I found this interesting news in the Science webpage relationated to health and lifestyle. This news is about the usual effects of radiation in humans and other very exiciting and interesting items of radiation such as it effects on seawater or food. This notice will answer all the questions you have about this terryfing problem. If i were you i would take a coffe and sit in front of the laptop readig this news, i hope you enjoy it!

Q&A: Health effects of radiation exposure

How does radiation have an impact on health?

Radioactive materials decay spontaneously to produce ionising radiation, which has the capacity to cause significant damage to the body's internal chemistry, breaking the chemical bonds between the atoms and molecules that make up our tissues. Damage to the DNA of a cell is particularly important.

The body responds by trying to repair this damage, but at high doses it is too severe or widespread to make repair possible, leading to short-term acute health effects.

There is also a danger of mistakes in the natural DNA repair process, which can lead in the long-term to cancer.

Regions of the body that are most vulnerable to acute radiation damage include the cells lining the intestine and stomach, and the blood-cell producing cells in the bone marrow.

The extent of the damage caused is dependent on how long people are exposed to radiation, and at what level.

 What are the immediate health effects of exposure to radiation?

Exposure to high levels of radiation - above one gray (the standard measure of the absorbed dose of radiation) - can result in radiation sickness, which produces a range of symptoms.

Nausea and vomiting often begin within hours of exposure, followed by diarrhoea, headaches and fever.

After the first round of symptoms, there may be a brief period with no apparent illness, but this may be followed within weeks by new, more serious symptoms.

At higher levels of radiation, all of these symptoms may be immediately apparent, along with widespread - and potentially fatal - damage to internal organs.

Exposure to a radiation dose of four gray will typically kill about half of all healthy adults.

For comparison, radiation therapy for cancer typically involves several doses of between one and seven gray at a time - but these doses are highly controlled, and usually specifically targeted at small areas of the body.

A sievert is a gray weighted by the effectiveness of a particular type of radiation at causing damage to tissues, and is used to measure lower levels of radiation, and for assessing long-term risk, rather than the short-term acute impact of exposure. There are 1,000 millisieverts (mSv) in a sievert.

People are exposed on average to around 2mSv of radiation a year from the natural environment, although there is considerable variation in this dose between individuals.

In the UK, the legal limit for radiation exposure from sources such as nuclear plants for members of the public is 1mSv a year, based on recommendations from the International Commission on Radiological Protection.

For emergencies, the upper limit is set higher - 5mSv or more - but these figures are set conservatively, at levels far below those that would significantly raise health risks. 

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