TABLE 2
Transfer Rate of Phi 6 From Farmers Market Fomites to Produce and Hands
Log and Transfer Rate With Low Level Inoculation (10 3 PFU/cm 2 )
Surface
Log and Transfer Rate With High Level Inoculation (10 7 PFU/cm 2 )
Log PFU/cm 2
Transfer Rate b (%)
Transfer Rate (%)
Log PFU/cm 2 a
Plastic
To bell pepper To cantaloupe
1.7 ± 0.3 1.5 ± 0.1 2.4 ± 0.2 2.0 ± 0.2 2.1 ± 0.4 1.9 ± 0.4 2.1 ± 0.3 1.5 ± 0.1 1.6 ± 0.1 2.0 ± 0.1 2.2 ± 0.1 1.7 ± 0.2
24 21 34 29 30 27 30 21 23 29 31 24
0.7 ± 0.5 0.9 ± 0.3 0.5 ± 0.3 0.5 ± 0.3 0.6 ± 0.3 0.4 ± 0.2 0.9 ± 0.1 0.3 ± 0.2 0.9 ± 0.2 0.3 ± 0.3 0.6 ± 0.3 0.3 ± 0.3
23 30 17 17 20 13 30 10 30 10 20 10
To lettuce To hands
Wicker
To bell pepper To cantaloupe
To lettuce To hands
Molded pulp fiber To bell pepper
To cantaloupe
To lettuce To hands
a Mean and standard deviation of phi 6 from each inoculated fomite (10 7 or 10 3 PFU/cm 2 ) to produce that touched the fomite surface for 1 hr or to hands that touched the fomite surface for 20 s ( N = 6). b The transfer rates (percentage) of mean and standard deviation of phi 6 from each inoculated fomite (10 7 or 10 3 PFU/cm 2 ) to produce that touched the fomite surface for 1 hr or to hands that touched the fomite surface for 20 s ( N = 6).
rus) was investigated on famers market fomi- tes (Beiza et al., 2021). In both studies, virus surrogates survived for a similar amount of time on their respective fomites. In our study, the tablecloth had the great- est initial reduction between days 1 and 2 (3.2 log PFU/cm 2 ). On day 3, it fell below the detection limit of 0.9 log PFU/cm 2 , and no PFUs were detected by day 7. While cardboard and molded pulp fiber coupons were observed to have greater initial reduc- tions (2.4 log PFU/cm 2 ) and a shorter time of detection (4 days), there are concerns related to their use because of the diculty of cleaning and sanitizing them correctly (U.S. Department of Health and Human Ser- vices, 2017). Cardboard has been found to be a common vehicle of cross-contamina- tion, especially if used for a long time (Krall, 2003). Therefore, cardboard should be con- sidered as a high risk for cross-contamina- tion, as cardboard is regularly reused for a
long time at farmers markets, creating an ideal environment for the growth of micro- organisms (Pollard et al., 2016). Wicker was shown to have the lowest initial reduction (2.0 log PFU/cm 2 ), longest detectible time (16 days), and the longest overall detec- tion (28 days) of phi 6. Plastic had the second- longest persistence by each of the metrics, with 2.1 log PFU/cm 2 , 13 days, and 19 days, respectively. Based on these results, increased vigilance should be observed in cleaning and sanitizing produce items to prevent possible transmission of virus particles. Hands have also been found to be a com- mon source of contamination and the spread of microorganisms, including viruses (Ansari et al., 1991; Scott, 2013). According to past studies, vendors at farmers markets under- take many tasks, such as handling produce and containers, touching their smartphones, and handling money without practicing proper handwashing or wearing gloves
(Behnke et al., 2012). These situations high- light the risk of cross-contamination from containers (fomites) to hands and vice versa. Simulation of Cross-Contamination With High and Low Level Phi 6 The transfer rates of phi 6 from artificially contaminated fomites to hands and produce are presented in Table 2. Experiments with high (10 7 log PFU/cm 2 ) and low (10 3 log PFU/ cm 2 ) initial concentrations were observed. At the low concentration, each fomite had a dierent produce sample that registered as the highest transfer rate. The combinations of plastic to cantaloupe, wicker to lettuce, and molded pulp fiber to bell pepper all had transfer rates of 30%. In each experiment, the high value sample was the only sample at or above the detection limit of 0.9 log PFU/cm 2 . The transfer from plastic to cantaloupe (30%) was much greater than other fomites (wicker: 13% and molded pulp fiber: 10%). The trans-
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July/August 2023 • Journal of Environmental Health
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