A nuclear medicine expert who was part of the medical relief effort after Chernobyl says the situation in Japan is nowhere near as dangerous to human health but there are worrying similarities.
Dr Robert Gale, a professor of haematology at the Imperial College London, has just been in the Fukushima evacuation zone.
He says the eruption of a nuclear power station and the contamination of soil, water and air is serious.
"The question is just how serious. Is this another Chernobyl or is this another Three Mile Island or somewhere in between?" he said.
Dr Gale says Chernobyl had an uncontained reactor which released of huge amounts of radioactive materials into the environment and ultimately all over the northern hemisphere.
"Speaking for the moment because things can change rapidly, this is not another Chernobyl. Here we have contained reactors," he said.
"We do have some spent fuel rods that are not contained and it is hard to imagine any situation in which you could ever get close to the health consequences of Chernobyl, but I have to say there are number of similarities.
"The complexity is certainly equal to Chernobyl in terms of trying to figure out how to contain the situation and how to mitigate the damage in the reactor.
"In fact in some ways the Chernobyl situation was quite a bit simpler because the entire reactor was exposed and it was possible to bombard it and stop the emissions. Whereas here, we are dealing with an intact structure and human beings have to get inside it and try to figure out what is going on."
Dr Gale says it is not entirely surprising that Japanese authorities do not have the reactors under control and cannot isolate the source of the highly radioactive water.
"This is a really complicated situation," he said.
"When you have physical damage to these complex machines, ultimately you have to get human beings in there to see what is going on and to put it right, and I think this thing won't be sorted out for some while.
"I mean it is not going to be sorted out in the next 24 to 48 hours because there is proper caution in exposing people to an acceptable levels of radiation.
"The workers are uniquely at risk for the dangers of high-dose radiation. High-dose radiation destroys the bone marrow so they are the only ones at risk from that kind of damage where we consider using intensive medical interventions."
Dr Gale says the rest of the population is at risk of three things.
"The most important one probably is cancer. There are the possibility of birth defects in children that are in the womb at the time of exposure, and then there is the possibility of genetic abnormalities," he said.
"We haven't seen the last two after the Chernobyl accident fortunately, but we have seen cancers specifically thyroid cancers in young people.
"There are about 6,000 cases of that. That was caused predominantly because young persons drank milk that was contaminated with radio iodine.
"That is a preventable situation. Withdrawing milk from the market, giving people a non-radioactive form of iodine that can, I would say, almost entirely, not entirely but almost entirely prevent thyroid cancers and those actions have been taken."
The Japanese government has banned the consumption of food and water from the Fukushima area.
Dr Gale says if the emissions were stopped today, it would take about 80 days for the radioactive iodine to be gone from the food and water in the area.
"But when we are dealing with caesium which is also released from nuclear reactors, we are talking about needing 300 years for that all to go away," he said.
The International Atomic Energy Agency is warning the crisis will be long-term.
Dr Gale says this ongoing disaster could, in some ways, be worse than the single catastrophic blast that happened at Chernobyl.
"The Chernobyl accident was absolutely a worst-case scenario, but it happened and it was over and once the sarcophagus could be constructed over the reactor, people could return to a sort of normal existence," he said.
"The problem we face here in Japan is daily or even hourly reports of radionuclide levels in drinking water, in spinach and people are really dreadfully confused. They just don't know how to conduct their lives.
"Some people are sending their families overseas, so in a public health and public information perspective, an ongoing disaster is far worse than a single event."
To listen to Dr Gale's full interview visit The World Today website.