ToxTalk Volume 19-3 - Society of Forensic Toxicologists

FROM THE HEALTH AND SAFETY COMMITTEE
Members: Daniellsenschmid (Chair), John Cody, Laurel Farrell and Elizabeth Marker
In this Issue of ToxTalk the Health and Safety Committee is pleased to include an article about tuberculosis and the seconP'--,·,
installment of a senesof bibliographies of health and safety related topics. Please feel free to submit comments \
suggestions to: Daniel Isenschmid. Ph.D., Wayne County Medical Examiners Office, 1300 E. Warren, Detroit, MI 48207
TUBERCULOSIS: HEALTH AND SAFETY IN THE FORENSIC LABORATORY
Submitted by: Elizabeth Marker, Ph. D.
Tuberculosis (TB), after a thirty year decline, has shown an eighteen percent increase in Incidence since 1985. Of
particular concern are Mycobacterium tuberculosis which show resistance to two or more of the antibiotics used in treatment.
The groups considered to be a high risk for active disease include blacks, Hispanics, Asian and Pacific islanders, native
Americans, intravenous drug users, the elderly and people with compromised immune systems such as those with HIV 1 .
Many of these groups closely correspond to the constituency of Medical Examiner/Coroner systems. It is Important, therefore,
that forensic laboratory staff recognize potential risks for exposure to TB. .
TB is spread in the general population by close and prolonged exposure to droplet nuclei containing the bacteria.
These aerosol droplets form when a living patient coughs, sneezes, spits or even sings. The chance of infection is dose
dependent: the greater the exposure to droplet nUClei, the greater the risk. The droplets are from 1-5 microns in size, small
enough to remain suspended in the air and to be carried by ambient air currents. In the forensic area, exposure is by
aerosolization of body fluids during an autopsy or during preparation of samples for analysis.
In the autopsy room, droplets can be generated by compression of the chest during the procedure and through the use
of saws. In the laboratory, aerosols can be produced during tissue homogenization or any procedure which forcibly mingles
sample and air such as pressurized "blow out~ of transfer pipettes with automated pipettors. Protection against these hazards
involves the use of engineering controls and appropriate work practices. Engineering controls include proper ventilation of
rooms and use of ventilating hoods. The autopsy room, with large amounts of aerosols, should have negative pressure and
direct ventilation to the outside. In the laboratory, laminar flow hoods with HEPA filters should be used for all processes which
produce significant amounts of aerosolization, such as homogenizing speCimens. ~,
The balance of laboratory safety relative to TB involves administrativ~ controls and common sense. The proper u~
of universal personal protection (barrier protection) should provide a reasonable degree of protection against all infectious~
hazards, including TB. However. dust or dust/mist masks have not been shown to protect against droplet nuclei; the only
accepted respiratory barrier is a respirator with an HEPA filter. These masks are expensive and require periodic fit check
testing. These respirators are in common use in autopsy rooms. In the laboratory, common sense would suggest that all
procedures which could cause the formation of an aerosol be done in properly ventilated areas. The use of disposable
glassware could reduce or eliminate any hazards associated with cleaning. Work areas should be periodically disinfected.
Finally, the tuberculin skin test should be administered at least once per year to all personnel directly involved with
autopsy specimens. A positive test requires further medical evaluation .
Tuberculosis is preventable .. By using good laboratory practice and appropriate protective equipment the risk of
infection to laboratory personnel can be reduced to an acceptable minimum.
1 Dooley, et al.,Guldelines for Preventing the Transmission of Tuberculosis in Health-Care Settings, with Special Focus on
HIV-Related Issues. Morbidity and Mortality Weekly Report, Centers for Disease Control, Dec. 1990, Vol. 39/ No. RR-17.
BIBLIOGRAPHY;
BIOLOGICAL HAZARDS (PART II)
Submitted by: Daniellsenschmid, Ph.D.
W.A. Nichols. Management· of occupation exposure to potential blood-borne Infections. Considerations for development of
office procedures to handle "needlestick injuries." Ark. Dent. 62 (3):18-22 (1991).
R.B. Otero. Universal precautions for handling body fluids. Therapeutic Drug Monitoring and Toxicology In-Service Training
and Continuing Education 11 (7): 7-12 (1990). American Association for Clinical Chemistry, Inc. Washington, D.C.
G. Pugliese. Occupational Safety and Health Administration moves blood-borne pathogen compliance to the front bumev--...
[editOrial]. Am. J. Infect. Control 20 (4): 167-169 (1992).
P. Rodriques~ Handling and disposal of infectious waste in the office setting. Orthop. Nurs. 10 (5): 24-26 (1991).
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ToxToIk Volume 19, No.3 (September 1993) Page 4