Individual Hazard Aspect Scores

As mentioned, for spill responders it is important to determine which hazards could present and should be prepared for. In the following paragraphs the calculation method for each of the hazards is presented.

General approach is as follows:

In which;

Hi Hazard Indicator for hazard i

E Equalization Factor

HW Hazard Weight Factor

Q Quantity per compartment

Hi Hazard Indicator

Each hazard is presented with different parameters and different units. For instance, toxicity by inhalation is expressed with a MAC value, whereas the flammability of a substance is indicated by it’s IMDG classification. For each hazards one or more parameters are chosen for use in indicating the level of hazardousness.

E Equalization Factor

As mentioned above, the hazard indicators for each hazard are of different origin and in different units. To make them comparable, an equalization factor has been assigned to each of the hazard indicators. Multiplying the hazard indicator with the Equalization factor will result in a dimensionless number that is an indication for the level of hazardousness. We call this the reference score (Hi · E)

Table 22 shows the reference score that was used in the development of the factor.

Table 22 reference scores for a spill amount of 1000 tons

Reference description	Reference Score
Very highly hazardous	10.000
Highly hazardous	1.000
Moderately hazardous	100
Slightly hazardous	10
Practically non-hazardous	1
Insignificantly hazardous	0,1
Non-hazardous	0

The equalization factor is only intended to make the hazard indicators comparable, and is not influenced by spill conditions.

HW Hazard Weight Factor

Not all hazards have equal adverse effects. Some hazards have to be considered more heavily for reasons of technical, social, political and emotional origin. In the following table, the hazard weight factors for the different hazard aspects are shown. The hazards to human beings are considered less important in open sea. Radioactivity is in all cases considered the worst hazard.

Table 23 Hazard weight factors

Hazard aspect	Open sea	Populated area	Vulnerable area
Toxicity by inhalation	0.0563	0.1166	0.0576
Explosiveness	0.0386	0.1166	0.0818
Flammability	0.0332	0.0686	0.0546
Aquatic toxicity	0.0894	0.0912	0.1147
Bioaccumulation	0.1902	0.1028	0.1362
Persistence	0.1552	0.1028	0.1487
Radioactivity	0.2735	0.2333	0.2882
Corrosiveness	0.0302	0.0628	0.0272
Long term health effects	0.1333	0.1053	0.0910

Q Quantity per compartment:Q

As mentioned before, elaborate models are available to model the behaviour of a spilled substance. These models can supply a very precise indication of the amount of substance in each compartment. However, when a quick estimation is needed, the behaviour classification can be used to estimate the amount in each compartment. Calculations, which indicate the behaviour of the substances spilled, are required for the procedure. These calculations are confined to calculations, which determine the ultimate amount(s) of substance passing into a particular compartment(s) (air, water surface, water column or sea floor).

In Table 24, the amount per compartment for each behaviour classification is shown. If an E or a D is listed in the table, the amount should be calculated using the formulas below.

In which; E amount evaporated (%of weight)

D amount dissolved (% of weight)

P vapour pressure (Pa)

S solubility (kg/m3)

The gravity scale value for accidental spills is the interpretation of the product of the location weight factor times the sum of nine hazard quantity scores: (1) toxicity by inhalation, (2) explosiveness, (3) flammability, (4) aquatic toxicity, (5) bioaccumulation, (6) persistence (7) radioactivity, (8) corrosiveness and (9) carcinogenicity. The reference scores for the different hazards are:

Toxicity by inhalation

Two hazard indicators for toxicity by inhalation have been defined: The TLV or MAC value and the IMDG code Classification. Because high TLV or MAC values indicate low toxicity, the reciprocal of this value has to be used. The following table lists the reference score based on indicator & equalization factor.

The hazard weight for toxicity by inhalation for different locations is:

Open sea 0,0563

Populated area 0,1166

Vulnerable area 0,0576

Toxicity by inhalation is only relevant for substances present in the air.

Qspilled = Qa

Explosiveness (liquids)

Explosiveness of liquid substances is indicated by their flash point. The reference score for explosive liquids can be calculated as follows:

In which:

Tfl = the substances flash point in ºC

The IMDG classification can also indicate explosiveness. The following table lists the reference score for different IMDG classifications.

Table 26 Reference scores for explosive liquids

Reference score	IMDG class
10.000
1.000	3.1 / 2.1 / 4.3 / 5.1 / 5.2
100	3.2 / 2.2
10	3.3
1
0.1
0

The hazard weight for explosiveness for different locations is:

Open sea 0,0386

Populated area 0,1166

Vulnerable area 0,0818

Explosiveness of vapours emitted is only relevant for substances present in the air.

Qspilled = Qa

Explosiveness (explosive articles)

IMDG classification is a substance’s indicates explosiveness of articles. The following table shows the reference score per relevant classification:

Table 27 Reference scores for explosive articles

Reference score	IMDG class
10.000	1.1
1.000	1.2
100	1.3
10	1.4
1	1.5
0.1
0

The hazard weight for explosiveness for different locations is:

Open sea 0,0386

Populated area 0,1166

Vulnerable area 0,0818

The complete amount of an explosive article presents the hazards, so the relevant quantity is the quantity in all the compartments.

Qspilled = Qa+ Qwa+ Qwc+ Qsf

Flammability

Flammability of substances is indicated by their flash point and their IMDG classification. The reference score for explosive liquids can be calculated as follows:

In which:

Tfl = the substances flash point in ºC

The following table shows the reference score per relevant classification:

Table 28 Reference scores for flammability

Reference score	IMDG class
10.000
1.000	3.1 / 2.1 / 4.1 / 4.2 / 4.3 / 5.1 / 5.2
100	3.2 / 2.2
10	3.3
1
0.1
0

The hazard weight for flammability for different locations is:

Open sea 0,0332

Populated area 0,0686

Vulnerable area 0,0546

Flammability is only relevant for substances that are not in the air and not submerged, therefore the amount on the water surface is the relevant quantity

Qspilled = Qws

Aquatic toxicity

Aquatic toxicity of substances is indicated by their LC50 and their GESAMP B classification. The following table lists the reference score based on indicator & equalization factor.

Table 29 Reference scores for aquatic toxicity

Reference score	LC50 (96)	GESAMP B1	IMDG Class.
10.000	0.1	=>4
1.000	1	3	6.1 / 6.2
100	10	2
10	100	1
1	1000
0.1	10000
0		0

The hazard weight for aquatic toxicity for different locations is:

Open sea 0,0894

Populated area 0,0912

Vulnerable area 0,1147

Aquatic toxicity is relevant for substances that have dissolved in the water column; the amount of a substance on the sea floor can also influence this hazard.

Qspilled = Qwc + 0,1 Qsf

Bioaccumulation

Bioaccumulation of substances is indicated by their GESAMP classification. The following table lists the reference score based on indicator & equalization factor.

Table 30 Reference scores for bioaccumulation

Reference score	Pow	GESAMP A1
10.000	> 4	=>4
1.000	> 3	3
100		2
10		1
1		1
0.1		1
0		0

The hazard weight for bioaccumulation for different locations is

Open sea 0,1902

Populated area 0,1028

Vulnerable area 0,1362

If the location is unknown, the average value can be used: 0,1431

Bioaccumulation is relevant for substances present in, or in contact with the water.

Qspilled = Qwa+ Qwc+ Qsf

Persistence

Persistence of substances is indicated by their half-life and GESAMP classification. The following table lists the reference score based on indicator & equalization factor.

Table 31 Reference scores for persistence

Reference score	Half life (days)	GesampE2	SEBC
10.000
1.000	> 91	Fp
100	> 28
10	> 7	F	F > 0
1	> 1
0.1
0

The hazard weight for persistence for different locations is

Open sea 0,1552

Populated area 0,1028

Vulnerable area 0,1487

Persistent substances are located on the sea floor or on the water surface. (gases and dissolved substances dilute thus are not persistent.:

Qspilled = Qws + Qsf

Radioactivity

Radioactivity of substances is indicated by their radiation level (millirems per hour) and their IMDG classification.

The following table lists the reference score based on indicator & equalization factor.

Table 32 Reference scores for radioactivity

Reference score	Radiation (mrem)	IMDG class
10.000		7 III
1.000		7II
100		7 I
10
1
0.1
0

The hazard weight for radioactivity for different locations is

Open sea 0,2735

Populated area 0,2333

Vulnerable area 0,2882

Radioactivity is relevant for substances regardless of their compartment. Therefore the total amount spilled is considered as the relevant quantity.

Qspilled = Qa+ Qwa+ Qwc+ Qsf

Corrosiveness

Corrosiveness of a substance is indicated by it’s IMDG classification. The following table shows the reference score per relevant classification:

Table 33 Reference scores for corrosiveness

Reference score	IMDG class
10.000
1.000	8 I
100	8 II
10	8 III
1
0.1
0

The hazard weight for corrosiveness for different locations is

Open sea 0,0302

Populated area 0,0628

Vulnerable area 0,0272

Corrosiveness is relevant for substances regardless of their compartment. Therefore the total amount spilled is considered as the relevant quantity.

Qspilled = Qa+ Qwa+ Qwc+ Qsf

Long-term health effects (& carcinogenicity)

Long-term health effects are indicated in the GESAMP profile of a substance. If there is any mention of long-term health effects in GESAMP profile column D3. A reference score of 1.000 is given.

Table 34 Reference scores for carcinogenicity

Reference score	Gesamp D3	IMDG code
10.000
1.000	Any rating
100
10
1
0.1
0		7

The hazard weight for long term health effects for different locations is:

Open sea 0,1333

Populated area 0,1053

Vulnerable area 0,0910

These hazards are relevant for substances regardless of their compartment. Therefore the total amount spilled is considered as the relevant quantity.

Qspilled = Qa+ Qwa+ Qwc+ Qsf