Annex – 2022 Guidelines for Risk and Impact Assessments of the Discharge Water from Exhaust Gas Cleaning Systems

 1 INTRODUCTION

1.1 These guidelines provide information on recommended methodology for risk and impact assessments that Member States should follow when considering local or regional regulations to protect the sensitive waters/environment from the discharge water from EGCS that complies with the Convention. These guidelines include assessments of the risks from a long-term perspective, with respect to aquatic quality, aquatic organism, and/or human health, and the impact assessment approach which may be applied to the specific receiving environment.

1.2 Member States are recommended to conduct an environmental risk assessment according to these guidelines when considering local or regional regulations.

1.3 The purpose of these guidelines is to provide a unified approach containing procedures that would support Member States to judge whether the introduction of restrictions/conditions of discharge water from EGCS would be needed and justifiable or not. In all aspects of risk and impact assessments the need for evidence-based decision-making should be balanced with the precautionary approach as set out in resolution MEPC.67(37).^footnote

 2 DEFINITIONS AND ABBREVIATIONS

2.1 Definitions

2.1.1 For the purpose of these guidelines,

• .1 ʺDischarge waterʺ means any water from an EGCS to be discharged overboard;

  .2 ʺWashwaterʺ means cleaning medium brought into contact with the exhaust gas stream for the reduction of SO_X;

  .3 ʺBleed-off waterʺ means an amount of aqueous solution removed from the washwater of an EGCS operating in closed-loop mode to keep its required operating properties and efficiency;

  .4 ʺEGCS residueʺ means material removed from the washwater or the bleed-off water by a treatment system or discharge water that does not meet the discharge criterion, or other residue material removed from the EGCS;

  .5 ʺEmissionsʺ means any release of substances, subject to control by this annex, from ships into the atmosphere or sea according to regulation 2.1.12 of MARPOL Annex VI^footnote;

  .6 ʺAggregated exposure approachʺ in relation to human exposure scenarios means the assessment of the total exposure to one substance resulting from more than one exposure pathway (inhalation, dermal and oral) and/or from more than one exposure scenario;

  .7 ʺArea to be assessedʺ means sea area where discharge water from EGCS is intended to be restricted under certain conditions;

  .8 ʺEmission factorʺ means the concentration of the product of individual substance in discharge water from EGCS per the typical flow rate, expressed as mg/MWh; and

  .9 ʺSea Area for calculating PEC (SAP)ʺ means sea area selected for simulation to estimate Predicted Environmental Concentrations (PECs) of the targeted chemicals, which should be a part of the area to be assessed.

2.1.2 Furthermore, the definitions in 2021 Guidelines for exhaust gas cleaning systems adopted by resolution MEPC.340(77) apply.

2.2 Abbreviations

2.2.1 For the purpose of these guidelines, the following abbreviations apply.

 3 PRINCIPLES

3.1 The use of EGCS in the area to be assessed should not cause unacceptable risks, especially from a long-term perspective with respect to marine organisms, aquatic quality and/or human health, as assessed in accordance with these Guidelines.

 4 APPLICATION

4.1 These Guidelines can be used by Member States when undertaking risk and impact assessments to ascertain whether EGCS discharge water can be discharged in their ports, harbours, estuaries, or coastal and other territorial waters.

4.2 The risk and impact assessments can be done at local, national or regional level (e.g. regional sea conventions) and be conducted at least in cooperation with neighbouring States. Alternatively, Member States can take into consideration risk and impact assessments undertaken by another Party.

 5 GENERAL REQUIREMENTS

5.1 Targeted chemical substances and their data-set

5.1.1 The targeted chemical substances for environmental risk assessment (ERA)

5.1.1.1 The targeted chemical substances for ERA should at least include the following ʺpriority hazardous substancesʺ:

• .1 cadmium;

  .2 lead;

  .3 mercury;

  .4 nickel;

  .5 vanadium;

  .6 chromium;

  .7 copper;

  .8 zinc;

  .9 acenaphthene;

  .10 acenaphthylene;

  .11 anthracene;

  .12 benzo(a)anthracene;

  .13 benzo(a)pyrene;

  .14 benzo(b)fluoranthene;

  .15 benzo(k)fluoranthene;

  .16 benzo(g,h,i)perylene;

  .17 chrysene;

  .18 fluoranthene;

  .19 fluorene;

  .20 indeno(1,2,3cd)pyrene;

  .21 naphthalene;

  .22 pyrene;

  .23 phenanthrene; and

  .24 dibenzo(a,h)anthracene.

5.1.1.2 The targeted chemical substances for ERA are not limited to the above priority hazardous substances. Other contaminants found in EGCS discharge waters may be added, taking into account the domestic regulations and specific factors from the sensitivity of the area to be assessed.

5.1.1.3 Also, for the area where the administration has concerns on eutrophication, relevant substances (e.g. nitrate, nitrite, ammonia and/or phosphate), which may dissolve into EGCS discharge waters, may be added.

5.1.2 Data-set for ERA

5.1.2.1 The Database of priority hazardous substances developed by the Organization, including physico-chemical data, ecotoxicological data and toxicological data, should be used for ERA.

5.1.2.2 Furthermore, the worst-case emission factors of the priority hazardous substances listed in paragraph 5.1.1.1 should be used for reasonable worst-case scenarios (see paragraph 6.2.2).

• .1 Emission Factors for the chemical substances are needed for ERA. In addition, the flow rate of the discharge water against exhaust flow may vary among EGCSs type and the load of engines connected to the EGCSs. However, such information does not depend on the location of the area to be assessed. Therefore, it is recommended that unified and representative Emission Factors (mg/MWh) based on the data for discharge water concentration and flow rate collected by the Organization be utilized.

• .2 If the Member States propose to use their original Emission Factors with a scientific reasoning based on their original measurement of EGCS discharge water, all the measurements should be analysed in accordance with the 2021 EGCS Guidelines.

5.1.2.3 The database will be placed to the IMO GISIS under a separate new item titled ʺChemicals in EGCS Discharge Waterʺ.

5.1.2.4 For the targeted chemical substances for ERA, which are not included in the list of priority hazardous substances, the Member States should prepare the information as in paragraphs 5.1.2.1 and 5.1.2.2.

5.2 Information of the area to be assessed

5.2.1 Data stated in paragraph 5.2.2 should be collected by the Member States implementing the risk assessment in accordance with these guidelines.

5.2.2 Information of the area to be assessed

5.2.2.1 The following information of the area to be assessed is required:

• .1 geographical designation of the area to be assessed;

• .2 representative water and sediment quality of the area to be assessed;

• .3 the meteorographic/oceanographic information in table 1 on each Sea Area for calculating PECs (SAP);

• .4 existing threshold concentrations (PNEC, Predicted No Effect Concentration or EQS, Environmental Quality Standards) for each substance (in water, sediment and/or biota) indicating the level in the environment below which there should be no harm (lethal or sub-lethal) to the aquatic ecosystem or human health, taking account of the likely bioavailability of the substances where relevant; and

• .5 information on how chemical, biological and physical characteristics of the receiving environments, including their pH and salinity, could affect the level of risk.

Table 1: Parameters used for long-term environmental assessment

5.2.2.2 It is recommended that the information of the area to be assessed be collected by actual measurements, while representative values from literature can be used in case actual measurements are difficult. For parameters that change according to the season/time of the year, the changes of such parameters should be all-inclusively taken into account to ensure the representativeness of values.

 6 RISK CHARACTERIZATION

6.1 Introduction

6.1.1 In this chapter, the methodology to assess the quantitative risks is described. Related international standards and/or existing guidance may be taken into account for risk characterization.

6.1.2 First, the daily loads (g/day) of all the chemical substances, which are discharged from EGCS, should be delivered based on the actual ship activities. Secondly, the PECs (ppt) of the chemical substances should be determined, taking into account the physico-chemical characteristics and the geographical and meteorographical/oceanographical conditions.

Also, the human exposure amount (g/kg-BW/day) may be delivered from the PECs. Finally, for risk characterization, the PEC and/or exposure amount, as predicted risk, is compared with the acceptance criteria. In general, if the ratios of PEC and PNEC, i.e. Risk Characterization Ratios (RCR) are less than 1, then the potential risks in the area to be assessed are acceptable. The cumulative effects of mixtures should be taken into account and a PEC/PNEC summation approach is recommended where PEC/PNEC ratios of all mixture components (PAHs and metals) are summed up to a final Risk Quotient. In addition, the Whole Effluent Toxicity testing may also be used to assess the cumulative effects of the targeted substances.

6.2 Emission scenarios

6.2.1 Activities

6.2.1.1 The actual activities (in total power output) of all ships operating in the SAP should be estimated, using received AIS data by satellites and/or local stations. The same methods described in the Fourth IMO GHG Study 2020 should be applied to calculate the hourly outputs of the main engine as kWh for each ship when operating in the SAP, using the information of SOG in the AIS signal. More simplified methodology may be used, such as utilising the averaged fuel consumption by ship types and sizes reported in the study and adjusting them by applying power curve between the actual power needed and speed obtained from AIS data.

6.2.1.2 The activities should include the power consumed in the auxiliary engines with the assumption that those would be all connected to EGCS, as far as corresponding data is available. To estimate the activities when the ships are stopped (mooring loading or unloading), relevant data from the ship or statistic data of ships^footnote should be used to assume the hourly outputs of the auxiliary engines as kWh for each ship when actual ship data is not available. Use of shore power or compliant fuel should be accounted for and excluded.

6.2.2 Reasonable worst-case scenarios

6.2.2.1 For Reasonable worst-case scenarios, the following assumptions should be applied:

• .1 the maximum ratio of ships using EGCS in the SAP should be set by the Member States, taking into account the current situation in the SAP and future increase;

• .2 all EGCSs installed onboard will be operated under open-loop operation, unless information to the contrary is available; and

• .3 the increase of the numbers of ships may be assumed taking into account the future growth of transportation amount and possible infrastructure expansion, as far as corresponding data is available.

6.2.3 The load of the targeted substances in discharge water

6.2.3.1 By multiplying the emission factors to the total activities, the load of each targeted substance in discharge water will be provided (g/day as the input for MAMPEC calculations).

6.3 Exposure assessment for PEC

6.3.1 Introduction

6.3.1.1 To assess the risk of EGCS discharge water, in principle, the worst PEC in the area to be assessed should be identified. However, when designating a wide area to be assessed with complex geographical conditions, it may be difficult to simulate the total area with a single SAP with simplified assumption. In this case, multiple SAPs may be set, and PECs should be estimated for all SAPs.

6.3.1.2 It should be noted that PECs from the long-term viewpoint should be estimated. The tools for PECs should be appropriately selected for the purpose or time scale (the exposure time experienced by an organism) of PNEC, DNEL and/or DMEL.

6.3.2 Tools for long-term PEC of substances

6.3.2.1 The environmental concentrations of each substance after 10 years should be predicted using MAMPEC (see appendix 1). The MAMPEC model can take into account the fate of pollutants (e.g. accumulation and persistency) when predicting the concentrations that may be influenced by the hydrodynamical properties of local situations.

6.3.2.2 Although MAMPEC provides default geographical parameters for each "typical" marine environment (e.g. open sea, shipping lane, estuary, commercial harbour, yachting marina and open harbour), the actual geographical parameters collected for each SAP should be applied. Also, if the SAP(s) are too complicated to apply MAMPEC because of complex geography and/or more discharge points than MAMPEC model allows, the other simulation using 3D CFD may be used.

6.3.2.3 As a first assessment, the maximum value in the surroundings from the MAMPEC-BW calculations (e.g. the maximum PEC in the surroundings area outside the harbour. See section 6.8 of the MAMPEC 3.1 HANDBOOK) should be used as a representative concentration. If the result of the first assessment indicates potential risks comparing with the acceptance criteria, the average value from the MAMPEC-BW calculations may be used.

6.3.2.4 When calculating PECs in the SAP(s), the background concentrations of chemical substances should be added.

6.3.3 Selection of SAP for long-term calculation

6.3.3.1 It is recommended that SAP(s) for long-term calculation using a representative area in the area to be assessed including consideration of highest-risk area where the pollutants tend to accumulate, taking into account the geography, oceanic currents and tides, and/or the area with a higher traffic density compared to other areas.

6.3.3.2 To avoid insufficient risk assessment, an SAP should not be too small compared to the area to be assessed, and all SAPs for long-term calculation should, at least, cover the size of typical marinas. In addition, to ensure that SAPs appropriately represent the area to be assessed, SAPs for long-term calculation should cover a large part of the area to be assessed. Though SAPs for long-term calculation will be selected by the Member States, taking into account geographical conditions, in case of simple shape of the area to be assessed, it is recommended that the total SAP(s) cover more than 50% of the area to be assessed or that the ship activities in the total SAP(s) are more than 50% of those in the area to be assessed. The risk assessment for at least half of the area or the ship activities would prevent the arbitrary consequences of the assessment that result from specific small SAP(s).

6.4 Human exposure scenarios

6.4.1 Exposure scenarios involving the general public

6.4.1.1 In addition to the PECs of the targeted chemical substances, the human exposure amount of these substances may be assessed by applying exposure scenarios.

6.4.1.2 Exposure may occur indirectly, as is the case for the general public who may swim in water in areas where EGCS discharge water has been discharged, who eat seafood that has been caught in (the vicinity of) a discharge area, and/or who drink water prepared from the receiving water that may have been exposed to the EGCS discharge water. The following situations have been identified as probable exposure scenarios for the general public. It is recognized that there will be situations when the risk of human exposure is greater, such as amongst subsistence harvesters, and in these instances additional consideration should be given. Each exposure scenario should take into account concentrations in the water (PECs) estimated, as described in paragraph 6.3:

• .1 recreational activities in the sea (swimming);

• .2 eating seafood exposed to EGCS discharge water; and

• .3 drinking water prepared from receiving water that may have been contaminated by the EGCS discharge water.

6.4.1.3 For each scenario, exposure amount may be calculated based on the PEC. An aggregated exposure approach may be applied (see appendix 2).

6.5 Risk assessment

6.5.1 Introduction

6.5.1.1 Prior to the comparison between exposure levels and acceptance criteria, screening on PBT and CMR for each targeted chemical substance should be performed. The ratio of the estimated exposure to the acceptance criteria defines the risk assessment quotient: PEC/PNEC for the aquatic quality and aquatic organism and/or exposure/DNEL or exposure/DMEL for the human health risk assessment.

6.5.1.2 In addition to the PEC/PNEC ratio approach, a whole effluent assessment taking into account the EGCS discharge water may be performed. More details are stated in paragraph 6.7.

6.5.2 Environmental risk assessment

6.5.2.1 Screening for potential Persistence (i.e. poor degradation in the environment), Bioaccumulation (i.e. accumulation in organisms and food chains) and Toxicity (PBT) are necessary, taking into account the following elements:

• .1 Persistence:

  Persistence should preferably be assessed in simulation test systems that determine the half-life under relevant conditions. Biodegradation screening tests may be used to show that the substances are readily biodegradable.

• .2 Bioaccumulation:

  The assessment of the (potential for) bioaccumulation should use measured bioconcentration factors in marine (or freshwater) organisms. Where these tests are not applicable, or if logPow <3, Bioconcentration Factor (BCF) values may be estimated using (Quantitative) Structure-Activity Relationship ((Q)SAR) models.

• .3 Toxicity:

  Acute and chronic ecotoxicity data, ideally covering the sensitive life stages, should in principle be used for the assessment of the toxicity criterion.

6.5.2.2 When assessing the environmental risk, discharge of pollutants from other sources impacting the area assessed should be taken into account.

6.5.3 Human health risk assessment

6.5.3.1 Screening for Carcinogenicity, Mutagenicity and Reproductive toxicity (CMR) properties for the chemicals is necessary.

6.6 Risk characterization and analysis

6.6.1 The ratio between the resulting PEC from the MAMPEC and PNEC is calculated, and where the result is below 1, the assumption is that no unacceptable risk will result from exposure to that chemical. In case that a background concentration of a chemical substance exceeds PNEC, it is assumed that unacceptable risk already exists from exposure to that chemical.

6.6.2 In addition to paragraph 6.6.1, the pH drops delivered from the additional PECs of sulfate/sulfite (i.e. sulphuric/sulphurous acid) should be assessed from the viewpoint of marine acidification. The pH drops can be estimated using the identified concentration (PEC) of sulfate/sulfite and the current and future alkalinity of seawater.

6.6.3 An assessment of secondary poisoning is redundant if the substance of concern demonstrates a lack of bioaccumulation potential (e.g. BCF <500 L/kg wet weight for the whole organism at 6% fat).

6.6.4 An assessment of sediment species is redundant if the potential of the substance of concern to partition into the sediment is low (e.g. K_oc <500 L/kg).

6.6.5 Accumulation of priority hazardous substances in sediments should be assessed in the port area

6.7 Whole Effluent Toxicity

6.7.1 Whole Effluent Toxicity (WET) testing using the actual discharge water from EGCS may be performed by the Member States.

6.7.2 The advantage of conducting a WET testing on the EGCS discharge water is that it aggregates and addresses the potential for interactions (i.e. cocktail effects) of the contents of the discharge water.

6.7.3 The Member States should provide both acute and chronic toxicity test data using internationally accepted test procedures to determine the toxicity of the EGCS discharge water when conducting WET testing.

6.7.4 To assess the adverse effects of the discharge water, either the use of pH buffer or filtration process should be avoided.

6.7.5 These toxicity tests should include chronic test methods with multiple test species (a fish, an invertebrate and a plant) that address the sensitive life-stage. The preference is to include both a sub-lethal endpoint (growth) and a survival endpoint.

6.7.6 The test results to be provided include: acute 24-hour, 48-hour, 72-hour and 96-hour Lethal (or Effect) Concentration at which 50% of the test organisms die (or effect) (L(E)C₅₀), chronic No Observed Effect Concentration (NOEC) and/or Effect Concentration at which 10% of test organisms show effect (EC₁₀), as appropriate based on the experimental design.

6.7.7 A dilution series including a 100% EGCS discharge water would be tested to determine the 50% of the test organisms die (or effect) using the statistical endpoints for acute ecotoxicity (EC₅₀).

6.7.8 Applying the assessment factor (see paragraph 6.3.3.1 and Table 5 in the Annex to BWM.2/Circ.13/Rev.4 on Methodology for information gathering and conduct of work of the GESAMP-BWWG) on the results of WET, PNEC_general expressed as dilution ratio should be determined both for short term and long term, the former delivered from the results of acute WET tests and the latter from chronic WET tests.

6.7.9 For the risk characterization applying the WET approach, the comparison between the risk thresholds and PEC will be needed.

6.7.10 From the short-term viewpoints, the ratio between the resulting dilution ratio from the short-term calculation of PECs and the PNEC_general from acute WET tests should be calculated, and where the result is below 1, the assumption is that no unacceptable risk will result from exposure to the aggregated ecotoxicity among the discharge water from EGCS.

6.7.11 An initial analysis could use a conservative approach where the dilution capacity would not be taken into consideration (no modelling or plumes analysis would be used). The rationale for taking a conservative approach is that there could be multiple discharges into one location (even though this is not necessarily the case).

6.7.12 From the long-term viewpoints, the ratio between the resulting dilution ratio from the long-term calculation of PECs and the PNEC_general from chronic WET tests should be calculated, and where the result is below 1, the assumption is that no unacceptable risk will result from exposure to the aggregated ecotoxicity of the discharge water from EGCS.

6.7.13 As the WET testing will cost, and should be performed at the laboratory with quality assessment and quality control (QA/QC) and with high expertise, the Member States may utilize the data collected by the Organization. NOTE: the results of WET both for acute and chronic may be included in the database developed by the Organization.

 7 IMPACT ASSESSMENT

7.1 The impact assessment approach may be applied to the specific receiving environment that is being assessed, at the relevant geographical levels, taking account of the type of water body, i.e. marine (open water), coastal and other territorial waters (within 12 nm from the coastline), estuarine, large harbour and small enclosed harbour environments and areas in the vicinity of dense shipping routes. In addition, saltwater, brackish water and freshwater situations and the effect of tides or their absence may be considered, as appropriate.

7.2 Application of impact assessment approach to the specific receiving environment by identifying and defining:

• .1 the existing status (ecological, chemical, environmental, cultural) of the receiving water bodies;

• .2 the likely effect on status of the discharge water discharges, in particular whether the discharge could result in failure to meet the objectives of the applicable environmental legislation;

• .3 the specific environmental stressors that may be affected by discharge water discharges;

• .4 the adverse effects arising from these stressors; and

• .5 the presence of priority hazardous substances on sediments affecting dredging operations in port areas.

7.3 Incorporation of the following steps for the specific receiving environment:

• .1 a systematic review of the impacts of the discharge water;

• .2 specific modelling for physical distribution and fate of the components in discharge water and comparing the PNEC and PEC considering the cumulative effects of the mixture, i.e. use the PEC/PNEC summation approach;

• .3 identification of the overall vulnerability of and potential damage to the environment, habitats or organisms that may be impacted, and the potential cost of restoration;

• .4 the identification of any direct or indirect socio-economic, cultural and human health impacts of the discharge water discharge;

• .5 whether there are any seasonal or temporal impacts that need to be considered;

• .6 identification of any practical mitigation measures that could minimise the potential impacts identified at this stage; and

• .7 water exchange rate in water bodies that may be affected by the presence of port infrastructures.

7.4 The adoption of restrictions or a ban on discharge water from EGCSs should be considered in areas where any of the following indicative criteria are fulfilled:

• .1 environmental objectives in the areas are not met, e.g. good chemical status, good ecological status or good environmental status are not achieved under applicable legislation;

• .2 the discharge of EGCS effluents represents an additional risk of deteriorating the environment and the resiliency of the climate system;

• .3 the EGCS discharge water conflicts with the conventions and regulations formulated to protect the marine environment (see UNCLOS Article 195, etc.); and

• .4 the EGCS discharge effluent represents an increase in the costs of management of dredged materials in ports.

7.5 An uncertainty analysis can be undertaken by identifying whether the potential adverse effects from discharge water discharges are well understood. This may include the effects on the immediate and downstream environment taking into account both spatial and temporal factors.

7.6 When restricting EGCS discharges, consideration should be given to investments already made by industry to comply with regulation 14 of MARPOL Annex VI and other relevant legislation, also taking, however, into account that the choice of EGCS as an alternative compliance option under regulation 4 of MARPOL Annex VI was primarily based on considerations of favourable economic competitiveness. In any case, not restricting EGCS discharges could also lead to the economic burden on governments (for example in relation to management of dredged materials), due to their need to restore environmental degradation, protect human health and impacts on the fishing or tourisms sector deriving from. These impacts should also be overall taken into account. The sooner such measures are taken, the lower the consequent impact will be on industry on Member States.

 8 NOTIFICATION TO THE ORGANIZATION

8.1 The Member States that have undertaken risk and impact assessments should notify the Organization of the result of the assessments together with the notification of local regulations on the discharges of discharge water from EGCSs.