That's when they started testing, and 500 used cars from Nagoya Port alone.
Japanese used cars are popular in Russia, Southeast Asia, and Africa. Despite the nuclear accident, the number of exported used cars in 2011 increased slightly over 2010 to 857,779 cars according to the Used Car Export Industry News, with Russia at the top with over 110K followed by the United Arab Emirates.
Kyodo News (2/25/2012):
Nagoya Port Authority disclosed on February 25 that 500 used cars were found with radiation levels at or exceeding 0.3 microsievert/hour, the standard set by the [used car] industry from August last year to January this year, and that the cars were returned to the shippers.
The used cars were to be exported outside Japan or to be transported to different parts of Japan. Nagoya Port Authority does not keep track of the cars returned to the shippers.
According to Nagoya Port Authority, 0.3 microsievert/hour standard was set by the Japan Harbor Transportation Association and All Japan Dockworkers' Union (JDU) to secure the safety of the dockworkers. The radiation testing has been done at ports in Japan since August last year.
Isn't that nice that 0.3 microsievert/hour is not for the safety of the buyers of the cars but for the dockworkers handling the cars and loading them?
It is also nice to know that the radiation levels of the used cars are measured ONLY IF the cars are transported from a port by ships. There is no testing at all if used cars are transported by land within Japan.
The earliest news I caught on this blog of radioactive used cars is from NHK News on April 24, 2011 when Russian authorities in the port of Nakhodka in Siberian Russia found 2 used cars emitting high radiation. The cars came from Niigata Port on April 16, and they were originally from Fukushima Prefecture.
Before the NHK news, there were "rumors" that were officially dismissed. One of the rumors on blogs and tweets that I heard was almost exactly what got finally reported by NHK, that there were many used cars exported from Japan after March 11, 2011 accident that are emitting very high radiation.