TEXTE Environmental Impacts of Exhaust Gas Cleaning Systems for Reduction of SOx on Ships — Analysis of status quo 
Report compiled within the framework of the project ImpEx 
it is recommended to sum up the PEC/PNEC quotient of every single substance to account for 
additive toxicity. 
As aforementioned (chapter 7.2), the single-substance approach alone seems to be inadequate 
for an environmental risk assessment of the complex mixture of EGCS discharge water. This is 
vecause there is a potential risk of toxic effects arising from cumulative or synergistic toxicity. In 
order to assess the risks of effects of complex mixture in the environment, other approaches are 
proposed in the literature (ECETOC, 2001). One practical method is the simple summation of 
PEC/PNEC quotients of the substances in the mixture. This approach is considered conservative 
and could be used as a first-tier when applying concentration addition (European Union, 2012). 
Ushakov et al. (2019) employed this approach but with the EQS of the Norwegian Environment 
Agency as PNEC and the pollutant concentrations at discharge as PEC. 
Table 5 shows diverging conclusions from the reviewed studies. Therefore, the methodology 
should be considered in detail when reviewing and comparing the studies. Especially the applied 
safety factors for the PNEC values have a drastic impact on the PEC/PNEC quotient. 
Table 5: Research studies assessing EGCS discharge water using the PEC/PNEC approach 
Research 
study 
CE Delft 
I 
Marena 
PEC 
(estimated or 
modelled dilution) 
Mean equilibrium 
water concentrations 
modelled with 
MAMPEC using 
average measured 
data 
Dilution factors were 
estimated based on a 
simple approach that 
considered the water 
displacement caused 
by the ship ©. 
OL: 6.3 x 10° 
CL: 1.5- 1.9 x 10° 
Equilibrium water 
and sediment 
concentrations of ten 
PAHs and five heavy 
metals modelled with 
MAMPEC using 
average (Hassellöv et 
al., 2020) and 
maximum 
concentrations 
(Faber et al., 2019) ©. 
PNEC ] PEC/PNEC ! 
{required dilution) 
Based on MAC-EQS and 
AA-EQOS of the Directive 
2013/39/EU for single 
pollutants included in 
the list of priority 
substances 9. 
0.06 iD 
Based on WET tests 
carried out within the 
study. 
OL: 1 x 10° 
CL: 0.4—-1x10°® 
OL: 6.3 
CL: 1.9-3.8 
PNEC for PAHs are 
taken from European 
Union (2008) and for 
metals from Linders et 
al. (2019). 
Using 
average 
conc. *- 
0.58 - 3.14 
Using 
maximum 
conc. (two 
PAHs and 
three 
metals) %. 
11-60 
Conclusions of the studies 
The impacts of using OL-EGCS 
are small in relation to the 
agreed water quality 
standards for 2021. Local 
hydrodynamic circumstances 
as well as background 
concentrations of priority 
substances should be taken 
into account when assessing 
the impacts of the use of 
EGCS-OL in a specific port. 
The values indicate a risk for 
harmful effects on the marine 
organisms in the area around 
the shipping lanes. The water 
from the OL system was 
found to be more toxic than 
the waters from the two CL 
systems. 
The application of the 
additive toxicity approach 
leads to PEC/PNEC around 1 
with the average discharge 
concentrations and discharge 
into a pristine environment, 
which indicates an 
environmental risk. 
Application of the maximum 
concentrations and/or 
background concentrations all 
result in a PEC/PNEC >1. 
19