Tatsuhiko Kodama began his 27 July testimony to Japan's parliament with what he knew. In a firm, clear voice, he said that the Radioisotope Center of the University of Tokyo, which he heads, had detected elevated radiation levels in the days following the meltdown of three reactors at the Fukushima Daiichi nuclear power station. But when it came to what wasn't known, he became angry. "There is no definite report from the Tokyo Electric Power Company or the government as to exactly how much radioactive material has been released from Fukushima!" he shouted.

Kodama's impassioned speech was posted on YouTube in late July and has received nearly 600,000 views, transforming him into one of Japan's most visible critics of the government. But he is not alone. Almost six months after an earthquake and tsunami triggered the meltdowns, other researchers say that crucial data for understanding the crisis are still missing, and funding snags and bureaucracy are hampering efforts to collect more. Some researchers warn that, without better coordination, clean-up efforts will be delayed, and the opportunity to measure the effects of the worst nuclear accident in decades could be lost. Kodama and a handful of Japanese scientists have become so frustrated that they are beginning grassroots campaigns to collect information and speed the clean-up.