AbstractsMedical & Health Science

Water in urban areas may pose a public health risk when people are exposed to urban water, because it may contain pathogens. These pathogens may originate from fecal bird droppings, runoff from paved surfaces (including e.g. dog feces), growth of micro-organisms in water and in some cases discharges of combined sewer overflows. Since the extent to which exposure to urban water poses a risk for public health was unknown, this thesis aimed to investigate health risks associated with urban water systems and to determine ways to minimize those risks. Chapter 1 provides an overview of pathogens that have caused outbreaks of waterborne illness. (The lack of ) Water quality guidelines, regulations and policies for urban water management are also addressed. Exposure to contaminated aerosols and water originating from water features may pose public health risks. In chapter 2, endotoxins (in air and water) and fecal bacteria (in water) of water features were measured as markers for exposure to microbial cell debris and enteric pathogens. Exposure to air and water near water features was shown to result in exposure to endotoxins and fecal bacteria, which may lead to respiratory health effects and gastrointestinal health complaints. Regression analyses showed that the endotoxin concentration in air was significantly influenced by the concentration of endotoxin in water, the distance to the water feature and the tangibility of water spray. This study provides estimates for aerosolisation ratios that were used as input for a quantitative microbial risk assessment in chapter 3 to quantify infection risks for exposure to splash parks. In the Netherlands, rainwater becomes more and more popular as an economic and environmentally sustainable water source for splash parks.The associated public health risk, however, and underlying risk factors were unknown. Therefore, in chapter 3, a quantitative microbial risk assessment was performed using Legionella pneumophila as a target pathogen to quantify the risk of infection for exposure due to inhalation and Campylobacter jejuni by ingestion. The risk of infection for a mean exposure duration of 3.5 minutes was 9.3*10-5 for inhalation of L. pneumophila and 3.6*10-2 for ingestion of C. jejuni. The results of the QMRA showed that using rainwater as source water for splash parks may pose a health risk. This study provided a methodology to quantify exposure volumes using observations on site. Furthermore, it gives insight into the effect of setting water quality standards, which may limit infection risks from exposure at splash parks. Splash parks have been associated with infectious disease outbreaks as a result of human exposure to poor water quality. To be able to protect public health, in chapter 4, risk factors were identified that determine poor water quality. Samples were taken at seven splash parks and were analyzed for E.coli. Higher concentrations of E. coli were measured in water of splash parks filled with rainwater or surface water as compared with sites filled with tap water.…