Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Bacteria on Hands
Name: Peter M.
Status: Student
Age: 16
Location: N/A
Country: N/A
Date: N/A 


Question:
What is the normal amount of single strand of bacteria on the human hand at any given time. How about the total amount of bacteria on the human hand?



Replies:
THe only data I could find was from a study where the efficacy of hand washing for nurses in an intensive care unit was studied. The unwashed hands contained an average of 84 colony forming units (the classical unit with which we count viable micro organisms) per hand. The method applied was to determine the amounts of organisms on the fingertip so I guess this number should be corrected for the complete surface of the hand. In 30% of people there were more than 200 CFU present. You should bear in mind that nurses wash their hands pretty often anyway. Your hands after working in the garden, or cleaning the dustbin, would probably contain a factor 10 or maybe 100 more organisms. Wet or moist hands release more organisms than dry hands. The moist factor in part explains why washed hands (even washed with soap) often show up with a heavier bacterial load than unwashed hands. But I couldn't find exact numbers on this.

Trudy Wassenaar



Click here to return to the Molecular Biology Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory