The Arsenal Files 4/The Arsenal Files 4 (Arsenal Computer).ISO/health/osha.38

Text File | 1995-01-22 | 8KB | 138 lines

INFORMATION DATE  19920805
DESCRIPTION       USDOL Program Highlights on Waste Anesthetic Gases
TOPIC             Waste Anesthetic Gases
SUBJECT           Waste Anesthetic Gases
ABSTRACT          The waste anesthetic gases and vapors of concern are
                  nitrous oxide and halogenated agents (vapors) such as
                  halothane, enflurane, methoxyflurane,
                  trichloroethylene, and chloroform. The list of workers
                  with potential for exposure to WAGs includes nurses,
                  physicians-surgeons, obstetricians,
                  gynecologists-operating room technicians, and recovery
                  room personnel; dentists and veterinarians and their
                  assistants; and other auxiliaries. Hospital emergency
                  room personnel may also be exposed, but not on a
                  regular basis. OSHA, therefore, has developed
                  technical instructions designed to give guidance for
                  coping with exposure to WAGs. The instructions cover
                  sampling methods, leak test procedures, medical
                  surveillance, disposal methods, training and exposure
                  to WAGs.



U.S. Department of Labor
Program Highlight
_________________________________________________________________________
Fact Sheet No. OSHA 91-38

                         WASTE ANESTHETIC GASES

    Anesthesia is as common to medical care as is antiseptic care of
wounds.  However, for too long exposure to and control of waste
anesthetic gases (WAGs) and vapors during surgical procedures have put
health care workers in jeopardy.  At any given time more than 250,000
people who work in hospitals, operating rooms, dental offices and
veterinary clinics, might be exposed unnecessarily to harmful levels of
WAGs.
    The waste anesthetic gases and vapors of concern are nitrous oxide
and halogenated agents (vapors) such as halothane, enflurane,
methoxyflurane, trichloroethylene, and chloroform.  The list of workers
with potential for exposure to  WAGs includes nurses, physicians-
surgeons, obstetricians, gynecologists-operating room technicians, and
recovery room personnel; dentists and veterinarians and their assistants;
and other auxiliaries.  Hospital emergency room personnel may also be
exposed, but not on a regular basis.

    OSHA, therefore, has developed technical instructions designed to
give guidance for coping with exposure to WAGs.  The instructions cover
sampling methods, leak test procedures, medical surveillance, disposal
methods, training and exposure to WAGs.

    - Exposure Concentrations.  No worker should be exposed to
concentrations of WAGs greater than 2 parts per million (ppm) of any
halogenated anesthetic agent, based on the weight of the agent collected
for a 45-liter air sample by charcoal adsorption over a sampling period
not to exceed one hour.

    Controlled agents and their respective weights corresponding to 2 ppm
are: chloroform, 9.76 mg/cu m; trichloroethylene, 10.75 mg/cu m;
halothane, 16.15 mg/cu m; methoxyflurane, 13.5 mg/cu m; enflurane, 151
mg/cu m; fluroxene, 10.31 mg/cu m.

    When such agents are used in combination with nitrous oxide, levels
of the halogenated agents well below 2 ppm are achievable.  In most
situations, control of nitrous oxide to a time weighted average
concentration of 25 ppm during the anesthetic administration period will
result in levels of about 0.5 ppm of the halogenated agent.

    The occupational exposure to nitrous oxide, when used as the sole
anesthetic agent, shall be controlled so that no worker is exposed at
eight-hour time weighted average (TWA) concentrations greater than 25 ppm
during anesthetic administration.

    A complete WAGs management program includes at the outset the
application of a well designed WAGs scavenging system.  Such a system
will consist of a collecting device (scavenging adapter) to collect WAGs
and vapors from breathing systems at the site of overflow; a ventilation
system to carry WAGs from the operating room; and, a method or device for
limiting both positive and negative pressure variations in the breathing
circuit which may be used by the scavenging systems.  Most anesthesia
equipment being manufactured today includes scavenging systems.

    The remainder of the WAGs management program should include work
practices minimizing gas leakage, the application of a routine equipment
maintenance program so that gas leaks are minimized, and periodic
exposure monitoring and provision for adequate general ventilation.

    - Work Practice Controls.  Steps that can be taken to reduce gas
leakage can include:  (1) Make sure that waste gas disposal lines are
connected.  (2)  Avoid turning on nitrous oxide or vaporizer until the
circuit is connected to the patient.  Switch off the nitrous oxide and
vaporizer when not in use.  Maintain oxygen flow until scavenging system
is flushed.

    - Personal Sampling.  The primary method of evaluating WAG
concentrations in air is by collecting a quantity of air in a sampling
bag and then introducing the sample to an infrared analyzer. Sampling
should be conducted based on the particular anesthetic agent in use.
Nitrous oxide can be sampled by using devices such a large plastic bag
pump or the Landauer nitrous oxide monitor.  Halogenated compounds should
be collected in charcoal tubes 107-110 using two tubes in series.

    - Engineering Controls.  A scavenging nasal mask consists of a
compact double mask system.  It must consist of a shroud large enough to
capture exhausted/escaping nitrous oxide exiting from a patient's mouth.
An inner mask is contained within a slightly larger outer mask and a
slight vacuum is present in the space between the masks.  The vacuum
scavenges gases exhaled by the patient as well as any excess gas from the
anesthesia machine that could leak from around the edges of the inner and
outer masks.  Two small hoses lead to the space between layers and are
for scavenging.

    - Medical Surveillance.  A medical surveillance program should be
made available to all employees who are subject to occupational exposure
to WAGs.  The program should contain:
    - Comprehensive pre-placement medical and occupational histories
which shall be maintained in the employees' medical records with special
attention given to the outcome of pregnancies of the employee or spouse,
and to the hepatic, renal and hematopoietic systems which may be affected
by agents used as anesthetic gases;
    - preplacement and annual physical examination of employees exposed
to anesthetic gases;
    - employees should be advised of the potential effects of exposure to
WAGs, such as spontaneous abortions, congenital abnormalities in
children, and effects on the liver and kidneys;
    - the records of any abnormal outcome of pregnancies exposed to WAGs
and vapors shall be documented and maintained for at least the duration
of employment plus 30 years.

_________________________________________________________________________
This is one of a series of fact sheets highlighting U.S. Department of
Labor programs. It is intended as a general description only and does not
carry the force of legal opinion.  This information will be made
available to sensory impaired individuals upon request.  Voice phone:
[phone]. TDD message referral phone: [phone].