To swim or not? More information could help us decide


Islanders and their guests must be forgiven for their bewilderment over the intermittent beach closings that impinged on summer enjoyment of Martha’s Vineyard beaches and ponds. The Whack-a-Mole craziness of it cries out for some thoughtful advice from health officials before next summer rolls around.

But, before we get to that, there is the report this morning that, apart from sea and pond water, beach sand harbors “a rich bacterial community,” in the words of Elizabeth Halliday, a biological oceanographer associated with the Woods Hole Oceanographic Institute and the Massachusetts Institute of Technology. Ms. Halliday describes these communities as “generally harmless.”

This summer, health officials in the two towns closed public and private beaches when the results of water quality tests showed high levels of enterococci bacteria, above the state standard for safe swimming.

According to the Massachusetts Department of Environmental Protection (DEP), such bacteria are indicator organisms that may mean fecal coliform bacteria contaminate water. High levels of enterococcus can cause skin irritation, vomiting, or diarrhea.

That’s what local health officials knew. But health officials don’t know what causes the spikes in bacteria levels that have led to beach closings. And, more important, they don’t know how to advise bathers and beachgoers about the associated health risks.

The tests whose results identify the surprising levels of this indicator bacterium do not discover the degree of real risk that may be attached to the findings. The information that does not accompany the reports of water tests for enterococci is the information that swimmers and beachgoers need, and it is the information that ought to govern the decision to close beaches.

While local health officials do the testing, as they are required to do, and while they close the beaches, as they are also required to do when test results exceed a standard, the governing protocol is inadequate to the actual task.

The caution that is evident in the state’s testing regimen and in the response by local health and recreation officials is admirable. One looks for nothing less. But, residents and guests need something more useful.

What would help is more information, including risk assessments rather than beach closings — distributed by health officials, perhaps in mailings to residents and property owners in the spring, or published on each town’s website — and tracking that would identify actual health problems associated with the recorded prevalence of the indicator bacteria.

A review of some of the literature related to enterococci and e-coli contamination finds that, while the state’s acceptable levels of contamination and consequent actions may be sensible in a macro sense, they are hardly based upon a conclusive understanding of how the bacteria can exist in unacceptable concentrations in an ocean beach one day and be safely absent the next. Plus, the actual existence of dangerous pathogens in the ocean water where the bacteria are detected is not generally measured.

As Times writer Dan Cabot reports this morning, Ms. Halliday, speaking about the work that’s been done to measure concentrations of bacteria in beach sand, the more one messes with the sand, the greater the risk of illness.

But, she adds, ” … in total, the incidence of these (generally minor) illnesses is very low . . . one or two extra illnesses per thousand above the baseline ‘normal’ rate.

“The good news is that we don’t tell people to stay off the beach, but by understanding this slight increase in risk, we can take steps to reduce our exposure – like taking time to wash our hands before eating or showering off after being buried in the sand.”

Understanding such sensible risk assessments and aware of appropriate prophylactic strategies, beachgoers will on their own be able to guide their reasonable use of Island beaches.