Global Challenges/Chemistry Solutions

Promoting public health: Hand washing really helps stop spread of disease

September 29, 2010

Hand-washing, long recognized as an effective
germ-fighting practice, also appears to play
an important role in improving the quality of
stored drinking water in poor countries.
Credit: iStock


Mothers have been right all along to make the kids wash their
hands before eating. Scientists are reporting dramatic new
real-world evidence supporting the idea that hand washing
can prevent the spread of water-borne disease. It appears in
a new study showing a connection between fecal bacteria
contamination on hands, fecal contamination of stored
drinking water, and health in households in a developing
country in Africa. The study is in ACS’ Environmental
Science & Technology
, a semi-monthly journal.

Generations of Doctor Moms have been reminding us to wash our hands. And the threat of pandemic influenza made that common-sense advice an article of public health policy. But does hand washing really work? Real-world evidence that soap and water do prevent disease and keep people healthy comes from a study published in the American Chemical Society’s Environmental Science & Technology, a semi-monthly journal. Here is Jenna Davis of Stanford University, co-author of the report:

“Today almost 3 billion people–– 43 percent of the people on the planet –– don’t have access to clean water flowing through pipes from reservoirs to their homes. This means they have to store water where they live. We have suspected that dirty hands play a role in microbial contamination of drinking water during collection, transport, and storage. But little work has been done to evaluate quantitatively the association between hand contamination and stored water quality within households.”

So, to get some definitive answers, the team measured levels of E. coli, fecal streptococci, and other disease-causing bacteria in wells, springs, and other sources; stored water; and on people’s hands. They focused on 334 households in communities in Dar es Salaam, a city of 2.5 million people in Tanzania, a developing country in Africa. There, city residents must depend on water collected and stored at home. Listen to Dr. Davis explain what she and her colleagues discovered:

“We found a strong link between fecal contamination on the hands of household residents and bacterial contamination in stored water in Dar es Salaam. Water stored in jugs and other containers in their homes contained nearly 100 times more fecal bacteria than the source where it was collected. We also found bacteria that cause disease on the hands of 50 percent of the people in our study.”

Armed with clear cut evidence that people with dirty hands were contaminating their own household water supplies in Tanzania, the team drew a main conclusion about how to improve the situation.

“Our study results suggest that reducing fecal contamination on hands should be investigated as a strategy for improving the quality of stored drinking water and health among households that don’t have access to purified, municipal water supplies. We believe that this is new, real-world evidence supporting the idea that hand washing can prevent the spread of water-borne disease. Past research showed that this stored water can have higher levels of bacterial contamination than its source. But nobody knew why. Now we have evidence about one likely cause.”

Smart Chemists/Innovative Thinking

Smart chemists. Innovative thinking. That’s the key to solving global challenges of the 21st Century. Be sure to check our previous Global Challenges podcast episodes by visiting Today’s podcast was written by Michael Bernstein. For the American Chemical Society, I’m Adam Dylewski in Washington.

Jenna Davis, Ph.D.
Photo courtesy of Andrew