Due to the elevated levels of radioactive iodine in the tap water of Tokyo – a problem attributed to a nuclear plant damaged in the March 11 earthquake and tsunami- parents have been advised to NOT let their children drink it.

Radiation exceeding legal limits has now been found in 11 different types of vegetables and milk in prefectures surrounding the damaged Fukushima Daiichi nuclear power plant. This has caused a stoppage in the shipping of many different products.

Countries like the US have completely stopped the import of milk, milk products, fresh vegetables and fruit from four Japanese prefectures, though certain products could be allowed in if tests show them to be safe, according to a Food and Drug Administration spokeswoman.

If you have ever wondered just how the radiation gets into the food and water and what kinds of effects it can have keep reading:

Radiation particles from nuclear plant to food, water and milk

Radioactive particles escaping from the Fukushima Daiichi plant can bind to dust, then travel in the air for some time before landing on the ground. Once these particles, they could be cesium-137 and/or iodine-131, land on the farm produce or in the water they contaminate them. It’s as simple as that.

The problem with leafy vegetables is that they have big surface areas (think spinach and lettuce) meaning all the more space on which the radiation particles can land, according to Marko Moscovitch, professor at Georgetown’s Department of Radiation Medicine.

Now when it comes to milk, the particles aren’t getting into the milk itself per se, they are landing on the grass that is then eaten by the cows, thereby infecting them.

Is it dangerous to eat the food, milk and water?

According to experts there is not a lot known about how dangerous eating radiation-contaminated food really is. That said, the experts who have spoken with CNN have all said that the contamination levels reported so far appear to pose very little risk.

Dr. James Cox, an oncology professor at the MD Anderson Cancer Center in Houston, said he thinks the radiation levels measured in the food and water in Japan pose a “nonexistent” immediate risk to humans, and “very low” long-term risk.

Spinach tested in a prefecture south of Fukushima showed radiation up to 27 times greater than the legal limit. Dr Sanjay Gupta, however, said a person “would have to eat the contaminated spinach from Japan every day for one year to get the same amount of radiation you would get from one chest CT (computed tomography) scan.”

A chest CT scan exposes the human body to about 7 millisieverts of radiation. The U.S. Nuclear Regulatory Commission says that an average person gets about 3.1 millisieverts annually from natural sources, and an average American – thanks in part to medical diagnostic procedures and other man-made sources of radiation – gets about 6.2 millisieverts per year.

Even low radiation doses can damage or alter the DNA of irradiated cells, the NRC says. And the radiation protection community “conservatively assumes that any amount of radiation may pose some risk for causing cancer and hereditary effect, and that the risk is higher for higher radiation exposures,” the NRC says.

Still, Drs Gupta and Moscovitch say it’s very unlikely that the radiation reported at this time in Japanese food would pose a risk to the health of the people of Tokyo and other parts of Japan.

“(The radiation is) not negligible my any means. But impact on human health? Not likely,” Gupta said on the CNN program “In the Arena.”

The concern about infants and the contaminated water

On Tuesday night officials warned parents to not give their children tap water after tests shows there were 210 becquerels of radioactive iodine per kilogram of water – two times higher than the limit that the government considers safe for infants.

While that sounded dire for small children the amount of iodine detected was lower than the level considered safe for adults: 300 becquerels per kilogram. A liter of water weights 1 kilogram. A becquerel is a measurement of radioactive intensity by weight.

Experts say that the level set for infants is “very conservative,” but elevated radiation levels are considered a problem for small children, because their thyroid glands are more susceptible to radioactive iodine.

“Erring on the side of caution for the extreme degree for children makes good sense,” Cox said. For adults, “as far as the immediate health risk, something that would make people sick, I don’t think that would come close to it.”

Is there a way to get radiation out of water?

According to the World Health Organization it is possible that standard water treatment procedures – including coagulation, sedimentation and filtration – might remove “significant amounts of radioactive contaminants.”

It is also possible to mix the radiation contaminated water with clean water in an effort to dilute the radiation dangers.