Science - April 5, 2011

On the lookout for radioactivity

Astrid Smit

Rikilt, the Institute of Food Safety, is monitoring the effects of the Japanese nuclear disaster. No alarmingly high levels of radioactivity have been detected so far.

Gerard Krijger carries out a gamma spectrometric measurement.
The levels of radioactivity from Japan are still within acceptable limits. reports Rikilt, which is monitoring the air in the Netherlands as well as imported products from Japan. The Netherlands has a network of 55 radioactivity detectors located all over the country. This National Network for Measuring Radioactivity in Food constantly measures the amount of radioactivity (especially radioisotopes of caesium and iodine) found in the food chain. Rikilt analyzes the data and issues a warning if the standard is in danger of being exceeded.
According to calculations, atmospheric dust particles from the Fukushima disaster area would reach the Netherlands within two weeks. That's right. The National Institute for Public Health and the Environment detected a small amount of Japanese radioactivity in atmospheric particles at the end of March, says Gerard Krijger of Rikilt. 'The amounts are negligible; we found a dose of less than a thousandth part of the natural background values.' The grass has no radioactivity.
Radioisotopes on parsley
Rikilt is also assisting in screening Japanese products arriving at Schiphol and the port of Rotterdam. The Customs Authority and the new Dutch Food and Consumer Product Safety Authority take a sample from every shipment and send this to Rikilt in Wageningen. There is only one shipment, consisting of parsley, this week. Rikilt found radioisotopes from Japan in this sample too. 'The concentration was not disturbing: 350 times below the standard.'
Japanese exports returning to normal
As Japanese exports had almost reached a standstill in the past weeks, only a few samples were examined. 'This week, Japanese exports are beginning to return to normal and the number of samples can go up to a thousand a week', adds Krijger. 'It will be interesting to see what measurements we will get.' The Netherlands imports many types of Japanese products: seaweed, fresh vegetables and fish - mostly for Japanese restaurants - and also cars and electronic products. 'Radioactivity can be removed from the last category but not from food. Food products are rejected if the radioactivity in them is too high. We want to prevent radioactivity from entering our food chain, directly or indirectly. For example, the Netherlands imports fish meal for its animal feed industry. As large amounts of radioactive water have leached into the sea, we are extra vigilant with this product', adds Krijger.