Food Protection Trends - March/April 2018 - 123
In 2013, our research group found that farmworker
hands exhibited a wide range of microbial contamination as
measured by indicator viruses and bacteria in the agricultural
production environment (2, 11). Among the multiple
pathways for microorganisms to contaminate produce on the
farm (e.g., hands, water, soil, tools and equipment surfaces),
we found an association between microbes on farmworker's
hands and produce (19, 20). In a second study, performed in
2014, we found that 46% of produce had fecal contamination
from a human source, further implicating hands as a vehicle
of produce contamination (27). In a third study, performed
in 2015, our group found that farmworker hands, after hand
hygiene had been performed, became re-contaminated with
microbes in as little as 30 minutes after tomato harvest, and
that these concentrations were equivalent to concentrations
on hands of workers who had not performed hygiene (6, 7).
Alhough hands are an important vehicle for microbial
contamination of produce, there is no rapid measure or
valid proxy of farmworker microbial load. Anecdotally,
visible soil on farmworker hands is thought to indicate
filth and microbial contamination that may lead to
contamination of produce and illness in the consumer.
To test this assumption, our goal was to take advantage of
data from our previous hand hygiene study (6) to assess
the relationship of visible soil with microbial load on
farmworker hands. Using the results of this study, we can
determine if farmworker hands with visible soil indicate
hands with microbiological contamination.
MATERIALS AND METHODS
Design of previous hand hygiene intervention study
dataset source
Farmworkers (n = 181) on two tomato farms located
near Nuevo León, Mexico participated in a hand hygiene
study between February and October 2014 (6). This study
compared the efficacy of two soap-based (traditional or
pumice) products and two alcohol-based hand sanitizer
(ABHS)-based hand hygiene techniques (ABHS or
SaniTwice™ with ABHS) to a no-hygiene control (6). For
traditional soap, we used 3.5 ml of Pearl Lotion Hand Soap
(a typical soap used on farms in Mexico), a non-antibacterial
and nonabrasive soap. For pumice soap, we used 6 ml of
GOJO Natural Orange Pumice Hand Cleaner, a gel-based
surfactant formula with pumice particles. ABHS use consists
of standard application of ABHS (PURELL Advanced
Instant Hand Sanitizer, manufactured by GOJO) to hands
and rubbing for 20 seconds, as the hands air dry. SaniTwice™
use is a two-step protocol for sanitizing hands in which
the participant uses an excess of sanitizing gel, rubs for 20
seconds, wipes with a paper towel, uses sanitizing gel again,
and continues rubbing the hands until dry.
All hands were standardized first by hand washing
(traditional soap) and drying, after which the worker
returned to work for one to two hours. Participants were
then randomly assigned to one of five treatment groups:
ABHS, SaniTwice™ with ABHS, traditional soap, pumice
soap, and control (no hygiene treatment). After hand hygiene
was performed, a photo was taken of each farmworker's
hands. After the photo was taken, the farmworker provided
a hand rinse sample by inserting the hands into a Whirl-Pak
bag that contained 750 ml of sterile 0.1% peptone water.
The hands were massaged through the bag by study staff
for 20 to 30 seconds. Hands were analyzed for bacterial
loads (Enterococcus spp., coliforms and E. coli) (6, 10)
and turbidity levels of the hand rinses at 600 nm, using a
spectrophotometer. The study was approved by the Emory
University Institutional Review Board, Atlanta, Georgia
(IRB00035460).
Design of the current study
To assess the relationship of visible soil to microbial
load on farmworker hands, the 78 photos of hands from
the previous study were matched to corresponding data
of bacterial loads and turbidity levels in hand rinses.
Additionally, we developed a novel scale that was used
to assess 5 aspects of visible dirtiness, the Visible Hand
Dirtiness Score.
Assessing visible hand dirtiness
Photographs (Fig. 1) of 78 farmworkers' hands were
assessed using a numerical scale that addressed five aspects
of cleanliness (Table 1) adapted from a previous study
(26) in which Pickering et al. described hand cleanliness
by describing soil on the palms, soil on the finger pads and
soil under the fingernails (26). In addition, we included
multicolored soil and total soil amount in our scale to assess
the visible cleanliness of the participants' hands.
A higher score corresponds to visibly dirtier hands in the
photograph. One point was added to the sample's Visible
Hand Dirtiness Score if there was visible dirt on the palm,
one point for the fingers, and one point for the fingernails.
One point was added to the score if multiple colors of soil
were present on the hands, because multiple colors of soil
could indicate contamination coming from different sources
(16). Lastly, "total dirt amount" was assessed on the total
amount of dirt on the hand, using the following scale: zero
points were added to the score if the hands were clean, with
no visible soil on any part of the hand. One point was added
if the hands had visible soil on less than 50% of the surface of
the hand. Two points were added if the hands had visible soil
on more than 50% of the surface of the hand. Three points
were added if the hands had visible soil covering the entire
surface of the hand. The scale ranges from 0 to 7, from visibly
cleanest to dirtiest.
Data collection for visible hand dirtiness score
After criteria had been developed for the Visible Hand
Dirtiness Score, to determine if the system was reliable, a
March/April Food Protection Trends
123
Table of Contents for the Digital Edition of Food Protection Trends - March/April 2018
Peracetic Acid and Hydrogen Peroxide Post-dip Decay Kinetics on Red Meat and Poultry
Knowledge, Attitudes and Practices Regarding Raw Milk Consumption in the Pacific Northwest
Knowledge and Implementation of Good Agricultural Practices among Kentucky Fresh Produce Farmers
Visible Soil as an Indicator of Bacteria Concentration on Farmworkers’ Hands
Beyond the Bio - Jim Dickson
PDG Highlight - The Food Safety Culture Professional Development Group
General Interest Paper Leveraging Current Opportunities to Communicate Lessons Learned from Root Cause Analysis to Prevent Foodborne Illness Outbreaks
General Interest Paper Safe Food for Canadians Regulations: Is Your Business Ready?
Industry Products
Coming Events
Food Protection Trends - March/April 2018 - Cover1
Food Protection Trends - March/April 2018 - Cover2
Food Protection Trends - March/April 2018 - 89
Food Protection Trends - March/April 2018 - 90
Food Protection Trends - March/April 2018 - 91
Food Protection Trends - March/April 2018 - 92
Food Protection Trends - March/April 2018 - 93
Food Protection Trends - March/April 2018 - 94
Food Protection Trends - March/April 2018 - 95
Food Protection Trends - March/April 2018 - Peracetic Acid and Hydrogen Peroxide Post-dip Decay Kinetics on Red Meat and Poultry
Food Protection Trends - March/April 2018 - 97
Food Protection Trends - March/April 2018 - 98
Food Protection Trends - March/April 2018 - 99
Food Protection Trends - March/April 2018 - 100
Food Protection Trends - March/April 2018 - 101
Food Protection Trends - March/April 2018 - 102
Food Protection Trends - March/April 2018 - 103
Food Protection Trends - March/April 2018 - Knowledge, Attitudes and Practices Regarding Raw Milk Consumption in the Pacific Northwest
Food Protection Trends - March/April 2018 - 105
Food Protection Trends - March/April 2018 - 106
Food Protection Trends - March/April 2018 - 107
Food Protection Trends - March/April 2018 - 108
Food Protection Trends - March/April 2018 - 109
Food Protection Trends - March/April 2018 - 110
Food Protection Trends - March/April 2018 - Knowledge and Implementation of Good Agricultural Practices among Kentucky Fresh Produce Farmers
Food Protection Trends - March/April 2018 - 112
Food Protection Trends - March/April 2018 - 113
Food Protection Trends - March/April 2018 - 114
Food Protection Trends - March/April 2018 - 115
Food Protection Trends - March/April 2018 - 116
Food Protection Trends - March/April 2018 - 117
Food Protection Trends - March/April 2018 - 118
Food Protection Trends - March/April 2018 - 119
Food Protection Trends - March/April 2018 - 120
Food Protection Trends - March/April 2018 - 121
Food Protection Trends - March/April 2018 - Visible Soil as an Indicator of Bacteria Concentration on Farmworkers’ Hands
Food Protection Trends - March/April 2018 - 123
Food Protection Trends - March/April 2018 - 124
Food Protection Trends - March/April 2018 - 125
Food Protection Trends - March/April 2018 - 126
Food Protection Trends - March/April 2018 - 127
Food Protection Trends - March/April 2018 - 128
Food Protection Trends - March/April 2018 - 129
Food Protection Trends - March/April 2018 - Beyond the Bio - Jim Dickson
Food Protection Trends - March/April 2018 - 131
Food Protection Trends - March/April 2018 - 132
Food Protection Trends - March/April 2018 - PDG Highlight - The Food Safety Culture Professional Development Group
Food Protection Trends - March/April 2018 - General Interest Paper Leveraging Current Opportunities to Communicate Lessons Learned from Root Cause Analysis to Prevent Foodborne Illness Outbreaks
Food Protection Trends - March/April 2018 - 135
Food Protection Trends - March/April 2018 - 136
Food Protection Trends - March/April 2018 - 137
Food Protection Trends - March/April 2018 - 138
Food Protection Trends - March/April 2018 - 139
Food Protection Trends - March/April 2018 - General Interest Paper Safe Food for Canadians Regulations: Is Your Business Ready?
Food Protection Trends - March/April 2018 - 141
Food Protection Trends - March/April 2018 - Industry Products
Food Protection Trends - March/April 2018 - 143
Food Protection Trends - March/April 2018 - 144
Food Protection Trends - March/April 2018 - 145
Food Protection Trends - March/April 2018 - 146
Food Protection Trends - March/April 2018 - 147
Food Protection Trends - March/April 2018 - Coming Events
Food Protection Trends - March/April 2018 - Cover3
Food Protection Trends - March/April 2018 - Cover4
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