Appendix 4 - Human Risk Assessment of Ballast Water Chemicals

 1 INTRODUCTION

1.1 In risk characterization for human health, the procedure is to compare the exposure levels to which the target groups are exposed or likely to be exposed with those levels at which no toxic effects from the chemicals are expected to occur. There are normally four stages when carrying out a quantitative risk assessment:

• .1 Hazard identification – what are the substances of concern and what are their effects?

• .2 Dose (concentration) – response (effect) relation – what is the relationship between the dose and the severity or the frequency of the effect?

• .3 Exposure assessment – what is the intensity, and the duration or frequency of exposure to an agent.

• .4 Risk characterization – how to quantify the risk from the above data.

1.2 It is proposed to apply a tiered approach when assessing the risk of the chemicals associated with the BWMS.

1.3 In the first Tier, the level of exposure to the substance below which no adverse effects are expected to occur should be derived for the relevant systemic effects. This level of exposure above, which humans should not be exposed to, is designated as the Derived No Effect Level (DNEL). Risks are regarded to be controlled when the estimated exposure levels do not exceed the predicted no effect levels (DNEL).

1.4 A DNEL is a derived level of exposure because it is normally calculated on the basis of available dose descriptors from animal studies such as No Observed Adverse Effect Levels (NOAELs) or benchmark doses (BMDs).

1.5 The DNEL can be considered as an "overall" No-Effect-Level for a given exposure (route, duration, frequency), accounting for uncertainties/variability in these data and the human population exposed by using appropriate Assessment Factors (AFs).

1.6 If an unacceptable level of risk is identified for any of the scenarios in the first Tier, a refinement of the exposure assessment and/or the assessment factors might be performed in the second Tier giving special attention to route-specific contributions and protection measures.

1.7 In order to determine the risks of chemicals associated with the treatment of ballast water, it is necessary to determine several parameters:

• .1 concentration of each chemical in the ballast water tank (and in the air phase above the water);

• .2 concentration of chemicals after discharging in the sea;

• .3 concentration of chemicals which may be transferred from the aquatic environment into the atmosphere; and

• .4 potential uptake of chemicals by humans through the various routes of exposure.

1.8 For the worker exposure situation in the ballast water tank (while performing sampling or cleaning), it is important to estimate the air concentrations in the ballast tank. The concentration of each chemical in the atmosphere above the water may be calculated using the Henry's Law Constant.

1.9 For the exposure situation regarding the general public (whilst swimming in the sea or consuming seafood), the calculated concentration of each chemical in the discharged treated ballast water needs to be used. These can be determined using environmental models and the MAMPEC-BW model version 3.0.1 or latest available version written for this purpose is the one preferred. It is normal practice to use the highest values obtained from this model which is the concentration anticipated in the harbour area.

1.10 It is important to note that the methodologies described in this document generally apply to DNELs of chemicals with a systemic and threshold related property, and do not apply to chemicals producing local effects, such as irritation. However, in some cases it is considered appropriate to derive a DNEL for a local effect when a reliable NOAEL is available. For chemicals with a non-threshold effect (i.e. cancer), a DMEL should be used.

1.11 No account has been taken of the naturally occurring background levels of contaminants in seawater, which, it is recognized, will be different in different parts of the world.

1.12 The approach described in this documentation takes into account the EU REACH guidance described in ECHA Guidance on information requirements and chemical safety assessment.

2 HUMAN EXPOSURE ASSESSMENT

2.1 Occupational

2.1.1 The exposure assessment is carried out through an evaluation of different exposure scenarios. An exposure scenario is the set of information and/or assumptions that describes how the contact between the worker and the substance takes place. It is based on the most important characteristics of the substance in view of occupational exposure, e.g. the physico-chemical properties, pattern of use, processes, tasks and controls. An exposure scenario will therefore describe a specific use of the treatment product with a set of specific parameters. Exposure estimates are intended to be used as a screening tool. The following situations have been identified as likely exposure scenarios for workers:

Table 1. Summary of occupational exposure scenarios

2.1.2 Delivery, loading, mixing or adding chemicals to the BWMS

2.1.2.1 There is potential for exposure to chemical substances during transfer of concentrated formulations in containers or within closed systems. It is considered that the risks are dealt with through the use of appropriate chemical protective clothing, in particular gloves. The applicant should provide details of the intended methods to be used to transfer Active Substances, Preparations or Other Chemicals, e.g. neutralizers, to the on-board storage and propose the appropriate personal protective equipment to prevent exposure.

2.1.2.2 Dilution of concentrated chemical products is often referred to as mixing and loading. On smaller vessels this process may be performed manually. Exposure through inhalation is considered unlikely for non-volatile or water-based chemical formulations. Potential dermal exposure of the hands can be estimated by several available models. It is recommended to use the UK Predictive Operator Exposure Model (POEM) for this estimation. In this model, the daily level of exposure during the handling of containers depends on the properties of the container (capacity and diameter of the opening) and the number of containers handled per day. Containers with narrow openings (< 45 mm) are not considered for this scenario.

Principal equation:

• Dose = skin exposure (mg/kg bw/d)
• f_RMM = risk mitigation factor (Tier 1 = 0, Tier 2 = 0.95)
• C = concentration of Active Substance (mg/L)
• N = number of containers handled, to be determined according to thetotal volume needed for the specific BWMS (d^-1)
• E = contamination per container handled (Tier 1 = 0.1 mL, Tier 2= 0.05 mL)
• f_derm = dermal absorption factor (default = 1)
• f_pen = penetration factor (default = 1)BW = body weight (default = 60 kg)
• BW = body weight (default = 60 kg)

The Tier 1 assessment is based on the handling of containers with an opening diameter of 45 mm and a volume of 10 L. For this case, UK POEM predicts a hand exposure of 0.1 mL fluid per container handled. The number of containers handled depends on the total volume of liquid that needs to be transferred. The Tier 2 assessment is based on the handling of containers with an opening diameter of 63 mm and a volume of 20 L. For this case, UK POEM predicts a hand contamination of 0.05 mL for each container. The total volume handled should be the same as in Tier 1, i.e. the number of containers handled is half of that in Tier 1. The exposure estimation can be further refined by the use of substance-specific values for the dermal absorption factor or the penetration factor, if available. Exposure can be reduced by the use of gloves. According to UK POEM, suitable gloves will reduce exposure to 5% of the original value. This value is used as a default for Tier 2.

2.1.2.3 On larger vessels, transfer of chemicals will more likely occur through closed transfer systems. These systems do not necessarily result in reduced levels of operation exposure. The connection and removal of adaptors may result in similar levels of exposure as those from open pouring operations. Therefore, calculation of exposure by the above equation is recommended also for these systems.

2.1.2.4 Measures to safeguard installations against unintended release of chemicals should be discussed under "Risks to the safety of the ship" (see chapter 7.1 of the Methodology).

2.1.3 Ballast water sampling

2.1.3.1 There is a potential risk for inhalation of chemicals that have evaporated into the air phase while performing the task of taking samples of the ballast water from the sampling facility. The worst concentration of chemicals in the air may theoretically be calculated using the Henry's Law Constant in the equation presented below:

where:

• C_air = concentration in air (mg/m³)
• H = Henry's Law Constant (Pa m³/mole)
• R = gas constant (8.314 Pa m³/mole K)
• T = absolute temperature (K)
• C_water = measured concentration in ballast water (μg/L)

2.1.3.2 If the applicant proposes that the sampling facility be placed in the engine room, a dilution factor of 100 may be introduced to estimate the concentration in the air surrounding test facilities. This is based on the assumption that any air released from the sampling facilities will be diluted by the surrounding air

2.1.3.3 Once a concentration of a volatile component has been estimated, a simple Tier 1 exposure assessment can be performed.

where:

• Dose_Tier1 = inhaled dose (mg/kg bw/d)
• C_air = concentration of volatile component in air (mg/m³)
• ET = exposure time (2 h/d)
• IR = inhalation rate (default = 1.25 m³/h)
• BW = body weight (default = 60 kg)

2.1.3.4 There is also a potential risk for dermal uptake of chemicals from the ballast water while taking samples from the sampling facility. The dermal uptake may be calculated using the equation below:

where:

• U_sd = dermal uptake (mg/kg bw/d)
• A_hands = surface area of two hands (0.084 m²)
• TH_dermal = thickness of the product area on the skin (0.0001 m)
• C_water = concentration of chemical in treated ballast (μg/L)
• BIO_derm = dermal bioavailability (default = 1)
• BW = body weight (default = 60 kg)

2.1.3.5 The aggregated uptake, that is the sum of the inhaled dose and the dermal dose, is then compared with the DNEL to assess whether the risk is acceptable or not.

2.1.3.6 If the Tier 1 risk assessment indicates an unacceptable risk, a Tier 2 exposure assessment can be performed by averaging the short-term daily exposure over an extended period of time, in accordance with a methodology developed by the U.S. EPA^footnote. For this purpose, employment duration of 20 years is assumed.

where:

• Dose_Tier2 = inhaled dose (mg/kg bw/d)
• f_RMM = risk mitigation factor
• C_air = concentration of volatile component in air (mg/m³)
• IR = inhalation rate (default = 1.25 m³/h)
• ET = exposure time (2 h/d)
• EF = exposure frequency (225 d/y)
• ED = exposure duration (20 y)
• BW = body weight (default = 60 kg)
• AT = averaging time (7,300 d (= exposure duration) for non-carcinogenic effects; 25,550 d (= life expectancy) for carcinogenic effects)

The dermal exposure is modified in an analogous manner.

2.1.3.7 For further refinement, the effect of risk mitigation measures may be taken into account using a system-specific risk mitigation factor.

2.1.4 Periodic cleaning of ballast water tanks

2.1.4.1 In this scenario a worker works in the emptied ballast tank, where he may be exposed to volatile components arising from treatment of the ballast water that have remained in the tank atmosphere after discharge of the treated ballast water. The concentration of chemicals in the air phase may be calculated in the same manner as in 2.1.3.1. A dilution factor of 10 is introduced based on the assumption that the ballast tank was previously filled to 90% capacity and so the air from the headspace will be diluted as the ballast water is discharged and fresh air is drawn in.

2.1.4.2 Once a concentration of a volatile component has been estimated, the Tier 1 exposure assessment can be performed as described in 2.1.3.3, using an exposure time of 8 hours/day (see Table 1).

2.1.4.3 The dermal uptake of chemicals from the sediment and sludge in the ballast tank may be calculated in the same manner as in 2.1.3.4 taking into account possible exposure to more parts of the body apart from the hands.

2.1.4.4 For risk assessment, the aggregated exposure is calculated according to 2.1.3.5.

2.1.4.5 If necessary, a Tier 2 exposure assessment can be performed as described in 2.1.3.6, using an exposure frequency of 5 days/year (see Table 1).

2.1.4.6 For this scenario effects of risk mitigation measures may be taken into account as described in the following. The data underlying the UK POEM model suggest that for higher levels of challenge, it is reasonable to assume that impermeable protective coveralls provide 90% protection against aqueous challenge. Protective gloves, for this type of work, are considered to always have the potential to get wet inside and the high-end default value is used as a measure of hand exposure even for the Tier 2 assessment (exposure occurs owing to water entering via the cuff). For boots, a lower default value may be selected to represent the worker wearing appropriate impermeable boots.

2.1.5 Ballast tank inspections

2.1.5.1 In this scenario a crew member or a port state inspector enters the emptied ballast tank and may be exposed to volatile components arising from treatment of the ballast water. The concentration of chemicals in the air phase may be calculated in the same manner as in 2.1.3.1, using a dilution factor of 10 to account for the dilution by fresh air drawn into the emptied ballast tank.

2.1.5.2 Once a concentration of a volatile component has been estimated, the Tier 1 exposure assessment can be performed as described in 2.1.3.3. Exposure time in this scenario is 3 hours/day (see Table 1).

2.1.5.3 No dermal exposure is assumed for this scenario, and the calculated inhaled dose can be directly used for risk assessment.

2.1.5.4 If necessary, a Tier 2 exposure assessment can be performed as described in 2.1.3.6, using an exposure frequency of 12 days/year (see Table 1).

2.1.5.5 For further refinement, the effect of system-specific risk mitigation measures may be taken into account.

2.1.6 Crew carrying out normal work on deck unrelated to any of the above

2.1.6.1 Exposure in this scenario is through inhalation of air released from the air vents on deck. The concentration of chemicals in the atmosphere surrounding the air vents may be calculated as detailed in 2.1.3.1 and 2.1.3.3, taking into account a dilution factor of 100 for the dilution by the surrounding atmosphere.

2.1.6.2 Once a concentration of a volatile component has been estimated, the Tier 1 exposure assessment can be performed as described in 2.1.3.3. Exposure time in this scenario is 1 hour/day (see Table 1).

2.1.6.3 No dermal exposure is assumed for this scenario, and the calculated inhaled dose can be directly used for risk assessment.

2.1.6.4 If necessary, a Tier 2 exposure assessment can be performed as described in 2.1.3.6, using an exposure frequency of 180 days/year (see Table 1).

2.1.6.5 For further refinement, the effect of system-specific risk mitigation measures may be taken into account.

2.2 General public

2.2.1 Indirect exposure of humans via the environment where treated ballast water is discharged may occur by consumption of seafood and swimming in the harbour area in the Tier 1 risk assessment. The Tier 2 risk approach is described in paragraph 2.2.5.2.

2.2.2 The following situations have been identified as likely exposure scenarios for the general public:

Table 2: Summary of exposure scenarios for the general public

2.2.3 Recreational activities (swimming) in the sea

2.2.3.1 Inhalation of chemicals partitioning into the air above the sea

2.2.3.1.1 Exposure in this scenario is through inhalation of air above the sea while swimming. The concentration of chemicals in the air may be calculated while using the Henry's Law Constant as already described in 2.1.3.1. However, in this case the concentration in the water is the PEC harbour value as calculated by MAMPEC, and taking into account a dilution factor of 100 (due to wind, turbulence and insufficient time for the chemical to reach equilibrium).

2.2.3.1.2 The inhaled dose may be estimated using the equation below, while taking into account various assumptions (number of swims, etc.):

where:

• U_si = inhalation intake of chemical during swimming (mg/kg bw/d)
• C_air = concentration in air (mg/m³)
• IR = inhalation rate – light activity assumed (1.25 m³/h)
• n = number of swims per day (5/d)
• D = duration of each swim (0.5 h)
• BIO_inh = fraction of chemical absorbed through the lungs (1)
• BW = body weight (default = 60 kg)

2.2.3.2 Dermal exposure to chemicals whilst swimming in the sea

Exposure in this scenario is via dermal uptake of chemicals when swimming, while using the following equation:

where:

• U_sd = dermal uptake per day during swimming (mg/kg bw/d)
• C_w = concentration in the water, i.e. PEC_MAMPEC (μg/L)
• TH_dermal = thickness of the product layer on the skin (0.0001 m)
• n_swim = number of events (5/d)
• A_skin = surface area of whole body being exposed to water (1.94 m²)
• BIO_dermal = bioavailability for dermal intake (default= 1)
• BW = body weight (kg)

2.2.3.3 Oral uptake of seawater contaminated with treated ballast water

The oral uptake via swimming is calculated according to the following:

where:

• U_so = amount of chemical swallowed (μg/kg bw/d)
• C_w = concentration in the water, i.e. PEC_MAMPEC (μg/L)
• IR_swim = ingestion rate of water while swimming (0.025 L/h)
• n_swim = number of swims per day (5/d)
• Dur_swim = duration of each swim (0.5 h)
• BIO_oral = bioavailability for oral intake (default = 1)
• BW = body weight (default = 60 kg)

2.2.3.4 Tier 2 swimming

If the Tier 1 risk assessment indicates an unacceptable risk, the exposure estimation for this scenario can be refined in a Tier 2 assessment, which is based on the concentrations of substances in the surrounding water instead of the harbour (as calculated with MAMPEC).

2.2.4 Consumption of seafood exposed to treated ballast water

2.2.4.1 The concentration of chemicals in the seafood that is being consumed is calculated in this way:

where:

• C_fish = concentration in fish (μg/kg)
• BCF = bioconcentration factor (L/kg)
• PEC_mampec = concentration of chemical in water derived from MAMPEC (μg/L)

2.2.4.2 The calculation of concentrations in seafood has to be carried out for all Active Substances and Relevant Chemicals. The cut-off value for the bioconcentration factor as described for the environmental risk assessment (paragraph 3.3.6.2 of the Methodology) is not applicable in the risk assessment for human health.

2.2.4.3 While taking into account the assumption that people in the area only eat fish that is being caught locally (worst-case scenario), the daily intake may be calculated in the following way:

where:

• U_fish = uptake of chemical from eating fish (μg/kg bw/d)
• QFC = quantity of fish consumed/day (= 0.188 kg/d (FAO, Japan))
• C_fish = concentration of chemical in fish (μg/kg)
• BIO_oral = bioavailability for oral intake (default = 1)
• BW = body weight (default = 60 kg)

2.2.5 Aggregated exposure (through swimming and consumption of seafood)

2.2.5.1 The total exposure to the general public whilst swimming in the sea and eating fish is the sum of the amount of chemical absorbed through eating fish plus the oral intake, dermal absorption and inhalation absorption whilst swimming.

2.2.5.2 If an elevated risk to the general public is identified in Tier 1, a Tier 2 calculation may be performed by taking into consideration the assumption that the general public activities take place in areas more remote to the actual harbour. For these calculations the standard output from MAMPEC regarding the concentrations in the surrounding water may be used.

2.2.6 Concluding remarks

2.2.6.1 It should be noted that whilst the above situations have been identified as typical worst-case exposure scenarios, it is recognized that there will be other situations when exposure of the general public may be greater or less. Due consideration should be given to such situations.

2.2.6.2 In addition, the consumer exposure (general public) is normally assessed as chronic/lifetime risk in order to protect the most vulnerable population groups taking also into account that they would not use protective equipment when exposed to chemicals.

3 CALCULATION OF DERIVED NO-EFFECT LEVELS (DNELS)

3.1 The next step of the risk assessment process includes the definition of toxicologically significant endpoints for comparison with the calculated aggregated exposure doses. These endpoints, for example No Observed Adverse Effect Levels (NOAELs), Lowest Observed Adverse Effect Levels (LOAELs) or Benchmark Doses (BMDs) from experimental animal studies, are then further transformed to Derived No-effect Levels (DNELs) or Derived Minimal Effect Levels (DMELs) for the characterization of toxicological risks to humans.

3.2 The DNEL can be considered as an 'overall' No-Effect-Level for a given exposure (route, duration, frequency). Uncertainties/variability in these data and the human population exposed are taken into account by using appropriate Assessment Factors (AFs) according to this equation:

4 DNELS FOR THE WORKER POPULATION

4.1 For the exposure at the workplace, the following DNELs may be calculated:

• .1 DNEL, short-term exposure (mg/kg bw): the dose descriptor might be an LD₅₀ from an oral or dermal study or an LC50 from an inhalation study.

• .2 DNEL, long-term exposure (mg/kg bw/d): the dose descriptor might be a NOAEL or LOAEL from a sub-acute, sub-chronic or chronic oral or dermal study or a NOAEC or LOAEC from an inhalation study.

4.2 It is also possible to derive DNELs for local effects. This is relevant for instance for corrosive/irritant substances that can produce immediate severe effects at the first site of contact (skin, eyes and/or respiratory tract).

5 DNELS FOR THE GENERAL PUBLIC

5.1 The exposure of the general public is normally assessed as chronic/lifetime risk in order to protect the most vulnerable population groups, taking also into account that they would not use protective equipment when exposed to chemicals.

5.2 Therefore, for the exposure of the general public via swimming or consumption of seafood, only one DNEL is calculated:

• .1 DNEL, general public: (mg/kg bw/d): the dose descriptor might be a NOAEL or LOAEL from a sub-acute, sub-chronic or chronic oral or dermal study or a NOAEC or LOAEC from an inhalation study.

6 DNEL CALCULATION FROM MAMMALIAN TOXICOLOGY ENDPOINTS

6.1 The DNEL may be calculated in accordance with the following equation:

where:

• Dose_descriptor = see 6.3
• CF_dr = experimental dosing regime, see 6.4
• ASF = interspecies allometric factor, see 6.5
• OSF = other interspecies scaling factor, see 6.6
• ISF = intraspecies scaling factor, see 6.7
• ESF = observed effect scaling factors, see 6.8
• SF_dur = duration scaling factors, see 6.9
• CF_abs = differential absorption factors, see 6.10

6.2 It should be noted that the DNEL is only appropriate for chemicals which cause a threshold systemic effect and is not appropriate for such effects as carcinogenicity for which a Derived Minimal Effect Level (DMEL) should be determined (see 7).

6.3 Dose descriptor

If the dose descriptor is a NOAEC or LOAEC from an inhalation study, expressed e.g. as mg/m³, the internal exposure, expressed as mg/kg bw/d, can be calculated using the standard respiratory volume (sRV) of the test species:

For the rat the sRV is 1.15 m³/kg bw/d

For the mouse the sRV is 1.03 m³/kg bw/d

6.4 Experimental dosing regime (CF_dr)

This factor is needed to correct the dose value when the dosing regime in an experimental animal study differs from the exposure pattern anticipated for the human population under consideration.

For example:

• .1 Starting NOAEL/NOAEC adjusted for treatment schedule (if dosing 5 days/week then a factor of 5/7 is applied)

6.5 Interspecies Allometric Scaling Factor (ASF)

6.5.1 Allometric scaling extrapolates doses according to an overall assumption that equitoxic doses (expressed in mg/kg/d) are related to, though not directly proportional to, the body weight of the animals concerned.

6.5.2 The following Allometric Scaling Factors are recommended for use in determining DNELs:

6.6 Other Interspecies Scaling Factor (OSF)

If no substance-specific data are available, the standard procedure for threshold effects would be, as a default, to correct for differences in metabolic rate (allometric scaling) and to apply an additional factor of 2.5 for other interspecies differences, i.e. toxicokinetic differences not related to metabolic rate (small part) and toxicodynamic differences (larger part). In case substance-specific information shows specific susceptibility differences between species, which are not related to differences in basal metabolic rate, the default additional factor of 2.5 for "remaining differences" should be modified to reflect the additional information available.

6.7 Intraspecies scaling factor for the general population (ISF_gp) and workers (ISF_w)

Humans differ in sensitivity to exposure to toxic substances owing to a multitude of biological factors such as genetic polymorphism, affecting e.g. toxicokinetics/metabolism, age, gender, health and nutritional status. These differences, as the result of genetic and/or environmental influences, are greater in humans than in the more uniform inbred experimental animal population. Therefore, "intraspecies" in this context refers only to humans, which are divided into the following groups:

• .1 workers, which are considered to be reasonably fit and of working age. As a result, the variation in the effect of a chemical on this group is considered to be relatively small, hence:

  • the scaling factor for workers (ISF_w) = 5

• .2 the general population, which are considered to include children, the elderly as well as the unfit and unwell. As a result, the variation in the effect of a chemical on this group is considered to be greater than that of workers, hence:

  • the scaling factor for the general population (ISF_gp) = 10

6.8 Observed effect scaling factors (ESF)

6.8.1 For the dose-response relationship, consideration should be given to the uncertainties in the dose descriptor (NOAEL, benchmark dose) as the surrogate for the true no-adverse-effect-level (NAEL), as well as to the extrapolation of the LOAEL to the NAEL (in cases where only a LOAEL is available or where a LOAEL is considered a more appropriate starting point).

6.8.2 The size of an assessment factor should take into account the dose spacing in the experiment (in recent study designs generally spacing of 2-4 fold), the shape and slope of the dose-response curve, and the extent and severity of the effect seen at the LOAEL.

6.8.3 When the starting point for the DNEL calculation is a LOAEL, it is suggested to use an assessment factor of 3. However, the benchmark dose (BMD) approach is, when possible, preferred over the LOAEL-NAEL extrapolation.

6.9 Duration scaling factors (SF_dur)

In order to end up with the most conservative DNEL for repeated dose toxicity, chronic exposure is the 'worst case'. Thus, if an adequate chronic toxicity study is available, this is the preferred starting point and no assessment factor for duration extrapolation is needed. If only a sub-acute or sub-chronic toxicity study is available, the following default assessment factors are to be applied, as a standard procedure:

_{"sub-acute" usually refers to a 28 day study}

_{"sub-chronic" usually refers to a 90 day study}

_{"chronic" usually refers to a 1.2-2 year study (for rodents)}

6.10 Differential Absorption Factors (CF_abs)

6.10.1 It is recognized that route-to-route extrapolation is associated with a high degree of uncertainty and should be conducted with caution relying on expert judgement.

6.10.2 For simplicity 100% absorption for the oral and the inhalation route for animals and humans is assumed. On the assumption that, in general, dermal absorption will not be higher than oral absorption, no default factor (i.e. factor 1) should be introduced when performing oral-to-dermal extrapolation.

7 CALCULATION OF DMELS – NON-THRESHOLD CARCINOGENS

7.1 Background

According to Procedure (G9), paragraph 5.3.12, the effect assessment of the Active Substances, Preparations and Relevant Chemicals should include a screening on carcinogenic, mutagenic and endocrine disruptive properties. If the screening results give rise to concerns, this should give rise to a further assessment.

7.2 The Linearized approach and the Large Assessment Factor approach

7.2.1 Carcinogens can have a threshold or non-threshold mode of action. When it comes to the threshold carcinogens these can be assessed by using a DNEL approach, however, in the case of the non-threshold carcinogens (i.e. with mutagenic potential) a different approach to risk assessment is recommended.

7.2.2 As a general rule, exposure in the workplace must be avoided or minimized as far as technically feasible. In addition, a risk for the general public from secondary exposure to a non-threshold carcinogenic substance is also unacceptable. However, calculation of an exposure level corresponding to a defined low risk is possible based on a semi-quantitative approach, i.e. a derived minimal effect level (DMEL). In contrast to a DNEL, a DMEL does not represent a safe level of exposure. It is a risk-related reference value that should be used to better target risk management measures.

7.2.3 At the present status of knowledge there are two methodologies which can be applied for deriving a DMEL. The "Linearized" approach essentially results in DMEL values representing a lifetime cancer risk considered to be of very low concern and the "Large Assessment Factor" approach similarly results in DMEL values representing a low concern from a public health point of view. If data allow, more sophisticated methodologies for deriving a DMEL may be applied. The choice of such alternative methodologies should be justified.

7.2.4 Cancer risk levels between 10^-4 to 10^-6 are normally seen as indicative tolerable risk levels when setting DMELs. Where these values are available from internationally recognized bodies, they can be used to set DMELs for risk assessment purposes.

8 RISK CHARACTERIZATION

8.1 General approach

The Risk Characterization Ratios (RCR) compares the exposure levels to various DNELs or DMELs. The RCR is calculated according to the following formula:

8.2 Occupational health risks

8.2.1 While considering ballast water sampling and tank cleaning operations, it should be assumed that the exposure routes of concern for Port State control officers and the crew will be inhalation and dermal exposure. The assumption being that the exposure will include inhalation to the highest concentration of each chemical in the atmosphere above the treated ballast water at equilibrium and the dermal uptake to the highest concentration of each chemical in the treated ballast water.

8.2.2 In the other two scenarios, ballast tank inspection and normal work on deck, only inhalation is taken into consideration.

8.3 Health risks for the general public

In the two scenarios applicable for general public, swimming in seawater contaminated with treated ballast water and ingestion of seafood which has been exposed to treated ballast water are taken into consideration.

8.4 Conclusion

8.4.1 If the RCR < 1, the exposure is deemed to be safe. 8.4.2 However, risks are regarded not to be controlled when the estimated exposure levels exceed the DNEL and/or the DMEL, that is, if the RCR > 1.

8.4.3 If the treated ballast water contains two or more chemicals with the same toxicological effect, these should be evaluated as an "assessment group". The RCR for an assessment group is calculated by addition of all RCRs of the individual components:

RCR_group = RCR_A + RCR_B + RCR_C + ··· .

For the group RCR the same conclusions apply as described above.

8.4.4 Based on past experiences with human health risk assessment of BWMS, the only 'assessment group' that has been identified so far is non-threshold carcinogens.

8.4.5 If an unacceptable level of risk is identified for any of the scenarios in the first Tier, the second Tier is applied. If still an unacceptable risk is identified further refinement of the exposure assessment and/or the assessment factors might be performed giving special attention to route-specific contributions and additional RMM.