Earlier this month, authorities at the Chinese port of Xiamen sent a ship back to Japan after it was found to be contaminated with low levels of radiation. The Mitsui OSK Lines vessel had been travelling within 125 kilometers (78 miles) of the earthquake-damaged Fukushima nuclear power station. And it is unlikely to be the only ship affected.

The first potentially contaminated cargo vessels heading for European ports are expected to arrive in mid-April. Regulators, harbor operators and shipping lines are about to find themselves in uncharted waters. And debate is heating up over how best to deal with the threat of radioactive vessels and cargo.

Hamburg, Germany's largest and Europe's second-busiest port, has assembled a special group to ensure operators are ready to deal with every eventuality. Although relatively little shipping traffic comes from Japan, Hamburg's office of interior affairs said the city would not be taking any chances.

"We want to see a radiation limit set," city spokesman Frank Reschreiter told Deutsche Welle, adding that the Federal Office for Radiation Protection is currently working on just that. "It should extend beyond national borders and should apply to any ship passing into EU waters."

Reschreiter also said there was a need - in addition to a "plan B" - for a "plan B2" which would make it easy to isolate and deal with any contaminated cargo that might find its way through security checks and onto German or European soil.

Prevention over cure

But not everyone considers it necessary to do more than is already being done. Alfons Guinier, Secretary General of European Community Shipowners' Associations says that, as long as vessels adhere to the Japanese authorities' guidelines, they should not pose a threat when entering EU waters.

"Maybe something will come up later, because things are changing every day, but we cannot do anything better than listen to the information from Japan," Guinier said.

And shipping companies say they are doing just that. Working to the principle of prevention over cure, they are taking what they deem to be appropriate and sensible precautions.

Immediately after the tsunami and earthquake hit Japan, Hapag Lloyd took all of its ships that had been within 100 kilometers of Fukushima out of circulation, contaminated or not. The company later decided to give Tokyo and Yokohama a wide berth and divert all its Japanese traffic through the port of Kobe.

In addition, Hapag Lloyd spokeswoman Eva Gjersvik said the shipping company had stopped carrying cargo that originated from within 100 kilometers of the damaged nuclear plant.

"We assume that in the rest of Japan, in areas where there is no radioactivity, cargo is not contaminated, so we transport it," she said. "But we also have independent surveyors on hand to spot-check it."

Moral duty

Danish shipping line Maersk, on the other hand, continues to serve the ports of Tokyo and Yokohama and says it plans to continue doing so as long as there is no danger to crew members.

"We have a long tradition and strong relationship with Japan and we take our responsibility to secure the lifeline of its more than 127 million people seriously," Maersk spokesman Michael Storgaard told Deutsche Welle.

He added, however, that Maersk was no longer accepting any export bookings from the area directly impacted by the tsunami and earthquake, and had implemented a 140 nautical mile (260 kilometer) no-go zone.

Storgaard said the company was also in constant consultation with "various national and international experts and local and global authorities" monitoring radiation levels. Supplies of iodine tablets have been made available for crew members if necessary.

Scientists say ships that have gathered radioactive material on deck would likely be washed clean of it during the long voyage from Asia to Europe. So are Hamburg and any other European ports that follow its lead to tighten security procedures going too far?

"Ultimately you can take a lot of precautions and do anything to prevent contaminated containers from being loaded, but there are always dangers," Hapag Lloyd's Eva Gjersvik said. "You can't rule anything out entirely."

Author: Tamsin Walker
Editor: Sam Edmonds