Environmental Engineering Reference
In-Depth Information
Human pathogens were here defi ned as microbes or microorganisms (virus,
bacterium, prion, or fungus) that cause a disease in humans. It should be noted that
many human pathogens are diffi cult to identify in water. Therefore IMO suggested
to use “indicator microbes” such as Escherichia coli and Enterococci and to limit
their acceptable numbers in ballast water discharges. Although these indicator
microbes themselves are usually harmless, natural mutations may result in human
diseases, as recently shown by a strain of bacteria known as enterohaemorrhagic E.
coli (EHEC), a natural mutation of E. coli (Carter et al. 2012 ). Further, the presence
of elevated numbers of human faecal bacteria like E. coli and Enterococci in water
indicates an improper wastewater treatment system and the water may consequently
also include other more problematic species, such as disease agents. IMO further
includes the toxic strains of Vibrio cholerae , the agent of the Cholera disease, in this
standard (D-2 standard).
In the context of this model less abundant target species in the recipient port
means a considerable difference in species abundance, e.g., if in the donor port a
species occurs with 100 ind/m 2 and in the recipient port with 10 organisms, the
recipient port clearly inhabits a less abundant target species population. However,
should the target species occur in the donor port with 2,000 ind/m 2 and in the recipi-
ent port with 1,500 ind/m 2 this can be considered as a comparable abundance. These
numbers should give an indication only, but need to be reconsidered as per the spe-
cies concerned.
The BWM RA model in the form of a fl ow chart is presented in Fig. 5 .
Risk Assessment for Selective Ballast Water Management
Measures
Risk Assessment Framework - Background, Principles,
Assumptions and End-Point
The precautionary principle 11 is applied as a fundamental principle (EU Commission
2000 ) in this RA process which considers all aquatic non-indigenous organisms as
being harmful, and assumes that all HAOP, if present in the ballast water donor port,
if discharged, will cause harm in the recipient environment. This sets the RA end-
point “at discharge” and means that already the discharge of ballast water from a
donor port with HAOP is an undesirable event (see above).
The quantity of discharged ballast water is also one of the factors possibly related
to the risk level. However, RA here does not relate the risk level to the quantity of dis-
charged ballast water as also a small quantity of harmful organisms present in the dis-
charged ballast water may result in critical consequences in the recipient environment.
11 Communication from the Commission on the Precautionary Principle, Brussels, 02.02.2000.
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