On 2014 Oct 20, David Keller commented:

Where is the evidence that washing poultry increases food-borne illness?

This study is based on the assumption that "washing of raw poultry" is a "potentially unsafe food handling practice" for consumers. This counter-intuitive notion forms the basis for a campaign by the U.S. Department of Agriculture (1) and the Food and Drug Administration (2) to educate consumers not to wash raw poultry prior to cooking.

The recommendation to not wash raw poultry is evidently based on a study of bacterial cross-contamination of kitchen surfaces (3), which is not a clinical endpoint. A more convincing study would compare the rate of food-borne illnesses in consumers who wash raw poultry versus the rate for consumers who do not wash raw poultry prior to cooking it. Perhaps splatter of trace amounts of bacteria during washing causes no harm to the health of consumers, while washing of raw poultry reduces surface bacterial contamination enough to be of benefit.

I hypothesize the following model: Washing raw poultry with water removes bacteria by mechanical actions, such as disruption of the biofilm on the surface of the meat, and carries away the vast bulk of the bacteria down the drain. While washing poultry may scatter small droplets of water laden with bacteria around the vicinity of the sink, these are not a threat if the sink is rinsed well. The chance of acquiring infection with salmonella, campylobacter or enterotoxigenic E. Coli is proportional to the size of the inoculum ingested. Rinsing poultry has the effect of diluting the concentration of bacteria on the meat and thereby reducing the bacteria count present in any under-cooked meat which is ingested. Unwashed poultry remains contaminated with higher bacterial counts, which increases the risk of infection from under-cooked portions of the meat. In addition, heat-stable toxins produced by bacteria present on unwashed meat (e.g. staphylococcus aureus) cannot be eliminated even with thorough cooking - they must be washed off. This hypothesis can be tested in a clinical trial, as described above.

Neither the FDA nor the USDA has cited a study which demonstrates that washing raw poultry increases the rate of food-borne illnesses in humans. Until they can do so, it is irresponsible for these agencies to advise consumers not to wash raw poultry prior to cooking it.

References

1: USDA website, accessed on 10/20/2014 http://www.fsis.usda.gov/wps/wcm/connect/2ceaa425-0488-4e86-a397-e2d9c470fc4a/Washing_Food.pdf?MOD=AJPERES

2: FDA website, accessed on 10/20/2014 http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm092815.htm

3: The evidence supporting the recommendation against washing raw poultry is not clearly specified on the FDA or USDA websites, but in an email to me, the webmaster of the USDA Meat and Poultry Hotline stated: "Our recommendation for consumers to not wash poultry is to prevent cross-contamination. There was recently a study by Drexel University (http://www.drexel.edu/dontwashyourchicken/ ) which showed that bacteria can spread several feet around the kitchen when washing meat and poultry." (email quoted with permission). The Drexel website identified the principal investigator of the cross-contamination study as J.J. Quinlan, Ph.D., but did not supply the citation to any specific publications when accessed on 10/20/2014, nor have several PubMed searches.

On 2014 Oct 20, David Keller commented:

Where is the evidence that washing poultry increases food-borne illness?

This study is based on the assumption that "washing of raw poultry" is a "potentially unsafe food handling practice" for consumers. This counter-intuitive notion forms the basis for a campaign by the U.S. Department of Agriculture (1) and the Food and Drug Administration (2) to educate consumers not to wash raw poultry prior to cooking.

The recommendation to not wash raw poultry is evidently based on a study of bacterial cross-contamination of kitchen surfaces (3), which is not a clinical endpoint. A more convincing study would compare the rate of food-borne illnesses in consumers who wash raw poultry versus the rate for consumers who do not wash raw poultry prior to cooking it. Perhaps splatter of trace amounts of bacteria during washing causes no harm to the health of consumers, while washing of raw poultry reduces surface bacterial contamination enough to be of benefit.

I hypothesize the following model: Washing raw poultry with water removes bacteria by mechanical actions, such as disruption of the biofilm on the surface of the meat, and carries away the vast bulk of the bacteria down the drain. While washing poultry may scatter small droplets of water laden with bacteria around the vicinity of the sink, these are not a threat if the sink is rinsed well. The chance of acquiring infection with salmonella, campylobacter or enterotoxigenic E. Coli is proportional to the size of the inoculum ingested. Rinsing poultry has the effect of diluting the concentration of bacteria on the meat and thereby reducing the bacteria count present in any under-cooked meat which is ingested. Unwashed poultry remains contaminated with higher bacterial counts, which increases the risk of infection from under-cooked portions of the meat. In addition, heat-stable toxins produced by bacteria present on unwashed meat (e.g. staphylococcus aureus) cannot be eliminated even with thorough cooking - they must be washed off. This hypothesis can be tested in a clinical trial, as described above.

Neither the FDA nor the USDA has cited a study which demonstrates that washing raw poultry increases the rate of food-borne illnesses in humans. Until they can do so, it is irresponsible for these agencies to advise consumers not to wash raw poultry prior to cooking it.

References

1: USDA website, accessed on 10/20/2014 http://www.fsis.usda.gov/wps/wcm/connect/2ceaa425-0488-4e86-a397-e2d9c470fc4a/Washing_Food.pdf?MOD=AJPERES

2: FDA website, accessed on 10/20/2014 http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm092815.htm

3: The evidence supporting the recommendation against washing raw poultry is not clearly specified on the FDA or USDA websites, but in an email to me, the webmaster of the USDA Meat and Poultry Hotline stated: "Our recommendation for consumers to not wash poultry is to prevent cross-contamination. There was recently a study by Drexel University (http://www.drexel.edu/dontwashyourchicken/ ) which showed that bacteria can spread several feet around the kitchen when washing meat and poultry." (email quoted with permission). The Drexel website identified the principal investigator of the cross-contamination study as J.J. Quinlan, Ph.D., but did not supply the citation to any specific publications when accessed on 10/20/2014, nor have several PubMed searches.