.BACKGROUND, MANMADE AND OCCUPATIONAL RADIATION EXPOSURE

Facts and Information about Radiation Exposure The Energy Collective,
Willem Post   19 March 2011“….

Background radiation comes from outer space (cosmic, solar), the earth (radon, potassium, uranium, thorium), food, and even other people. US natural background radiation exposure is an average of 3.6 mSv/yr; Australia 2.4 mSv/yr; Ramsar (Iran) 260 mSv/yr

Manmade average exposure is 2.6 mSv/yr, of which CT scans 55%, other diagnostic & therapeutic 24%, other 21%

US total radiation exposure, background plus manmade, is an average of 3.6 + 2.6 = 6.2 mSv/yr per person, increased from 3.6 mSv/yr about 20 years ago when CT scans were much less common.

The 6.2 mSv/yr average is misleading, because the majority of people have only x-rays during their lifetime, whereas a small percentage of people have CT scans, cancer treatments with radioactive isotopes, angiograms, stent implants, etc. These people have exposures several times greater than 6.2 mSv/yr during their treatment periods.

Example: On October 1, 2011, radiation at a hospital entrance (people walking in and out) near Fukushima in Japan was measured at 0.51 microSv/hr. Someone working at the entrance would be exposed to 0.51 x 2,000 hr/yr = 1.02 mSv/yr which is well within (background + manmade) radiation range. This radiation exposure has to be typed, converted to dose and adjusted with factors to estimate any health impact.

http://theenergycollective.com/willem-post/53939/radiation-exposure

Notable Radiation Events: According to UN and US National Academy of Sciences Reports:

– More than 500 atmospheric atomic device detonations released about 70 billion curies; almost all of it is from instantaneous, short-life, gammy radiation, little from medium and long-life isotopes.

– Chernobyl, 1986, released about 100 million curies; most of it spread as medium and long-life isotopes over a very large geographical area; the plant had no concrete containment vessel, as many other former USSR plants.

Radioactive iodine concentrates in the thyroid which may cause thyroid cancer 2-3 years after exposure. Of all the children exposed by drinking milk from 1986 to 2002, 16 years, about 4,000 were diagnosed with thyroid cancer. As of September 2005, 15 had died, with more to come in future years.

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CancerRisk.html

– Fukushima Daiichi, 2011, released about 10 million curies; most of it spread as medium and long-life isotopes by the prevailing winds over the Pacific Ocean.

– Three Mile Island, 1979, released about 50 curies; the plant has a concrete containment vessel, as do all other US nuclear power plants.

Note: Worldwide, nuclear plants without proper containment vessels should be decommissioned and dismanteld, i.e., no more Chernobyls!

1 curie = 37 billion atomic disintegrations per second = 37 billion Becqerel

High Radiation Exposure Occupations: Examples of industries with significant occupational radiation exposure, IN ADDITION to the above background + manmade exposure:

– Airline crew (the most exposed population), 4.6 mSv/yr

– Industrial radiography

– Medical radiology and nuclear medicine

– Uranium mining

– Nuclear power plant and nuclear fuel reprocessing plant workers, 3.6 mSv/yr

– Research laboratories (government, university and private)

Note: Pilots are more likely to get colon, rectal, prostate and brain cancers; female crew members are twice as likely to suffer breast cancer, and, if pregnant, increase the risk of Down’s syndrome and leukemia for their unborn children; the fetus statutory limit is 1 mSv/yr. An explanation for the pilots may be their sedentary working conditions, the poor airline food, the radio headset and the instrument and radar radiation in the cockpit.

Here is a URL which calculates radiation doses for various isotopes, distance from the source, shielding, etc.

http://www.radprocalculator.com/Gamma.aspx

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


%d bloggers like this: