A fifteen-month fortnightly survey of microbial health risk indicators and pathogens has been carried out at 25 freshwater recreational and water supply sites distributed throughout New Zealand, for: E. coli, Clostridium perfringens spores, F-RNA bacteriophage, somatic coliphage, human enteroviruses, human adenoviruses, Cryptosporidium oocysts, Giardia cysts, Salmonella and Campylobacter. Sites were selected to represent five geographical areas covering New Zealand and five categories of predominant environmental impact: birds, dairy farming, forestry/undeveloped, municipal, and sheep/pastoral farming. Six of the sites were also source waters for treated drinking-water supplies. Of the indicators, E. coli was detected in 99 % of all samples, with somatic coliphage being detected most of the time (89 %). Of the pathogens tested, Campylobacter and human adenoviruses were inferred to be the most likely to cause human waterborne illness to recreational freshwater users. Using data from all sites, an estimated 5 % of notified campylobacteriosis cases in New Zealand could be attributable to water contact recreation. The critical value for E. coli as an indicator of increased Campylobacter infection is in the range of 200 -500 E. coli per 100 ml. This result has been used to derive new national water quality guidelines for recreational fresh water in New Zealand.

Ammonia is released in the environment by many industries and other human activities. The major quantifiable sources of ammonia released to aquatic ecosystems across Canada are municipal wastewater treatment plants, at an estimated total quantity of 62,000 tonnes per year. Given the sources of ammonia releases in the environment and the properties of the substance, terrestrial plants and aquatic organisms are potential risk targets. A tiered assessment approach has been used to determine the ecological risk in the aquatic environment from ammonia released in municipal wastewater effluents. The results obtained for two case studies with the probabilistic risk analysis used in the highest tier support the conclusion that the conditions encountered in these two locations can lead to ammonia concentrations capable of producing an adverse ecological impact.

Environmental hazard assessments for chemicals are carried out to define an environmentally "safe" level at which, theoretically, the chemical will not negatively affect any exposed biota. Despite this common goal, the methodologies in use are very diverse across different countries and jurisdictions. This becomes particularly obvious when international scientists work together on documents with global scope, e.g., in the World Health Organization (WHO) International Program on Chemical Safety. In this article, we present a study that describes the extent of such variability and analyze the reasons that lead to different outcomes in deriving a "safe level" (termed the predicted no effect concentration [PNEC] throughout this article). For this purpose, we chose 5 chemicals to represent well-known substances for which sufficient high-quality aquatic effects data were available: ethylene glycol, trichloroethylene, nonylphenol, hexachlorobenzene, and copper (Cu). From these data, 2 data sets for each chemical were compiled: the full data set, that contained all information from selected peer-review sources, and the base data set, a subsample of the full set simulating limited data. Scientists from the European Union (EU), United States, Canada, Japan, and Australia independently carried out hazard assessments for each of these chemicals using the same data sets. Their reasoning for key study selection, use of assessment factors, or use of probabilistic methods was comprehensively documented. The observed variation in the PNECs for all chemicals was up to 3 orders of magnitude, and this was not simply due to obvious factors such as the size of the data set or the methodology used. Rather, this was due to individual decisions of the assessors within the scope of the methodology used, especially key study selection, acute versus chronic definitions, and size of assessment factors. Awareness of these factors, together with transparency of the decision-making process, would be necessary to minimize confusion and uncertainty related to different hazard assessment outcomes, particularly in international documents. The development of a "guideline on transparency in decision-making" ensuring the decision-making process is science-based, understandable, and transparent, may therefore be a promising way forward.

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In this case study, we examine the role of science and scientists in community-led collaborative policy processes. We outline the shift from science-led linear policy processes to community-led science-informed policy processes. This case study illustrates how practice evolved to ensure that scientists provided reliable, credible, and salient evidence to help community decision-makers. From this experience, a set of principles for scientists working in these environments was created. These principles include scientists recognising their changing role, scientists sharing the burden of uncertainty, scientists speaking in the communities’ language, and scientists creating fit for purpose assessment frameworks.