TOKYO (AP) — Influential scientists who help set Japan's radiation exposure limits have for years had trips paid for by the country's nuclear plant operators to attend overseas meetings of the world's top academic group on radiation safety.

The potential conflict of interest is revealed in one sentence buried in a 600-page parliamentary investigation into last year's Fukushima Dai-Ichi nuclear power plant disaster and pointed out to The Associated Press by a medical doctor on the 10-person investigation panel.

Some of these same scientists have consistently given optimistic assessments about the health risks of radiation, interviews with the scientists and government documents show. Their pivotal role in setting policy after the March 2011 tsunami and ensuing nuclear meltdowns meant the difference between schoolchildren playing outside or indoors and families staying or evacuating their homes.

One leading scientist, Ohtsura Niwa, acknowledged that the electricity industry pays for flights and hotels to go to meetings of the International Commission on Radiological Protection, and for overseas members visiting Japan. He denied that the funding influences his science and stressed that he stands behind his view that continuing radiation worries about Fukushima are overblown.

"Those who evacuated just want to believe in the dangers of radiation to justify the action they took," Niwa told the AP in an interview.

The official stance of the International Commission on Radiological Protection is that the health risks from radiation become zero only with zero exposure. But some of the eight Japanese ICRP members do not subscribe to that view, asserting that low-dose radiation is harmless or the risks are negligible.

The doctor on the parliamentary panel, Hisako Sakiyama, is outraged about utility funding for Japan's ICRP members. She fears that radiation standards are being set leniently to limit costly evacuations.

"The assertion of the utilities became the rule. That's ethically unacceptable. People's health is at stake," she said. "The view was twisted so it came out as though there is no clear evidence of the risks, or that we simply don't know."

The ICRP, based in Ottawa, Canada, does not take a stand on any nation's policy. It is a charity that relies heavily on donations, and members' funding varies by nation. The group brings scientists together to study radiation effects on health and the environment, as well as the impact of disasters such as Chernobyl and Fukushima. In Japan, ICRP members sit on key panels at the prime minister's office and the education ministry that set radiation safety policy.

The Fukushima meltdowns, the worst nuclear disaster since Chernobyl, brought a higher level of scrutiny to Japan's nuclear industry, revealing close ties between the regulators and the regulated. Last month, some members of a panel that sets nuclear plant safety standards acknowledged they received research and other grant money from utility companies and plant manufacturers. The funding is not illegal in Japan.

Niwa, the only Japanese member to sit on the main ICRP committee, defended utility support for travel expenses, which comes from the Federation of Electric Power Companies of Japan through another radiation organization. Costs add up, he said, and he has spent tens of thousands of yen (thousands of dollars) of his personal money on ICRP projects and efforts to decontaminate Fukushima. All ICRP members fly economy, except for long flights such as between Argentina and Japan, he said.

The Federation declined comment.

Clouding the debate about radiation risks are the multiple causes of cancer, including diet, smoking and other habits. That's why it is extremely difficult to prove any direct link between an individual's cancer and radiation, or pinpoint where one cause begins and another ends.

The ICRP recommends keeping radiation exposure down to 1 millisievert per year and up to 20 millisieverts in a short-term emergency, a standard that takes into account the lessons of Chernobyl.

"Health risks from annual radiation exposure of 20 millisieverts, the current level for issuance of orders to evacuate an affected area, are quite small particularly when compared against the risks from other carcinogenic factors," the ICRP says.

The risk of getting cancer at 20 millisieverts raises the already existing 25 percent chance by an estimated 0.1 percent, according to French ICRP member Jacques Lochard, who visits Japan often to consult on Fukushima.

While that's low, he says it's not zero, so his view is that you should do all you can to reduce exposure.

Kazuo Sakai, a Japanese ICRP member, said he was interested in debunking that generally accepted view. Known as the "linear no threshold" model of radiation risk, the ICRP-backed position considers radiation harmful even at low doses with no threshold below which exposure is safe.

Sakai called that model a mere "tool," and possibly not scientifically sound.

He said his studies on salamanders and other animal life since the Fukushima disaster have shown no ill effects, including genetic damage, and so humans, exposed to far lower levels of radiation, are safe.

"No serious health effects are expected for regular people," he said.

The parliamentary investigation found that utilities have repeatedly tried to push Japanese ICRP members toward a lenient standard on radiation from as far back as 2007.

Internal records at the Federation of Electric Power Companies obtained by the investigative committee showed officials rejoicing over how their views were getting reflected in ICRP Japan statements.

Even earlier, Sakai received utility money for his research into low-dose radiation during a 1999-2006 tenure at the Central Research Institute of Electric Power Industry, an organization funded by the utilities.

But he said that before his hiring he anticipated pressures to come up with research favorable to the nuclear industry and he made it clear his science would not be improperly influenced.

Niwa, a professor at Fukushima Medical University, said that residents need to stay in Fukushima if at all possible, partly because they would face discrimination in marriage elsewhere in Japan from what he said were unfounded fears about radiation and genetic defects.

Setting off such fears are medical checks on the thyroids of Fukushima children that found some nodules or growths that are not cancerous but not normal.

No one knows for sure what this means, but Yoshiharu Yonekura, president of the National Institute of Radiological Sciences and an ICRP member, brushes off the worries and says such abnormalities are common.

The risk is such a non-concern in his mind that he says with a smile: "Low-dose radiation may be even good for you."

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Associated Press researcher Julie Reed contributed to this report. Follow Yuri Kageyama on Twitter at www.twitter.com/yurikageyama