Assessment of human health risks from marine bathing beach：based on quantitative microbial risk assessment

Abstract:

[Background] Quantitative microbial risk assessment (QMRA), a valuable tool for estimating the burden of disease due to the exposure to pathogenic microorganisms, has been widely used abroad. However, the application in China is in its infancy and there is a lack of data on human exposure in marine bathing beaches. [Objective] To collect exposure data of swimming populations and apply them in marine bathing beaches to assess the feasibility of fecal coliform as a risk assessment indicator. [Methods] The correlation of water quality and fecal coliform concentration in six marine bathing beaches with environmental factors was analyzed, and the exposure data of domestic swimming populations were collected based on questionnaire survey. Then QMRA was employed to evaluate the risk of gastrointestinal diseases from each marine bathing area. [Results] Fecal coliform concentration in the six bathing areas was significantly correlated (P<0.01) with water temperature, air temperature, and total cloud cover. The fecal contamination in the southern bathing areas was more serious than that in the northern bathing areas, and the 95th percentile of fecal coliform concentration was much higher than the threshold of the domestic "poor" water quality standard. The volume of seawater swallowed by children, male adults, and female adults in a single bathing event was 35.1 mL (95% confidence interval=32.4–37.8, α=0.578, β=0.016), 45 mL (95% confidence interval=31.1–59.3, α=0.532, β=0.012), and 35.7 mL (95% confidence interval=29.7–41.8, α=0.753, β=0.032), respectively. The risk of gastrointestinal diseases from all six marine bathing sites was well below the safety threshold set by the US Environmental Protection Agency. [Conclusion] It is recommended Enterococcus and human Bacteroides, rather than fecal coliform which can reflects fecal contamination, be used as indicators of human health risk from marine bathing sites.