Natural radioactivity

Radioactive elements occur naturally in the environment and there are tiny amounts in many foods. This doesn’t cause any harm, and should not be a concern.

What is natural radioactivity?

Natural radioactivity comes from radioactive elements like uranium and thorium. These occur naturally in rocks, soil, and water. Radioactive elements continually emit a small amount of radiation.

Different types of rock have different amounts of radioactive elements. This means that some areas have higher levels of natural radioactivity than others.

How can radioactivity affect health?

Exposure to high levels of radioactivity can cause cancer and other diseases. However, low levels of radioactivity are not a concern. Natural radioactivity has always been in the environment. It doesn’t do any harm.

Natural radioactivity in our food

All foods contain natural radioactivity. Plants absorb radioactivity from the soil. Animals that eat plants absorb it from them. Fish absorb radioactivity from the water. Food generally has very low levels of natural radioactivity and is safe to eat.

Soils in New Zealand naturally have small amounts of uranium and polonium. In 2013, a study found that these occur in our food at levels similar to those seen overseas. These levels are considered safe.

Natural and anthropogenic radionuclide activity concentrations in the New Zealand diet – Journal of Environmental Radioactivity

Foods containing higher levels of natural radioactivity

Shellfish can contain relatively high levels of natural radioactivity. This means that people who eat shellfish could get more radiation in their diet than others – but it’s still only a tiny amount, and it shouldn’t be a concern. Even if you eat a lot of shellfish, your diet will have a similar amount of radiation to the diets of people in many other parts of the world.

Activity concentrations of Caesium-137 and Polonium-210 in seafood from fishing regions of New Zealand and the dose assessment for seafood consumers – Journal of Environmental Radioactivity

We don’t yet know why shellfish have higher levels of radioactivity. New Zealand Food Safety and the University of Canterbury have started researching the reasons.

Surveys show safe levels in New Zealand diet

Scientists have measured the natural radioactivity of foods in New Zealand. They’ve found the level of radiation in food we eat is similar to the levels in other countries. Both natural radioactivity and radioactivity from human sources were at safe levels.

Deterministic and Semiprobabilistic Modeling of the Committed Dose from Radionuclides and the Chemical Burden from Uranium in the New Zealand Diet – Journal of Food Protection

Since 1960, the Ministry of Health has measured radioactivity in the air, rain, and seawater, as well as milk powder.

Environmental radioactivity monitoring programme – Ministry of Health

Who to contact

If you have questions about information on this page, email info@mpi.govt.nz

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