Health Effects of Radiation

[JimD]

We keep hearing about radiation on the evening news these days. I don't think there is any cause for concern in the U. S. and not much of one in Japan but it made me curious so I looked up the data on health effects. I thought some of you might be interested. This information relates to near term impact, not statistically higher rates of cancer later. The data to support the statistics is very shaky IMHO so I don't pay a lot of attention to it.

50 Rem (abbreviated R in the following) - nausea

55 R fatigue

70R Vomiting

75R hair loss after 2-3 weeks

90R diarrhea

100R hemorrage

400R possible death within 2 months

1000R possible death in 1-2 weeks

2000R possible death in minutes to hours

A typical background radiation in the U. S. is 300 milli Rem - three tenths of 1 R. The regulatory limit in the U. S. for a worker in a nuclear power plant is 5 R. When they say somebody is "contaminated" that means they had measurable contamination on them. It could be only a few milli Rem. When the radiation spiked at 40R/hour in units 2-3 in Japan, that meant that the workers were at risk if they stayed unprotected in that radiation field for more than a couple hours. If they stayed in that radiation for 10 hours, they might die. The radiation did not stay that high for 10 hours but that was serious.

The offsite doses I have seen were in the range of 7-12 milli Rem per hour at the site boundry. So at the peak at the boundry you'd have to hang out about 420 hours (17.5 days) to have a near immediate health effect (nausea). At 10 times this long, you would be at risk of dying. The radiation diminishes rapidly with distance. In the industry, they teach us time, distance, and shielding. We control the time of exposure, the distance from the source of exposure and when we need to, we put shielding between the worker and the source of exposure. Concrete is pretty good shielding, lead is very good shielding, nearly any solid or liquoid provides worthwhile shielding. When the radiation spiked at 40R/hour the workers were wearing some form of shielding.

The fact that the radiation at the boundrys has stayed so low is why I don't think there is any significant risk even in Japan. There may be more colorful things happen like the lube oil fire in Unit 4 but the cores are already significantly cooler than they started and are continuing to cool so the risk is getting lower all the time.

Jim

[sparkeyjames]

That was an absolutely glowing summation of radiation dosage and protection.

Jim

[Turaj]

Very interesting! I knew there would be different effects depending on the level and exposure time but no understanding of the relative magnitudes. Thanks for taking the time to post it.

[LCHIEN]

most of the radiation measurements in the Japan crises are given in Sieverts (Sv), milliSieverts (mSv), and microSieverts (uSv).
Conversion factors: THere's 100 Rem = 1 Sievert and 1 Rem = .1 mSv.
I hear local Fukushima plant radiation has spiked to around 400mSv/hr or about 4 Rem/hr.

Then to put it into perspective,
Standing around there for 12 hours would get you to the first level JimD specified.

[All Thumbs]

Then to put it into perspective,
Standing around there for 12 hours would get you to the first level JimD specified.

Are they (disaster workers) wearing any protective clothing as they do this? Something lined with lead or something?

If yes, how effective is this in reducing your exposure?

[LCHIEN]

Are they (disaster workers) wearing any protective clothing as they do this? Something lined with lead or something?

If yes, how effective is this in reducing your exposure?

they're wearing masks and breathing apparatus to keep from inhaling the light radioactive isotopes to keep them out of the body where they would be absorbed and radiate continuously from within This helps avoid long term cancer risks). They're wearing protective clothes that stop lightweight particles like alpha particles but don't do a thing to stop higher energy particles like X-ray and gamma ray particles which are particularly damaging. it's like a crap shoot, you hope that most of the particles don't hit anything vital... they're at serious risk of radiation sickness as JimD described... a nasty way to die.

[sailor55330]

Interestng that our experts here feel that the dangers are slight while media and governement agencies are describing the efforts as "suicide missions", especially the helicopter flights.

All I know is a freind of mine who was a nuclear engineer on a sub for many years doesn't seem to think the dangers are in the slight zone anymore.

Here's hoping for the best because if this thing goes, Chernobyl might seem tame.

[LCHIEN]

Interestng that our experts here feel that the dangers are slight while media and governement agencies are describing the efforts as "suicide missions", especially the helicopter flights.

All I know is a freind of mine who was a nuclear engineer on a sub for many years doesn't seem to think the dangers are in the slight zone anymore.

Here's hoping for the best because if this thing goes, Chernobyl might seem tame.

its a matter of distance and dilution.
THe overflights by helos dropping water I hear they're limiting the pilots to about 20 minutes since the direct gamma and x-ray radiation is going straight up from the stored fuel pond they are trying to fill.

In the US, the danger is of course smaller because the radiation is spread out over a much larger area by the time it gets here, rays will be weak. I think they are claiming radiation will be unmeasurable even though the jet stream will take it over parts of the US. But another danger will be pollution by radioactive isotopes like iodine and cesium and strontium. heavier parts will have dropped in the ocean thru gravity and rain but what does get here will be in the soil and the food chain has been shown to reconcentrate those. Once ingested the body further concentrates those in the thyroid and bones leading to thyroid cancers and leukemia. Still distance cures all and the concentrations will be much less falling 6000 miles away than 50 miles away.

[LCHIEN]

Interestng that our experts here feel that the dangers are slight while media and governement agencies are describing the efforts as "suicide missions", especially the helicopter flights.

All I know is a freind of mine who was a nuclear engineer on a sub for many years doesn't seem to think the dangers are in the slight zone anymore.

Here's hoping for the best because if this thing goes, Chernobyl might seem tame.

its a matter of distance and dilution.
THe overflights by helos dropping water I hear they're limiting the pilots to about 20 minutes since the direct gamma and x-ray radiation is going straight up from the stored fuel pond they are trying to fill.

In the US, the danger is of course smaller because the radiation is spread out over a much larger area by the time it gets here, rays will be weak. I think they are claiming radiation will be unmeasurable in the US. But another danger will be pollution by radioactive dust containing isotopes like iodine and cesium and strontium. heavier parts will have dropped in the ocean thru gravity and rain but what does get here (the jet stream will take it over parts of the US) will be in the soil and the food chain has been shown to re-concentrate those. Once ingested the body further concentrates those in the thyroid and bones leading to thyroid cancers and leukemia. Still distance cures all and the concentrations will be much less falling 6000 miles away than 50 miles away.

[JimD]

The workers in the plant also wear monitoring devices, TLDs they are called I forget what that stands for, that allow them to know what they've been exposed to. I hope this system is still working (it's a matter of people continuing to use them and then somebody looking at them). This allow the exposure to be limited to safe levels. My guess is people are getting more than they are supposed to (more than 5R) but hopefully not enough more for at least any immediate health impact (i.e. less than 40R). The concern, if this is true, will be cancer risk longer term. We assume that goes up with increasing exposure but the data does not seem to support that - at least up to some point.

[jackellis]

I now live at 6,000 feet, where there's less atmospheric shielding to protect me from cosmic radiation. I live above granite which means potentially higher exposure to radon. Based on my understanding of the effects and Jim D's explanation, I'm not terribly concerned about the near-term effects of radioactive debris from Japan. I might want to drink less milk, eat less beef, and stick to greenhouse-grown produce. Maybe.

The accidents are a cause for some concern from radioactive debris, but not a cause to panic. This is nothing close to Chernobyl.

The bigger cause for concern is that we'll forsake the use of nuclear energy altogether, which would be a shame.

[JimD]

The studies that have been done of people who get more than a normal background dose due to elevation, living or working near granite, having radon in their houses, or living near natural uranium deposts have shown a lower than normal incidence of the kind of cancers that would be expected to be due to radiation. That is in addition to the nuclear industry workers who get more than the average person and have no higher cancer incidence. That is why I think the effect of more background in Japan is not so obvious. The data I have seen suggests that there is no effect of even doubling or more the background. The negative correlation suggests it could even be helpful (possibly by stimulating the body's natural defenses).

Jim