Wednesday, December 28, 2011

New Radiation Safety Levels

The Japanese government has announced new radiation exposure and ingestion limits that will become law by next Spring.

The current level for food radiation caesium exposure, currently set at 500 becquerels per kilogram, will be lowered to 100.  The limit for milk will be brought down from 200 becquerels per liter to 50, and for drinking water the new limit will be just 10 becquerels per liter, down from 200.

The government claims that the new limits are in line with international guidelines, and that the strictness of the new rules is to ensure a margin of safety.

However these claims are only partly correct.  Yes, the World Health Organization suggests a limit of 10 becquerels for water, but notes that the limit is extremely conservative, and not meant for 'nuclear emergencies', but considered over a lifetime.  If an infant were to drink a liter of water containing 10 becquerels of radiation, the infant would receive 0.00024 millisieverts of exposure, worlds away from the level of 100 millisieverts a year which has an actual measurable risk.

And in regard to caesium radionucleotides in food, the new limit for food is 10 times as strict as that recommended by the WHO; and the American FDA will not intervene until 12 times the limit.

The government panel that decided the new safety measures knows very well that public health is not affected one way or the other by these guidelines.  The new levels are not really about safety; the old levels were already extremely safe, even needlessly conservative.  The new measures are really a misguided attempt by the government to regain public trust by arbitrarily lowering radiation standards, reassuring the radiation-fearful public that everything really is 'okay'.

Adding difficulty to misjudgement, the new standards will create a huge headache for laboratories and other affected agencies, because new highly sensitive equipment will be needed.  Indeed there is some doubt over whether substantial amounts of food, water or milk can be tested at all, logistically speaking.

But it's the hypocrisy of the effort that maddens me.  Inevitably some agricultural products will fall foul of the new limits, resulting in rising levels of public fear and unnecessary food wastage.  Meanwhile, these low levels of radiactivity are dwarfed by the carcinogens and pollutants regularly introduced into the environment by other sources and other industries.  See here for an example of FDA limits being exceeded by 1000 times in an oil spill and barely being newsworthy, let alone scaring an entire nation.


Charles said...

I discovered your blog a few days ago, read a couple of your article and is now following your articles.
I share your ideas about today's Japanese communication. But since the government has to earn back popularity, I don't see how the current situation could be managed differently.
This country is so complex and such a politic mess that showing confort and safety is the only way to gather the citizens.

Captaincassowary said...

Thanks Charles. I agree the Japanese government is in a bind. They know that Fukushima is safe; they also know that if they say that they won't be believed.