In a set of papers published Thursday in the Journal of Heredity, a U.S. publication, Japanese and U.S. scientists warned that radioactive materials released from by the core meltdowns at the Fukushima No. 1 power plant could have caused abnormalities in the genes of nearby birds and insects.

One of the experts, Timothy Mousseau of the University of South Carolina, called for wide-ranging and long-term research on ecosystems, such as a genetic-level analysis, drawing a comparison with what happened to such species after the 1986 Chernobyl disaster in present-day Ukraine.

In a paper published on the journal's website, Mousseau said barn swallows with abnormal white spots on their plumage were found near the Chernobyl plant after the disaster and that the discovery of similarly plumaged swallows in Fukushima was also reported in the wake of the 2011 crisis.