Even several years after the 2011 Fukushima nuclear power plant disaster, food contaminated from the meltdown is still harming animals, according to a new study. Specifically, butterflies eating food collected from cities around the site showed higher rates of death and disease.

The Fukushima Dai-ichi nuclear power plant released large amounts of radiation into the surrounding atmosphere. While no significant human health effects have been reported, scientists from the University of Rukyus in Japan are studying the impact on the area's wildlife.

So far, previous studies have found that monkeys in the area are suffering from blood anomalies linked to nuclear fall-out, and some West Coast albacore tuna have trace amounts of radiation linked to the 2011 disaster. Now, this new study, published in the journal BMC Evolutionary Biology, is focusing on pale blue grass butterflies flying near Fukushima.

Researchers fed groups of these butterflies leaves from six different areas at varying distance from the disaster site, and then investigated the effects on the next generation. Feeding offspring the same contaminated leaves as their parents, it turns out, only enhanced the effects of the radiation, while their peers who nibbled on uncontaminated leaves were relatively normal.

Even ingesting low levels of radiation, ranging from 0.2 to 161bq/kg, caused a significant effect on the lifespan in these butterflies. Not to mention butterflies fed leaves with higher caesium radiation doses were also smaller and some had morphological abnormalities such as unusually shaped wings.

"Wildlife has probably been damaged even at relatively low doses of radiation, and our research showed that sensitivity varies among individuals within a species," lead author Joji Otaki, a professor at the University of Rukyus, said in a press release.

While these findings are concerning, not all hope is lost. The effects of eating contaminated food can be significant, and can be passed on, but on the bright side, "eating non-contaminated food improves the negative effects, even in the next generation," Otaki says.