It's been more than seven years since the catastrophic meltdown of the Daiichi nuclear power plant in Fukushima, Japan, but a team of French researchers has found evidence of that disaster here in the Bay Area, in the storied wine bottles of the Napa Valley.
Researchers looked for the radioactive particle, cesium-137, in vintages from 2009 to 2012, expecting to see an increase after 2011, when the meltdown happened. Cesium-137 is a byproduct of the uranium fission used in nuclear power generation, and was also found in higher levels in French wines made after the Chernobyl power plant disaster of 1986.
In a study published in the MIT Technology Review, researchers found that by vaporizing Napa wine at 500 degrees Celsius, they were able to detect tiny amounts of the radioactive isotope amid the ashes: about double the amount that was present in wines made before the meltdown. Much like the French wines studied after the Chernobyl disaster, the team found higher levels of the particle in red wines than they found in rosé.
The technique used for the study was pioneered by French pharmacologist Philippe Hubert, who originally devised the procedure to combat wine fraud — that is, labeling a younger vintage as an older one in order to inflate the price. By scanning the radioactive signature of the wine, Hubert could determine, for instance, if it was made before nuclear testing began in the 1960s — in which case, the wine would have no detectable cesium-137 − or if it was made shortly after the Chernobyl disaster, in which case the cesium-137 levels would be elevated.
Researchers stress that while the elevated levels of the radioactive particle could be seen in Napa wines for decades to come, they remain well below the threshold for causing human harm.