One question that emerged among the public immediately after Tokyo won the right to host the 2020 Olympics was whether Prime Minister Shinzo Abe made an incorrect statement, or told an outright lie, about the contaminated water issue at the Fukushima No. 1 nuclear plant.

During the Tokyo bid delegation’s final presentation before the International Olympic Committee in Buenos Aires on Saturday, Abe stressed that the “effects from the contaminated water have been perfectly blocked within the (artificial) bay” of the wrecked nuclear complex, and said “the situation is under control.”

Experts have long pointed out that irradiated water from the plant has kept gushing into the Pacific far beyond the man-made bay, although the government continues to claim that most radioactive materials have been contained within a silt fence that forms a barrier directly in front of reactor units 1 through 4. Reactors 1, 2 and 3 suffered core meltdowns in March 2011.

The silt fence was deliberately set up with many openings so it can withstand waves and tidal movements.

When disclosing the results of a simulation last month, Tokyo Electric Power Co. admitted that a lot of water — and probably radioactive materials — was penetrating the fence and pouring into the wider ocean. The simulation assumed that 50 percent of the water inside the fence becomes mixed with seawater daily due to tides and other factors.

Tepco, based on the findings, concluded that a maximum of 10 trillion becquerels of radioactive strontium-90 and a further 20 trillion becquerels of cesium-137 may have reached the ocean.

At a news conference Tuesday, Chief Cabinet Secretary Yoshihide Suga admitted that contaminated water has escaped through the silt fence. But at the same time, he stressed that surveys have shown that the levels of radioactive materials in coastal waters around the nation, including off Fukushima Prefecture, are far lower than international safety thresholds.

“Even at the maximum, the density of (radioactive) cesium is less than one-five hundredth of the World Health Organization standards for drinking water, which poses no (health) problems at all,” Suga said.

“So (based on this, Abe) said (in Buenos Aires that) the effect has been totally blocked” within the bay of Fukushima No. 1, Suga said.

However, Suga did not answer repeated questions on the possibility that the density readings might be lower simply because tainted water is being diluted with massive amounts of seawater, and not because Tepco or the government has the situation “under control” as Abe claimed.

Jota Kanda, a professor at Tokyo University of Marine Science and Technology, pointed out that densities of radioactive materials within the artificial bay have stopped falling recently, despite the huge amounts of seawater that flow in and out every day.

This indicates a certain amount of new radioactive materials are flowing nonstop from the plant’s wrecked reactor buildings into the sea, he said.

Kanda, however, also noted that the total amount of radioactive materials detected in contaminated water samples has been so low that it is unlikely to pose any danger to human health.

Surveys of fish caught around Japan’s shores have shown no alarming concentrations of radioactive materials in recent months.