USE OF CHEAPER BRICKS - HEALTH CONCERNS

Construction cost of buildings is increasing by the day. Everybody is familiar with the “red bricks”, which are seen stacked up in any construction site. It is estimated that the cost of construction of a brick wall has gone up from about 500 rupees a square meter in 2003 to over a thousand rupees in 2007!

Cheaper alternatives suggested are: 1) bricks made up of “fly ash”, a waste product from coal-based thermal power plants and 2) gypsum load-bearing panels. The fly ash contains the natural radionuclides which are present in the coal and get concentrated in the fly-ash while burning. Gypsum salt (Phospho-gypsum), obtained as a waste product of the phosphoric acid production process, generally contains significant amount of naturally occurring radioactivity, mainly uranium and its decay products. The radionuclides of concern are: Uranium-238, Radium-226, Thorium-232 and naturally occurring K-40. A few hundreds of Becquerel (unit to express the quantity of radioactivity) of the activity per kg of the materials are likely to be present.

The storage areas of such materials or the houses made by using bricks made out of such materials are potential sites of radioactive radon (Rn-222) gas (decay product of Ra-226) inhalation hazard. From radiation protection considerations, it is suggested that before such materials are used for commercial exploitation, an assessment of the materials is made for their radioactive content. If necessary, the material should be processed to remove the radioactivity content as much as possible. Clearance from the appropriate authorities may be required before large scale use of the “waste” materials.

ICRP APPROVES NEW FUNDAMENTAL RECOMMENDATIONS ON RADIATION PROTECTION

International Commission on Radiological Protection (ICRP, a non-governmental, independent organization, founded in 1928), in its meeting held at Essen, Germany during 19-21 March, 2007 approved a set of new fundamental recommendations on the protection of man and the environment against ionizing radiation. These recommendations will replace the existing 1990 Recommendations of the ICRP, published in 1991 (ICRP-60, 1991). The new recommendations take into account of new biological and physical information and trends in the setting of radiation standards. For the first time, recommendations were made giving more emphasis to protection of the environment and developing a framework for protection of non-human species.

In brief (as per the final draft): Individual related protection principles remain the same. There are changes in Radiation weighting factors, particularly for protons and neutrons and Tissue weighting factors (reduced for some organs/tissues). There is considerable reduction in the nominal risk coefficient for hereditary effects. However, there is no change in the numerical values in individual-related dose limits applicable for all planned exposure situations.

The recommendations will be published in the Commission’s journal, the Annals of the ICRP, 2007.

SYMBOLS TO WARN OF THE PRESENCE OF RADIOACTIVE MATERIALS

This new symbol (ISO 21482), a triangular shape with three icons - the trefoil emitting radiation, a skull and a man running away - is meant to warn of the presence of dangerous levels of ionizing radiation on large sealed radioactive sources. The symbol conveys: Danger - Run Away – Do Not Touch. The new symbol does not replace the old one but is in addition to it. IAEA recommends that the symbol may be used on IAEA Category 1, 2 and 3 sealed radiation sources.




The trefoil symbol, the magenta image (Berkeley Lab, US) on a yellow background is being used for decades to denote / warn the presence of radioactive material. The history of the symbol is not very clear, though as it looks today, it originated from Oak Ridge National Lab in late forties. The symbol, however, has little recognition beyond the nuclear community.