November 1994

Effective Sterilization:  The Autoclave

The autoclave is the best known and most common piece of sterilization
equipment used in hospital and clinical research laboratories.  It sterilizes
items placed within its chamber by displacing air with steam and exposing
them to great heat over a defined period of time.  There are many variables
that contribute to effective steam sterilization, so make sure that the
autoclave functions optimally and that it is properly loaded in order to reduce
any chance of ineffective sterilization.  

How The Autoclave Works

There are two general types of steam sterilizers:  gravity displacement, in
which the displaced air flows out the drain through a steam-activated exhaust
valve; and pre-vacuum, in which a vacuum is pulled to remove the air
before steam is introduced into the chamber.  With both types, as the air is
replaced with pressurized steam, the temperature in the chamber increases. 
This results in temperature increases within the load that, under most
conditions, are sufficient to treat the materials to be sterilized.

Treatment by steam sterilization is time and temperature dependent;
therefore, it is essential that the entire load be exposed to the necessary
temperature for a defined period of time.  The autoclave's chamber usually
heats up before the containers and the materials within it, so be sure to allow
ample time for sterilization to occur.  To kill most pathogens, a steam
treatment takes about 30 minutes at 20 lbs./square inch.  Some spore forming
bacteria require a longer time for destruction.

Problems That Can Arise

For effective and efficient sterilization, degree of steam penetration is the
critical factor.  For steam to penetrate throughout the load, the air must be
completely displaced from the treatment chamber. Residual air in the
sterilizer chamber can prevent effective sterilization by:

reducing the ultimate possible temperature of the steam regardless of
pressure

causing variations in temperature

prolonging the time needed to attain the maximum temperature

inhibiting steam penetration into porous materials


Loading The Chamber

Since sterilizer performance is directly related to this vital function of air
displacement, ensure that the proper packaging materials are used and that
the autoclave's chamber is properly loaded.  To ensure that complete
displacement of air will occur:

do not use deep containers (which may prevent displacement of air from
the bottom)

do not use cardboard boxes or heat-sensitive plastic bags (which
disintegrate during treatment and do not allow sterilization to occur).  Use 
instead glass bottles or containers and plastic bags with temperature sensitive
indicators that verify when the proper temperature has been achieved.

load the chamber properly (so steam can circulate freely within the
chamber)

open all bags and loosen bottle caps and stoppers immediately before
placement in the steam sterilizer

place plastic bags within a rigid container before steam treatment in order
to prevent spillage and drain clogging

Other Tips

Never autoclave volatile  chemicals, especially those having toxic vapors. 
Persons involved in steam sterilization should be trained in the proper
techniques both to attain proper sterilization and to minimize personal
exposure to the hazards posed by the wastes.  These techniques include use of
protective equipment, minimization of aerosol formation, and prevention of
spillage during autoclave loading.

All steam sterilizers should be routinely inspected and serviced.  Monitoring
the steam sterilization process is required to ensure effective treatment.  It is
recommended that the sterilization process be monitored weekly to insure
that proper procedures are being followed and that the equipment is
functioning properly.


Bloodborne Pathogen Retraining:  A New Format

The Department of Occupational and Environmental Safety has acquired
several copies of the Bloodborne Pathogen Standard re-training videotape. 
Departments whose employees require annual bloodborne pathogen
retraining can meet this requirement by showing the videotape at
departmental meetings.

In addition to viewing the tape the following requirements must be met:

the attendance log enclosed with the copy of the videotape must be
maintained and submitted to DOES after the session is complete.  The
attendance log must have:  the instructor of the session (print and sign your
name), the department, and the training session date and location.  Each
employee must then print and sign his or her name and social security
number.  It is vital that this log be kept and submitted to us.  

OSHA requires that personnel have the opportunity to ask questions.
Encourage your staff to call our department (x2907) or University Health
Service (x2450) with any questions they may have.

If they have not already been vaccinated, each employee must be offered
the opportunity to get vaccinated or sign a disclaimer declaring that they do
not wish to be vaccinated at that time.  This must be done at the retraining
session.


Instructions for requesting a videotape are as follows:

call x2907 to reserve a copy of the tape.  You will receive an attendance log
and an instruction sheet along with the video.

Videotapes must be signed out and signed in upon its return.

Tapes will be lent out for three working days at a time.  They must be
returned by the assigned due date along with the completed attendance log.


Training on the dangers of occupational exposure to human blood and blood
products is required at the time of initial assignment to tasks where
occupational exposure may take place and annually thereafter as long as
human blood or blood products are used.

DOES will still do the initial training when new employees are hired or
newly assigned work with human blood products.  However, the annual
retraining session can be done much more conveniently by each department
through use of this videotape.

If you have questions concerning running a retraining session, call DOES at
x2907.


Industrial Hygiene on Campus

Industrial hygiene is a diverse field utilizing principles from chemistry,
biology, and physics. Since its inception as a profession, industrial hygienists
have been devoted to protecting the health of the worker and maintaining a
safe workplace. 

Industrial hygiene involves:  preventing  chemical exposure, determining if a
worker has been exposed, and selecting the proper personal protective
equipment to prevent future exposures.  It also deals directly with the worker
if there has been exposure to prevent it in the future.

The scope of an industrial hygiene project can range from checking the
humidity level in a room to a large-scale environmental remediation project,
such as what needed to be done in the Rockefeller building.  DOES has also
handled projects such as checking CWRU's drinking water for lead (there was
none) and monitoring formaldehyde.

DOES has the capability to test for just about anything-if we cannot do it in
house then we take the necessary sample and send it out for testing.  Some of
the more popular in-house testing we do checks for mercury, asbestos,
formaldehyde, and organic solvents.

Preventing exposure and developing a safe environment are the most
important aspect of industrial hygiene.  Therefore the main tools of an
industrial hygienist are preventative measures:  proper training, the
Chemical Hygiene Plan (CHP), and each chemical's Material Safety Data
Sheets (MSDS), which provide a wealth of information about chemical use. 
Testing is always secondary to prevention.

If you believe you have an industrial hygiene problem, call Safety Services at
x2907.


Containing Radioactive Liquid Waste

In order to make handling of liquid waste as safe as possible, researchers need
to keep the following in mind:

Store liquid waste in plastic, not glass bottles.  This may prevent breaking
or cracking.

Double-contain it by placing it inside a deep tray or putting the bottle
inside a bigger large-mouthed container.  If the container should leak, there is
a second one there to prevent the waste from spreading.


These items must be done before waste technicians will remove your waste. 
Reusable plastic containers can be ordered from scientific companies in
various sizes-choose sizes that are easy to handle and that are appropriate to
the amount of waste your lab produces.  We recommend one-gallon
containers unless your lab produces a large amount of short-term waste; then
we can supply five-gallon containers.


Safety Manuals On-line

Both the Radiation Safety Manual and the CWRU Chemical Safety Manual
are on-line and can be reached by any computer connected to CWRUnet.

To access these manuals on the Macintosh, go into "Administration zone" on
CWRUnet, where you will see listed "Rad and Chem Safety."  Follow the
directory from there.  The manuals are available in Microsoft Word,
WordPerfect, and a standard RTF format to accommodate most word
processors.

To access the manuals through DOS, you must use ftp.  From CWRUnet,
access the ftp program; from freenet type "go netapps" at the choice prompt. 
At the parameter (CWRUnet) or hostname (freenet) prompt, type in our
number address "129.22.116.18." At the Login (CWRUnet) or name (freenet)
prompt, type in "ftp" or "anonymous."  The subdirectories RadManual and
ChemManual are in the SafetyDocs directory.  CWRUnet will download files
directly to your PC, while freenet will copy files to your work directory.

It is mandatory under OSHA that every lab have a copy of their Chemical
Hygiene Program (most people have adopted the CWRU Safety Manual)
readily accessible to every employee of that lab.  It does not matter if the
manual is on computer or in a hard copy, as long as every employee of the lab
knows how to reach it quickly.  However, the on-line versions of these
manuals do not have the tables and charts appearing in the hard copy, so we
recommend a hard copy of the necessary manual for every lab.

If you have any trouble accessing these manuals through CWRUnet,  call
DOES at x2906.


Distillation and Reclamation:  CWRU's New Still

A spinning band still, designed to reclaim substances that would normally be
disposed of as hazardous waste, is now in operation in Quail Building, next to
the offices of the Department of Occupational and Environmental Safety.

The still is unique for several reasons, most importantly its size:  it is capable
of holding up to 50 liters at a time.  It is equipped with a self-contained
suppression system in case of fire,  dyking, and it has a hydrocarbon alarm if
temperatures increase so rapidly as to bypass the condenser.

Also unique is the still's computer system, which can be programmed to meet
various specific needs.  The still will heat at various step rates, depending
upon the compound in the still and what safe distillation temperature is
required.  It can also be programmed to hold at specific condenser head
temperatures in order to get the most precise cut possible, the purest
distillation of the reclaimed substance.

The still's first project is "recycling" the chemical waste in Smith Building. 
Most of the hazardous waste that comes out of Smith consists of about 3%
methyl isobutyl ketone (or MIBK, a regulated substance), 10% acetic acid, and
water.  The new still can reclaim the MIBK out of the waste at a 94% purity
level, which can then be re-used by researchers.  The remaining water and
acetic acid solution, pH corrected to 7.0 to comply with sewer regulations, is
no longer considered hazardous and can be poured down the drain.

This is only the first of many uses DOES has in mind for the new still:  it will
also be used to separate acetone, a regulated substance, out of the acetone and
water solution used by many departments for rinsing glassware. 

The savings to the university in the long run will be tremendous; for
example, on the Smith Building project alone we will save $21,600 in disposal
costs.  This in itself nearly pays for the still (bought from BR Instruments at
$24,000).  

Just as important is the reduced amount of hazardous substances that the
university will put into circulation:  because substances like MIBK and
acetone can be recycled and reused, it means less regulated substances must be
bought and used on campus.  This in turn drastically reduces the amount of
hazardous waste that must be disposed of by the university, which not only
saves the university money but reaffirms its commitment to be
environmentally aware.

Any questions concerning the still and its uses for the future should be
directed to the Safety Services division of the Department  of Occupational
and Environmental Safety  at x2907.


Do You Have a Use for the Still?

The Department of Occupational and Environmental Safety is actively
looking for more uses for the new still.   If you think you have a substance
that can be reclaimed, we would like to know.

Currently we are looking for Primary Investigators whose labs have a
relatively pure waste stream containing common solvents  such as xylene,
tylene, or ethyl acetate.  We can distill out of the waste a near
chromatographically pure material, which we will return to the lab so it can
be re-used.   This way labs can save money, and more importantly, reduce the
amount of waste being introduced into the environment.

Recycling is a smart move:  we urge you to find out more about its uses and
possibilities.  If you think your lab has a use for the new still, or if you have
questions about the possibility of recycling a part of your lab's waste, we
encourage you to contact Richard Dell in the Safety Services department  at
x2907.


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