Scientists point to the current zero tolerance policy as a disincentive to implement more extensive testing since the presence of Listeria at any level will result in an obligatory recall.

There is a measure of support for a policy that will permit up to 100 cfu (colony forming units) of Listeria in foods that will not support the growth of the pathogen.  Foods with a pH value of less than 4.0 and a water activity of less than 0.9 will not support the growth of the pathogen.  In contrast foods classified as ready-to-eat and regarded as high-risk should be subject to more frequent assay to protect public health.