Risk-Based Threshold of Gull-Associated Fecal Marker Concentrations for Recreational Water

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• 作者：Kendra I. Brown ; Katherine E. Graham ; Alexandria B. Boehm
• 刊名：Environmental Science & Technology Letters
• 出版年：2017
• 出版时间：February 14, 2017
• 年：2017
• 卷：4
• 期：2
• 页码：44-48
• 全文大小：310K

文摘

A sensitive and specific marker of gull fecal contamination, Catellicoccus (CAT), has been used to conduct microbial source tracking in surface waters throughout the world, yet there are no guidelines for interpreting measured concentrations. Here, we use quantitative microbial risk assessment to evaluate CAT concentrations within a risk-based framework and develop a threshold at which the U.S. Environmental Protection Agency illness benchmark (∼3 illnesses/100 swimmers) is exceeded. We modeled illness risk from exposure to different concentrations of CAT in bathing waters using a Monte Carlo approach that considered densities of CAT and infectious zoonotic pathogens Salmonella and Campylobacter in gull feces, volume of water ingested during bathing, and dose–response relationships. We measured CAT densities in 37 fresh gull fecal droppings from six California beaches. Log₁₀ densities ranged from 4.6 to 9.8 log₁₀ copies CAT/g of wet feces. When the level of CAT exceeds 4 × 10⁶ copies/100 mL of water, the median predicted illness exceeds 3 illnesses/100 swimmers.