type. It is smaller and
lighter than currently available filters. It oper-
ates on four AA batteries and is capable of
disinfecting 16 ounces of water in about sixty
seconds. A liter of water takes eighty seconds.
(The ultraviolet light source on the instru-
ment's tip is inserted into the water and
stirred.) Alkaline batteries provide twenty to
forty water treatments; rechargeable batteries
provide sixty to seventy treatments; lithium
batteries provide 130 to 140 treatments.
The device costs $199, so it is not cheap.
Four replacement lithium batteries would cost
$11.90.
The Steri-Pen could be a moderately ex-
pensive replacement for filtration and chemi-
cal disinfection, particularly for individuals
who can not use iodine. How well it would
stand up to being crammed into a backpack
and other rigors of outdoor use is not stated.
The device appears to be particularly useful
for travelers because a glass of water could be
very easily disinfected in a hotel room in only
sixty seconds.
