It is the usual practice that food for human consumption that has been dropped onto unsanitary surfaces should be discarded and is unsafe for human consumption. (Dawson et al., 2018). However, there is a well-known perception that if food is dropped onto the floor for a short amount of time, it will still be safe for consumption as bacteria do not have enough time to settle on the food and contaminate it.
Yet, bacterial cross-contamination from surfaces to food is known to contribute to foodborne diseases (Miranda. et al., 2016), such as Norovirus and Salmonella. Bacterial transfer from the surface to food can happen very quickly, contaminating instantly in some cases (Rettner, 2016).
Most humans in the world mainly follow the common myth, the 5-second rule, and it has even been studied as both a sociological effect and a public health recommendation.
As a matter of fact, 87% of people say they would eat food dropped on the floor or have done so, with the majority following the five-second rule, based on research done by Aston University Birmingham UK (Aston, 2014). It is estimated that in the United States, there are 9.4 million episodes of foodborne illness, 55,961 hospitalisations, and 1,351 deaths per year from various causes (Scallan, et al., 2011) (Lipschutz, et al., 2022). When data were analysed from 1998 to 2013, 12% of all outbreaks reported to the Centres for Disease Control (CDC) were linked to surface cross-contamination (the transfer of harmful bacteria from one person, object, or place to another) (Lipschutz, et al., 2022).
Hence, the aim of this study is to address sustainable development goals, Good health, and well-being, reinforcing the importance of sanitation on food contact to minimise the risk of possible illnesses such as food poisoning and foodborne illness (Dawson, et al., 2006).
In a similar study by Brookshire (2017), she tested the 5-second-rule in 2017 using bologna, dropping it onto clean and dirty tiles, and subsequently incubated the pantry dish, which included the bacteria on its bologna when it came into contact with the floor. Through the experiment, she found out that the amount of time the food was in contact with the floor did not really affect the number of bacteria on the food. Though, as the number of seconds the food comes into contact with the floor increases, the number of colonies of bacteria also detected increases.
In another experiment by Miranda et al. (2016) which experimented if longer contact times increase cross-contamination of Enterobacter aerogenes from surfaces to food, it was observed and concluded that the risk of illness from bacterial transfer from a surface to food is dependent on factors including the prevalence, concentration, and type of organism; the nature of the food (especially moisture); and the nature of the surface topology; as well as the length of time the food is in contact with the surface. They further added that the popular saying, the five-second rule is a significant oversimplification of what actually happens when bacteria transfer from a surface to food.
The previous studies demonstrated the possibility that illnesses and diseases such as foodborne illness and bacterial cross-contamination are due to the consumption of food that was in contact for a short period of time with an unsanitary surface area. If this is true, even if food is dropped on the floor for a short period of time, it might still actually be unsafe for human consumption. Therefore through our experiment, we would find out the relationship between the number of seconds the bread came into contact with the dirty floor (independent variable) and the growth of bacteria in terms of the number of grids (dependant variable), proving whether the amount of time, in seconds, spent in contact with the dirty floor affects the growth on the bread. As such, we would be finding out the change (increase/decrease) in colonies over the three days and calculating the bacterial change (increase/decrease) per day; hence having accountable results to prove the reliability of the 5-second rule and sharing our findings with the public to educate and address the sustainable goals, Good Health, and Well-being.
Our research question is as follows:
How does the number of seconds in contact with the floor affect the number and the growth of bacteria?
We decided to test the following hypothesis:
Different timings (seconds) of contact of food with the dirty floor surface will have different numbers of bacteria contaminating it.
Specifically, we hypothesise that food (bread) dropped on the dirty floor for 5 seconds would have fewer bacteria contaminating it than food (bread) dropped on the dirty floor for longer seconds (30 seconds, 1 minute, and 5 minutes specifically). We plan to do 6 experiments; control(no bread - just the agar plate), 0 seconds(bread not dropped), 5 seconds, 30 seconds, 1 minute, and 5 minute.
The independent variable is the number of seconds the piece of bread is in contact with the floor.
The dependent variable is the growth of bacteria (in terms of number).
The controlled variables are:
Brand and type of food (bread).
Area (cm^2) of the food (bread).
The amount of surface area (cm^2) the food (bread) is in contact with the tiles.
Distance (cm) from phone camera to petri dish when taking the photograph.
Mass of agar in the Petri dishes.
The temperature the agar plates are stored in (37 °C).