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From: TSS (
Date: October 21, 2004 at 4:00 pm PST

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Subject: Effects on instruments of the World Health Organization-recommended protocols for decontamination after possible exposure to transmissible spongiform encephalopathy-contaminated tissue
Date: Thu, 21 Oct 2004 17:05:46 -0500
From: "Terry S. Singeltary Sr."
Reply-To: Bovine Spongiform Encephalopathy

##################### Bovine Spongiform Encephalopathy #####################

Wiley InterScience :: Article Full Text HTML Page 1 ot 6

Journal of Biomedical Materials Research Part B: Applied

Effects on instruments of the World Health Organization-recommended protocols for decontamination after possible exposure to transmissible spongiform encephalopathy-contaminated tissue

Stanley A. Brown *, Katharine Merritt, Terry 0. Woods, Deanna N. Busick ,
United States Food & Drug Administration, Center of Devices and Radiological Health, Office of Science and Technology,
Rockville, Maryland 20850

email: Stanley A. Brown (
'Correspondence to Stanley A. Brown, FDA/ CDRH, HFZ-150, 9200 Corporate Blvd., Rockville, MD 20850

This article is a US Government work and, as such, is in the public domain in the United States of America.


Creutzfeldt-Jakob disease " mad cow disease " decontamination " surgical instruments " corrosion


It has been recommended by the World Health Organization (WHO) and Centers for Disease Control and Prevention
(CDC) that rigorous decontamination protocols be used on surgical instruments that have been exposed to tissue
possibly contaminated with Creutzfeldt-Jakob disease (CJD). This study was designed to examine the effects of these
protocols on various types of surgical instruments. The most important conclusions are: (1) autoclaving in 1/V NaOH will
cause darkening of some instruments; (2) soaking in 1 N NaOH at room temperature damages carbon steel but not
stainless steel or titanium: (3) soaking in chlorine bleach will badly corrode gold-plated instruments and will damage
some, but not all, stainless-steel instruments, especially welded and soldered joints. Damage became apparent after the
first exposure and therefore long tests are not necessary to establish which instruments will be damaged. © 2004 Wiley
Periodicals, Inc. J Biomed Mater Res Part B: AppI Biomater

Received: 29 January 2004; Revised: 13 May 2004; Accepted: 23 June 2004


Transmissible spongiform encephalopathies (TSEs) comprise a group of diseases that include Creutzfeldt-Jakob Disease
(CJD) in humans, bovine spongiform encephalopathy (BSE or mad cow disease) in cattle, and scrapie in sheep.[1] The
infectious agents (prions) found in these diseases are very difficult to destroy. They are not completely inactivated by
conventional sterilization methods such as steam autoclaving (even at elevated temperatures) or by ethylene oxide gas.[2-
6] Transmission of CJD in humans and animals by contaminated instruments has been demonstrated, but the'devices

Wiley InterScience :: Article Full Text HTML Page 2 of 6

were not subjected to modern cleaning, disinfection, and sterilization methods.[7-9] In the absence of any scientific study
demonstrating successful decontamination, there is a growing public health concern regarding the spread of the disease
by potentially contaminated surgical or dental instruments subjected to standard hospital cleaning and sterilization

The World Health Organization (WHO) has recommended the instruments be incinerated. However, because some
instruments are expensive, WHO has suggested some stringent cleaning procedures for potentially pnon-contaminated
instruments before routine cleaning and sterilization if they are to be reused. The Centers for Disease Control and
Prevention (CDC) has recommended on its web site[3] the most stringent WHO procedures should be considered:

1 Immerse in a pan containing 1N sodium hydroxide (NaOH) and heat in a gravity displacement autoclave at 121°C for
30 min: clean: rinse in water; and subject to routine sterilization. [CDC NOTE: The pan containing sodium hydroxide
should be covered, and care should be taken to avoid sodium hydroxide spills in the autoclave. To avoid autoclave
exposure to gaseous sodium hydroxide condensing on the lid of the container, the use of containers with a rim and lid
designed for condensation to collect and drip back into the pan is recommended. Persons who use this procedure
should be cautious in handling hot sodium hydroxide solution (postautoclave) and in avoiding potential exposure to
gaseous sodium hydroxide, exercise caution during all sterilization steps, and allow the autoclave, instruments, and
solutions to cool down before removal.]

2 Immerse in 1N NaOH or sodium hypochlorite (20,000 ppm available chlorine) for 1 h; transfer instruments to water;
heat in a gravity displacement autoclave at 121°C for 1 h; clean; and subject to routine sterilization. [CDC NOTE:
Sodium hypochlorite may be corrosive to some instruments.]

3 Immerse in 1 N NaOH or sodium hypochlorite (20.000 ppm available chlorine) for 1 h: remove and rinse in water, and
then transfer to open pan and heat in a gravity displacement (121°C) or porous load (134°C) autoclave for 1 h; clean;
and subject to routine sterilization. [CDC NOTE: Sodium hypochlorite may be corrosive to some instruments.]

The CDC added cautionary notes indicating risks associated with these procedures. The issue of note under method 1 has
been addressed previously.[10] The purpose of the present study was to address the instrument damage issues.



To investigate the effects of the various steps in these protocols, five separate protocols were used:

A Autoclave in 1N NaOH at 121°C for 60 min, followed by a 30-min rinse in ASTM 1 purified water in the ultrasonic
cleaner, and dry with a towel. To contain the caustic vapors,[10] instruments were placed in a Nalgene pipet sterilizing
pan with lid (Nalge Co., Rochester NY). This was repeated for 5 cycles.

B Soak for 1 h in 1 N NaOH at room temperature, followed by a 30-min rinse in ASTM 1 water in the ultrasonic cleaner,
and dry. This was repeated for 5 cycles.

C Soak for 1 h at room temperature in household bleach (5.25 or 6% sodium hypochlorite). followed by a 30-min rinse in
ASTM 1 purified water in the ultrasonic cleaner, and dry. This was done until damage was observed or it had been
done for 5 cycles.

D Autoclave at 121°C for 60 min in water, in a dry stainless-steel pan with a lid, or in a pan wrapped in a towel. Care was
taken to dry them after each run. This was repeated for 5 cycles.

E Place in detergent in the ultrasonic cleaner at 60°C for 30 min followed by a 30-min ultrasonic treatment in ASTM 1
water. The instruments were not dried after the first run but were left on the bench. In the subsequent two runs they
were dried after the rinse.

All autoclaving was done in a Harvey SterileMax bench top gravity displacement steam sterilizer (Barnstead Thermolyne,
Dubuque, IA). All ultrasonic cleaning was done at 60°C in a Branson model 3510 (Branson, Danbury, CT).


A selection of surgical instruments to encompass various materials and complexities was purchased from Roboz Surgical
(Gaithersburg. MD). These included surgical scissors, several spreaders, hemostats. needle holders, tubing clamps, and a
variety of tweezers by Dumont of Switzerland. All were stainless steel except for one type of tweezer made of carbon steel
and one type made of titanium. Upon receipt it was noticed that some instruments were marked Roboz Germany and
some were marked Pakistan, although the same catalogue number was used. A selection of less expensive stainless
instruments was purchased from a laboratory supply house (VWR). These instruments were either not labeled, or they
were labeled Pakistan.


Tungsten, platinum-indium, and bipolar neurosurgical recording electrodes were purchased from Stoelting (Wood Dale, IL).
They were subjected to room-temperature protocols B (NaOH), or C (bleach).

Wiley InterScience : Article Full Text HTML Page 3 of 6


The instruments were observed after each treatment cycle. Those with apparent damage were examined under
magnification. Those showing extreme damage were removed and did not undergo further treatment. After all of the
instruments had undergone the treatments, they were carefully evaluated under magnification. In some cases corrosion
was examined by scanning electron microscopy (SEM) with chemical analysis by energy dispersive X-ray analysis

Function and Cleaning

Calfs liver was purchased from a grocery store. Sheep blood in Alsever's was obtained from Remel (Kansas City, KS).
Instruments showing damage were used on the calfs liver or dipped in blood and the accumulation of tissue or blood was
noted. Then the instruments were subjected to protocol E for routine cleaning, examined under the microscope for debris,
and Bradford's reagent was placed onto the spots of damage to detect residual protein.[11]

Corrosion Testing

Several specifications for surgical instruments call for corrosion testing with copper sulfate. ASTM publishes two versions
of this method, both of which were used in these studies. Method A967 applies generally to stainless-steel parts, while
method F1089 applies specifically to surgical instruments.

To test per ASTM A967,[12] the parts were swabbed and kept wet for 6 min with a solution of 0.7 wt % H2SO4 and 1.6wt
% CuSO4 . 5H2O in DW. They were then carefully rinsed and dried, taking care not to disturb copper deposits if present.

The criteria for passing the test was that they shall not exhibit copper deposits. To test according to ASTM F1089,[13]
parts were swabbed and kept wet for 6 min with a solution of 9.6 wt % H2SO4 and 3.8 wt % CuSCO4 . 5H2O in DW. They

were then rinsed thoroughly in tap water and vigorously cleaned to remove any nonadherent copper plating. To pass the
test all surfaces should show no visual signs of copper plating except in serrations, teeth, locks, ratchets, braze junctions,
or solder joints. Dulling of polished surfaces or copper plating at periphery of solution drops was not cause for rejection.



Protocol A.

In general, autoclaving in NaOH more than once caused darkening of the instruments, especially in the closed portions of
box joints, as shown with the instrument labeled 1 in Figure 1. Some of the Pakistani stainless-steel instruments became
darkened as shown in Figure 2, while the titanium tweezers became very dark. This discoloration could not be scrubbed or
easily polished off. There did not seem to be any change in function, and tissue or blood did not accumulate on the dark
spots or the rainbow areas. Routine cleaning did not remove the darkening.

Figure 1. Jaws and box joints of two Mayo-Hager carbide-faced needle
holders. The instrument on the top, labeled 3, was immersed in bleach
for 1 h and shows severe corrosion. The lower instrument, labeled 1,
was autoclaved five times in 1N NaOH and shows some mild
discoloration on the outside of the box joint, and significant blackening
in the inner surface of the box joint.
[Normal View 31 K Magnified View 135K]

Figure 2. Surgical scissors after protocol A, autoclaving five times in 1N
sodium hydroxide for 1 h. The upper instrument was made in Germany,
the lower instrument in Pakistan.
[Normal View 31 K | Magnified View 141 K]

Protocol B.

The five 1-h soaks in 1 N NaOH caused corrosion on the carbon-steel tweezers and the steel spring on the Agricola tissue
spreader and a slight discoloration of the titanium tweezers. There was no apparent damage to the other Roboz surgical
instruments and they were bright and shiny. Some of the inexpensive clamps from VWR were slightly discolored, but this
could easily be wiped off.

Protocol C.

Undiluted household bleach (5.25% or 6% sodium hypochlorite) caused pitting and other evidence of corrosion to many of

Wiley Intel-Science :: Article Full Text HTML Page 4 ot 6

the instruments, most notably at welds and carbide jaws, as shown on instrument 3 in Figure 1. and gold-coated handles
as shown in Figure 3. Some of the Pakistani instruments showed no damage and some of the Roboz instruments did show
damage as shown in Figure 4. Pitting on the inexpensive instruments was typically seen around the finger holes, welds,
and scissor blades. The damage was evident after the first or second treatment. Those that showed damage got worse,
but those that did not show damage after the second exposure did not show it after five exposures.

Figure 3. The gold-plated finger holes of the same needle holders shown
in Figure 1. The upper instrument shows severe corrosive attack to the
gold plating due to the bleach. The lower instrument shows no attack to
the gold and only minimal discoloration of the stainless steel after
autoclaving in sodium hydroxide.
[Normal View 34K | Magnified View 147K]

Figure 4. Tube occluding clamps after protocol C, soaking five times for
1 h in chlorine bleach. The upper instrument was made in Germany, the
lower instrument in Pakistan.
[Normal View 30K | Magnified View 125K]

Protocol D.

Instruments subjected to autoclaving in water showed slight dulling of the polish, and a hint of corrosion at the edge of the
box joints. Instruments autoclaved in an empty pan showed no damage.

Protocol E.

Instruments subjected to routine cleaning also showed some damage. The carbon-steel pick-ups rusted badly, the spring
on a spreader rusted, and there were some rust spots on the scissors. This was observed after the first run and is probably
a result of leaving the instruments wet on the bench top.


The localization of the tissue and blood was observed with low power microscopy and did not show unusual adherence to
damaged areas. Observation after cleaning revealed no residual material. The use of Bradford's reagent did not identify
protein residues.

Corrosion Testing

All instruments which were not damaged by the decontamination protocols passed both copper sulfate tests. However,
some of those showing damage also passed. Some of the damage-prone areas passed A967 but only marginally passed
F1089, most notably the spring of the Agricola spreader, the screw in the scissors, and the welded U-guide of the tubing


The room temperature soaks in 1 N NaOH (protocol B) did not appear to harm the electrodes when examined with low
power magnification. Functional testing was not within our capabilities; such testing would be important for the user of such
electrodes. The treatment in bleach (protocol C) showed some corrosion products after the first immersion. After the
second immersion the solder joint was corroded away and the electrode tip and the connector were no longer one piece.


The protocols used in these studies were a worst case, in that no cleaning or rust inhibitors such as instrument milk were
utilized between cycles. Furthermore, autoclaving in sodium hydroxide was done for 1 h rather than the recommended 30
min. The most notable damage was localized corrosion around box joints and carbide jaws and gold-coated handles.
Figures 1 and 3 show the jaws and handles of two Mayo-Hager needle holders with carbide-faced jaws and gold-coated
handles, both labeled CE Stainless Germany. These are examples of effects of a single soak in bleach (upper instrument)
and autoclaving five times in sodium hydroxide (protocol A). Severe pitting corrosion due to bleach can be seen at box joint
and adjacent to the carbide face off the holder labeled 3 in Figure 1. In contrast, the holder labeled 1 in Figure 1 shows the
blackening effect of protocol A on the inner part of the box joint and a little discoloration outside the joint.

Figure 3 shows the severe pitting of the gold coating after a 1-h soak in bleach and the shiny appearance aftef autoclaving
five times in sodium hydroxide (protocol A). Examination by SEM demonstrated deep localized pitting throughout the

Wiley Interscience :: Article Full Text HTML Page 5 of 6

coated region. Chemical analysis by EDXA confirmed that there was gold in the coating. This degree of attack to the gold
coatings was confirmed with several other expensive instruments. After a 1-h immersion in bleach, the devices would be
surrounded by black corrosion products. This attack was seen even after soaking in a 1/10 dilution of bleach. The gold
handles passed both copper sulfate corrosion tests.

Another device-related observation was that in some cases where the same instrument type was available labeled
Germany and Pakistan, the latter tended to suffer more corrosion. An example of the differences seen with autoclaving in
NaOH (protocol A) are shown in Figure 2. The upper instrument was labeled Stainless Germany CE and was bright and
shiny. The photograph suggests there is some darkening of the blade near the hinge, but this is just an artifact of light
reflection from a polished surface. The lower scissor, labeled S.S.PAKISTAN P, had a very dark mottled discoloration.

Differences between German and Pakistani instruments were also seen after soaking in bleach. Figure 4 shows a typical
comparison after five 1-h soaks in bleach (protocol C). The upper tube occluding clamp, labeled Stainless Germany CE,
had a matte finish and was unchanged after treatment. This instrument also fully passed the ASTM F1089 corrosion test.
The lower clamp, labeled STAINLESS PAKISTAN, showed severe pitting or perhaps crevice corrosion at the junction of
the U-guide. During the ASTM F1089 test, copper plating occurred near the U-guide, but because the plating scrubbed off,
the clamp still technically passed the test. The Pakistani instrument also showed corrosion of the jaw (visible in Figure 4, 7
mm away from the weld) and crevice corrosion inside the box joint (not visible in the figure).

Much of the damage from autoclaving in NaOH was cosmetic and would not affect the performance or cleaning of the
instruments. Autoclaving in sodium hydroxide caused blackening in the closed portions of the box joints as shown in Figure
1. This could have been minimized if the box joints had been opened. Other instruments showed some diffuse darkening.
Of note was the significant discoloration to the titanium tweezers. This effect of hot alkali treatment has been utilized in
surface modification of titanium implants.[14]

Soaking in NaOH had the least effect on instruments of all the WHO methods tested. Only the carbon-steel tweezer and
the coil spring of the Agricola spreader were damaged by room temperature 1 N NaOH. The carbon-steel tweezer was
included in these studies as a positive control. It is of interest that a 30-min immersion in 1.3N NaOH at 71 "C to 80°C is a
recommended step for neutralizing nitric acid used for passivation in the manufacturing of the type of stainless steels used
for surgical instruments.[12] Thus, it is to be expected that these stainless steels are resistant to sodium hydroxide.

Immersion in sodium hypochlorite bleach did cause severe damage to some instruments. Stainless steel adjacent to
carbide jaws on needle holders (Figure 1)was severely corroded and would have been functionally weaker, as would the
spring on the Agricola spreader. Instruments with gold-coated handles suffered severe corrosion of the coating (Figure 3)
as well as elsewhere. These instruments were clearly not reusable. However, many of the inexpensive Pakistani
instruments suffered minimal damage after decontamination in bleach. It should be noted that the commercial bleach used
was changed from 5.25% to 6% sodium hypochlorite during the course of these studies. Both concentrations meet the
WHO guidelines of 20,000 ppm available chlorine. However, one must insure that chlorine-free bleach solutions are not
used for these decontamination protocols.

Copper sulfate corrosion testing did not always predict which instruments would be damaged by decontamination.
Although a failure or a marginal pass was a good indicator that damage was likely, as with the spreader spring, a pass did
not necessarily mean damage would not occur. Besides this lack of sensitivity, the copper sulfate tests have several other
limitations. Some of the locations on the instruments that are most likely to be damaged by the decontamination protocols
(e.g., joints) are exempt from ASTM F1089. Additionally, copper sulfate tests mostly serve to verify that the steel surface is
passivated and do not address or predict chloride attack (as by bleach). For example, the gold handles that corroded badly
in bleach passed both tests. Another limitation of the copper sulfate tests is that they only apply to certain specific types of
stainless steels. The ASTM F899 standard for stainless steels used for surgical instruments includes specifications for a
wide range of alloys to meet the range of properties necessary for instruments.[15] However, because surgical instrument
suppliers rarely specify the exact alloy used (and sometimes more than one alloy may be used for identical instruments), it
is difficult to determine whether the copper sulfate tests are applicable to a particular instrument.

Surgical instruments are manufactured with stainless-steel alloys which conform to chemical and mechanical requirements
of ASTM F899[15] and ISO standard 7153-1.[16] The differences seen between different instruments, in terms of
susceptibility to corrosion in chlorine bleach, could be attributable to small differences in chemical composition, or to
mechanical cold working during manufacturing. In discussing these issues with staff at laboratories that do chemical
analysis of instruments, it became clear that chemical analysis of the instruments in this study would probably not provide
much insight. Hardness testing was conducted on many instruments, and no deviation from specifications was observed.
Therefore, it remains incumbent on the instrument users to establish how their particular instruments will be affected by
these decontamination protocols.

The results of this study indicate that some of the protocols recommended by WHO and CDC[2][3] may cause damage to
the instruments. This study did not allow us to predict exactly which individual instruments would be damaged. In general,
inexpensive carbon-steel instruments are easily damaged, gold plating is damaged by bleach, and soldered and welded

wiley Intel-Science :: Article Full Text HTML Page 6of6

joints are attacked by bleach. Autoclaving in sodium hydroxide caused some discoloration, but its use requires care and
special containment pans and lids[10] to avoid damage to autoclaves or personnel. Of the three, soaking in sodium
hydroxide produced the least amount of damage to instruments.


1 Brown P, Gibbs CJ Jr, Rodgers-Johnson P, Asher DM, Sulima MP. Goldfarb LG. et al. Human spongiform
encephalopathy: the NIH series of 300 cases of experimentally transmitted disease. Ann Neural 1994: 35: 513-529.

2 WHO infection control guidelines for transmissible spongiform encephalopathies. Report of a WHO Consultation.
Geneva: WHO: March 1999. WHO/CDS/CSR/APH/2000.3. Available at:

3 Centers for Disease Control and Prevention. Bovine Spongiform Encephalopathy and Creutzfeldt-Jakob Disease.
Available at:

4 Taylor DM, Fraser H, McConnell I, Brown DA, Brown KL, Lamza KA, Smith GR. Decontamination studies with the
agents of bovine spongiform encephalopathy and scrapie. Arch Virol 1994; 139: 313-326. Links

5 Burger D, Gorham JR. Observation on the remarkable stability of transmissible mink encephalopathy virus. Res Vet
Sc/1977; 22: 131-132. Links

6 Brown P, Liberski PP, Wolff, A, Gajdusek, DC. Resistance of scrapie infectivity to steam autoclaving after
formaldehyde fixation and limited survival after ashing at 360°C: practical and theoretical implications. J Infect Dis
1990; 161:467-472. Links

7 Bernoulli C, Siegfried J, Baumgartner G, Regli F, Rabinowicz T. Gajdusek DC, et al. Danger of accidental person-to-
person transmission of Creutzfeldt-Jakob disease by surgery. Lancet 1977; 1: 478-479. Links

8 Gibbs CJ Jr, Asher DM, Kobrine A, Amyx HL, Gajdusek DC. Transmission of Creutzfeldt-Jakob disease to a
chimpanzee by electrodes contaminated during neurosurgery. J Neurol Neurosurg Psychiatr 1994; 57: 757-758.

9 Brown P, Preece M, Brandel J-P. latrogenic Creutzfeldt-Jacob disease at the millennium. Neurology 2000; 55: 1075-
1081. Links

10 Brown SA, Merritt K. Use of containment pans and lids for autoclaving caustic solutions. Am J Infect Control 2003; 31:
257-260. Links

11 Merritt K, VM Hitchins, SA Brown. Safety and cleaning of medical materials and devices. J Biomed Mater Res (AppI
Biomat) 2000; 53: 131-136. Links

12 ASTM A967, Standard specification for chemical passivation treatments for stainless steel parts. In: Annual book of
standards. Vol 01.05. West Conshohocken, PA; ASTM: 2001.

13 ASTM F1089, Standard test method for corrosion of surgical instruments. In: Annual book of standards, Vol 13.01.
West Conshohocken, PA; ASTM: 2002.

14 Nishiguchi S, Kato H, Fujita H, Kim H-M, Miyaji F, Kokubo T. Nakamura T. Enhancement of bone-bonding strengths of
titanium alloy implants by alkali and heat treatments. J Biomed Mater Res (AppI Biomat) 1999: 48: 689-696. Links

15 ASTM F899, Standard specification for stainless steels billet, bar, and wire for surgical instruments. In: Annual book of
standards, Vol 13.01. West Conshohocken, PA; ASTM: 2002.

16 ISO Standard 7153-1, Surgical instruments - Metallic materials - Part 1: Stainless steels. Geneva; International
Standards Organization: 1999.tss,ftx_abstss


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