How Clean IS That Table?

While you watch restaurant staff clean table after table with the same grimy rag you probably wonder, just how clean is this table? Two studies examined the same question.

In 1979, a study documenting the sanitary benefits of paper placemats was conducted by the Food Protection Laboratory of the Syracuse Research Corporation. Samples were collected from tabletops and placemats on the same tables in several restaurants using specialized bacterial collection plates. The plates were incubated and the number of bacterial colonies on each plate was calculated. Results from this study demonstrated that placemats help in the reduction bacterial transfer from tabletops. Numbers of bacteria on tabletops were 214 times greater than numbers of bacteria on the placemats and the number of pathogenic bacterial colonies was approximately 100 times greater on tabletops.

A more recent study, conducted in 1997 by UW Oshkosh Environmental Studies staff member Allison Collins-Rainboth and three UW Oshkosh Microbiology students, found similar results to the study conducted by the Food Protection Laboratory of the Syracuse Research Corporation. Samples were collected from placemats and tabletops in the cities of Berlin and Oshkosh. The objective of this study was to expand upon the study conducted in 1997 to include new groups of facilities (Table 1) and a more detailed breakdown of the microorganisms present. In the restaurants and daycares the objective was to evaluate microbial loads on placemats versus uncovered tables. In long-term care facilities, lodging, and hospitals tray covers were compared to uncovered trays.

Results:
A total of 50 facilities, in the five aforementioned groups, agreed to have their locations participate in this study. All sample analysis was conducted by the microbiology graduate students. The overall totals and coliform means are summarized in Table 2.

Table 2. Average total and coliform counts for table top/tray (TT) and placemats/tray covers (PM).
Category	Tabletop/Tray	Placemat	TT Coliforms	PM Coliforms
Restaurants	362.4	50.8	28.7	1.2
Daycares	1578.4	0a	302	0a
Long-Term Care	126.2	5.8	8.9	0
Lodging	256.8	12.1	34.7	0
Hospitals	150.1	9.8	2.6	0
aNo facilities used placemats

Most groups of facilities were more than willing to let us into their facility to test surfaces and the participation rate was ~75%. The lone exception was the hospital group. It took over 200 phone calls to set-up the 10 site visits, and hospitals in two states were used. This group was very reluctant to allow testing in their facilities and several facilities were sampled over a wide geographic range. Additionally, the bureaucratic nature of these facilities required multiply levels of approval at times and made this group as time consuming as all other groups combined.

The daycare group did not have any placemat data due to the fact that none of the facilities we contacted used placemats. All other groups (Long-term care, restaurants, hospitals, and lodging) showed a statistically significant difference between the samples that had placemats/tray covers when compared to samples that did not use this protective barrier (Table 3). While the daycare facilities had no statistics conducted due to the lack of placemat, these facilities had the highest levels over overall microbes and ten-times the amount of coliforms of the next highest facility group. Interestingly, no daycares we contacted used placemats. It would not be surprising if placemats would benefit these facilities as much, or likely more, than any other group in this study. Given the very high levels of microbes and coliforms (Tables 1 & 2) found in daycares, and the likelihood of disease transmission between children, it appears that these facilities could make effective use of placemats.

Restaurants and lodging facilities were the next two groups with the highest levels of overall microbes and coliforms.

Discussion:
This study shows similar results to the two previous studies mentioned in the Introduction. The placemats/tray covers provided an excellent barrier to the inadvertent contact with microorganisms at a number of facilities. Statistical analysis of the overall microbial means within each group showed a significant difference in all groups that had both covered and uncovered sites. Additionally, the daycare group did not use placemats, but likely could benefit from their use due to their relatively high level of microbes and coliforms. This overall lack of microbial contact would likely translate into a more sanitary environment, and consequently an environment that would be less likely to transmit disease causing microorganisms to unsuspecting users of these facilities. This principal is no more important than in a daycare where children lack the basic understanding of sanitation and personal hygiene.

Given the relatively low cost of these paper products they could be a value-added public health benefit to all these facilities. A cost-benefit analysis may be warranted to show operators of these facility types that the benefits of using placemats/tray covers far outweigh any addition costs to the facility. If more facilities used these barriers it would be an asset to environmental public health and may be able to prevent the spread of common illnesses.