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Chemical hazard label

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Subject: Corrosion, List of warning symbols
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Chemical hazard label

"Danger of death" redirects here. For other uses, see Near-death (disambiguation).

Hazard symbol are recognizable symbols designed to warn about hazardous materials, locations, or objects, including electric currents, poisons, and other things. The use of hazard symbols is often regulated by law and directed by standards organizations. Hazard symbols may appear with different colors, backgrounds, borders and supplemental information in order to specify the type of hazard.

Types of hazard symbols

Name hazard symbol Symbol Unicode Image
General caution U+2621
Poisonous sign U+2620
Radioactivity sign U+2622
Ionizing radiation sign ? ? Radioactivity
Non-ionizing radiation sign ? ?
Biohazard sign U+2623
Warning sign U+26A0
High voltage sign U+26A1
Chemical weapon symbol
Laser hazard sign ? ?
More hazard signs can be found on the list of DIN 4844-2 warning signs

Poison sign

The skull-and-crossbones symbol (☠), consisting of a human skull and two bones crossed together under the skull, is today generally used as a warning of danger, particularly in regard to poisonous substances.

The symbol, or some variation thereof, specifically with the bones (or swords) below the skull, was also featured on the Jolly Roger, the traditional flag of European and American pirates. It is also part of the WHMIS home symbols placed on containers to inform that the contents are poisonous.

In the United States, due to concerns that the skull and bones symbol's association with pirates encourages children to play with toxic materials, the Mr. Yuk symbol is also used to denote poison.

Radioactive trefoil symbol

The international radiation symbol (also known as trefoil) first appeared in 1946, at the University of California, Berkeley Radiation Laboratory. At the time, it was rendered as magenta, and was set on a blue background.[1] (See right.) The modern version used in the U.S. is magenta against a yellow background, and it is drawn with a central circle of radius R, an internal radius of 1.5R and an external radius of 5R for the blades, which are separated from each other by 60°. The trefoil is black in the international version, which is also acceptable in the U.S.[2]

On February 15, 2007, two bodies—the International Atomic Energy Agency (IAEA) and the International Organization for Standardization (ISO)—jointly announced the adoption of a new ionizing radiation warning symbol to supplement the traditional trefoil symbol. The new symbol, to be used on sealed radiation sources, is aimed at alerting anyone, anywhere to the danger of being close to a strong source of ionizing radiation.[3] It depicts, on a red background, a black trefoil with waves of radiation streaming from it, along with a black skull and crossbones, and a running figure with an arrow pointing away from the scene. The radiating trefoil suggests the presence of radiation, while the red background and the skull and crossbones warn of the danger. The figure running away from the scene is meant to suggest taking action to avoid the labeled material. The new symbol is not intended to be generally visible, but rather to appear on internal components of devices that house radiation sources so that if anybody attempts to disassemble such devices they will see an explicit warning not to proceed any further.[4][5]

Biohazard sign

Developed by the Dow Chemical Company in 1966 for their containment products.[6]

According to Charles Baldwin,[6] an environmental-health engineer who contributed to its development: "We wanted something that was memorable but meaningless, so we could educate people as to what it means." In an article in Science in 1967, the symbol was presented as the new standard for all biological hazards ("biohazards"). The article explained that over 40 symbols were drawn up by Dow artists, and all of the symbols investigated had to meet a number of criteria: "(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; (v) symmetrical, in order to appear identical from all angles of approach; and (vi) acceptable to groups of varying ethnic backgrounds." The chosen scored the best on nationwide testing for memorability.[7]

It is used in the labeling of biological materials that carry a significant health risk, including viral samples and used hypodermic needles.


All parts of the biohazard sign can be drawn with a compass and straightedge. The basic outline of the symbol is a plain trefoil, which is three circles overlapping each other equally like in a triple Venn diagram with the overlapping parts erased. The diameter of the overlapping part is equal to half the radius of the three circles. Then three inner circles are drawn in with ⅔ radius of the original circles so that it is tangent to the outside three overlapping circles. A tiny circle in center has a diameter ½ of the radius of the three inner circles, and arcs are erased at 90°, 210°, and 330°. The arcs of the inner circles and the tiny circle are connected by a line. Finally, the ring under is drawn from the distance to the perimeter of the equilateral triangle that forms between the centers of the three intersecting circles. An outer circle of the ring under is drawn and finally enclosed with the arcs from the center of the inner circles with a shorter radius from the inner circles.[2]

Warning sign

Main article: Exclamation mark

On warning signs, an exclamation mark is often used to draw attention to a warning of danger, hazards, and the unexpected. In Europe, this type of sign is used if there are no other appropriate signs to denote a hazard.[8] When used in traffic signs a plate describing the hazard must be present. On an upright sign it is usually mounted under the exclamation mark.

Chemical hazard

A chemical hazard label is a pictogram applied to containers of dangerous chemical compounds to indicate the specific risk, and thus the required precautions. There are several systems of labels, depending on the purpose (container for handling, container for transportation).

GHS chemical hazard symbols and statements

Main article: GHS hazard pictograms
and GHS hazard statements are designed to harmonize internationnaly the chemical hazard mentions. They have been implemented by several countries, starting by Europe.

European chemical hazard symbols

In Europe, a standard is used, as fixed - by the CLP regulation(2008) for the chemical container, that follows the GHS recommendations; see European CLP/GHS hazard symbols.

Examples of European warning for flammable substances:

- by the European Agreement concerning the International Carriage of Dangerous Goods by Road(ADR) for additionnal packaging for the transportation. Vehicles carrying dangerous goods have to be fitted with orange signs, where the lower number identifies the substance, while the upper number is a key for the threat it may pose. These symbols cannot be readily interpreted without the aid of a key.[dubious ]

Canada chemical hazard symbols

USA chemical hazard symbols

(TSCA, US regulations)

The U.S.-based National Fire Protection Association (NFPA) has a standard NFPA 704 using a diamond with four colored sections each with a number indicating severity 0—4 (0 for no hazard, 4 indicates a severe hazard). The red section denotes flammability. The blue section denotes health risks. Yellow represents reactivity (tendency to explode). The white section denotes special hazard information. One example of a special hazard would be the capital letter W crossed out (pictured right) indicating it is water reactant. This label is used primarily in the USA.

Other countries hazard symbols

Non-standard warning signs

A large number of warning signs of non-standard designs, are in use around the world. An example is the one on the right at the Beromünster Reserve Broadcasting Tower.

See also


External links

  • Hazchem Guide from The National Chemical Emergency Centre
  • European Chemicals Bureau
  • Directive 2001/59/EC
  • Hazchem panel information
ar:رمز الخطر

bg:Международни символи за химична опасност ca:Símbols de perillositat cs:Chemické symboly nebezpečí da:Faresymbol de:Gefahrensymbol es:Símbolo de riesgo químico fr:Étiquette de danger des substances chimiques it:Simboli di rischio chimico ku:Nîşanên xeterê nl:Gevaarsymbool ja:ハザードシンボル no:Faresymboler pt:Símbolo de risco ru:Символы опасности simple:Hazard symbol fi:Varoitusmerkintä sv:Farosymbol tr:Tehlike sembolleri zh:危险性符号

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