Biological Hazards Sample Clauses

Biological Hazards. The environmental and human factors that influence microbial water quality must be considered for aquaculture. Influences on bacterial pathogens and indicator organisms, such as Enterococci and E. coli, originate from human sewage and animal faeces. These can enter waterways from wastewater treatment works, sewage and storm tank overflow and boat discharge, among sources (Science for Environment Policy, 2015). For floating islands, human sewage is a potential nearby source when other use options involve human presence, especially for domestic residence, but also for harbours. Human wastewater can result in an actual risk to public health only if all of the following occur (Mara & ▇▇▇▇▇▇▇▇▇▇, 1989): a) either an infective dose of an excreted pathogen reaches the aquaculture site, or the pathogen multiplies at the site to form an infective dose; b) the infective dose reaches a human host; c) the host becomes infected; and d) the infection causes disease or further transmission. If (d) does not occur, then (a), (b) and (c) can pose only potential risks to public health. Moreover, if this sequence of events is broken at any point, the potential risks cannot combine to constitute an actual risk (Mara & Cairncross, 1989). It should be noted that enteric viruses and bacteria survive for considerably shorter periods in seawater than in fresh water, as described by ▇▇▇▇▇▇▇ (1992):  Bacteria Fecal coliforms undergo a 90 percent reduction in 0.6-8 hours in seawater, compared to 20-100 hours in fresh water. Fecal streptococci and salmonellae may survive a little longer than fecal coliforms in seawater.