Contamination from Japan's nuclear disaster shows up in food and water
Authorities across Asia stepped up checks this week on Japanese imports after radioactive contaminants showed up in food and water in quake-stricken Japan following blasts at a nuclear plant last week.
Experts are most worried about three radioactive substances -- iodine-131, caesium-134 and caesium-137 -- all of which can cause various types of cancer years later.
Caesium-137 is of particular concern as it can stay in the environment and potentially cause havoc for hundreds of years. It takes 30 years for this contaminant to lose its power by half -- what experts refer to as a "half life."
At this rate, it would take at least 240 years for the contaminant to exhaust all its radioactivity.
"Caesium-137 can last for hundreds of years. If exposed, one can get spasms, involuntary muscular contractions and may lose the ability to walk. It also causes infertility. High doses will also damage a person's DNA and cause cancer later," said Lee Tin-lap, an associate professor at the Chinese University's School of Biomedical Sciences in Hong Kong.
But a few experts stressed there was no need for panic yet.
Levels of caesium-137 detected in spinach in Japan over the weekend stood at an average of 350 becquerels per kilogram, well below the European Union's limit of 1,000 becquerels for dairy produce and 1,250 for all other food items.
"Becquerels are like atoms," said Pradip Deb, senior lecturer in Medical Radiations at the School of Medical Sciences, Royal Melbourne Institute of Technology University.
"A liter of milk has billions and billions of atoms ... and this is just 350."
Caesium-134 has a half-life of 2 years, which will take about 20 years for it to become harmless.
The radioactive spill has prompted food checks in the Philippines, Hong Kong, South Korea, China, Singapore and Malaysia, with Taiwan's government extending surveillance to include even electronics and tech items, chemicals and machinery. In addition to iodine and caesium, Thailand is also looking out for Strontium 90.
Photo shows Apples with ''Produced in Japan'' stickers at a Japanese supermarket in Hong Kong March 21, 2011. Credit: Reuters/Bobby Yip