The biological impacts of ingested radioactive materials on the pale grass blue butterfly

Abstract

A massive amount of radioactive materials has been released into the environment by the Fukushima Dai-ichi Nuclear Power Plant accident, but its biological impacts have rarely been examined. Here, we have quantitatively evaluated the relationship between the dose of ingested radioactive cesium and mortality and abnormality rates using the pale grass blue butterfly, Zizeeria maha. When larvae from Okinawa, which is likely the least polluted locality in Japan, were fed leaves collected from polluted localities, mortality and abnormality rates increased sharply at low doses in response to the ingested cesium dose. This dose-response relationship was best fitted by power function models, which indicated that the half lethal and abnormal doses were 1.9 and 0.76 Bq per larva, corresponding to 54,000 and 22,000 Bq per kilogram body weight, respectively. Both the retention of radioactive cesium in a pupa relative to the ingested dose throughout the larval stage and the accumulation of radioactive cesium in a pupa relative to the activity concentration in a diet were highest at the lowest level of cesium ingested. We conclude that the risk of ingesting a polluted diet is realistic, at least for this butterfly, and likely for certain other organisms living in the polluted area.

Geographical distribution of morphological abnormalities and wing color pattern modifications of the pale grass blue butterfly in northeastern Japan

“…, ; Nohara et al . ,b) so that the present results can be compared directly with previous results. Wing color pattern modifications were examined visually with the naked eye.…”

“…, , ; Nohara et al . ,b; Taira et al . , ), gall‐forming aphids (morphological abnormalities in field samples) (Akimoto ), the Japanese monkey (possible hematological aberrations) (Hayama et al .…”

Ingestion of radioactively contaminated diets for two generations in the pale grass blue butterfly

“…We further quantified caesium radioactivity in pupae that ingested contaminated leaves and determined the mathematical relationships between the ingested dose of caesium and the resultant rates of mortality and abnormalities [11]. We found that the mortality and abnormality rates increased sharply under low doses of caesium ingestion, following a power function.…”

Fukushima's lessons from the blue butterfly: A risk assessment of the human living environment in the post-Fukushima era

“…Previously, my research team carried out a feeding experiment in which the host plant leaves from Fukushima were fed to the larvae of the pale grass blue butterfly from Okinawa, one of the least‐contaminated localities in Japan (Hiyama et al 2012; Nohara, Hiyama et al ; Nohara, Taira et al ; Taira, Hiyama et al ). This simple but important experiment tested if the Fukushima leaves are safe enough for butterfly larvae to eat.…”

“…Faced with an accident that shook the entire nation, our laboratory team decided to use this butterfly as a model to assess the biological impacts of the Fukushima accident (Otaki , , ). Our team has published a series of articles that help to understand how the butterflies in Fukushima have coped with the aftermath of the FDNPP accident (Hiyama, Nohara et al ; Hiyama et al , ; Nohara, Hiyama et al ; Nohara, Taira et al ; Taira et al ; Taira, Hiyama et al ; Taira, Iwasaki et al ). Comments from the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) on our research can be found in the UNSCEAR Report (UNSCEAR ).…”