What counts as "low dose" radiation?
There have been many arguments here of "low dose" vs. "linear dose" models.
However what is low dose exactly? If a salad has .3 Bq of Cs-137 would it be "really low dose"? Or would "low dose" be more like 8-15 Bq of Cs-137?
Safe = Zero
As we can see with the US Government and their European (Soviet) Union and Japanese counterparts raising the "safe" level, obviously "low-dose" radiation is whatever is below the politically-motivated "safe" level.
If tomorrow's "low-dose" is too high, they'll just raise the limit.
Dosage - Converting Hourly to Yearly
Folks,
We are reading about radiation levels in the media given in units/hour, but our official agencies often give risk values in units/year. Since radiation exposure is cummulative, it would be nice to consider how the hourly exposure adds up.
My handheld geiger counter is measuring about 0.10 microSieverts/hour here in Los Altos, and has been pretty much since March 11 (range 0.07 - 0.14).
Multiply that by 8760 (number of hours in a year) and I'm getting 876 microSieverts per year. Since 1 rem = 10,000 microSieverts, at this rate I'm getting 0.0876 rem per year. Well under the "low dose" mentioned by Joseph.
Working the other way, in order to get 1 rem in a year, I'd need to be getting 1.14 microSieverts per hour.
INTRODUCTION Lower limits of
INTRODUCTION
Lower limits of detection (LLDs) have been calculated for radionuclides of
environmental and ecological interest. The detection limits are risk-based and were
derived using a methodology similar to that described by the Environmental Protection
Agency for determining Preliminary Remediation Goals (PRGs) [EPA 1991]. PRGs, and
the LLDs calculated in this report, are calculated assuming a risk level of 10-6,the risk
deemed acceptable by the EPA.
LLDs have been calculated for radionuclides in water and soil. Water concentrations are
based on risks resulting from the consumption of drinking water while soil concentrations
are based on risks from incidental soil ingestion and external radiation exposure from
ground surface contamination.
water/
LLD_w[pCi/mL] = Risk
CR [L/d] • 1000 [mL/L] .SF_ g [risk/pCi] • EF [d/yr] *ED [3rr]
Soil Ingestion. Detection limits, based on ingestion, for radionuclides in soil are given
by,
LLI_ [pCi/g] = Risk
IR [g/d] * SF._8 [risk/pCi] • EF [d/yr] *ED [yr]
External Exposure to Ground Surface Radionuclides. Detection limits for
radionuclides in soil resulting in a risk of 10-6from external exposure are given by,
LLI_ [pCi/g] = Risk • 8760 [hr]yr]
ET [br/d] • -__ql-Tiext [risk/yr per pCi/g] • EF [d/yr] • ED [yr]
Okay...
...That's your EXPOSURE. Now factor in everything you eat / consume / absorb / come into contact with over the course of an entire year.
These Governmental levels assume that 10% of the food supply is contaminated, and that said contamination "only" lasts for a year, right? Well, what happens when the ENTIRETY of the food supply is contaminated -- as is almost certainly the case by now, five weeks in -- and the contamination lasts (although not at the same levels, probably -- iodine may go down rapidly, cesium may aggregate and go way, way UP) for the rest of your life?
Not to mention the fact that these "exposures" are INSIDE you, CONSTANTLY, not just for a five-second medical test... Oh, Hell, nevermind. I'm sick of beating the armaggedon drum. Unlike some people, I DON'T WANT THIS TO BE TRUE. I view "Threads" as a horror movie, not a training video, or a recruitment tool.
Am I wrong? Let me know, please.
Rick Cromack.
Allen, Texas
RichardFCromackJr@gmail.com
You were right Rick
These guys are fooling themselves!
This is an exceptionally useful chart for comparing exposure
http://www.informationisbeautiful.net/visualizations/radiation-dosage-ch...
You can see on this chart many "radioactive" exposures oftened discussed here on this forum for comparison purposes.
The Physicians for Social Responsibility released this statement on risk and "low doses" last week:
"As the crisis in Japan goes on, there are an increasing number of sources reporting that 100 milliSieverts (mSv) is the lowest dose at which a person is at risk for cancer. Established research disproves this claim. A dose of 100 mSv creates a one in 100 risk of getting cancer, but a dose of 10 mSv still gives a one in 1,000 chance of getting cancer, and a dose of 1 mSv gives a one in 10,000 risk.
"Even if the risk of getting cancer for one individual from a given level of food contamination is low, if thousands or millions of people are exposed, then some of those people will get cancer."
http://www.psr.org/news-events/press-releases/psr-concerned-about-report...
For a really excellent straightforward analysis of all these risks and how to interpret them I recommend this report by the Physicians for Social Responsibility (Nobel Peace Prize winner):
http://www.psr.org/resources/health-risks-releases-radioactivity.pdf
Do you mean 10 rem or 10
Do you mean 10 rem or 10 mrem?
Please could I ask, Joseph,
Please could I ask, Joseph, if 1 rem equals 10msv? How many msv would we normally get in one year - is it about 3 msv?
Thanks.
Joseph, How many Cat Scans
Joseph, How many Cat Scans would you need to get to get 10 Rem?
Joseph, Wow 10 Cat scans
Joseph,
Wow 10 Cat scans sounds like alot of radiation. What am I missing here?
Wow - it sounds like even
Wow - it sounds like even the super low dose isn't that low. It amounts to one full body CT-scan! And when "low dose" is referred to, over what time frame is that - a year, a day, an hour? Confusing...
Thanks
How would that transfer to picocuries as Bq?
how does mrem compare with
how does mrem compare with CPM? How many CPM's equal an above the limit dose?
Welcome to the new reality!!
What these guys are saying is we are essentially screwed, but in really nice words. We just read that the level of radiation from one CT Scan can up your risk of cancer, but a low dose is considered 9 CT's in one year.
Welcome to the new reality!! Where even nuclear physicists pretend that it's safe to breath "low dose" radiation, all the time!!
I'm sorry for needing
I'm sorry for needing further clarification...So from now on living for a year will expose us to the same amount of radiation as one CT Scan. What about a year from now? How much do you project will be released before the leaks are stopped..and what will our annual exposure be five years from now? Am I incorrect in assuming radiation levels will rise based on the time it takes to stop the leak? Have you discussed PROJECTED levels based on the information given by TEPCO regarding the 'best case scenario" time frame for stopping output of radiation? I hope I phrased those questions coherently. Thank you BRAWM!
data on detection limits
RADIONUCLIDE DETECTION LIMITS REQUIRED TO
ESTIMATE HEALTH EFFECTS IN CERCLA RISK
ASSESSMENT (U)
LDs have been calculated for radionuclides in water and soil. Water concentrations are
based on risks resulting from the consumption of drinking water while soil concentrations
are based on risks from incidental soil ingestion and external radiation exposure from
ground surface contamination.
Water/soil concentrations are given in Table 1 for the requested radionuclides. Four
radionuclides (Pb-210, Ac-228, Th-228, and Th-230) have been added to the list since
they are daughter products in either the natural thorium decay series (Th-232) or the
natural uranium decay series (U-238). Concentrations in the table are those that would
result in a 10-6risk to individuals exposed to radionuclides via the pathways described
above.
Table 1. CERCLA Risk-Based Radionuclide Detection Limits
i ii#ii il_,el _I _
Detection Limits
Water Soil (ingestion) Soil (external)
Nuclide (pC i/m L) (pCi/g) (pC i/g)
H 3 88E-01 15E+04
C-14 53E-02 88E+02
K-40 4 3E-03 72E+01 15E+00
Co-60 32E03 53E+01 97E02
Sr-89 16E-02 26E+02 18E+03
Sr-90 14E-03 2 4E+01
Y-90 15E-02 2 5E+02
Tc-99 37E-02 61E+02 14E+08
Ru-106 5 0E-03 8 4E+01
Sb 125 57E-02 94E+02 70E-01
i 129 25E-04 42E+00 20E+02
Cs-134 1 2E-03 19E+01 1 6E-01
Cs-137" 1 7E-03 28E+01 42E-01
Eu-152 23E02 38E+02 23E-01
Eu-154 16E-02 26E+02 20E-01
Eu-155 11E-01 18E+03 14E+01
Pb-210t 9 3E-05 16E+00 64E+03
Ra-226 4 0E-04 66E+00 70E+01
Ra-228 4 8E-04 7 9E+00
Ac-228t 9 5E-02 16E+03 2 9E-01
Th-228t 4 3E-03 72E+01 15E+03
Th230t 37E-03 61E+01 15E+04
Th-232t 4 0E-03 66E+01 32E+04
U-233 30E03 5 0E+01 2 0E+04
U234 3 0E-03 50E+01 28E+04
U- 235 3.0 E-03 5.0E +01 3.5 E+00
U-238t 3.0 E-03 5.0E+01 4.0E+04
Np-237 2.2 E-04 3.6E+00 1.1 E+02
Pu-238 2.2 E-04 3o6E+00 3.0 E+04
Pu-239 2.1 E-04 3.5E+00 4.9E+04
Pu-240 2.1 E-04 3.5E+00 3.1E+04
Pu-242 2.2 E-04 3.6E+00 3.6E+04
Am- 241 2.0 E-04 3.3 E+00 1.7E+02
Am -243 2.0 E-04 3.3 E+00 3.5 E+01
Cm-243 2.5E-04 4.2E+00 5.2E+00
Cm-244 3.0E-04 5.0E+00 2.8E+04
Cm-245 2.0 E-04 3.3 E+00 1.6E+01
Cm-246 2.0E-04 3.3E+00 3.1E+04
Cm-247 2.2E-04 3.6E+00 9.1 E-01
Cm-248 5.2E-05 8.7E-01 3.8E+04
"includes gamma emissions from Ba-137m.
tin natural uranium (U-238) or thorium (Th-232) decay series
hey someone is up early on
hey someone is up early on Saturday