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7 in the Chemical f aboratory Edited by NORMAN V. STEERE, 140 Melbourne Ave., S.E. Minneapolis, Minn. 55414
XC. Identification of Hazardous Materials-Part
feature
VII
NORMAN V. STEERE Hazard Identification Symbols The basic form of the hazard symbol is the diamond, which is commonly recognized as s. danger signal such as the road sign? which convey warning messages in words or special shapes such as curved arrows. The NFPA No. 704M system divides the diamond into four quadrants and uniformly conveys emergency health hazard degree in the left quadrant, flammability hazard degree in the top quadrant, instability or reactivity hazard degree in the right quadrant, and special information in the bottom quadrant. Federal Standard No. 313 utilizes the same b% sic shape for the ha~itrdsymhol,butcenters the diamond in a. square with very brief wording to explain the numbers, abbreviations, and waterreactivity symbol. For integration of hazard identification symbols with other markings and labels, Federal StandsrdNa. 313 permits the diamond alone hut adds in the qoadrants the name of the hazard and the brief (and often misleading) wording from thelargersquare. Standard siaes and permissible variations, and standard colors and options in their use are discussed in the next two sections, followed by comments on legibility.
Sizes The standard size for the square is 4 in. on each side, for the diamond is Z1/s in. on each side, and for the hazard degree in. The waternumbers is 1 or reactivity symbol (W) is specified as '/* or in., as are the abbreviations for specific hazards, but the size may be reduced further when it is necessary to show multiple specific hazards. Thickness of the strokes of the numbers is snecified a s 6/az in., with any borders required to be in. thick. Type sise for the brief explilnetory t e r n s msy vary from 7 to 8 point. Symbols smaller than the 4 in. square and the 2'/1 in. diamond are permitted for small containers with two dimensions less than 6 in. Siae of symbols shall be "commensnrate with surface avitilahle." Smaller size symbols are also permitted and dimensions "shall he optional with the supplier when symbols are incorporated in other labels, integrated with other markings or applied to containers as part of a labeling process" such as stencil or silk screen. However, if the symbol size is reducedr'the symbols shall be of w c h sise and locat~onas to be readily legible." Unit and subunit containers with less than 5 sq. in. of continuous marking sur-
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applied an specification tags attached with wire ties. The hazard svmbals mctv be on s. separate tag or an one required by MILSTD-129-Marking for Shipment and Storage.
Colors Supplementing the standard spatial arrangement of the hazard symbol, blue, red, and yellow backgrounds or numbers may he used for showing the degree of emergency health hazard, flammability hazard, and reactivity (instability) hazard. The standard specifies that hasard degree nu%erals and specific hazard letters may be white with a black border or all white, on backgrounds of blue (health hazard), red (flammability), yellow (reactivity or instability), and white (specific hazards), or that if the background is white the numerals may be the colors indicated. The colors specified in the standard are too dark to permit use of black numerals. The author believes t h a t lighter blues, reds, and yellows would allow use of black numerals and provide a, color system with better contrast and legibility, greater fade resistance and continued contrast for labels that are to be exposed to sunlight and weathering, and a more effective system where numerals may have to he filled in a t many locrttions. The use of color for hazard symbols is optional under the standard, with the only requirement being that the printing and background colon shall contrast. Optional use of color was allowed so that the added costs of multi-color printing would not be required. Other considerations may have been the facts that colors tend to fade after exposure and time, and that colors are not reliable as the sale basis of
For integration with other morkingr and in. corporation with other labels.
HEALTH HAZARD 4 Deadly 3 Extreme danger 2- Hamdous 1- Slightly hazardous D Normal material
-
SPECIFIC HAZARD
Flath Poinn 4- Below 7F
F
REACTIVITY
Acid
OXY ACID
Alkali
ALK
4. May detonate 3. Shock and hest
COmtive COR
of people.
Use NO WATER W
Legibility Legibility of hazard symbols from a. distance seems to be an important criteria. that has been generally overlooked, even though mention is made that when symbol size is reduced the informat.ion must be readily legible. The need for legibility from a distance is related to the sise of container and the spill ~ossibilities,and to the severity of hazards of the contents. The need to read the deerees of hazard are certainly greater for a 55-gal drum of nitromethane than far 1p t of castor oil.
Size of h a s a d signal numbers is one factor, but shape, proportion, spacing and background are also important. The 1-in. numbers will be legible from a. maximum of about50 f t , but only if there is a reasonable amount of lieht, . . if the hackeround con1 l n . t ~ rllrrply a!.J I , n,t ~ . I I I I I P I P ~ n:th mtwlrnny n l r - . w y , n d i f 111e .;11,1po n1.d plqmrtmn of r1.r i.uabcrs arr H, I H I P ~ I I ~ ~ ? . (Continued on page A B 6 )
Volume 49, Number 4, April 1972
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designed for distance legibility as those used for Federal Highway System signs.
Criteria for Application of Symbols Hazard identification symbols are required by the standard for all materials which are potentially dangerous and which require controls to assure adequate safety to life and property. Ordinary paper products, stationary, andlumber are not to be identified as hazardous. "Hazardous materials are found in all Federal Supply Classes, and judgment most beexercised to determine which must be controlled." Because certain Federal Supply Classes include so many toxic or combustible materials, all shipping containers of nonhaeardous materials in these classes (34, 68, 79, 80, 91, and 89) are to be marked with "0" in the hasard diamonds of the svmbol or "NO HAZARD, FED. STD. 3i3." Containers of materials with hazardous characteristics defined in the standard are to be marked with hazard identification symbols unless the degree of hazard or container size are below certain limits. However, Section 87.3.1 of the standard presents a potential conflict, with the statement "Specifically, any material list,ed as hazardous in Nat,ional Fire Pro-
Degree of Hazard Section ,310.3 exempts from the hasard symbol labeling requirement any material which is not in one of the following categories: Emergency Health Hazard of 2,3, or 4 Flash point less than 300°F (which includes part of Flammability Haeard 1and all of 2, 3, and 4) Instability or Reactivity Haeard of 2, 3, or 4 Specific Hamrd-oxidizing, corrosive or water-reactive materials as previously defined Under the degree of hanard criteria, hazard identification symbols would be required for materials sucb as dry Aldrin (20-0), mineral seal ail (0-1-0, flash point 275"F), and barium eblorate (1-0-2), but would not be requhed for materials sucb as aluminum powder (0-1-I), mineral oil (0-1-0, flash point 380°F), barium peroxide (1-0-l), or calcium oxide (14-1).
Table 1.
0
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Location of Symbols Unit and sub-unit containers (over 4 fluid oz. capacity) with less tban 5 sq. in. of continuous marking surface may have hazardous contents identified by attached tags rather than surface marking. If hazard identification symbols are not combined with other required container marking, they are to be applied adjacent to such marking in a conspicuous place. Two baaard symbols are required for each barrel or drum, one an the body near the bung and one on the head. Labeling and Precautionary Information I t seems to be t,he intent of Federal Standard No. 313 that hazardousmaterials are also required to be marked with precautionary labeling that conforms to the MCA Guide to Precautionary Labeling of Hazardous Chemicals. This practice is required by many State regulations and is mire common on laboratory chemicals than industrial chemicals. Limitation of Hazard Symbols and Labels Haeard identification symbols are no panacea, nor are the best of precautionary labels. Symbols alone do not provide enough information to control spills, provide f i a t aid or handle other exposures. Lzbels alone do not invite reading and are often so carefully written they minimize concern. The best combination seems to be hazard symbols which serve as headlines to draw attention and emphasize the importance of the messages contained in the precautionary information on the label. Precautionary labels in general have the limitation that available space dictates very brief wording. Chemical labels that
Proposed criteria of rating degree of health hazard
Hazard rating Commonly used term 4 3 2 1
Container Size Materials which would be required to bear hazard symbols by the degree of hazard criteria may be exempt by eontainer size criteria. "Unit and sub-unit packages having contents of 4 fluid oe. or less are not required to be marked with the symbols of this standard," according to Section S7.1.2 of Federal Standard No. 313. However, intermediate containers must bear the hasard symbol if any two dimensions are greater tban 5 in., and small containers must be delivered in shipping containers marked with the appropriate hazard symbol.
Extremely toxic Highly toxic Moderately toxic Slightly toxic or practically nontoxic Relcltively harmless
Relative toxicity criteria -Inhalation4-hr vapor exposure, rats Skin oral mortality Rabbits LD501 of 216 to LD50 Rats w/kg mglkg 416 P P ~
22,600
>15,000
I Journal of Chemical Education
provide hazard warning to prospective users without alarmine them into nonuse
high but occasionally too low, is a signal to read the precautionary label and to establish controls to manage the hazard of formation of explosive peroxides.
limitations which must be recognized. Degree of health haeard shown represents only the emergency health hazard from a spill or brief exposure to fire or personnel, not the long-term chronic exposure hazard, or the hazard from anunlikely ingestion. Further, the degree of health hazard may be assigned because a material is corrosive by contact, such as sulfuric acid, because the material iis toxic by inhalation, such as chlorine gas, or because the material may cause sensitization and dlergic reaction later, such as toluene diisocyanate. Degree of flammability hazard may be misleading as when a material with hazard rating 2 behaves as flammable as a. 3 because of ambient temperature or heated surfaces, or as when not usually flammable materials such as anhydrous ammonia and trichloroethylene with hazard rating of 1burn or explode as a 40ra3. Degrees of reactivity or instability hazard assigned to show susceptibility to release of energy may be based on water reactivity, polymerization, self-accelerating decomposition, heating under confinement, thermal and mechanical shock, or other reactions. In the case of several chemicals an instability hazard rating of 1 is assigned to warn of the possible hazard because pmlonged and adverse storage may allow formation of peroxides which &re extremely shock sensitive. The hses r d rating of 1, which will usually be too
Need for Further Definitions Degrees of emergency health hazard and instability hazard need further definition in terms of animal andlaboratory test data so that manufacturing chemists can fulfill their responsibility to determine what degree of hazard to assign their products. Chemical manufacturers and shippers are likely to have difficulty in complying with the Federal Standard far hazard identification symbols because of the limited number of chemicals with published haeard degree =stings, and because there are no standards for reproducible test criteria. for establishing degree ratings for emergency health haaardsorinstability hazards. Laboratory test methods and standards are established for the defined flammability hazards, although same parameters are not included. In the absence of animal and laboratory test criteria for hitaard ratings, chemicd manufscturers or shippers may avoid requirements for marking unit intermediate shipping containers by underclassifying health and instability hazards of chemicals withflash points above 300°F. One proposed criteria of rating degree of health hazard is s h o r n in Table 1.
Reference "Safe Handling Procedures for Compounds Developed by the Petro Chemical Industry," A.I.H.A. Quarkvly, 15, No. 2, (June, 1954), p. 141.
