Surveys of Food Intake Just after the Nuclear Accident at the Fukushima Daiichi Nuclear Power Station

Abstract

* Corresponding authorAs a result of the nuclear accident at the Fukushima Daiichi nuclear power station (FDNPS) after the Great East Japan Earthquake on March 11, 2011, volatile radionuclides including iodine-131 were released into the environment and contaminated open-field vegetables, raw milk, tap water, etc. It is important for the health care of residents to correctly comprehend the level of their exposure to radioactive substances released following the accident. However, an evaluation of the internal exposure doses of residents of Fukushima Prefecture as a result of the ingestion of foods, which is indicated in the report issued by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR)1 is based on a number of assumptions. For instance, the estimation assumes that foods were ingested as usual, without regard to the places to which residents were evacuated after the accident, the places where food shipment restrictions were imposed, and so forth. The present report aims to improve the accuracy of estimation of the amount of food actually ingested at evacuation areas, in order to reduce as much as possible the level of uncertainty in conventional values estimated directly after the accident, which were in fact values based on conservative assumptions. More concretely, as basic source material to more accurately estimate internal exposure doses from food ingestion, various patterns of evacuation and dietary habits at the time of the accident of the residents of 13 municipalities in Fukushima Prefecture who were evacuated during the period from directly after the accident of March 11, 2011 until the end of March are clarified in this report. From survey results, most of the food that evacuees took immediately after the accident was confirmed to have been sourced from either stockpiles prepared before the accident, or relief supplies from outside of the affected areas. The restriction orders of food supplies such as contaminated vegetables and milk, and tap water intake were implemented within several days after the major release of radionuclides on March 15, 2011. In addition, collapse in supply chains, i.e., damage to distribution facilities, lack of transportation vehicles or electricity, and the closure of retail stores, contributed to a situation where food or supplies contaminated with iodine -131 were not consumed in large quantities in general, even before the food restriction order. Since people consumed tap water and water from other sources before the implementation of restriction orders in affected areas, we surveyed the status of water as a potential route of internal exposure.

Estimation of children’s thyroid equivalent doses in 16 municipalities after the Fukushima Daiichi Nuclear Power Station accident

“…However, we thought that TEDs from these contaminated foods might be small. Because of disturbances in the milk processing facilities and shipping systems, in addition to transient closure of three major markets in Fukushima and the prolonged closure of many retail stores [ 21 ], it was difficult for many residents to consume foods originating from within Fukushima. In addition, monitoring of contaminated vegetables and milk began on 16 March 2011 and restricted distribution began a few days later in Fukushima [ 21 ].…”

Thyroid Doses in Children from Radioiodine following the Accident at the Fukushima Daiichi Nuclear Power Plant

“…These models assumed that the residents continued to consume milk contaminated with 131 I for a certain period of time, which was considerably different from the situation in the FDNPP accident. A survey of the food supply system suggested that consumption of the contaminated food and drink items by residents would have been limited shortly after the accident due to prompt countermeasures and the collapse in supply chains in the prefecture [9].…”

Communicating with residents about 10 years of scientific progress in understanding thyroid cancer risk in children after the Fukushima Dai-ichi Nuclear Power Station accident

“…Seventh, in contrast to UNSCEAR’s supposition that Fukushima residents consumed contaminated vegetables and other foodstuffs grown in Fukushima Prefecture, Hirakawa et al . [ 40 ] investigated the food and water supply in Fukushima immediately after the accident and concluded that most Fukushima residents consumed non-contaminated food that had been stocked before the accident and did not consume contaminated milk or vegetables. This was because of destruction of the food supply chain after the accident and the closure of retail stores in Fukushima [ 40 ].…”

“…[ 40 ] investigated the food and water supply in Fukushima immediately after the accident and concluded that most Fukushima residents consumed non-contaminated food that had been stocked before the accident and did not consume contaminated milk or vegetables. This was because of destruction of the food supply chain after the accident and the closure of retail stores in Fukushima [ 40 ]. After reopening, retail stores sold fish, vegetables and milk that were produced in areas other than Fukushima, and these foods had been screened for contamination before shipment [ 10 ].…”