Lettuce samples of the iceberg variety, from traditional, organic
and hydroponic cropping systems were purchased in two hypermarkets
in the city of Joao Pessoa, Brazil. Samples were collected on
a weekly basis from May 2010 to April 2011. The sampling unit
established for this analysis was one head of lettuce, regardless of
weight or size, and 60 samples per cropping system. Of these 60
samples, 30 were used for bacteriological analyses and 30 for
parasitological analyses; a total of 180 specimens were analyzed.
The samples were obtained from the hypermarket individually
wrapped in polyethylene bags, without manual contact, and
transported to the laboratory in thermal bags.