Journal of Medical Physics
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Year : 2007  |  Volume : 32  |  Issue : 2  |  Page : 81-84


Department of Radiotherapy, Dr. BRAIRCH, All-India Institute of Medical Sciences, New Delhi - 110 029, India

Correspondence Address:
T Ganesh
Department of Radiotherapy, Dr. BRAIRCH, All-India Institute of Medical Sciences, New Delhi - 110 029
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0971-6203.33249

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How to cite this article:
Ganesh T. News. J Med Phys 2007;32:81-4

How to cite this URL:
Ganesh T. News. J Med Phys [serial online] 2007 [cited 2022 Jul 3];32:81-4. Available from:

   New UN radiation symbol launched by IAEA and adopted by ISO on February 15, 2007 Top

How many of us know the history behind the very well known radiation warning symbol - the black-and-yellow trefoil symbol? I am afraid it will be very few! We come across the sign practically every day, but we hardly have bothered to know how the symbol got associated with warning about radiation, when and by whom it was invented.

The three-bladed radiation symbol (see cover) has its roots in the University of California Radiation Laboratory in Berkeley, where it was first used for warning about radiation in 1946. [1] Originally the symbol was printed in magenta color against a blue background, and the current version was finalized in the mid-1950s. No one knows why the originators at Berkeley chose the trefoil as the symbol denoting radiation. One can only speculate. Probably the central circle denotes the radiation source, and the blades represent radiation.

Given these speculations, it is doubtful and debated whether the symbol was ever meant to warn general public against the dangers of large ionizing radiation. It is not surprising that in investigating some of the serious radiological accidents involving spent teletherapy radioactive sources in the recent past, IAEA came out with the observation, 'The trefoil symbols on the source containers failed to convey the potential radiation hazard. The signs and warning labels that were present were not understood by the individuals who gained access to these containers. There is a need for an international review of the usefulness of the trefoil symbol, whether it is intended as a warning or simply to inform of the presence of radiation. Another intuitively understandable symbol might provide a more effective warning to the public of the potential hazard, particularly for Category 1 or 2 sources.' [2],[3]

Subsequently, an 11-nation survey was initiated, and it was found that a vast majority of the respondents had no idea of what the symbol meant. It clearly underlined the need for creating a more reliable symbol warning general public in a more effective way. The search for a new symbol was started, and the assignment was daunting. The challenge was to create a symbol that would be universally acceptable - irrespective of the education, cultural orientation or age - and, at the same time, one that clearly conveyed the message: 'Danger - Run Away - Do Not Touch.' In a 5-year project that involved experts from diverse fields, Vienna school children, the International Organization for Standardization (ISO), 50 designs were created; and based on the feedback, the field was reduced to 5 designs. These 5 designs were then tested by an 11-nation survey, including India, in which 1,650 participants took part. The 'winning' design was identified as a triangular shape with three icons: the trefoil emitting radiation, a skull and a man running away (see cover). The background color is red. These images, taken together, did the best job in eliciting the right reaction.

The symbol had across-the-board acceptance since the test results did not show any significant differences in culture, gender, age, education or community size; hence its selection was easy. However, many within the industry saw it as alarmist and were apprehensive that the new symbol would have an overall negative impact on the minds of people regarding radioactivity and its useful applications. But the IAEA has clarified that the new symbol was not intended to replace the old trefoil symbol and it would be in addition to it. The new symbol would be placed over the radioactive source or shielding or under the cover in such a way that it will not be visible under normal use and it would be visible only when someone attempted to dismantle the radioactive source. The symbol will not be placed on the external surfaces of transport packages, freight containers, conveyances or building-access doors. The IAEA has recommended that the symbol be used in IAEA Category 1, 2 and 3 sealed sources like sources used in food irradiators, teletherapy sources, industrial radiography sources, etc. (dangerous sources that can cause death or injury). [4]

The symbol was published by IAEA on February 15, 2007. The ISO accepted it as 'Supplementary Ionizing Radiation Warning Symbol' on same date under ISO 21482. The old trefoil symbol had ISO number ISO 361.

The respective national regulatory bodies (like Atomic Energy Regulatory Board, India; and Nuclear Regulatory Commission, USA) have not made the use of this new symbol mandatory. Some of the source manufacturers are expected to follow the IAEA recommendations voluntarily and affix the symbol accordingly in the coming months.

   International commission on radiological protection approves new fundamental recommendations on radiological protection Top

At its meeting in Essen, Germany, 19-21 March, the International Commission on Radiological Protection, ICRP, approved a new set of fundamental recommendations on the protection of man and the environment against ionizing radiation. These recommendations will replace the Commission's previous recommendations (from 1990).

'The decision on March 21, 2007, to approve the new recommendations marks the completion of a project that started 9 years ago and included an unprecedented two rounds of completely public, worldwide consultation on earlier drafts . . . The value of the advice we have received during these consultations, from numerous international and national organizations, from professional bodies, from experts and interested laymen, cannot be overestimated,' says ICRP Chairman, Dr. Lars-Erik Holm.

The new recommendations take into account the new biological and physical information and trends in the setting of radiation standards. While much more information is available now than in 1990, the overall estimate of the risk of various kinds of harmful effects after exposure to radiation remains fundamentally the same.

The three basic principles of radiological protection are still justification of activities that could cause or affect radiation exposures , optimization of protection in order to keep doses as low as reasonably achievable and the use of dose limits. The new recommendations feature an improved and streamlined presentation, give more emphasis to protection of the environment and provide a platform for developing an updated strategy for handling emergency situations and situations of preexisting radiation exposures.

After copyediting, the new recommendations will be published in the Commission's journal, the Annals of the ICRP .

[From the website of International Commission on Radiological Protection,]

   Recent publication of interest from International Atomic Energy Agency Top

Organization of a Radioisotope-Based Molecular Biology Laboratory IAEA TECDOC Series No. 1528

Molecular techniques applied to human health have been revolutionized by the polymerase chain reaction (PCR) during the past 15 years. The identification of prognostic markers of cancer, drug-resistant profiles of microorganisms, the development of diagnostic tests and genotyping systems and the follow-up after treatment of human diseases have been major tasks for biomedical laboratory workers. The use of radioisotopes in molecular techniques, as a step in the detection process or for increased sensitivity and specificity, is well established, making it ideally suitable for technology transfer. The technology has specific requirements in the way the laboratory is organized, in quality assurance and in radiation safety. The current publication provides guidance for the establishment of radioisotope-based molecular biology laboratories and thus aims to increase the dissemination of these molecular advances.

[The publication can be freely downloaded from the IAEA website using the following link:]

   US airports introduce passenger X-ray screening Top

On February 23, 2007, Sky Harbor International Airport in Phoenix, USA, became the first US airport where passengers were subjected to body x-ray screening. Soon the international airports in Los Angeles and New York would join the bandwagon.

The new device peeks underneath passengers' clothing to search for guns, bombs or liquid explosives using the x-ray backscatter technology and produces images that reveal hidden objects like gun, narcotic contrabands, etc. The images are 'stunning,' to say the least. The machine beams a low-energy X ray at the passenger, which after it bounces off the surface of the skin is processed by computer software that highlights metals or elements like nitrogen that are found in explosives or weapons. The X ray is not strong enough to penetrate much beyond the skin, so it cannot find weapons that may be hidden in body cavities.

The images are so much revealing that many found them objectionable and called the scan a 'virtual strip-search.' In order to protect the privacy of passengers, special 'privacy' software intentionally blurs the image, creating a chalky outline of a body that is clear enough to see a collarbone or weapon but flattens revealing contours.

The vending-machine-size device, known as SmartCheck, poses no health hazards. The machine, manufactured by American Science and Engineering Inc,, generates about as much radiation as a passenger would get flying for about 2 min at about 30,000 feet, or fewer than 10 µRem per scan.

As professionals employed in this field, the question that comes naturally to our minds is that 'If hundreds of millions of people are scanned, can the population dose reach levels where a few cancers are possible?' What does the Health Physics Society (HPS) say in answer to this question? HPS states that two ideas should be understood to answer this question. First, the question includes neither consideration of the benefits from introducing backscatter x-ray scanning nor consideration of all alternatives offering the same or similar benefits. Secondly, statistical collective risk is irrelevant when individual risk is below some very low level.

In radiation protection, no exposure is justified unless it produces a positive net benefit, a philosophy which is universally adopted throughout the world. In the case of screening passengers, the benefit is increased security to the society and possible prevention of terrorist attacks. The alternative of not scanning offers no benefit. Thus, the increase in security justifies the increase, however slight, in risk.

One may argue that this is a risk imposed on members of the public by government and that the beneficiaries may not be the people who undergo the risk. For example, if one is able to stop a terrorist attack on World Trade Center (WTC) by x-ray scanning of all airline passengers with backscatter systems, the real beneficiaries would be the people in the WTC while the same act would place all the airline passengers at some individual risk, though it would be very small. It is not unusual for governments to make such decisions in many public health and national security issues.

Now, what about the collective risk? The kind of 'collective risk thinking' in the question has been considered of little use by mainstream scientific bodies. When individual risk falls below some level, say, 0.000 001 per lifetime, of contracting cancer, that risk is 'below regulatory action' for agencies that protect public health. [5]

At 0.005 millirem per scan, the constraint of 25 millirems per year per source or practice would be 5,000 scans per year (or 20 scans per day, 5 days per week, 50 weeks per year), an improbably high number for anyone.

While introducing new technology, we must certainly address all the issues concerning its potential for adverse health effects, particularly when it comes to technology that employs ionizing radiation. Looking from the viewpoint of increased security for all, which the alternative technologies cannot provide, it becomes clear that the benefits far outweigh the risks. Besides that, the risk to any individual from frequent backscatter x-ray scans is truly trivial, so that the notion of collective risk, spread out over a huge population, is not meaningful.

[The New York Times dated February 24, 2007; The Hindu dated February 25, 2007; and]

   Microdosimeter to detect radiation on lunar, Mars missions Top

Thanks to researchers in the National Space Biomedical Research Institute (NSBRI), USA, astronauts on missions to moon and Mars can now look forward to a new microdosimeter that can measure radiation doses on the cellular level and help determine regulatory dose limits for scientific and medical purposes. The device would be rugged, light weight and portable - one that can make real-time measurements of radiation environments that are crucial in conducting the missions. Spacesuits and spacecrafts integrated with microdosimeter sensors can help assess risk, provide warning at the onset of enhanced radiation so astronauts can take protective action. The sensors will measure the radiation dose in tiny microscopic elements similar in size to a red blood cell. On Earth, the microdosimeter's capabilities will be useful for nuclear material cleanup, in detecting radioactive devices and to monitor patients undergoing radiotherapy.

[From: The Hindu dated March 1, 2007]

   Time, distance, shielding - and coffee! Top

'Coffee, or more precisely its ingredient caffeine, is regarded as harmful to human health for many decades now. But it also protects against the biological effects of radiation,' writes Dr. P. C. Kesavan (The Hindu, April 19, 2007). It is well known that the hydroxyl radicals produced by energy deposition by ionizing radiation cause the biological damages. The 'reactive oxygen species' (ROS), which are products of reaction of free radicals with oxygen, are even more damaging than the hydroxyl radicals. Studies by Dr. Kesavan and his colleagues have revealed that caffeine effectively scavenges off hydroxyl radicals and it outcompetes oxygen in reacting with electrons and prevents the formation of ROS. So, the fundamental mechanism of radioprotection by caffeine involves neutralizing/elimination of the ROS. Hence it is expected that caffeine would reduce the risk of the free-radical-and ROS-mediated diseases, whether cardiovascular, diabetes type 2, arthritis or cancer, etc.

Dr. Kesavan writes that, as suggested by Prof. M. S. Swaminathan, we should develop organic coffee and coffee beans with elevated levels of caffeine, chlorogenic acid, etc., for radiation workers and others in stressful occupations.

   Indian-American paves the way for MRI being more accurate Top

An Indian-American scientist working at the Florida State University (FSU) has collaborated a project that paves the way for producing magnetic resonance imaging (MRI) with better contrast. Dr. Naresh Dalal, the Dirac Professor of Chemistry and Biochemistry at FSU, has recently conducted experiments with other researchers from FSU, the University of Colorado and the National Institute of Standards and Technology that uncovered unique properties in a molecular magnet - Fe8. Their paper 'Efficacy of the single-molecule magnet Fe8 for MRI contrast agent over a broad range of concentration' was published in the highly regarded Polyhedron journal.

Fe8 is a molecule made up of eight iron ions that form a tight molecular bond. It has a powerful magnetic field, which is obviously important in generating a very clear image with an MRI device. It is non-toxic, water-soluble and hence it is safe. Because of its unique properties, it may soon evolve as the most preferred contrast agent in MRI.

The single-molecule magnet Fe8, one of the strongest magnets known, was synthesized by Dr. Dalal and another FSU researcher Vasanth Ramachandran in FSU.

[From: The Hindu dated February 15, 2007]

   Pakistan nuclear regulatory authority's efforts to eliminate orphaned sources Top

Orphaned radioactive sources or sources without proper ownership have often been the cause of radiation accidents. In an effort apparently aimed at eliminating orphaned sources, Pakistan Nuclear Regulatory Authority had recently issued advertisement in Urdu newspapers warning people that radioactive material that may have gone missing from medical or industrial or agricultural research facilities could be harmful. The advertisement was not linked to any specific missing or stolen radioactive material. The agency's efforts once again underline the importance of accounting for every radioactive source and the IAEA's and its member states' commitment to completely eliminate orphaned radioactive sources.

[From The Times of India dated May 4, 2007]

   References Top

1.Stephens LD, Barrett R. A brief history of a "20th Century Danger Sign". Health Phys 1979;36:565-71.  Back to cited text no. 1  [PUBMED]  
2.The Radiological Accident in Istanbul. Published by IAEA: Vienna; 2000.  Back to cited text no. 2    
3.The Radiological Accident in Samut Prakarn. Published by IAEA: Vienna; 2002.  Back to cited text no. 3    
4.Lodding L. Drop it and Run. IAEA Bulletin: March 2007.p.70-2.  Back to cited text no. 4    
5.Hrejsa AF. The use of low dose x-ray scanners for passenger screening at public transportation terminals should require documentation of the "informed consent" of passengers. For the proposition. Med Phys 2005;32:651-2.  Back to cited text no. 5    


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