After the 2011 earthquake and subsequent nuclear accident, there are significant discrepencies in the percentages of deaths recognized as related to the disaster, The Yomiuri Shimbun has learned.

Across 25 municipalities affected in Fukushima Prefecture, the figures range from 33% in the city of Date to Soma's 100% as of the end of January this year, according to municipal governments.

The differences apparently stem from the fact that the central government has yet to provide clear guidelines for determining quake-related death. In the 25 municipalities, there were a total of 2,017 deaths deemed quake-related as of the end of January, exceeding the 1,604 deaths directly caused by tsunami and other elements of the March 11, 2011, disaster.

There are more than 600 cases that failed to be recognized, and some of the bereaved family members have filed lawsuits against relevant municipalities, seeking the reversal of the decision. In one case in Minami-Soma, Fukushima Prefecture, the father of a man in his 50s was in the hospital for treatment for dementia at the time of the outbreak of the nuclear crisis at the Fukushima No. 1 nuclear power plant.

The father died of pneumonia at age of 82 in February 2014 after being transferred to multiple hospitals both inside and outside the prefecture. The municipal government did not deem this case connected to the 2011 disaster.

"It's not a matter of money," says the son. "I just want it to be officially recognized that the life of my father was shortened by the accident."

Kobe University Prof. Yasuhiro Ueno, a specialist in forensic medicine, said the major gaps in the percentage of recognized cases among neighboring municipalities is a cause for serious concern.

"As time goes by, it becomes more difficult to determine the causal relationship between a disaster and deaths because of the increased influence of such factors as a person's chronic disease," Ueno said. "It's necessary to unify the rules, including those relating to the period for accepting applications."