After reading this article, I certainly felt more confident that something is being done about salad greens and food safety. E. coli and Salmonella food poisoning can both be devastating illnesses.
On the other hand, this article discusses the same problem and does provide more information to be aware of i.e., how pathogens can enter produce in the fields by coring the lettuce, for example. It also mentions the California Leafy Greens Products Handlers Marketing Agreement (LGMA) food safety program. The Comments are also worth reading.