FAQs: Japan nuclear concerns
The damage to the Daiichi nuclear power plant in Fukushima, Japan, and the subsequent detection of radioactivity in certain food samples from neighbouring areas have raised concerns about the safety of food from Japan. The Japanese authorities have regulations in place relating to provisional regulatory limits of radioactivity in food and food monitoring is being implemented. Measurements of radionuclide concentrations in food have been taking place and are being released by the Japanese authorities.
The following questions and answers produced by the FAO and WHO address some of the international concerns over the safety of food produced in Japan.
Can food produced in other countries be affected by the events in Japan?
- Radioactive material has been released into the environment from damaged Japanese nuclear power plants. Radiation levels measured to date in other countries are far below the level of background radiation that most people are exposed to in every day circumstances and do not present health or transportation safety hazards, according to the United Nations organizations closely monitoring the situation.
- Minute amounts of radioactive caesium and iodine might be found using very sensitive detection methods but this should not affect foods produced in other countries as the amounts involved will be well below acceptable levels and would not pose a health concern to those who eat the food.
What are the potential health effects of consuming contaminated food?
- Consuming food contaminated with radioactive material will increase the amount of radioactivity a person is exposed to and could increase the health risks associated with exposure to radiation. The exact effect will depend on which radionuclides have been ingested and the amount. According to data reported so far, radioactive iodine and caesium are the main contaminants, and concentrations in some food samples have been detected at levels above the Japanese regulatory limits.
- Radioactive iodine has a half-life of eight days and decays naturally within weeks. If ingested, it can accumulate in the body, particularly the thyroid gland, and increase the risk of thyroid cancer, particularly in children.
- The ingestion of potassium iodide is an established method to prevent the accumulation of radioactive iodine in the thyroid.
- Radioactive caesium has a half-life longer than that of radioactive iodine (up to 30 years).and can stay in the environment for many years. Like all radionuclides, exposure to radiation from radioactive caesium can result in a increased risk of cancer.
Is all food production in Japan affected by the nuclear emergency?
- No, not all foods will be affected. Food that was dispatched or commercially packaged before the emergency situation would not be affected. However, some food produced in areas where radioactive material has been deposited has been found to be contaminated. This is why the Japanese authorities have instituted monitoring and are taking measures to address the issue.
What impact will this have on food and food production in Japan?
- The impact on food and food production in Japan will depend upon the types of radionuclides and the amount of radioactivity deposited or present where food is being produced or harvested. Although radioactive iodine in food is of immediate concern after nuclear emergencies, it has a relatively short half-life and will naturally decay over a short time frame. Radioactive caesium has also been detected in food. In contrast to radioactive iodine, radioactive caesium can linger in the environment for many years and could continue to present a longer term problem for food, and food production, and a threat to human health.
How do food products become radioactive?
- Foods can become contaminated with radioactive materials when they are released as the result of a nuclear or radiological emergency. In these circumstances, radioactive material falling from the air or carried in rain water or snow, can deposit on the surface of foods like fruits and vegetables or animal feed. Also, over time, radioactivity can build up within food, as radionuclides are transferred through soil into crops or animals. Radioactivity can also be washed into rivers, lakes and the sea where fish and seafood could take up the radionuclides. The severity of the risk depends on the radionuclide mix and the level of contaminant released.
- Radioactivity cannot contaminate food that is packaged; for example, tinned or plastic-wrapped food is protected from radioactivity as long as the food is sealed.
Why is food affected in areas beyond the evacuation zone?
- During a nuclear emergency, an evacuation zone is established to prevent people from being exposed to immediate and unacceptable levels of radiation posing a threat to human health. However, contamination of food can occur through uptake from soil to crops, or to animals through feed, even when levels of radioactive contamination are lower than those which might pose a direct threat to human health. The standards for acceptable limits for radioactivity in food are set at low levels in order to take into account the possibility of contaminated food being eaten over an extended period of time and resulting in a cumulative dose.
Are there rules for radioactivity in foods for international trade?
- There are internationally agreed Codex Guideline Levels (GLs) for radionuclide levels in internationally traded food following a nuclear or radiological emergency. These GLs are published by the Joint FAO/WHO Codex Alimentarius Commission.
- The GLs state that, “as far as generic radiological protection of food consumers is concerned, when radionuclide levels in food do not exceed the corresponding Guideline Level, the food should be considered as safe for human consumption. When the Guideline Levels are exceeded, national governments shall decide whether and under what circumstances the food should be distributed within their territory or jurisdiction. National governments may wish to adopt different values for internal use within their own territories, where the assumptions concerning food distribution that have been made to derive the Guideline Levels may not apply, e.g., in the case of widespread radioactive contamination. For foods that are consumed in small quantities, such as spices, that represent a small percentage of total diet and hence a small addition to the total dose, the Guideline Levels may be increased by a factor of 10”.
- GLs for radionuclide levels can be found in the Codex General Standard for Contaminants and Toxins in Food and Feed – (CODEX STAN 193-1995)
What actions are being taken to monitor the safety of food from Japan?
- In response to the nuclear accident in Japan, Japanese authorities have instituted monitoring of food products and have restricted the consumption and distribution of some products in certain prefectures, or areas found to contain radionuclides exceeding Japan's provisional regulation value. Findings from food monitoring in Japan and decisions related to the consumption and distribution of food products are published regularly on the Ministry of Health, Labour and Welfare web site.
- Many countries have implemented food control measures to mirror actions taken within Japan. Some countries have indicated they now require documentation verifying the safety of products and/or the prefecture of origin of the food. Other countries have suspended food imports from Japan. In addition, many countries have increased monitoring on foods imported from Japan.
What general advice can be given to food consumers and producers in the event of a nuclear emergency?
- The response to an emergency involving radioactivity should be the same as the response to any emergency involving any hazardous material contaminating food. In the early stages of an emergency, and if it is safe to do so, it is possible to take immediate actions to prevent or minimize the contamination of food by radiological materials. For example, it is possible to do the following:
- protect food and animal fodder which is stored in the open; cover with plastic sheets or impermeable tarpaulins;
- close the ventilation of greenhouses to protect growing vegetables;
- bring livestock in from pastures and move animals into a shed or barn;
- harvest any ripe crops and place under cover before any fallout has been recorded; and
- don’t harvest after fallout – wait for further instructions after contamination has been recorded.
- Many other short-, medium- and long-term actions need to be considered in areas confirmed to be seriously contaminated, such as:
- avoid consumption of locally produced milk or vegetables;
- avoid slaughtering animals;
- avoid consumption and harvesting of aquatic animals and plants (including fish, shellfish, and algae); and
- avoid hunting or gathering mushrooms or other wild or collected foods.