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Radiation Monitoring

Dose rates have been provided by Japan’s Ministry of Education, Culture, Sport, Science and Technology for 47 cities and towns, representing a comprehensive nationwide monitoring network. As of Friday, the dose rates at some locations around 30 km (18 mi) from the Fukushima plant had risen significantly in the prior 24-hour period (in one location, from 80 to 170 µSv per hour, and in another, from 26 to 95 µSv per hour). However, such increases were not seen at all locations at this distance from the plant. Dose rates to the northwest of the plant were observed in the range of 3 to 170 µSv per hour, with the higher levels observed around 30 km from the plant. Dose rates in other directions are in the range of 1 to 5 µSv per hour.

Exposure Assessment

A person who has been exposed to radiation has had radioactive waves or particles penetrate the body, like having an x-ray. A person can be exposed to radiation by coming close to radioactive material or a contaminated person, place, or thing.

Direct Risk to Individuals from the Fukishima Release

Japanese authorities informed the International Atomic Energy Agency that the evacuation of the population from the 20-kilometre zone around Fukushima Daiichi has been successfully completed. Japanese authorities also advised people living within 30 kilometres of the plant to remain inside. The NRC administrator stated Wednesday that if the United States were facing a similar situation, it would order a much larger evacuation zone than Japan has 20 km (12 mi), and so the US has called on Americans within 80 kms (50 mi) of the Japan nuclear plant area to leave. The workers inside the plant are at a great risk and have to be evacuated when the levels spike). Children under 18 and fetuses inside the 12 mile zone are also thought to be at higher risk. 

Food Issues

There are many questions as to what risk the resulting spread of radiation in the atmosphere and groundwater will have on possible exposure to the population. A nuclear fallout will release radioactive particles from the atmosphere and these will contaminate the surface on which they are deposited. This would mean standing crops, fruit and vegetable farms, grazing land and water sources. This would then find its way into humans if they consume the food directly or indirectly through milk and meat products from animals who consume contaminated vegetation and water.

On Saturday, the Japanese Health Ministry announced that it had detected elevated levels of radiation in spinach and milk at farms up to 90 miles from Japan’s crippled nuclear reactors. The U.S. Food and Drug Administration released a statement on Friday that they will be monitoring food imported from Japan.

Risk to Residents in the U.S.

Currently there is no threat that the radiation released into the atmosphere will do harm to residents in the U.S.  However, the U.S. EPA has deployed extra radiation detectors throughout the country that will send real time data via satellite to EPA officials who will make the data available to the public online.


How Exponent Can Assist

Exponent offers unparalleled multidisciplinary expertise and rapid response capabilities to provide stewardship in addressing issues of radiation health effects. We provide our clients with a team of scientific, engineering, environmental, risk, food, and health specialists that is unique in the industry.  Our scientists routinely publish in the areas of quantitative risk modeling, and have worked extensively with National Institute of Health, U.S. EPA, U.S. Department of Energy, NASA, and other government. 

For More Information, Please Contact:

Dr. David Hoel
Principal Scientist
571) 227-7215 tel
(571) 227-7299 fax

Dr. Hoel has more than 40 years of experience in the fields of epidemiology, statistics, and risk analysis. He is internationally known for his work in risk assessment and has served on and also chaired numerous committees for the WHO and the U.N., as well as the U.S. National Academy of Sciences, the National Institute of Health, the EPA, and the FDA. Dr. Hoel’s research has focused on risk assessment methods, with particular interest in low-dose radiation exposures and cancer. This work has included stays in Hiroshima as a Director at the Radiation Effects Research Foundation, and Dr. Hoel currently is a Scientific Counselor for the Radiation Effects Research Foundation and a member of the National Academies’ Board on Nuclear and Radiation Studies.

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