Understanding

Radiation

Natural and Man-made

We are all exposed to ionising radiation from natural sources all the time- called natural background radiation.This radiation is always around us whether we are indoors or outdoors.

outer space- Cosmic Rays bombard the earthEarth- which itself is significantly radioactive due to Radioactive substances in the earth’s crust

These are extremely energetic particles, primarily protons originating from Sun, stars, galaxiesThese react with air and finally reach us as muons, gamma rays, neutrons and electrons

When earth was formed it contained many radioactive isotopes.Long lived isotopes and their decay products are still present and are irradiating us constantly

Radon comes from the decay (change) of Uranium. Uranium decays through a long chain of radionuclides that includes radon.

Radon is a noble gas, not chemically active, so it migrates through porous materials like the ground and your house's foundation.

The radon itself has a small chance of decay as you breath it in and out.Most of our actual dose comes from the decay products of radon. These radon progeny are particles not gases, and can be deposited in your lungs as you breath. There they have some chance of decaying before your body can get rid of them, resulting in a radioactive dose.

There are several other naturally occurring radioactive nuclides. Most notable are Carbon-14 (C-14) and Potassium 40 (K-40). They eventually make their way into our food chain. Once ingested, they decay and give us an internal dose.

Humans are exposed to radiation from natural sources.The sources include the ground we walk on, the air we breath, the food we eat – the entire solar system on the whole. Everything in our world contains small amounts of radioactive atoms like Potassium 40, Radium 226 and Radon 222.

Average Annual Radiation Exposure ( micro Sv)Type Source World

AverageRange

Air 1260 200 – 10000

Internal 290 200 - 1000

Terrestrial 480 300 - 1000

Cosmic 390 300 - 1000

Natural

Total ~2400 1000 -13000

Place Average Maximum Minimum

Bhuj 692 876 561

Nagpur 736 858 674

In India the background natural radiation is available from fields measured by INDIAN ENVIRONMENTAL RADIATION MONITORING NETWORK (IERMON) by BARC, DAEThe IERMON network has several stations across the country and the readings of the radiation fields are available on-line in DAE. The data show that there is at least 10 % variation in the radiation fields on both the sides of average readings.

We also receive radiation dose due to man-made sourcesMedical radioactivity exposures during diagnostic radiology such as X-rays and CAT scans , nuclear medicine and radiotherapy gives radiation dose to usDose is also received from nuclear fall-out, occupational exposures and from radioactive discharges during operation of Nuclear Power Plants

� A CT scan gives a dose of 5000-10000 micro Sv.� PET scans give a similar dose from an internal injected radioactive source.� A screening CT+PET scan gives a whole-body dose of 15000 micro Sv.� Today many people benefit from radiation diagnostic scans and some have radiation therapy for cancer.This radiation and radioactivity, internal and external, are essentially the same types as that emitted at Fukushima.

Average Annual Radiation Exposure ( micro Sv)

Type Source World Average

Range

Air 1260 200 – 10000Internal 290 200 - 1000Terrestrial 480 300 - 1000Cosmic 390 300 - 1000

Natural

Sub-total ~2400 1000 -13000Medical 600 30 - 2000Fall-out 7 0 - 1000Others 5.2 0 - 20000

Man Made

Sub-total ~600 0 - 20000Total ~3000 0 - 20000

Karunagappally taluk in costal Kerala has radiation background up to 70,000 micro Sv/y due to the deposits of Thorium in the sand.

In some parts of Ramsar, a city in Northern Iran people have been receiving up to 260,000 micro Sv/y dose due to natural radiation background. Cytogenetic studies show no significant differences between people in the high background compared to people in normal background areas.

High natural radiationThorium sandsStudy conducted by

Regional Cancer Centre, Trivandrum

Jayalekshmi P et al. High natural radiation and cancer in Karunagapally, Kerala

Compared to the average natural radiation background dose of 2400 micro Sv/y the radiation dose from Indian Nuclear Power Plants during 2010 was 0.42 to 39.6 micro Sv to the persons near plant boundaries which is insignificant compared to the natural background and the seasonal variations in natural background at a place.

National regulations are based on “reduce radiation to

As Low As Reasonably Achievable (ALARA),”

close to natural levels, not for safety but for social reasons.

Ref: United Nations Scientific Committee on the Effects of Atomic Radiation

UNSCEAR - Appendix B

Thanks for your kind attention

Low or modest levels of nuclear radiation and radioactivity are not harmful.Fear of radiation causes personal stress and social damage that is very harmful.Current evacuation regulations are scientifically unreasonable and cause hardship.International “safety” levels based on the

lowest achievable can be relaxed upwards by a large factor.

Workers at Chernobyl- No worker with less than 2000 mSv died from ARS.Workers at Fukushima- After six weeks 30 workers had received between 100-250 mSv.- So there will be no deaths from ARS at Fukushima.Radiation therapy to cure cancer- Patients receiving radiotherapy spread over about 6 weeks to curecancer get a daily dose of 2000 mSv to the tumour that kills thecancer cells.- They also receive daily 1000 mSv to many healthy organs andtissue that survive -- more than 20,000 mSv per month.- That is more than 5 X an acute fatal dose (4,000mSv).- Credible data?Most people personally know someone who has benefited from suchtreatment.- How? Recovery from radiation damage.After each daily treatment healthy organs just have time to repair theradiation damage - and the tumour cells just do not.