In the months following the 2011 meltdowns at Japan’s Fukushima Daiichi nuclear power plant, residents of Los Angeles were being exposed to levels of dangerous alpha radiation nearly 1,000 times above normal levels, a government study found,
The data came from a July 2012 presentation at the National Conference on Radiation Control. The presentation was given by Joji Ortego, Principal Radiation Protection Specialist for Los Angeles County Radiation Management.
Following the Fukushima meltdowns, Los Angeles county heard many concerns from residents about the potential health impacts of radiation crossing the Pacific Ocean from the disaster. So they commissioned a study of radiation levels in the area. The report notes that federal agencies delayed in providing information to the county, and that the state Radiologic Health Branch was unable to provide inspectors due to budget constraints. The state lab was unable to provide a reasonable turnaround time for sample analysis, so the county instead hired a local radiation monitor manufacturer for the analysis.
Radiation levels exceed federal thresholds
Samples were taken between April 29 and May 2, 2011, approximately seven weeks after the radioactive releases from Fukushima. The county found that gross alpha radiation levels at a location in Los Angeles were 300 femtocuries per cubic meter (fCi/m3), and levels at a Hacienda Heights location were 200 fCi/m3.
For context, the Lawrence Livermore National Laboratory reports the average (annual median) level of gross alpha activity for the state of California as just 0.38 fCi/m3 – that is, 790 times lower.
The levels detected in Los Angeles County were a full 100 times higher than the level that requires an investigation at a U.S. nuclear laboratory, according to the Environmental Monitoring Plan at Brookhaven National Laboratory: “If the gross alpha activity in the [air] filters is greater than 3 fCi/m3, then collect more samples in the vicinity, and project manager will review all detections above the limits … All values greater than the above-stated gross alpha/beta concentration shall trigger an investigation.”
Finally, the Los Angeles County levels were almost 15 times higher than the federal regulatory limit for alpha radiation, which is 21 fCi/m3, according to a 2010 document from Idaho National Laboratory.
Even worse than it sounds
What do all these numbers mean for human and environmental health?
Alpha radiation is one of four major types of radiation emitted by radioactive atoms. It is also referred to as “alpha particles,” or a “Helium nucleus.” Other types of radiation are beta radiation, gamma radiation and neutrons.
Of alpha, beta and gamma radiation, alpha radiation is by far the most dangerous if found inside the human body. That’s because unlike beta or gamma radiation, alpha radiation is easily absorbed by cells, where it can cause serious damage, including to DNA. Alpha particles can enter the body if they contaminate food or water, or if they are breathed in – hence the concern among both nuclear laboratories and Los Angeles county about airborne levels of alpha radiation.
The alpha radiation detected from the Fukushima disaster most likely comes from plutonium 239, which is produced as a byproduct in many nuclear reactors. No alpha radiation, however, is emitted by cesium-137, which is probably the most prolific isotope emitted by Fukushima that is still circulating in the environment (iodine-131, also emitted in large quantities, has a very short half life and has probably mostly vanished from the environment by now).
But whereas the beta and gamma radiation emitted by radioactive cesium may not be as dangerous from within the body, it is actually far more dangerous if found outside the body – for example, in the contaminated water and soil around the Fukushima plant, or the contaminated water being dumped into the Pacific Ocean. That’s because beta and gamma radiation is far more able to penetrate the body’s external defenses, and tear apart cells and DNA as it passes through.
Sources for this article here.