A skull and crossbones, a running person and radiating ionizing waves, all on a deep red triangle, joined other more common warning symbols today as part of a United Nations effort to reduce needless deaths and serious injuries from accidental exposure to large radioactive sources such as food irradiation and cancer therapy equipment.

The new symbol will not be visible under normal use, but only if someone attempts to disassemble a device that is a source of dangerous radiation. It will not be located on building access doors, transportation packages or containers.

“We can’t teach the world about radiation but we can warn people about dangerous sources for the price of a sticker,” UN International Atomic Energy Agency (IAEA) radiation specialist Carolyn Mac Kenzie said of the symbol launched by her agency and the International Organization for Standardization (ISO), a worldwide federation of national standards bodies.

The new symbol is aimed at alerting anyone, anywhere, to the potential dangers of being close to a large source of ionizing radiation and will supplement the decades-old three-cornered trefoil, which looks like an electric fan and has no intuitive meaning, and little recognition beyond those educated to its significance.

“I believe the international recognition of the specific expertise of both organizations will ensure that the new standard will be accepted and applied by governments and industry to improve the safety of nuclear applications, protection of people and the environment,” IAEA Radiation, Transport and Waste Safety Director Eliana Amaral said.

The symbol is the result of a five-year project conducted in 11 countries and was tested with different population groups – mixed ages, varying educational backgrounds, male and female – to ensure that its message of “danger – stay away” was crystal clear and understood by all. Developed by human factor experts, graphic artists, and radiation protection experts, it was tested by the Gallup Institute on 1,650 people in Brazil, Mexico, Morocco, Kenya, Saudi Arabia, China, India, Thailand, Poland, Ukraine and the United States.

The symbol, intended for IAEA Category 1, 2 and 3 sources defined as capable of death or serious injury, including food irradiators, teletherapy machines for cancer treatment and industrial radiography units, will be placed on the device housing the source as a warning not to dismantle it or get any closer.

Many manufacturers plan to use the symbol on new large sources. Strategies to apply the symbol on existing large sources are being developed by the IAEA.