That's because it could be tainted with e-coli bacteria.
The producer says a shipment of romaine lettuce was sold as Tanimura and Antle field fresh wrapped - single head romaine.
It may have a sell-by date of august 19th - on its plastic bag.
There are no reports of illness so far.
Anesthesia and Learning
Children under three - who go under general anesthesia - are more likely to experience learning deficits by the time they're 10.
Doctors say children exposed to anesthesia had lower scores in language and abstract reasoning tests.
Also previous studies on baby rodents has shown anesthesia interferes with brain development.
The findings appear in the journal "Pediatrics."
Singing and Driving
Participants were told to familiarize themselves with two songs so that they would feel comfortable singing along.
Results show singing while driving - was rated as more mentally demanding.
It also caused slower and more variable speeds - and slightly reduced hazard perception.
Researchers say drivers may be compensating for their singing by changing their driving habits.