The BEACHES Study: health effects and exposures from non-point source microbial contaminants in subtropical recreational marine waters.
BACKGROUND
Microbial water-quality indicators, in high concentrations in sewage, are used to determine whether water is safe for recreational purposes. Recently, the use of these indicators to regulate recreational water bodies, particularly in sub/tropical recreational marine waters without known sources of sewage, has been questioned. The objectives of this study were to evaluate the risk to humans from exposure to subtropical recreational marine waters with no known point source, and the possible relationship between microbe densities and reported symptoms in human subjects with random-exposure assignment and intensive individual microbial monitoring in this environment.


METHODS
A total of 1303 adult regular bathers were randomly assigned to bather and non-bather groups, with subsequent follow-up for reported illness, in conjunction with extensive environmental sampling of indicator organisms (enterococci).


RESULTS
Bathers were 1.76 times more likely to report gastrointestinal illness [95% confidence interval (CI) 0.94-3.30; P = 0.07]; 4.46 times more likely to report acute febrile respiratory illness (95% CI 0.99-20.90; P = 0.051) and 5.91 times more likely to report a skin illness (95% CI 2.76-12.63; P < 0.0001) relative to non-bathers. Evidence of a dose-response relationship was found between skin illnesses and increasing enterococci exposure among bathers [1.46 times (95% CI 0.97-2.21; P = 0.07) per increasing log(10) unit of enterococci exposure], but not for gastrointestinal or respiratory illnesses.


CONCLUSIONS
This study indicated that bathers may be at increased risk of several illnesses relative to non-bathers, even in the absence of any known source of domestic sewage impacting the recreational marine waters. There was no dose-response relationship between gastroenteritis and increasing exposure to enterococci, even though many current water-monitoring standards use gastroenteritis as the major outcome illness.
Nova Southeastern University COM/MPH, Fort Lauderdale, FL 33328, USA. jmfleish@nova.edu
Jay M
JM
Fleisher
Lora E
LE
Fleming
Helena M
HM
Solo-Gabriele
Jonathan K
JK
Kish
Christopher D
CD
Sinigalliano
Lisa
L
Plano
Samir M
SM
Elmir
John D
JD
Wang
Kelly
K
Withum
Tomoyuki
T
Shibata
Maribeth L
ML
Gidley
Amir
A
Abdelzaher
Guoqing
G
He
Cristina
C
Ortega
Xiaofang
X
Zhu
Mary
M
Wright
Julie
J
Hollenbeck
Lorraine C
LC
Backer
D000328:Adult; D000367:Age Factors; D001493:Bathing Beaches; D016983:Enterococcus / Q000302:isolation & purification*; D004781:Environmental Exposure / Q000009:adverse effects*; D005767:Gastrointestinal Diseases / Q000209:etiology; D016908:Gram-Positive Bacterial Infections / Q000209:etiology*; D006801:Humans; D008875:Middle Aged; D009792:Oceans and Seas; D011446:Prospective Studies; D012141:Respiratory Tract Infections / Q000209:etiology; D012722:Sewage / Q000382:microbiology; D012737:Sex Factors; D017192:Skin Diseases, Bacterial / Q000209:etiology; D013997:Time Factors; D014873:Water Pollutants / Q000009:adverse effects* / Q000032:analysis; D014876:Water Pollution / Q000009:adverse effects* / Q000032:analysis
D012722:Sewage; D014873:Water Pollutants