Thinking About The Children Of Fukushima: Food, Water, Playing Outside – What’s Safe?

On September 11th, ANT Hiroshima hosted a symposium presented by Dr. Nanao Kamada, Chairman of the Board of Directors, Hiroshima Atomic Bomb Survivors Relief Foundation, who spoke about his findings in regard to a visit to Fukushima to investigate the levels of radiation that remain in the environment following the nuclear disaster that unfolded in the wake of the earthquake and tsunami in the north east of Japan on March 11th of this year.

Order of Presentation

  1. Basic information on radiation
  2. Physical examinations personally conducted in Fukushima
  3. Determining exact radiation dose (Measurements)
  4. Efforts to decrease external and internal radiation levels (Decontamination)
  5. You have the right to decide for yourself, so take action.

Radioactivity and Radiation
The ability of a substance to emit radiation is known as radioactivity. 


  • Charcoal (Radioactive material) (Unit: Becquerel, Bq)


  • Heat ray (Radiation) (Unit: Gray, Gy)
  • Unit to measure emission of radiation (the emitter): Becquerel
  • Unit to measure dose of radiation (the receiver): Sievert
  • Unit to measure dose per particular organ or total body dose (Sievert)

Types of Radiation (Devices to detect them vary.)

  • α ray (Alpha)
  • β ray (Beta)
  • γ ray (Gamma)
Alfa beta gamma radiation Alpha particles are stopped by a sheet of paper. Beta particlesare stopped by an aluminium plate. Gamma rays are stopped by 4 meters of lead.
Alfa beta gamma radiation
Alpha particles are stopped by a sheet of paper. Beta particlesare stopped by an aluminium plate. Gamma rays are stopped by 4 meters of lead.

Chronology of Evacuation and Regulatory Changes

  • March 11th: Earthquake. Emergency shutdown of first, second and third reactors at the Daiichi Nuclear Power Plant.
  • March 12th: Government designates areas within 20 km of the Daiichi Plant the No-Entry Zone. 
  • March 15th: Government designates areas between 20 and 30 km the Indoor Emergency Evacuation-Ready Zone. 
  • March 19th: Five times the allowed limit of radioactive iodine detected in raw milk from Kawamata Town. 
  • March 21st: Radioactive iodine detected in water from Iitate Village waterworks.
  • April 20th: Shipment of sand lance is suspended.
  • April 22nd: Planned Evacuation Zones designated in certain areas outside 20 km. 
  • June 2nd: Shipment of tea leaves is suspended. 
  • June 16th: Specific evacuation sites outside No-Entry Zone are set up. 
  • July 19th: Shipment of Fukushima beef is suspended.

Objectives of Dr. Kamada’s Research and Examinations in Fukushima

After the Hiroshima atomic bombing in August 1945, the dangers of internal exposure to radiation was neither understood nor treated. Children are three times more susceptible to radiation than adults. So Dr. Kamada felt it was his responsibility to propose examinations for residents, with these objectives in mind.

  1. Finding evidence to enable better decision-making for children’s safety.
  2.  Following the Fukushima nuclear plant accident, internal exposure must be carefully studied.

External Radiation Exposure Level by May 5
Annual Regulation Value: 20 mSv
Maximum Radiation Exposure Level / Minimum Radiation Exposure Level
Range: 4.9~13.5 mSv

Internal Radiation Exposure Level
Iitate Village
Urine Sample
Axis Concentration (Bq/ L)
Cesium 137
Cesium 134

Findings of Examinations in Fukushima

  1. On May 5th, radioactive cesium was detected in all tested residents, but in minute amounts.
  2. Radioactive iodine was detected in some residents. The largest detected dose was 3.2 mSv. Contaminated food intake is thought to be the major source.
  3. Although their external exposure levels were below the annual recommended limit of 20 mSv, to avoid continued exposure, I advised the residents I examined to evacuate in a timely manner.
  4. To limit internal exposure, I advised them to avoid locally cultivated vegetables and plants growing wild in the local mountains such as mushrooms.

Differences between the Hiroshima Atomic Bombing and the Fukushima Nuclear Plant Accident (Residents)

In both cases, local communities and infrastructure (houses and employment) collapsed amid rising anxiety about health disorders.

Hiroshima Fukushima
Single exposure to a large dose of radiation Prolonged exposure to small doses
Direct exposure to radiation Indirect exposure to radiation
Great variance in dose Doses are consistently small
Exposure upon entering the contaminated area Exposure upon evacuating the contaminated area
Internal exposure denied (not recognized) Threat of internal exposure recognized
Quantity of radioactive materials dispersed is 9kg Incomparably greater dispersion of radioactive materials
Blast, fire and horrible scenes Anxiety caused by exposure without the means to detect it or protect from it

Keep Measuring
External Exposure Level
Areas around homes, school routes and areas around schools
Side ditches, roadside trees and school lawns

Air Dose Map

Recall where you were to estimate your exposure levels.
For more details, download this Fukushima air dose map.

To Estimate External Dose

A: Radiation levels where you were (microsievert/ hour)

a Hours working outside
b Hours inside wooden housing
c Hours inside concrete housing
d Hours inside vehicles

Single Day Dose: a×A+{(b×A)×0.4}+{(c×A)×0.1}+ {(d×A)×0.8}}

Example: You were in an area with radiation levels around 2.1 microsievert/ hour.
If you stayed outside for 8 hours, in a wooden house for 12 hours, and in a car for 4 hours, then:

8×2.1+{(12×2.1)×0.4}+{(4×2.1)×0.8}=33.6 μSv

To calculate total dose=Add up your daily dose levels.

Regulations on Internal Dose

Japan has stricter regulations than other developed countries.

For a comparative table see:

Radioactive Iodine Dose Calculation (example)

If one eats each day for 1 week 200 grams of vegetables contaminated with 100 becquerels of iodine
per kilogram.
A:Effective Dose (μSv)
Ca:Radioactive Material Concentration 100Bq/kg
Ka:Effective Dose Conversion Coefficient (μSv/ Bq) = 0.022
(Based on Oral Ingestion Data Table No.1)
Q:Amount of Intake 0.2kg/ day
T:Duration of Intake ; About one week =7 days
A=100×0.022×0.2×7= 3.08 μSv

Radioactive Cesium Dose Calculation (example)

A person weighing 60 kilograms who eats 100 becquerels of food containing Cesium 137
Dose = 0.00002×0.48×100×90 =0.0014 millisieverts

Fixed Whole-Body Geiga Counter

In addition, there are 45 portable whole-body geiga counters in all of Japan.

The effective period for accurate dose determination using whole-body geiga counters is over.

122 residents of Iitate, Kawamata and Minamisoma underwent examinations at the National Institute of Radiological Sciences (NIRS) in Chiba starting on June 28.
On August 17, the results were reported. No abnormal values were detected.

Is it safe to drink the water, play outside, eat the food?

  • Water: All municipalities, including Iitate Village and Fukushima City, have examined water samples from simple waterworks; the results show no levels over government-set limits since April 1. 
  • Playing Outside: There is no problem playing on school grounds that have been decontaminated, but radiation levels on nearby lawns and other places must be measured. 
  • Food: We must be very careful about some varieties of foods.

To Protect Ourselves against External Exposure

  1. Removing sources: Remove top soil and wash off surfaces.
  2. Shortening exposure time: Don’t stay outside for long periods.
  3. Keeping distance from radiation sources: Collect contaminated soil in remote places.
  4. Shielding from radiation: Cover up contaminated soil.

Efforts to Reduce External Dose

On August 25, the Japanese government decided to decrease the annual dose limit from 20 millisieverts to 1 millisievert.

Efforts to Reduce External Exposure to Radiation
Residents can wait any longer for effective measures so here is what can be done in the meantime:

  • Keep measuring

Instructions for decontamination work:

  • Wear masks
  • Wear gloves
  • Wear rubber boots
  • Take nothing into the mouth
  • Keep a water supply
  • Bring dosimeters

Efforts to Reduce Internal Exposure 

  1. Gather information about contaminated food. Check the origin of foods, especially fish, mountain vegetables, mushrooms and rice.
  2. When cooking, exercise ingenuity and avoid large fish bones.
  3. Eat a wide variety of foods.

Elements that can Remove Active Oxygen Generated by Radiation

  1. Vitamins: Vitamin A, Vitamin C and Vitamin E
  2. Minerals: Zinc, Chrome
  3. Polyphenols (Plant Pigment): Anthocyanin from red wine, Catechin from tea

Reduce the Risk of Disease

Diseases don’t develop suddenly. Each disease grows from a bad sprout. Get rid of bad sprouts at an early stage and strengthen your resistance by enhancing immunity.

  1. Disciplined lifestyle
  2. Balanced meals
  3. Alleviate stress – Think positively

Foods that Help Fight Cancer

Foods higher in the table have stronger cancer preventive power. These include:

garlic, cabbage, licorice, soybeans, ginger, carrot, celery, parsnip, onion, tea, turmeric, brown rice, whole wheat, tofu, orange, lemon, brussel sprouts, tomato, eggplant, green pepper, broccoli, cauliflower, grapefruit

Take control—determine your own direction.

  • Past event = Present challenge =  Perspective for the future
  • Think positively
  • Work together
  • Set an example because children are watching

Act to Counter Invisible Radiation

  1. Keep measuring – Cooperate with municipalities, and/or do it yourself.*
  2. Pay attention to food – Urge your municipalities to provide information.
  3. Take regular health checks – We need a system that allows affected people to be examined wherever they evacuate.


*Monitoring (Measuring) by citizens can apply great pressure to the Japanese government and companies.

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