Next time you decide to take the family to the beach or the local swimming hole — even if your local health department has not issued a health warning — you might want to leave the younger kids at home.
According to a new study, children 10 years old or younger are more likely than older kids and adults to get sick from swimming in bacteria-contaminated water.
Doctors have long suspected that young children might be at greater risk of swimming-related illness than adults, but this is the first study to find hard evidence that this is so.
Dr. Timothy J. Wade of the EPA's National Health and Environmental Effects Research Laboratory in Chapel Hill, North Carolina, and fellow researchers also found that a new method for gauging water quality — checking for bacterial DNA — was quicker than the standard technique and also better at predicting health risks from exposure to pollution.
"Overall the current guidelines are protecting public health, but this probably has the potential to do better," Wade said, "Results can be obtained much faster and therefore an action could be taken much faster."
The researchers compared water contamination levels and illness among visitors to three beaches on Lake Michigan and one on Lake Erie in 2003 and 2004.
Local health authorities typically test beach water quality by growing bacteria from water samples, a process which can take 24 to 48 hours. The newer method can assess contamination levels in as little as two hours.
In the EPA study, the researchers tested water quality. Then, 10 to 12 days later they interviewed people who had been visiting the beach on that day to see if they had become sick. They took 1,359 water samples and conducted 21,105 interviews.
The risk of coming down with gastrointestinal illness after a beach visit rose as the amount of the bacterium Enterococcus in the water increased, the researchers found, but the risk was greater among children 10 years old and younger.
Enterococcus comes from human fecal matter and can cause urinary tract infections, bacterial endocarditis, diverticulitis and meningitis.
If you are concerned about the safety of your swimming water or want to know how it is monitored, check with the local health department.
These findings are reported in the May 2008 issue of the journal Epidemiology.