Organic foods are a $16 billion a year business, and some are concerned that Department of Agriculture standards and independent third-party verification may be insufficient to prevent fraud.
But Spanish scientists have developed a method of using "nitrogen isotopic discrimination" to determine if non-organic, synthetic fertilizers were used on plants. Since organic fertilizers have nitrogen isotopes that differ from synthetic fertilizers, it is possible to distinguish produce grown using the two different methods.
USDA organic standards are widely considered to be trustworthy, because independent third-party assessors check on farm practices. The USDA recently cracked down on at least one large dairy that let its standards lapse.
The Daily Green February 5, 2008http://www.thedailygreen.com/healthy-eating/eat-safe/organic-food-fraud-47020403
Journal of Environmental Quality January 4, 2008; 37:182-185 (Free Full Text Article)http://jeq.scijournals.org/cgi/content/full/37/1/182