The Sept. 18 article, “Spinach E. coli case hits Maine,” reports that state health officials “are urging Mainers to discard their bagged spinach and thoroughly wash all their fruits and vege-tables – even if they say ‘pre-washed’ on the package. …”

As a microbiologist, I have tested supermarket leafy vegetables and found that E. coli were not all removed by thorough washing. Other investigators, including the Center for Food Safety and Quality Enhancement, have confirmed this finding. The center reported that the organisms could survive even chlorine treatment of contaminated lettuce.

The safest procedure to inactivate E. coli on leafy vegetables is to cook the food. Washing does not completely remove them.

Marjorie Dole

Trenton