The silent killer

Shishir Reza writes about the anthropogenic sources of radiation in our country and how these can be tackled

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Radiation occurs when energy or particles carry high energy into the environment. Due to the high energy content, radiation can cause harm to micro-organisms and scratch the exterior tissue of human body, plant and animal bodies.

As the chemical properties of radioactive isotopes of an element are similar to non-radioactive isotopes, a biological system is unable to differentiate them. Important radio isotopes hazardous to biosphere are − manganese-54, cobalt-58, cobalt-60, strontium-90, zirconium-95, caesiun-135, polonium-210, radon-222, radium-226, thorium-230, uranium-233, plutonium-239 and so on.

Many radioactive isotopes are taken by the biological system which are used, accumulated and passed on to the higher tropic levels in the food chain. As a result, the radioactive source is lodged within the body, often in concentration many times higher than the original medium in which the organism concerned survives.

Medical and diagnostic uses of radioactivity are the most important sources of radiation to general public. There are numerous x-ray clinics and hospitals located within populated areas, all over the world. Radioactive isotopes of cobalt, iodine etc are frequently used for diagnostic or curative purposes in the treatment of cancers, hyperthyroidism etc. A large number of people frequent these places and receive radiations on a daily basis.

In addition to the continuous radiation from cell phone towers, there is radiation from telephones, wireless phones, computers, laptops, television towers, FM towers etc. We are exposed to all this radiation that is unfavourable for us.

Colour television, refrigerators, oven, camera, headphone, computer screens, video games etc are also easygoing sources of radiation to common people. Even if people are aware of radiation risk, they may not have the option to move away from these utensils and tower − installed in their homes, work place, school, university or park.

In Bangladesh, mobile phones have seen a surge with total number of subscribers jumping to 135 million at the end of December 2016 from 26.66 million at the end of May 2007. At the same time there has been a significant increase in the installation of mobile base stations. There are more than 12 core cell phone bases and nearly 21,600 cell phone towers in Bangladesh to meet the demand.

In general, three types of mobile towers are being used in Bangladesh: Roof Top Towers, Green Field Towers and Green Field Roof Top Towers. There are three indicators to measure radiation covering the four frequency bands and unfortunately all indicators have already crossed the standard level of radiation in Bangladesh.

The first is Power density. The safety limits of power density given by World Health Organisation (WHO) at different frequency bands are CDMA 450-2.2 W/M2, GSM900- 4.7 W/M2, GSM1800-9.0 W/M2, and UTMS-10.01 W/M2. After carrying out some measurements, Bangladesh Telecommunication Regulatory Commission (BTRC)  found that radiated power density of mobile tower sites in the country are in the following range − CDMA450-2.5 W/M2, GSM900- 10.38 W/M2, GSM1800-10.35 W/M2, UTMS-5.5 W/M2.

Then comes Electric field strength whose standard limits provided by WHO are CDMA450-29 V/M, GSM900-42 V/M, GSM1800-58 V/M and UTMS-61 V/M. Electric field value found by BTRC at different frequency bands of mobile towers were CDMA450-62.56 V/M, GSM900-51.05 V/M, GSM1800-71.50 V/M and UTMS-65.05 V/M.

Third is the specific absorption rate related to electric field value and absorption rate by human tissue. WHO’s standard value for specific absorption rate for various frequencies in 1.66 w/kg. But the absorption rates at various frequencies in Bangladesh are CDMA450- 1.75 w/kg, GSM900- 1.83 w/kg, GSM1800- 1.91 w/kg, UTMS- 2.05 w/kg.

In this context, some primary steps can be taken to ensure that radiation does not affect human health in the years to come. As such, guidelines of WHO can be followed while setting-up towers and transmission frequencies. Towers both ground-based and roof-based should not be installed within 50 metres of schools or hospitals.

Cellphone operators have to careful about radiation. Installation of towers in the suburban areas must be avoided and 24 hours monitoring of cell tower radiation must be done at different places. Also, antennas should be mounted over 30 metres from ground and warning signs can be posted near cell towers to warn people about the dangers of radiation. It’s also high time for the government and private hospitals to make radiation free medical zones.

To conclude, people need to be more careful about the overuse of modern-day instruments.

The writer is environmental analyst & associate member of Bangladesh Economic Association