From Baldwin, C.L. and Runkle, R.S.

Science 158: 264-265, 1967

Biohazards Symbol: Development of a Biological Hazards Warning Signal

Abstract. The need for a symbol to warn of potential infection hazards became apparent during Public
Health Service contract work on the development of containment facilities for virus - leukemia research. A
program of direct inquiry and a search of the literature revealed that there was no universally used signal
and that scientific and safety organizations concurred in the need for one. Criteria for symbol design were
established, and final selection was based on “uniqueness" and "memorability." The National Institutes of
Health is recommending use of the symbol as a warning of biological hazard.

The scientific community, engaged in infectious disease research, has accepted as unfortunate, but
unavoidable, the occasional accidental infection of microbiology laboratory personnel and associated non-
laboratory personnel. Since the mid-1940's, the seeming inevitability of such accidents has received an
increasing amount of study. The eventual consensus was that perhaps most of these accidents need not
happen, providing proper precautionary measures are taken and enforced. The last decade, in particular,
saw great strides in the development of containment systems and in the design of safety equipment to
protect the laboratory worker, his work, and the exterior environment from contamination by infectious
agents. A new science of containment, founded on the concept of continuous agent control through the
creation of intelligently designed barrier systems, has emerged. Design of these barriers is based on a
rational assessment of risk; the barriers may be created in the form of solid walls, pressure differentials to
control movement of air, controlled movement of personnel and materials, or inactivation of the infectious
agents themselves. In the maintenance of the barrier systems, one essential factor is that, at all times, the
locations of the infectious agents must be known. In order not to inadvertently violate the barrier systems,
each person in the vicinity must know what equipment, glassware, rooms, corridors, and ducts are
contaminated by the infectious agents, and that thereby, they constitute a biological hazard.
Unfortunately, such biological hazards, like radiation hazards, are usually impossible to detect by
cursory examination only. Being invisible, odorless, and tasteless, they require special procedures for
detection. It seems logical, then, to mark the location of "biohazards," as they are commonly called, with a
suitable warning sign that is readily noticed and easily recognized,
During investigations of biological control and containment conducted under contract for the
National Cancer Institute, the need for such a symbol became apparent to the Dow biohazards research and
development team, A search of the literature revealed that, while certain biological warning signs are used
by various agencies, a universal symbol to warn of danger from infectious or potentially infectious agents -
a symbol whose immediate significance is known to all - does not exist. Colleagues in the field of
biological research concurred, in reply to direct query, that such a warning symbol is needed.
Universally accepted symbols for hazards that are not readily detectable have already been
established, such as those used in denoting
radioactive areas. Similar warning notices are
being sought to point out danger due to laser
emission. In biology laboratories, however, a
number of different symbols are in use; none
of these has been universally accepted, and
none imply or encompass all possible
biohazards. For example, an inverted blue
triangle bearing the term "BIO" is used by the
Army to warn of biological contamination; a
rectangular "hot-pink" label, with radiating
yellow bands, is used by the U.S. Navy
Fig. 1 Biohazard warning symbol. The sign laboratories in areas containing infectious
color stipulated in the standard form is organisms; a red and black sign is used by the
fluorescent orange-red. National Institutes of Health to mark restricted
areas; and the white snake-and-staff imprint on
a violet field is sponsored by the Universal
Postal Convention to mark infectious materials during transit.
 In formulating the design for the proposed biohazards symbol, six criteria were established,
mainly dealing with the psychology of recognition and retention. These criteria, in order of their
importance, are that the symbol be (i) striking in form in order to draw immediate attention; (ii) unique and
unambiguous, in order not to be confused with symbols used for other purposes; (iii) quickly recognizable
and easily recalled; (iv) easily stenciled; (iv) symmetrical, in order to appear identical from all angles of
approach; and (vi) acceptable to groups of varying ethnic backgrounds. Dow artists created more than 40
symbol designs, of which six were selected for testing. A survey to ascertain acceptability of the six
symbols was conducted among Dow employees. This survey was directed toward determining uniqueness
and memorability.
To select the final symbol, a nationwide survey, based on precepts well established in mass-
psychology experimentation, was conducted in two parts. First, the candidate symbols were tested for
uniqueness by determining which had the least prior association for the viewer. Three hundred subjects,
males and females, from 25 cities and with various amounts of income and formal education were shown
the six symbols along with 18 other commonly used symbols. They were asked what each symbol meant,
or was used for. Participants were also encouraged, if un- certain, to guess at the meaning. A
“meaningfulness score” was obtained for each symbol based on the percentage of respondents who offered
any association whatever, to the symbol. Since the purpose was to determine the least meaningful symbol,
the smaller scores identified the most desirable symbols.
One week after the initial survey had been conducted, participants were revisited for a
"memorability" test. The original respondents were shown a group of 60 symbols which included the 24
seen during the first test. They were asked to identify those symbols which they had been shown on the first
interview. Each symbol was given a "memorability score" that depended on the percentage of participants
who correctly identified the symbol as having appeared in the earlier test.
Identical memorability scores were obtained for two of the six test symbols, and these scores
exceeded the average for the other 18 symbols tested. Since one of the two also obtained the lowest score in
the meaningfulness test, it emerged as the one symbol best qualified as being both unique and memorable
(Fig. 1).
Having evolved a suitable symbol, the next step was to attach the desired significance to it. It
became important to define as clearly as possible how and under what circumstances the symbol should be
used. A use standard was therefore prepared. This standard stipulates that the symbol "shall be used to
signify the actual or potential presence of a biohazard and shall identify equipment, containers, rooms,
materials, experimental animals, or combinations thereof which contain or are contaminated with viable
hazardous agents." It also defines the term "biohazard," for the purpose of the standard, as being: "those
infectious agents presenting a risk or potential risk to the well being of man, either directly through his
infection or indirectly through disruption of his environment."
This symbol and the recommendations regarding usage have been submitted to the United States
of America Standards Institute for inclusion in their next revision of the "Standard Specifications for
Industrial Accident Prevention Signs," Z3S.1 code.
This symbol, in fluorescent fire-orange color, has been evaluated during a 6-month period at the
National Cancer Institute and other selected laboratories engaged in studies involving hazardous agents.
These cooperating research groups included the U.S. Army Biological Laboratories and U.S. Department of
Agriculture laboratories, as well as a number of commercial and academic laboratories working under
National Institutes of Health research grants and contracts.
In view of its acceptance by the scientists during this evaluation, the National Institutes of Health
is recommending that this symbol be used as a general biological hazard warning.

CHARLES L. BALDWIN
Dow Biohazards Research and
Development Department,
Pitman-Moore Division,
The Dow Chemical Company,
Indianapolis, Indiana

ROBERT S. RUNKLE
National Cancer Institute,
Bethesda, Maryland
 Note

1. The subject material of this paper was presented at the 6th Annual Technical Meeting of the American
Association for Contamination Control, Washington, D.C., 18 May 1967. The work was performed for the
National Cancer Institute under contract No. PH 43-65-1045.

7 July 1967