recommend reading the attachment to the proposed rules, " regulatory
impact assessment", especially the section on "a pure food model" for a
better understanding of the issues involved:
http://www.ams.usda.gov/nop/rule/ria.htm
 
also suggest the previously mentioned consumer reports study as a third
party view:
http://www.consumerreports.org/Special/News/Reports/9712n001.htm