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Assessment of the Potential for Cross Contamination of Food Products by Reusable Shopping Bags
Charles P. Gerba1, David Williams1 and Ryan G. Sinclair2
1
Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ
2
School of Public Health, Loma Linda University, Loma Linda, CA
June 9, 2010
Summary
Most foodborne illnesses are believed to originate in the home. Reuse of bags creates an
opportunity for cross contamination of foods. The purpose of this study was to assess the
potential for cross contamination of food products from reusable bags used to carry groceries.
Reusable bags were collected at random from consumers as they entered grocery stores in
California and Arizona. In interviews it was found that reusable bags are seldom if ever washed
and often used for multiple purposes. Large numbers of bacteria were found in almost all bags
and coliform bacteria in half. Escherichia coli were identified in 12% of the bags and a wide
range of enteric bacteria, including several opportunistic pathogens. When meat juices were
added to bags and stored in the trunks of cars for two hours the number of bacteria increased
10-fold indicating the potential for bacterial growth in the bags. Hand or machine washing was
found to reduce the bacteria in bags by >99.9%. These results indicate that reusable bags can
play a significant role in the cross contamination of foods if not properly washed on a regular
basis. It is recommended that the public needs to be educated about the proper care of
reusable bags by printed instructions on the bags or through public service announcements.
Full article at: http://uanews.org/pdfs/GerbaWilliams...tamination.pdf
Charles P. Gerba1, David Williams1 and Ryan G. Sinclair2
1
Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ
2
School of Public Health, Loma Linda University, Loma Linda, CA
June 9, 2010
Summary
Most foodborne illnesses are believed to originate in the home. Reuse of bags creates an
opportunity for cross contamination of foods. The purpose of this study was to assess the
potential for cross contamination of food products from reusable bags used to carry groceries.
Reusable bags were collected at random from consumers as they entered grocery stores in
California and Arizona. In interviews it was found that reusable bags are seldom if ever washed
and often used for multiple purposes. Large numbers of bacteria were found in almost all bags
and coliform bacteria in half. Escherichia coli were identified in 12% of the bags and a wide
range of enteric bacteria, including several opportunistic pathogens. When meat juices were
added to bags and stored in the trunks of cars for two hours the number of bacteria increased
10-fold indicating the potential for bacterial growth in the bags. Hand or machine washing was
found to reduce the bacteria in bags by >99.9%. These results indicate that reusable bags can
play a significant role in the cross contamination of foods if not properly washed on a regular
basis. It is recommended that the public needs to be educated about the proper care of
reusable bags by printed instructions on the bags or through public service announcements.
Full article at: http://uanews.org/pdfs/GerbaWilliams...tamination.pdf