Biology of Humans 6th Edition by Judith Goodenough,Betty McGuire

Exercise 12

An important function of skin is to be a protective barrier against infectious organisms. Cleanliness is important to the skin's ability to perform this function, and hand sanitizers are a popular way to achieve cleanliness. But are all sanitizers created equal Below are excerpts from R. Babeluk et al., "Hand hygiene-evaluation of three disinfectant hand sanitizers in a community setting."1 The entire article can be found at: www.plosone.org/article /info%3Adoi%2F10.1371%2Fjournal.pone.0111969 This study involved "sixty undergraduate students... [who had] no prior training in hand hygiene and were therefore believed to be representative of the general (non-healthcare) population.... The 60 volunteers were briefed to attend the two testing sessions at the University, using public transport. They were also asked to contaminate their hands by touching typical everyday surfaces (i.e. hand rails, door handles, vending machines, money) with both hands prior to testing. "On arrival at the University laboratory, a swab of each subject's left palm and finger tips was taken and cultured on agar plates to determine a maximum spectrum of microbes present. This provided the base line for the testing. "The volunteers were randomized into three groups of 20, each group was allocated one of the three hand sanitizers." The participants then cleaned their hands with the assigned sanitizer. Their hands were swabbed and the swabs were plated as before. "Before disinfection... there was no significant difference between the groups in the bacterial load detected on hands." Following disinfection, "there was a significant overall reduction in bacteria following hand disinfection with all three products." Two of the three sanitizers "led to a satisfactory bacterial reduction." The researchers conclude that there "are significant differences in efficacy between products that have been certified in accordance with the applicable European standards, compared to the non-certified product. The two certified products achieved superior outcomes compared to the non-certified product."
Is the conclusion in the paper valid based on the experimental design and results