The BEACHES Study: health effects and exposures from non-point source microbial contaminants in subtropical recreational marine waters

• Published in: International journal of epidemiology Vol. 39; no. 5; pp. 1291 - 1298
• Main Authors: Fleisher, Jay M, Fleming, Lora E, Solo-Gabriele, Helena M, Kish, Jonathan K, Sinigalliano, Christopher D, Plano, Lisa, Elmir, Samir M, Wang, John D, Withum, Kelly, Shibata, Tomoyuki, Gidley, Maribeth L, Abdelzaher, Amir, He, Guoqing, Ortega, Cristina, Zhu, Xiaofang, Wright, Mary, Hollenbeck, Julie, Backer, Lorraine C
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.10.2010
• Subjects: Adult; Age Factors; Bathing Beaches; Biological and medical sciences; enterococci; Enterococcus - isolation & purification; Environmental Exposure - adverse effects; Gastrointestinal Diseases - etiology; Gastrointestinal illness; Gram-Positive Bacterial Infections - etiology; Humans; indicator organisms; Infection; Medical sciences; Middle Aged; Miscellaneous; Oceans and Seas; Prospective Studies; Public health. Hygiene; Public health. Hygiene-occupational medicine; recreational water quality; respiratory illness; Respiratory Tract Infections - etiology; Sewage - microbiology; Sex Factors; Skin Diseases, Bacterial - etiology; skin illness; Time Factors; Water Pollutants - adverse effects; Water Pollutants - analysis; Water Pollution - adverse effects; Water Pollution - analysis; Enterococcus; Organism; Respiratory disease; respiratory illness; Exposure; Beaches; Gastrointestinal; Indicator; Source; Marine environment; Streptococcaceae; skin illness; Marine; Water quality; recreational water quality; indicator organisms; Bacteria; Micrococcales; Skin; Bathing; Gastrointestinal illness; Contaminant; Public health; enterococci
• ISSN: 0300-5771; 1464-3685; 1464-3685
• DOI: 10.1093/ije/dyq084

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 log10 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.