There is some serious panic going on in the land of Twitter about the fact that one of the reactors at Fukushima uses mixed fuel containing plutonium:

There is no such thing as a “safe dose” of plutonium.

MOX plutonium fuel used in Fukushima’s Unit 3 reactor two million times more deadly than enriched uranium.

RADIATON HEADING FOR THE US!!!DEADLY PLUTONIUM CLOUD HEADING FOR THE US,CANADA.

You’re right if they declared plutonium released – mass panic for sure.

Certainly, plutonium is not the first substance you would choose to sprinkle on your Weeties in the morning. It is radioactive and toxic – but nowhere near as dangerous an element as some would have you believe.

Plutonium first gained its notoriety as the working ingredient in nuclear bombs, but most of the hysteria about the substance dates back to a fear campaign whipped up by Helen Caldicott, who famously claimed that if one pound of plutonium was evenly distributed, it could cause lung cancer in everyone on earth.

This is tosh.

Compared to many chemicals, bacteria and heavy metals, there is nothing especially toxic about plutonium, and because of its long half life, it is not severely radioactive either.

Studies have shown the survivors of Nagasaki and Hiroshima had their life expectancies cut short by an average of about four months. This was demonstrated when the guy who survived both Hiroshima (a uranium bomb) and Nagasaki (a plutonium bomb) lived to 93.

As the World Nuclear Association points out:

Comparisons between toxic substances are not straightforward since the effect of plutonium inhalation would be to increase the probability of a cancer in several years time, whilst most other toxins lead to immediate death. Best comparisons indicate that, gram for gram, toxins such as ricin and some snake venoms and cyanide are significantly more toxic. Consider also that all the cleaning products that we have in our kitchen are toxic if we absorb them, whilst some of the products that are spread onto crops are toxic as well.

However, studies have shown that people who were exposed to large amounts of plutonium have actually done fine. Around 25 workers in Los Alamos inhaled varying amounts of plutonium during the 1940s and long term studies showed that many fewer of them contracted cancer than would be expected even if they had not been exposed. Long term studies of people around Los Alamos have found no problem. Two workers inhaled “the most toxic substance in the world” just six years ago, and they soon returned to work.

The truth about plutonium was famously demonstrated on American television when the distinguished physicist Dr Bernard Cohen carefully calculated the risk and offered to eat as much plutonium on camera as anti-nuclear activist Ralph Nader would eat pure caffeine. He declined the challenge which is just as well, or Nader would no longer be with us.

There is more information at this forum with some real physicists discussing Cohen’s challenge, including this observation:

I met one of two people who were involved in separate glove box explosions that resulted in particles and solution of Pu compounds being imbedded in them. He was in his 60s approaching retirement, and after about 20+ years, he had no indications of adverse affects on his health.

Plutonium is also about 50 percent heavier than lead, so if it is dispersed in any way, it will simply fall quickly to earth – it will not travel in “radioactive clouds”. Speaking of radioactivity, it is safe enough to hold a large lump of the stuff in your gloved hand – check out some of the images on Google.

To my knowledge there is no suggestion that plutonium has been detected around Fukushima at this stage, but even if it has been, there is nothing to panic about.

Plutonium is not the most toxic substance in the world – not even close.