The data, photos and the graph are from Security Tokyo, with express permission to reprint.
Item: skim milk power in 1kg bag, commercial use
Manufacturer: Zenrakuren (all-Japan federation of dairy industry)
Manufactured in: Kita Fukuoka Factory in Iwate Prefecture
Cesium-134: 10 Bq/kg
Cesium-137: 13 Bq/kg
Total cesium: 23 Bq/kg
17,500 seconds precise measurement
Measurement error ±0.3Bq/kg (Cs-137)
Measurement using germanium semiconductor detector with proper calibration
Radioactive cesium has been constantly detected since the nuclear accident last year, albeit in small amounts (usually less than 20 becquerels/kg), from milk and milk products produced in Tohoku and northern Kanto. The cause may be the feed that milk cows eat. Until April 1, 2012, the safety limit for animal feed was 400 becquerels/kg (lower than for humans, which was 500 becquerels/kg). With the new safety limit of 100 becquerels/kg of cesium for humans, the safety limit for animal feed has also been revised down to 100 becquerels/kg.
Skim milk powder is used commercially for baked goods (bread, cookies, etc). It is also used for health supplements.