I:\MEPC\56\2.doc 

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INTERNATIONAL MARITIME ORGANIZATION

IMO 

E

MARINE ENVIRONMENT PROTECTION 

COMMITTEE 

56th session 

Agenda item 2 

MEPC 56/2

 14 December 2006

 Original: ENGLISH

HARMFUL AQUATIC ORGANISMS IN BALLAST WATER 

Basic Approval of Active Substances used by the Hybrid Ballast Water Treatment System 

using Seawater Electrolytic Process

Submitted by Japan 

SUMMARY

Executive summary: This document contains non-confidential information for Basic 

Approval of Active Substances used by the Hybrid Ballast Water 

Treatment System using Seawater Electrolytic Process as required by 

the Procedure for approval of Ballast Water Management systems that 

make use of Active Substances (G9). Relevant documents together 

with the application dossier have been submitted to Marine 

Environment Division of the Organization for review by the 

GESAMP - Ballast Water Working Group. 

Action to be taken: Paragraph 3 

Related documents: BWM/CONF/36, MEPC 53/24/Add.1, MEPC 55/2/15 and BWM.2/Circ.6 

Introduction 

1 This document contains non-confidential information for Basic Approval of Active 

Substances in accordance with the Procedure for approval of Ballast Water Management systems 

that make use of Active Substances (G9) adopted by resolution MEPC.126(53). 

2 Relevant documents and application dossier prepared by Mitsubishi Heavy 

Industries, Ltd. have been verified by the Ministry of the Environment and the Ministry of Land, 

Infrastructure and Transport, the competent authorities in Japan and the complete application 

dossier will be made available to the GESAMP-Ballast Water Working Group in accordance 

with the provisions contained in BWM.2/Circ.6. 

Action requested of the Committee 

3 The Committee is invited to consider the proposal for approval and decide as appropriate. 

***

MEPC 56/2 

I:\MEPC\56\2.doc 

ANNEX 

1 INTRODUCTION 

The applicant proposes a seawater electrolytic process for the deactivation of planktons and 

bacteria in the ballast water treatment system. This application is based on the Procedure for 

approval of Ballast Water Management systems that make use of Active Substances (G9). 

The seawater electrolytic process is to be installed at the stage subsequent to the mechanical 

treatment (filter treatment, etc.). Once the mechanical treatment removes or deactivates large 

organisms (the minimum dimension: 50μm or more), the seawater electrolytic process will 

deactivate the plankton and sterilize bacteria remaining in the ballast water. Upon completion of 

treatment the ballast water will comply with the discharge standard of regulation D-2 of 

International Convention for the Control and Management of Ships’ Ballast Water and 

Sediments. The process can also be adjusted to retain enough concentration of active chlorine in 

the ballast water to inhibit the re-growth of organisms within ballast tanks after treatment. 

This seawater electrolytic process produces active chlorine from natural seawater on-board. The 

process has technical achievements of the “Marine-Growth-Prevention Systems” (MGPS®) for 

ships and power plants. Mitsubishi Heavy Industries, Ltd. has been producing MGPS®

for 40 years and has garnered substantial experience in the development, design, and 

manufacture of ships and ship equipment. This application believes that MGPS® is a safe and 

economical system for ships and crews applicable without the storage of chemicals on board. 

And by designing lineup of the system capacity to respond to the different flow rates of ballast 

pumps, the process can be applied to ballast pumps of any flow rate for common ships. 

Water chlorination is a safe and reliable disinfection procedure used worldwide for the drinking 

water sanitation. 

Once active chlorine deactivates the planktons and bacteria in ballast water, it is easily 

decomposed into harmless chlorine ion, a natural component of seawater, through spontaneous 

decomposition by reactions with organic matter in natural seawater and temperature. Active 

chlorine has no persistence or bioaccumulation. 

The applicant evaluated the toxicity of seawater treated with electrolytically generated chlorine 

under the conditions that simulate ballast water treatment and then evaluated the risks using 

literature data. The results of these evaluations indicate that the influence on the environment of 

the ballast water discharges treated by this system is acceptable. 

2 DATA-SET 

The data set on Active Substances and relevant chemicals used for this study is summarized in 

Appendix 1. 

2.1 Identification of the Substance or Preparation (G9: 4.1) 

2.1.1 Preparations 

No commercially available preparations are used. The seawater electrolytic process produces an 

Active Substance on shipboard using portions of the seawater taken as ballast water. 
MEPC 56/2 

ANNEX 

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2.1.2 Active Substances 

This application evaluates free active chlorine produced by seawater electrolysis as the Active 

Substance. 

Chlorine (Cl2) gas is generated at seawater electrolysis. This Chlorine (Cl2) gas rapidly dissolves 

into seawater to form free active chlorine (a mixture of hypochlorous acid (HClO) and 

hypochlorite ion (ClO-

)) (see section 3.3 for details). The seawater electrolytic system harnesses 

the disinfectant actions of free active chlorine to deactivate regulated organisms. 

Pure free active chlorine (a mixture of hypochlorous acid (HClO) and hypochlorite ion (ClO-

)) is 

not available as a preparation on the market. For this reason, there are almost no relevant data on 

the free active chlorine produced by the seawater electrolytic process necessary for the evaluation 

in the Procedure for approval of Ballast Water Management systems that make use of Active 

Substances (G9). To compensate, the applicant mainly uses data relating to sodium 

hypochlorite (NaClO) as reference data for the evaluation of the free active chlorine in this 

application. NaClO rapidly hydrolyzes in water and resides there as free active chlorine. Thus, 

the HClO and ClO- could be evaluated using data on NaClO. 

And as mentioned in the upcoming section 2.1.3, free active chlorine rapidly reacts with nitrogen 

compounds and organic compounds in natural seawater to form a mixture of free active chlorine 

with chloramines generally composed of total residual chlorine (TRC) or total residual 

oxidant (TRO). 

This makes it difficult to assess the toxicity of pure free active chlorine in toxicity tests using test 

animals such as aquatic organisms. In many reports the toxicity has been assessed as TRO or 

TRC. In toxicity assessment using data on TRO or TRC, however, the influence of 

Monochloramine is small. The applicant also assesses the Active Substance using data on TRC or 

TRO in this application. 

Table 1. Active Substances 

Item Information for Active Substances 

IUPAC name Hypochlorous acid Hypochlorite ion 

CAS number 7790-92-3 7681-52-9 

UN number - - 

Molar mass 52.46 51.46 

Empirical formula HClO ClOStructural formula 

O

H Cl

Cl O-

Purity of technical 

material and 

identification of 

impurities 

Purity is not defined so that HClO is produced with on site; 

Concentration of TRC: 

Effluent of the seawater electrolytic apparatus: 

 10 mg/l (Maximum) 

Effluent of electrolytic cell: 

 1,500 mg/l (Maximum) 

Stabilizers or necessary 

additives Not included 
MEPC 56/2 

ANNEX 

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2.1.3 Relevant Chemicals (G9: 2.1.4) 

The disinfection by-products (DBPs) are evaluated as relevant chemicals in this seawater 

electrolytic system. 

Most of the Active Substance decomposes to harmless chlorine ion, a natural component of 

seawater, via disinfection/deactivation reactions with plankton and bacteria. Small amount of the 

substance, however, form DBPs by reacting with the nitrogen compounds and organic 

compounds contained in natural seawater. 

2.1.3.1 Reaction with nitrogen compounds and Active Substance 

Inorganic nitrogen (ammonia, nitrous acid, nitric acid) and organic nitrogen reside in natural 

seawater as nitrogen compounds. Among these, ammonia reacts with the Active Substance 

formed by seawater electrolytic treatment to form chloramines. The following equations show 

examples of reaction formulae with HClO and ammonia: 

NH3 + HClO → NH2Cl + H2O (1) 

NH2Cl + HClO → NHCl2 + H2O (2) 

NHCl2 + HClO → NCl3 + H2O (3) 

Dichloramine (NHCl2) formed in Equation (2) is decomposed to nitrogen gas (N2) via the 

reactions shown by equation (4): 

2NHCl2 + H2O → N2 + HClO + 3H+ + 3Cl- (4) 

The reaction of Equation (4) occurs in the acidic region (<pH 4.4) and thus will never occur at the 

pH of seawater (around 8). The proportion of chloramines present depends on pH, as shown in 

Fig. 1. At pH 7 (10oC), for example, NH2Cl is 91% and NHCl2 is 9% (Pain A, (1950)). 

From the foregoing, we learn that monochloramine (NH2Cl) is one of the main chloramines 

present in seawater at the pH of around 8. 

Monochloramine, a kind of combined chlorine, is known exert the same type of disinfectant 

activity as free active chlorine, but it does so too weakly to qualify for use as a main Active 

Substance in the seawater electrolytic system. The applicant therefore defines monochloramine 

not as an Active Substance, but as a relative chemical, in its evaluations for this application. 

But as mentioned above, chlorine-treated natural seawater is thought to contain a mixture of free 

active chlorine and chloramines. When the applicant uses data from reports on toxicity 

assessments carried out as TRC or TRO and toxicity assessment tests on treated seawater carried 

out for this application, the assessments results must therefore be considered to include the 

toxicity effect of chloramines. 
MEPC 56/2 

ANNEX 

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Fig. 1. Relation between pH value and presence of chloramines 

2.1.3.2 Reaction with organic compounds and Active Substance 

DBPs are formed when active chlorine species reacts with organic compounds in natural water. 

Various compounds have been identified in studies prompted by concerns over the health effects 

of DBPs generated from the chlorination of drinking water (U.S. EPA (1999)). However, most 

DBPs are present in only very small amounts in chlorinated drinking water, and non-identified 

compounds may also be present. Thus, sufficient data have yet to be obtained on the toxicity and 

amounts of all of the DBPs formed. 

Trihalomethanes and halogenated acetic acids (chlorinated and/or brominated compounds) are 

reported to be the main DBPs generated in chlorine disinfection. But, natural seawater contains 

about 65mg/l of bromine ion. Thus, substitution reactions between chlorine ion of free active 

chlorine and bromine ion may occur at seawater chlorination. As the results of the reactions, 

chlorinated and/or brominated trihalomethanes are generated. They can be formed by the 

following reactions: 

(1) Reaction to form trihalomethanes 

 RCOCH3 + 3HOX → CHX3 + RCOOH + 2H2O (X=Br or Cl) (5) 

 

(2) Reactions to form halogenated acetic acids 

 RCHO + HOX → RCOOH + H+

 + X- (6) 

 RCOOH + HOX → RXCOOH + H2O (7) 

 RXCOOH + HOX → RX2COOH + H2O (8) 

 RX2COOH + HOX → RX3COOH + H2O (9) 
MEPC 56/2 

ANNEX 

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Table 2. Disinfection by-products for natural water 

Trihalomethanes Haloacetic acids 

Trichloromethane 

(CHCl3) 

Bromodichloromethane 

(CHBrCl2) 

Dibromochloromethane 

(CHBr2Cl) 

Tribromomethane 

(CHBr3) 

2-monochloroacetic acid 

(CH2ClCOOH) 

2,2-dichloroacetic acid 

(CHCl2COOH) 

2,2,2-trichloroacetic acid 

(CCl3COOH) 

2-monobromoacetic acid 

(CH2BrCOOH) 

2,2-dibromoacetic acid 

(CHBr2COOH) 

2,2,2-tribromoacetic acid 

(CBr3COOH) 

2-bromo-2-chloroacetic acid 

(CHBrClCOOH) 

2-bromo-2,2-dichloroacetic 

acid 

(CBrCl2COOH) 

2,2-dibromo-2-chloroacetic 

acid 

(CBr2ClCOOH) 

The applicant carried out preliminary tests to confirm the amount of trihalomethanes and 

halogenated acetic acids formed in seawater chlorination by the seawater electrolytic process. 

Two types of seawater were used for the tests: one with a relatively high concentration of organic 

compounds (from Yokohama Port/Tokyo Bay) and one with a low concentration of organic 

compounds (Oigawa Port/Shizuoka Bay). The tests were performed using a small, 

laboratory-sized electrolytic apparatus (capacity of the electrolytic cell: 500 ml) fitted with an 

electrode of a type similar to that used for the actual seawater electrolytic apparatus. The test 

seawater was placed in the electrolytic cell and electricity was turned on to generate a 50±3 mg 

FAC/l electrolytic solution. After measurement of the FAC by iodometry, the electrolytic 

solution and untreated test seawater were mixed to obtain treated seawater with a 

FAC concentration adjusted to 5.0 mg FAC/l. 

The DBPs and pH were analyzed at the Japan Food Research Laboratories, a registered water 

quality examination organization under Section 20, Paragraph 3 of the Water Works Law of 

Japan (The Ministry of Health, Labor and Welfare). 
MEPC 56/2 

ANNEX 

Page 6 

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Table 3. Analytical results of disinfection by-products in electrolytically generated 

chlorine-treated natural seawater 

Item Analysis value 

(mg/l) 

Detection 

limit 

(mg/l) 

Sample Condition

 Sampling Point 

Sampling Date 

Initial chlorine concentration 

POC 

 DOC 

 TOC (=DOC+POC) 

 PH 

Tokyo 

Bay 

2006.7 

(5.0)a,b

2.49 b

0.82 b

3.31 b

8.3 (21°C) 

Oigawa Port 

2006.9 

(5.0) a,c

0.1c

1.0c

1.1c

8.1 (19°C) 

0.05 

2(μg) 

0.05 

- 

- 

Trihalomethanes

trichloromethane (CHCl3) 

bromodichloromethane (CHBrCl2) 

dibromochloromethane (CHBr2Cl) 

tribromomethane(CHBr3) 

N.D. 

N.D. 

0.006 

0.16 

N.D. 

N.D. 

0.003 

0.15 

0.001 

0.001 

0.001 

0.001 

Haloacetic acids

2-monochloroacetic acid (CH2ClCOOH) 

2,2-dichloroacetic acid (CHCl2COOH) 

2,2,2-trichloroacetic acid (CCl3COOH) 

2-monobromoacetic acid (CH2BrCOOH) 

2,2-dibromoacetic acid (CHBr2COOH) 

2,2,2-tribromoacetic acid (CBr3COOH) 

2,2-bromochloroacetic acid (CHBrClCOOH) 

2,2,2-bromodichloroacetic acid (CBrCl2COOH) 

2,2,2-dibromochloroacetic acid (CBr2ClCOOH) 

N.D. 

N.D. 

N.D. 

N.D. 

0.02 

0.03 

N.D. 

N.D. 

N.D. 

N.D. 

N.D. 

N.D. 

N.D. 

N.D. 

0.01 

N.D. 

N.D. 

N.D. 

0.01 

0.004 

0.02 

0.01 

0.01 

0.01 

0.01 

0.01 

0.01 

a: Test seawater was electrolyzed to prepare an electrolytic solution containing about 50 mg of FAC/l. FAC was 

quantitatively determined by iodometry followed by mixing of the electrolytic solution with test seawater. 

b: Results of analysis carried out by the applicant. 

c: Results of analysis carried out by the organization in toxicity tests on treated seawater (see paragraph 5.2). 

N.D.:Not Detection. 

Two kinds of trihalomethanes (tribromomethane, dibromochloromethane) and two kinds of 

brominated acetic acids (2,2-dibromoacetic acid, 2,2,2-tribromoacetic acid) were detected. 

Among these, tribromomethane showed the maximum concentration of 0.16 mg/l. The 

concentrations of the other compounds were below the detection limits. The differences in the 

concentrations of the organic compounds in seawater conferred only small effects on the amounts 

of the by-products formed and composition ratios. (Japan Food Research Laboratories, Analysis 

Certificate, No. 106064894-003 (2006)), Japan Food Research Laboratories, Analysis 

Certificate, No. 106091274-003 (2006)). 

Based on these results, four of the DBPs, namely, tribromomethane, dibromochloromethane, 

2,2-dibromoacetic acid, and 2,2,2-tribromoacetic acid, are evaluated as relevant compounds in 

this application. 
MEPC 56/2 

ANNEX 

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2.1.3.3 Relevant Chemicals evaluated in Basic Approval 

From the foregoing, monochloramine (described in section 2.1.3.1) and four compounds of DBPs 

(described in section 2.1.3.2) (tribromomethane, dibromochloromethane, 2,2-dibromoacetic 

acid, 2,2,2-tribromoacetic acid) are assessed as the relevant chemicals. 

The influences of other by-products (those that may be contained in the treated seawater) were 

assessed as toxic effects from the treated seawater in the toxicity evaluation tests and the risk 

assessment of discharges from the treated ballast water. 

Table 4. Relevant Chemicals in ballast water management system 

IUPAC 

name 

monochloramine tribromomethane 

dibromochloromethane 

2,2-dibromoacetic acid 2,2,2-tribromoacetic acid 

CAS 

number 10599-90-3 75-25-2 124-48-1 631-64-1 75-96-7 

Molar 

mass 

51.48 252.73 208.8 217.8 296.7 

empirical 

formula NH2Cl CHBr3 CHBr2Cl CHBr2COOH CBr3COOH 

structural 

formula 

N

H

Cl

H H C

Br

Br

Br H C

Cl

Br

Br H C

Br

Br

COOH Br C

Br

Br

COOH

2.1.4 Other chemicals 

Hydrogen gas is generated by the cathode reaction through the electrolytic reaction of seawater. 

There have been no reports, however, on the toxicity of hydrogen gas against organisms (human, 

fish, mammalian, etc.) or other influences on the environment. This precludes the evaluation of 

hydrogen gas as a subject of toxicity assessment in this application. The safety of hydrogen gas 

as an inflammable gas is briefly discussed in the section on safety to the vessel body. 

2.2 Effects on aquatic organism (G9:4.2.1.1) 

The applicant collected information (literature) on the effective concentration of each compound 

against aquatic organisms and assessed the reliability of the data according to the method of 

Klimisch et al. (1997). Klimisch et al. (1997) classifies reliability of data into four ranks shown 

in Table 5. Unless otherwise stated, this application only describes data classified as rank 1 or 

rank 2. While almost no papers report the toxicity values of free active chlorine (hypochlorous 

acid and hypochlorite ion) as they are, many have reported the results of toxicity tests using 

sodium hypochlorite to form free active chlorine. Thus, the applicant collected the data on free 

active chlorine mainly from the literature on sodium hypochlorite. 

The concentration of free active chlorine (hypochlorous acid (HClO) and hypochlorite ion 

(ClO-

)) is written as FAC. 
MEPC 56/2 

ANNEX 

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Given that free active chlorine are liable to form oxidizers in natural water, most of the Active 

Substance concentrations are arranged in terms of total residual chlorine (TRC), total residual 

oxidant (TRO), or chlorine-produced oxidant (CPO). 

The value of TRC includes that of free active chlorine and combined active chlorine 

(chloramines etc.). Both The value of TRO and CPO include that of TRC and other oxidants. 

Concentrations of oxidants except TRC are very low at chlorination; both TRO and CPO are 

about the same of TRC. 

Table 5. Categories/codes of reliability (Klimisch et al. 1997) 

Code Category 

1 Reliable without restriction 

2 Reliable with restrictions

3 Not reliable 

4 Not assignable 

2.2.1 Acute aquatic toxicity 

2.2.1.1 Free active chlorine 

In an acute aquatic toxicity test using Oncorhynchus kisutch (fish/saltwater), 96h LC50

was 0.032mg TRO/l (Thatcher (1978)). According to the report using Ceriodaphnia dubia 

(crustaceans/freshwater), 24h LC50 was 0.005 mg FAC/l according to running water system 

giving no feed (Taylor (1993)). In an acute aquatic toxicity test using Thalassiosira pseudonana 

(algae/saltwater), 24h IC50 (growth rate) was 0.075 mg TRC/l (Gentile et al. (1976)). Further, in 

an acute aquatic toxicity test using Crassostrea virginica(mollusks/ estuarinewater) in which 

chlorine (Cl2) was added to free active chlorine. As a result, 96h EC50 was 0.023 mg TRC/l 

(Roberts and Gleeson (1978)). 

2.2.1.2 Relevant chemicals 

(1) Monochloramine 

In an acute aquatic toxicity test using Oncorhynchus kisutch (fish/saltwater), 96h LC50

was 0.079-0.083 mg/l (Larson, G.L. et al. (1978)). Further, in an acute aquatic toxicity test using 

Gammarus pseudolimnaeus (crustaceans/freshwater), 96h LC50 was 0.22-0.235 mg/l (Arthur, 

J.W et al. (1971)). There has been no report on acute aquatic toxicity value in terms of EC50 of 

monochloramine against algae. 

(2) Tribromomethane 

In an acute aquatic toxicity test using Cyprinodon variegatus (fish/saltwater), 96h LC50 was 

7.1 mg/l (Ward et al. (1981)) according to running water. Further, statistically computed 

96h NOEC was 2.9 mg/l (Heitmuller et al. (1981)). In an acute aquatic toxicity test using 

Daphnia magna (crustaceans/freshwater), 24-48h LC50 was 46-56 mg/l and 48h NOEC was less 

than 7.8 mg/l (LeBlanc, G.A.(1980)). Furthermore, in an acute aquatic toxicity test using 

Skeletonema costatum (algae/saltwater), 96h EC50 was 12.3 mg/l (ECOTOX (2005)). 
MEPC 56/2 

ANNEX 

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(3) Dibromochloromethane 

Only freshwater organism tests of dibromochloromethane are reported. 

In an acute aquatic toxicity test using Oryzias Latipes (fish/freshwater), 96h LC50 was 79mg/l 

(NITE(2006a)). In an acute aquatic toxicity test (growth) using Selenastrum capricornutum 

(algae/freshwater), 72h EC50 was 6.1mg/l and 72h NOEC was 2.9mg/l (NITE(2006a)). In an 

acute aquatic toxicity test (immobilization) using Daphnia magna (crustacean/freshwater), 

48h EC50 was 27mg/l (NITE(2006a)). Further, in an acute aquatic toxicity test using 

Tetrahymena pyriformis(protozoa/freshwater), 24h LC50 was 65 mg/l (Yoshioka, Y. et al.(1985)). 

(4) 2,2-dibromoacetic acid 

Only freshwater organism tests of 2,2-dibromoacetic acid are reported. 

An aquatic toxicity test on 2,2-dibromoacetic acid as a decomposed matter of dibromoacetamide 

was carried out, and in an acute aquatic toxicity test using Pimephales promelas

(fish/freshwater), 96h LC50 was 6.9-mg/l (Mayes, M.A. et al. (1985)). 

(5) 2,2,2-tribromoacetic acid 

No report on acute aquatic toxicity of 2,2,2-tribromoacetic acid against aquatic organisms is 

available. 

2.2.2 Chronic aquatic toxicity 

2.2.2.1 Free active chlorine 

In a chronic aquatic toxicity test using Menidia peninsulae (fish/saltwater), 28d NOEC 

was 0.04 mg CPO/l (CPO: chlorine produced oxidant) (Goodman (1983)). In a test using 

Pandalus danae (crustaceans/saltwater), 1month NOEC was 0.05 mg FAC/l (Gibson (1976)). 

In a chronic aquatic toxicity test with Microcosm (algae/freshwater), 7d NOEC (biomass) 

was 0.0027 mg TRC/l (Cairns (1990)). Further, in a chronic aquatic toxicity test using 

Crassostrea virginica (mollusk/brackish water), 15d LOEC (14% effect) was 0.014 mg TRO/l 

(Liden (1980)). The NOEC of free active chlorine can be estimated to be LOEC/2, and 

15d NOEC is to be 0.007 mg TRO/l. 

2.2.2.2 Relevant chemicals 

(1) Monochloramine 

There is no report on the chronic toxicity of monochloramine and the NOEC has not been 

reported. 

(2) Tribromomethane 

There are only a few reports on the chronic aquatic toxicity of tribromomethane against aquatic 

organisms. Ward et. al. (1981) carried out a test against Cyprinodon variegates (fish/saltwater) 

and obtained a result of 28d NOEC (juvenile mortality) = 4.8-8.5 mg/l. 
MEPC 56/2 

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(3) Dibromochloromethane 

 

Only acute aquatic toxicity tests with freshwater organism of Dibromochloromethane are 

reported. 

In a reproduction toxicity test using Daphnia magna (crustacean/freshwater), 21d EC50 was 

1.5mg/l and 21d NOEC was 0.063mg/l. In a prolonged toxicity test using Oryzias latipes

(fish/freshwater), 21d NOEC was 3.2 mg/l (NITE (2006)). 

(4) 2,2-dibromoacetic acid 

No report on the chronic aquatic toxicity of 2,2-dibromoacetic acid is available. 

(5) 2,2,2-tribromoacetic acid 

No report on the chronic aquatic toxicity of 2,2,2-tribromoacetic acid is available. 

2.2.3 Endocrine disruption effects 

There are no report showing that free active chlorine and the relevant chemicals have endocrine 

disruption effects on aquatic organisms. 

2.2.4 Bioaccumulation 

2.2.4.1 Free active chlorine 

There is no report on the observed value of BCF and Log Pow of free active chlorine. 

According to the calculated value using the calculation program (EPI SuiteTM, U.S.EPA) based 

on QSAR, the Log Pow value of HClO is -0.87(estimated) (that of NaClO is -3.42(estimated)), 

the value smaller than Log Pow≥3, which is the rough indication for bioaccumulation potential. 

In addition, free active chlorine bioaccumulation potential easily decomposes by contact with 

organic compounds, it is speculated that free active chlorine is not high bioaccumulation 

potential compound. 

2.2.4.2 Relevant chemicals 

(1) Monochloramine 

There is no report on the observed value of BCF and Log Pow of monochloramine. 

According to the calculated value using the calculation program (EPI SuiteTM, U.S.EPA) 

based on QSAR, the Log Pow value of monochloramine is -1.19, the value smaller than 

Log Pow=3 which is the rough indication for bioaccumulation potential, it is speculated that this 

chemical is not high bioaccumulation potential compound. 

(2) Tribromomethane 

According to ATSDR (2005), the Log Pow value of tribromomethane was 2.4(observed), 

because the value smaller than Log Pow=3, which is the rough indication for bioaccumulation 

potential, it is considered that this chemical is not high bioaccumulation potential compound. 
MEPC 56/2 

ANNEX 

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Further, the calculated value of BCF using the calculation program (EPI SuiteTM, U.S.EPA) 

based on QSAR is 14. This value is smaller than BCF>2000, which is the rough indication for 

bioaccumulation potential. This result also supports that this chemical is not high 

bioaccumulation potential compound. 

(3) Dibromochloromethane 

There is no report on the observed value of BCF. According to ATSDR (2005), the Log Pow of 

tribromomethane is 2.16(observed), because the value smaller than Log Pow=3, which is the 

rough indication for bioaccumulation potential, it is considered that this chemical is not high 

bioaccumulation potential compound. 

Further, the calculated value of BCF using the calculation program (EPI SuiteTM, U.S.EPA) 

based on QSAR is 9.2. This value is smaller than BCF>2000, which is the rough indication for 

bioaccumulation potential. This result also supports that this chemical is not high 

bioaccumulation potential compound. 

(4) 2,2-dibromoacetic acid 

No report on BCF of 2,2-dibromoacetic acid is availableAccording to Schultz et al. (1999), Log 

Pow value is 1.22(observed), because the value smaller than Log Pow=3 which is the rough 

indication for bioaccumulation potential, it is considered that this chemical is not high 

bioaccumulation potential compound. 

Further, the calculated value of BCF using the calculation program (EPI SuiteTM, U.S.EPA) 

based on QSAR is 3.2. This value is smaller than BCF>2000, which is the rough indication for 

bioaccumulation potential. This result also supports that this chemical is not high 

bioaccumulation potential compound. 

(5) 2,2,2-tribromoacetic acid 

No report on BCF of 2,2,2-tribromoacetic acid is available. According to Schultz et al. (1999), 

Log Pow value is 2.07(observed), because the value smaller than Log Pow=3, which is the rough 

indication for bioaccumulation potential, it is considered that this chemical is not high 

bioaccumulation potential compound. 

Further, the calculated value of BCF using the calculation program (EPI SuiteTM, U.S.EPA) 

based on QSAR is 3.2. This value is smaller than BCF>2000, which is the rough indication for 

bioaccumulation potential. This result also supports that this chemical is not high 

bioaccumulation potential compound. 

2.2.5 Sediment toxicity and Food web/population effects 

2.2.5.1 Free active chlorine 

As the Log Pow value of hypochlorous acid is -0.87 (estimated) (that of sodium hypochlorite 

is - 3.42(estimated)), which is smaller than the rough indication value for bioaccumulation 

potential of Log Pow=3, free active chlorine is not considered to have high bioaccumulation 

potential. Therefore the possibility of accumulation to the higher-level predator in the food 

web is low. 
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The Koc value of hypochlorous acid is 14.3l/kg (estimated by EPI Suite TM) (that of sodium 

hypochlorite is 14.3(estimated by EPI Suite TM)). Because Koc is smaller than 500l/kg, it is 

considered that soil adsorption potential of free active chlorine is low. 

Also, environmental distribution ratio of hypochlorous acid and sodium hypochlorite are 

calculated according Level III Fugacity model. The value of environmental distribution ratio of 

hypochlorous acid and sodium hypochlorite are both 0.0713% (estimated by EPI Suite TM). 

Therefore, hypochlorous acid and sodium hypochlorite are considered to have low sediment 

persistence. Consequently, the risk of exposure to benthic organism is considered low. 

2.2.5.2 Relevant chemicals 

(1) Monochloramine 

As the Log Pow value of monochloramine is –1.19 (estimated), which is smaller than the rough 

indication value for bioaccumulation potential of Log Pow=3, monochloramine is not considered 

to have high bioaccumulation potential. Therefore the possibility of accumulation to the higher 

level predator in the food web is low. 

The Koc value of monochloramine is 14.3l/kg (estimated by EPI Suite TM). Because Koc is 

smaller than 500l/kg, it is considered that soil adsorption potential of monochloramine is low. 

Also, environmental distribution ratio of monochloramine is calculated according 

Level III Fugacity model. The value of environmental distribution ratio monochloramine 

is e both 0.0679% (estimated by EPI Suite TM) . Therefore, monochloramine is considered to 

have low sediment persistence. Consequently, the risk of exposure to benthic organism is 

considered low. 

(2) Tribromomethane 

As the Log Pow value of tribromomethane is 2.4(observed), which is smaller than the rough 

indication value for bioaccumulation potential of Log Pow=3, tribromomethane is not considered 

to have high bioaccumulation potential. Therefore the possibility of accumulation to the higher 

level predator in the food web is low. 

The Koc value of tribromomethane is 218.8l/kg (observed, DiToro et al.(1991)). Because Koc is 

smaller than 500l/kg, it is considered that soil adsorption potential of tribromomethane is 

relatively low. 

Also, environmental distribution ratio of tribromomethane is calculated according Level III 

Fugacity model. The value of environmental distribution ratio tribromomethane is e 

both 0.0165% (estimated by EPI Suite TM). Therefore, tribromomethane is considered to have 

low sediment persistence. Consequently, the risk of exposure to benthic organism is 

considered low. 

(3) Dibromochloromethane 

As the Log Pow value of dibromochloromethane is 2.16 (observed), which is smaller than the 

rough indication value for bioaccumulation potential of Log Pow=3, dibromochloromethane is 

not considered to have high bioaccumulation potential. Therefore the possibility of accumulation 

to the higher-level predator in the food web is low. 
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The Koc value of dibromochloromethane is 84l/kg (ATSDR(2005)). Because Koc is smaller 

than 500l/kg, it is considered that soil adsorption potential of dibromochloromethane is 

relatively low. 

Also, environmental distribution ratio of dibromochloromethane is calculated according Level III 

Fugacity model. The value of environmental distribution ratio dibromochloromethane is e 

both 0.0149% (estimated by EPI Suite TM). Therefore, dibromochloromethane is considered to 

have low sediment persistence. Consequently, the risk of exposure to benthic organism is 

considered low. 

(4) 2,2-dibromoacetic acid 

As the Log Pow value of 2,2-dibromoacetic acid is 1.22 (estimated), which is smaller than the 

rough indication value for bioaccumulation potential of Log Pow=3, 2,2-dibromoacetic acid is 

not considered to have high bioaccumulation potential. Therefore the possibility of accumulation 

to the higher-level predator in the food web is low. 

The Koc value of 2,2-dibromoacetic acid is 1.90l/kg (estimated by EPI Suite TM). Because Koc is 

smaller than 500l/kg, it is considered that soil adsorption potential of 2,2-dibromoacetic acid is 

relatively low. 

Also, environmental distribution ratio of 2,2-dibromoacetic acid is calculated according Level III 

Fugacity model. The value of environmental distribution ratio 2,2-dibromoacetic acid is e 

both 0.0703% (estimated by EPI Suite TM). Therefore, 2,2-dibromoacetic acid is considered to 

have low sediment persistence. Consequently, the risk of exposure to benthic organism is 

considered low. 

(5) 2,2,2-tribromoacetic acid 

As the Log Pow value of 2,2,2-tribromoacetic acid is 2.07 (estimated), which is smaller than the 

rough indication value for bioaccumulation potential of Log Pow=3, 2,2,2-tribromoacetic acid is 

not considered to have high bioaccumulation potential. Therefore the possibility of accumulation 

to the higher-level predator in the food web is low. 

The Koc value of 2,2,2-tribromoacetic acid is 2.74l/kg (estimated by EPI Suite TM). Because Koc 

is smaller than 500l/kg, it is considered that soil adsorption potential of 2,2,2-tribromoacetic acid 

is relatively low. 

Also, environmental distribution ratio of 2,2,2-tribromoacetic acid is calculated according 

Level III Fugacity model. The value of environmental distribution ratio 2,2,2-tribromoacetic acid 

is e both 0.0715% (estimated by EPI Suite TM). Therefore, 2,2,2-tribromoacetic acid is considered 

to have low sediment persistence. Consequently, the risk of exposure to benthic organism is 

considered low. 
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2.2.6 Determination of PNEC 

2.2.6.1 Free active chlorine 

The sensibility value of Ceriodaphnia dubia (freshwater organism) was the highest 

(24h LC50=0.005 mg FAC/l) on valid short-term toxicity data of free active chlorine. However, 

the value is not adapted, because this ballast water treatment system designed for seawater. 

96h EC50=0.023mg TRC/l of mollusks is adapted, because the value is high next except that of 

Ceriodaphnia dubia. 

The sensibility value of microcosm (freshwater organism) was the 7d NOEC=0.0027 mg TRC/l 

on valid long-term toxicity data of free active chlorine. However, the value is not adapted, 

because this ballast water treatment system designed for seawater. 15d NOEC=0.007 mg TRO/l 

of mollusks is adapted, because the value is clearly higher than that of fish 

(28d NOEC=0.04mgCPO/L). 

Because there is no valid long-term toxicity data of marine algae, Assessment Factor is 

considered 100 on the determination of PNEC of free active chlorine in seawater. Therefore, 

PNEC is calculated using valid long-term toxicity data of mollusks. The value of PNEC 

is 0.007 mg TRO/l/100 = 0.07цg TRO/l. 

When the concentration of free active chlorine in the discharged ballast water is in the range 

of 0.1-3.0mg TRC/l (paragraph 3.1), it is considered that free active chlorine in the discharged 

ballast water has acute aquatic toxicity. 

2.2.6.2 Relevant chemicals 

(1) Monochloramine 

Only an acute toxicity data of fish (96h LC50 = 0.079-0.083mg/l) was reported as valid toxicity 

data of monochloramine. Monochloramine is less sensibility than free active chlorine 

(96h EC50=0.023mg TRC/l). Therefore, even if the toxicity of Active Substance is evaluated 

using TRC or TRO, there is no significant influence of toxicity of monochloramine. Then, it is 

considered that the result of evaluation is almost about free active chlorine. 

(2) Tribromomethane 

The value of 96h LC50=7.1mg/l of fish is the most highest value of sensibility of 

tribromomethane. Then, it is adapted as valid short-term toxicity data of tribromomethane in 

seawater. 

The valid data using fish, crustaceans and algae are reported, and 96h NOEC=2.9mg/l that is 

acute toxicity data of fish is adopted for determination of PNEC. Assessment factor should be 

100 due to applying the valid acute toxicity data to the NOEC, but 10 was applied to the 

assessment factor. Because the acute toxicity data was lower than the chronic toxicity data. 

PNEC of tribromomethane was NOEC/10 = 0.29mg/l. 

When the concentration of tribromomethane in the discharged ballast water is 0.16mg/l 

(see paragraph 2.1.3.2, table3), it is considered that tribromomethane in the discharged ballast 

water has no acute aquatic toxicity. 
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(3) Dibromochloromethane 

PNEC of dibromochloromethane could not be determined, because there is no report on toxicity 

data of marine organism. 

(4) 2,2-dibromoacetic acid 

PNEC of 2,2-dibromoacetic acid could not be determined, because there is no report on toxicity 

data of marine organism. 

(5) 2,2,2-tribromoacetic acid 

PNEC of 2,2,2-tribromoacetic acid could not be determined, because there is no report on 

toxicity data of marine organism. 

2.3 Mammalian toxicity (G9:4.2.1.2) 

2.3.1 Acute toxicity 

2.3.1.1 Free active chlorine 

WHO has reported the oral LD50 for calcium hypochlorite in rats as 850 mg/kg (WHO (2003)). 

2.3.1.2 Relevant chemicals 

(1) Monochloramine 

Abdel-Rahman, M.S. et al. carried out a gavage test in Sprague-Dawley rats and reports that at a 

dosage of 0.18-0.8 mg/kg, elevation of blood glutathione level was observed 15 to 30 minutes 

after the administration, but it returned to normal level after more than 120 minutes. No effect 

was found in a blood osmotic fragility test (Abdel-Rahman, M.S. et al. (1984)). 

(2) Tribromomethane 

Tribromomethane is known to have the lowest oral acute toxicity among trihalomethanes. The 

oral LD50 for tribromomethane in ICR Swiss mice (both sexes) was reported as 1400-1550 mg/kg 

(Bowman, F.J. et al. (1978)) and that in Sprague-Dawley rats (both sexes) as 1147-1338 mg/kg 

(Chu, I. et al. (1980)). 

(3) Dibromochloromethane 

The oral LD50 in ICR Swiss mice is reported as 800-1200 mg/kg (Bowman, F.J. et al. (1978)) 

and that in Sprague-Dawley rats as 848-1186 mg/kg (Chu, I. et al. (1980)). 

(4) 2,2-dibromoacetic acid 

The oral LD50 in Sprague-Dawley rats is reported as 1737 mg/kg (Linder et al. (1994a)). 
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(5) 2,2,2-tribromoacetic acid 

No report is available concerning acute toxicity of 2,2,2-tribromoacetic acid. 

2.3.2 Effects on skin and eye 

2.3.2.1 Free active chlorine

Loden carried out skin irritation tests on sodium hypochlorite (2, 20, 35, 50% solutions) in 

rabbits in accordance with OECD Guideline 404, and reports of irritation index 1.2 with 

the 2% solution and irritation index 5.2-5.3 with the 20, 35 and 50% solutions (IUCLID (2000)). 

Pashley conducted eye irritation tests on sodium hypochlorite (0.005%, 0.052%, 0.525%. 5.25% 

solutions) in New Zealand white rabbits (8 rabbits of assorted sexes). The 5.25% solution 

showed an irritating effect, which were not healed in 7 days. Effect was observed with 

the 0.525% solution until after 2 and 6 hours. No effect was observed with the 0.052% 

and 0.005% solutions (Pashley (1985)). 

No effect was found in the skin sensitization test with mixture of 5.65% NaClO solution and 

water (50/50 mixture) against guinea pigs (IUCLID(2000)). 

2.3.2.2 Relevant chemicals 

(1) Monochloramine 

Monochloramine showed an irritating effect on the respiratory system (HSDS (2006)). 

(2) Tribromomethane 

Tribromomethane is known to have moderate irritating effects on respiratory organ, skin and eye. 

It is reported that an eye drop test with non-dilution solution and a repeated skin contact test in 

rabbits showed moderate irritation, which, however, were healed after one to two days 

(Torkelson, T.R. et al. (1994)). 

According to ACGIH, the time weighted average (TWA) concentration for skin is 0.5 mg/l. 

No report is available concerning human inhalation toxicity of tribromomethane. Dogs exposed 

to ≥7000 ppm became deeply anesthetized after 8 minutes and died after a 1-hour exposure 

(RAIS, (2006)). 

(3) Dibromochloromethane 

Dibromochloromethane is known to have irritating effects on respiratory organ, skin and eye. No 

report is available concerning human inhalation toxicity of dibromochloromethane. 

(4) 2,2-dibromoacetic acid 

As 2,2-dibromoacetic acid is a strong acid, unneutralized solution may causes serious burn to 

akin and eye. 
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(5) 2,2,2-tribromoacetic acid 

As 2,2,2-tribromoacetic acid is a strong acid, unneutralized solution may causes serious burn to 

akin and eye. 

2.3.3 Repeated-dose toxicity 

2.3.3.1 Free active chlorine 

As a result of 90-day administration of free active chlorine (0-250 mg/l) through drinking water 

to Sprague-Dawley rats, no consistent change in organ weight or tissues was observed. The “no 

observed adverse effect level (NOAEL)” was determined as 250 mg/l (16.7-24.9 mg/kg/d) 

(Daniel, F.B. et al. (1990a)). 

In a 90-day administration test (0-200 mg/l) through drinking water to B6CF3F1 mice, decrease 

of the weight of pancreas and liver was observed in 100 and 200 mg/l-administered groups of 

male mice. With female mice, increase of heart weight was observed in 200 mg/l-administered 

group. The NOAEL was determined as 50 mg/l (10-12 mg/kg/d) (Daniel, F.B. et al. (1991)). 

2.3.3.2 Relevant chemicals 

(1) Monochloramine 

As a result of 90-day administration (0-200 mg/l) of monochloramine through drinking water to 

Sprague-Dawley rats, decrease of water intake at all dose levels and decrease of feed intake in 

male rats at 200mg/l dose were observed. However, as remarkable decrease in body weight gain 

was observed only in 200 mg/l-administered group and for other reasons, the NOAEL was 

determined as 100mg/l (5.8-7.7 mg/kg/d) (Daniel, F.B. et al. (1990a)). 

In a 90-day administration test (0-200 mg/l) through drinking water to B6CF3F1 mice, decrease 

of feed intake was observed in both sexes (particularly female) at 200mg/l dose. Likewise, water 

intake decreased in both male and female mice at all dose levels, with the effect on female mice 

being bigger. Decrease in body weight gain was observed in both sexes at 200mg/l dose. The 

NOAEL was determined as 50 mg/l (8.6-9.2 mg/kg/d) (Daniel, F.B. et al. (1991)). 

(2) Tribromomethane 

As a result of 13-week gavage tests on corn oil including tribromomethane using F344/N rats and 

B6CF3F1 mice, hepatocyte vacuolation was observed only in male rats administered with 

50 mg/kg/d or more and in male mice administered with 200 and 400 mg/kg/d. This 

phenomenon was not observed in female rats and female mice. In this study, the NOAEL for rat 

was computed as 25 mg/kg/d and that for mice as 100 mg/kg/d (NTP (1989)). 

(3) Dibromochloromethane 

As a result of a 90-day gavage test on corn oil including Dibromochloromethane (0-200 mg/kg/d) 

using Sprague-Dawley rats, decrease in body weight gain was observed at 200mg/kg/d dose. 

The NOAEL for gavage of dbromochloromethane was determined as 50 mg/kg/d (Daniel, 

F.B. et al. (1990b)). 
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(4) 2,2-dibromoacetic acid 

In a 28-day administration test in mice (B6CF3F1 mice) through drinking water, the NOAEL is 

computed as 38 mg/kg/d (WHO (2004)). 

In a 3-month administration test in mice (B6CF3F1 mice) through drinking water (0-2,000 mg/l), 

all the mice survived until the end of the test period. However, decrease in body weight gain and 

that in water intake were observed in 1,000 and 2,000 mg/l-administered groups. In groups 

administered with 500 mg/l or more, substantial increase of liver weight was found in both 

sexes (NTP (2005)). 

Likewise, in a 3-month administration test in rats (F344/N rats) through drinking water, decrease 

in body weight gain, decrease in water intake and substantial increase of liver weight were found 

(NTP (2005)). 

(5) 2,2,2-tribromoacetic acid 

No report is available on a repeated dose test on 2,2,2-tribromoacetic acid. 

2.3.4 Chronic toxicity 

2.3.4.1 Free active chlorine 

A test was carried out in which drinking water treated with sodium hypochlorite was 

administered to F344 rats for 2 years. To male rats, 0, 4.2, 7.3 or 13.6 mg/kg/d was administered 

and to female rats, 0, 4.2, 7.8 or 14.4 mg/kg/d was administered. Water intake decreased 

depending upon the dosage. No effect was observed on body weight and survival rate. Also, no 

significant effect was observed on carcinogenicity (NTP (1992)). 

In a test using B6C3F1 mice, 0, 7.3, 14.0 or 23.8 mg/kg/d was administered to male mice 

and 0, 7.6, 14.2 or24.2 mg/kg/d was administered to female mice for 2 years. Water intake 

decreased depending upon the dosage. No effect was observed on body weight and survival rate. 

Also, no effect was observed on carcinogenicity (NTP (1992)). 

From the above, the NOAEL was determined as 14.4 mg/kg/d. 

2.3.4.2 Relevant chemicals 

(1) Monochloramine 

A test was carried out in which drinking water treated with chloramine was administered to F344 

rats for 2 years. To male rats was administered 0, 2.1, 4.8 or 8.7 mg/kg/d and to female rats, 

0, 2.8, 5.3 or 9.5 mg/kg/d was administered. Although decrease in water and feed intake and a 

slight decrease in body weight were observed, no clinical change was found at the end of the test 

(NTP (1992)). 

In a test using B6C3F1 mice, 0, 5.0, 8.9 or 15.9 mg/kg/d was administered to male mice, and 

0, 4.9, 9.0 or 17.2 mg/kg/d to female mice for 2 years. Although decrease in water and feed 

intake, and body weight decrease were observed, there was no change in the survival rate. As a 

result of histopathological examination, no clinical effect was found (NTP (1992)). 
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(2) Tribromomethane 

Drinking water to which tribromomethane was added was administered to male F344 rats and 

B6C3F1 mice for one year and clinical indicators of kidney toxicity was examined. The dose 

level of tribromomethane was 6.2, 29 or 57 mg/kg/d for rats and 8.3, 39 or 73 mg/kg/d for mice. 

Increase in clinical indicators relating to tubular and glomerular injuries was shown in mice of all 

the treatment level. Urine N-acetyl-β-glucosamidase increased at 39 and 78mg/kg/d dose. As in 

mice, urinary protein increased in rats of all the test groups. However, no evidence showing loss 

of tubular function has been obtained. Urine aspartate-transaminase increased at 29 and 

57 mg/kg/d dose. NOEC is not reported. (Moore, T.C. et al. (1994)). 

(3) Dibromochloromethane 

Gavage tests on corn oil including dibromochloromethane were carried out in F344/N rats and 

B6C3F1 mice. Liver lesions were observed in all the test groups of rats (0, 40, 80 mg/kg/d) and 

mice (0, 50, 100 mg/kg/d). Hepatic focal necrosis and liver calcification were observed at 

100mg/kg/d, and in female mice, fatty changes were observed in all dose levels. NOEC is not 

reported (NTP (1985)). 

(4) 2,2-dibromoacetic acid 

In a 2-year administration test (0-1,000 mg/l) in B6CF3F1 mice through drinking water, increase 

in body weight gain was observed at the dosages of 50 mg/l and 500 mg/l in male mice. 

However, no difference was found between control groups in female mice (NTP (2005)). 

In the case of a 2-year administration test in F344/N rats through drinking water, survival rate of 

test groups at the end of the test period showed no difference between control groups. Decrease 

in body weight gain was observed at the dosage of 500 or 1,000 mg/l, whereas water intake 

decreased at the dosage of 1,000 mg/l (NTP (2005)). 

(5) 2,2,2-tribromoacetic acid 

No report relating to chronic toxicity of 2,2,2-tribromoacetic acid is available. 

2.3.5 Developmental and reproductive toxicity 

2.3.5.1 Free active chlorine 

No information relating to the results of tests carried out in accordance with OECD 414 or 416 is 

available. 

A reproductive toxicity test was carried out in which drinking water subjected to chlorine 

treatment with sodium hypochlorite (100 mg FAC/l) was administered by drinking to BDII rats 

over 7 generations. No effect on fertilizing ability was observed (Druckrey (1968)). 

Reproductive toxicity tests were carried out in which drinking water subjected to chlorine 

treatment with sodium hypochlorite (10 mg TRC/l) was administered by drinking to C3H/BL 

mice and C57BL/6J mice for 6 months. No effect on reproduction was observed (Les (1968)). 
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2.3.5.2 Relevant chemicals 

(1) Monochloramine 

A reproductive toxicity (fertility) test was carried out in which chloramine-treated water 

(0-10 mg/kg/d) was administered by gavage to Long-Evans rats for 66 to76 days (including 

breeding period). No change was observed in fertility, viability, litter size and day of eye 

opening. Furthermore, no effect on sperm count, direct progressive sperm movement, percent 

sperm mobility and sperm morphologic characteristics was observed. The NOAEL was estimated 

as 10 mg/kg/d in this study (Carlton, B. et al. (1986)). 

(2) Tribromomethane 

According to the report of Ruddick, J.A. et al., fetotoxicity was observed in Sprague-Dawley rats 

administered with 50-200 mg/kg of tribromomethane by gavage, but no fetal malformation was 

observed (Ruddick J.A. et al. (1983)). 

In a 105-day gavage test in Swiss CD-1 mice, no effect was observed on fertility, litters per pair, 

live pups per litter, sex of live pups and pup body weights (WHO (2000)). 

(3) Dibromochloromethane 

A water drinking test on dibromochloromethane (0, 0.1, 1.0, 4.0 mg/l) added water was carried 

out in ICR Swiss mice over 2 generations. In high dose level (4.0mg/L) of the F1 generation, 

decrease in fertility and gestational index were observed, whereas in the F2 generation, reduction 

in fertility was only observed in highly dose level (4.0mg/L). In moderately dose level (1.0mg/L) 

and highly dose level (4.0mg/L) of the F1 and F2 generations, decrease of litter size and that of 

viability index were shown. Neither dominant lethal nor teratogenic effects were observed in 

both generations (WHO (2000)). 

(4) 2,2-dibromoacetic acid 

A 9-day or 20-day gavage test on 2,2-dibromoacetic acid (0, 62. 5, 125, 250 mg/kg/d) in 

Holtzman rats was carried out, and E2 was increased remarkably in 250 mg/kg/d-administered 

groups. The NOAEL was estimated as 125 mg/kg/d in this study (Cummings et al. (1998)). 

(5) 2,2,2-tribromoacetic acid 

No report relating to developmental and reproductive toxicity of 2,2,2-tribromoacetic acid is 

available. 

2.3.6 Carcinogenicity 

2.3.6.1 Free active chlorine 

A test in which drinking water subjected to chlorine treatment with sodium hypochlorite was 

administered by water drinking to F344 rats for 104 weeks was carried out. To male rats was 

administered 0, 4.2, 7.3 or 13.6 mg/kg/d and to female rats, 0, 4.2, 7.8 or 14.4 mg/kg/d was 

administered. No carcinogenicity was shown in male rats. In female rats, mononuclear leukemia 

slightly increased in 7.8 and 14.4 mg/kg/d groups. However, it was considered that this could not 

be regarded as the evidence of carcinogenicity (NTP (1992)). 
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In a test using B6C3F1 mice, as a result of administering 0, 7.3, 14.0 or 23.8 mg/kg/d to male 

mice, and 0, 7.6, 14.2 or 24.2 mg/kg/d to female mice for 104 weeks, no carcinogenicity was 

observed (NTP (1992)). 

According to the carcinogenicity assessment of International Agency for Research on Cancer 

(IARC), sodium hypochlorite is classified as Group 3 (not classifiable as to carcinogenicity to 

humans) (IRIS). 

2.3.6.2 Relevant chemicals 

(1) Monochloramine 

As no data showing carcinogenicity of monochloramine to humans is available, monochloramine 

is classified with Group 3 (not classifiable as to carcinogenicity to humans) according to the 

carcinogenicity assessment of IARC and Group D (not classifiable as to human carcinogenicity) 

by U.S. Environmental Protection Agency (U.S. EPA). 

(2) Tribromomethane 

IARC assessed carcinogenicity of tribromomethane and concluded that only insufficient evidence 

is available as to the carcinogenicity to humans and that the evidence is limited regarding the 

carcinogenicity to experimental animals. As a result, tribromomethane was classified as Group 3 

(not classifiable as to carcinogenicity to humans) (IARC (1991, 1999)). 

U.S. EPA classifies tribromomethane as Group B2 (probable human carcinogen) (IRIS). 

(3) Dibromochloromethane 

IARC assessed carcinogenicity of dibromochloromethane and concluded that only insufficient 

evidence is available as to the carcinogenicity to humans and that the evidence is limited 

regarding the carcinogenicity to experimental animals. As a result, dibromochloromethane was 

classified as Group 3 (not classifiable as to carcinogenicity to humans) (IARC (1991, 1999)). 

U.S. EPA classifies this compound as Group C (probable human carcinogen) (IRIS). 

(4) 2,2-dibromoacetic acid 

In a 2-year administration test (0-1,000 mg/l) through drinking water in B6CF3F1 mice, 

incidence of liver neoplasms increased in both sexes at all dose levels and that of multiple 

hepatocellular adenoma, hepatocellular adenoma or cancer remarkably increased in male of all 

the administration groups and female of 500 mg/l and 1,000 mg/l-administered groups 

(NTP (2005)). 

In the case of a 2-year administration test through drinking water in F344/N rats, incidence of 

malignant mesothelioma considerably increased in male mice of 1,000 mg/l-administered group. 

Incidence of mononuclear cell leukemia was elevated in female mice and particularly, high 

incidence was shown in female mice of 1,000 mg/l-administered group (NTP (2005)). 

2,2-Dibromoacetic acid is not included in the substances subject of carcinogenicity assessment 

by IARC. 
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(5) 2,2,2-tribromoacetic acid 

No report on carcinogenicity of 2,2,2-tribromoacetic acid is available. This compound is not 

included in the substances subject of carcinogenicity assessment by IARC. 

2.3.7 Mutagenicity/genotoxicity 

2.3.7.1 Free active chlorine 

Sodium hypochlorite showed mutagenicity in Salmonella tymphimurium TA100 (in vitro) in the 

presence of a metabolic activation system (S9mix) (Ishidate (1984)). 

A cytogenetic assay carried out in human embryo stem cell (in vitro) showed mutagenicity 

(Sasaki (1980)). 

A micronucleus assay was carried out in male ddY mice (in vivo), but mutagenicity was not 

observed (Hayashi (1988)). 

A chromosomal aberration test was carried out in CD-1 Swiss mice (in vivo), but mutagenicity 

was not observed (Meier et al. (1985)). 

2.3.7.2 Relevant chemicals 

(1) Monochloramine 

In a reverse mutation test using Salmonella tymphimurium, slight increase of reverse mutation is 

reported (Thomas,E.L. et al. (1987)). However, in a test using mice (CD-1 mice), mutagenicity 

was not shown (Meier, J.R. et al. (1985)). 

(2) Tribromomethane 

As regards the mutagenicity of tribromomethane, there are reports with different results and 

conclusion is yet to be made. In reverse mutation tests using Salmonella tymphimurium, some 

reports conclude that tribromomethane has mutagenicity (Simmon ,V.F. et al. (1978) and 

Simmon V.F. (1977)), and others show that the compound has no effect on mutagenicity 

(NTP (1989a), Rapson W.H.8 (1980), Varma M.M. (1988)). 

Likewise, concerning mutagenicity tests in mammals, there are two kinds of report, one showed 

that the compound has mutagenicity (Morimoto, K. (1983), Fujie, K. (1993)) and the other report 

showed that it has no effect thereon (Galloways, S.M. et al. (1985)). 

(3) Dibromochloromethane 

As regards the mutagenicity of dibromochloromethane in bacteria, there are reports with different 

results as in the case of tribromomethane. In reverse mutation tests using Salmonella

tymphimurium, some reports showed that the compound has mutagenicity (Simmon, V.F. et al.

(1978), Simmon V.F. (1977), Varma M.M. (1988)) and others showed that it has no effect 

thereon (NTP (1985), Zeiger, E. et al. (1987)). 
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On the other hand, many reports show the results that dibromochloromethane has carcinogenicity 

in mammals such as human lymphocytes (Morimoto, K. et al. (1983)), rat erythroblastic 

leukemia K3D cells (Fujie, K (1993)), etc. 

(4) 2,2-dibromoacetic acid 

As a result of a reverse mutation test using Salmonella tymphimurium TA100, mutagenicity was 

observed in the range of 10-3,000 mg/l (Giller, et al. (1997)). Although NTP reported 

mutagenicity of 2,2-dibromoacetic acid as a result of a reverse mutation test using Salmonella

tymphimurium TA100, no mutagenicity was observed in the test using Salmonella tymphimurium

TA98 (NTP (2005)). 

(5) 2,2,2-tribromoacetic acid 

As a result of a reverse mutation test using Salmonella tymphimurium, mutagenicity was 

observed in the range of 2,000-10,000 mg/l (Giller, et al. (1997)). 

2.4 Data on environmental fate and effect under aerobic and anaerobic conditions 

(G9: 4.2.1.3) 

2.4.1 Modes of degradation (biotic; abiotic) 

2.4.1.1 Free active chlorine 

Gaseous chlorine (generated on the anodal surface of an electrolysis vessel) rapidly hydrolyzes in 

water with a pH more than 5 and forms hypochlorous acid as shown in Equation (10). Hydrolytic 

constant of Equation (10) are 1.5 x 10-4 (mol/l)2

 (0°C) and 4.0 x 10-4 (mol/l)2 (25°C). More than 

99% in terms of a formula weight concentration of chlorine of 10-3mol/l in pure water is 

hydrolyzed (Morris (1978)). 

 Cl2 + H2O ↔ HClO + H+ + Cl-

 (10) 

On the other hand, hypochlorous acid is an oxidizer, a disinfectant and primarily an inorganic 

substance. Therefore, it is said that it is not proper to discuss its biodegradability (IUCLID 

(2000)). 

Taylor measured decay rate of hypochlorous acid and hypochlorite ion in the acute aquatic 

toxicity test. The decay rate ware reported as follows; the half life at pH 7.0 (main formula is 

HClO) is about 0.8hour and the half life at pH 8.0 (main formula is ClO-

) is about 1.4 hour 

(Taylor et al. (1993)). 

2.4.1.2 Relevant chemicals 

(1) Monochloramine 

Decomposition rate of monochloramine in water is slow and it is relatively a stable compound 

(Rice, R.G. et al. (1986)). The half-life of monochloramine by hydrolysis is reported as 10 hours 

(Margerum et al., (1978)). 

No report on biodegradation of monochloramine is available. 
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(2) Tribromomethane 

The rate constant of hydrolysis for tribromomethane is estimated as 3.2x10-11/sec (Mabey, W. 

et al. (1978)), and this is a stable compound in water (estimated half life is 686 years). 

In the long-term risk assessment of the treated ballast water discharges (section 5.3), the 

behaviors of tribromomethane concentration in natural seawater were considered for degradation 

rate that is k = 0.00978 (day-1) = 0.693/t1/2 (decay) set in the database of CHEMMAP (Science 

and technology Co., Ltd. and Asia-Pacific Applied Science Associates (2006), Appendix B). 

Tribromomethane is considered a volatile compound. According to trial calculation, the half-life 

of tribromomethane is 1h (riffle)-581 h (pool) (Kaczmar, S.W. et al. (1984). 

The rate constant for the vapor-phase reaction of tribromomethane with 

photochemically-produced hydroxyl radicals has been estimated as 4.94x10-14 cm3/molecule-sec 

at 25 °C using a structure estimation method. This corresponds to an atmospheric half life of 

about 325 days at an atmospheric concentration of 5x105

 hydroxyl radicals per cu cm. 

(HSDB,(2006)) 

Although aerobic biodegradation of tribromomethane is limitative, it is reported that 

tribromomethane is easily degraded anaerobically, for example, by methanogenic bacteria or 

denitrifying bacteria. In denitrifying condition, 60 ug/l of tribromomethane was degraded to 59, 

37, 35, and 2 ug/l after 2, 3, 4, and 6 weeks, respectively (HSDB (2006)). Through field 

investigation, the half-life of trihalomethane by anaerobic degradation is estimated as 21-42 days. 

(3) Dibromochloromethane 

The rate constant of hydrolysis for dibromochloromethane is estimated as 8.0x10-11/sec (Mabey, 

W. et al. (1978)), and dibromochloromethane is a stable compound in water (estimated half life 

is 274 year). 

However, dibromochloromethane is considered a volatile compound. According to trial 

calculation, the half-life of dibromochloromethane is 0.7h (riffle)-398 h (pool) (Kaczmar, S.W. 

et al. (1984). 

The rate constant for the vapor-phase reaction of chlorodibromomethane with 

photochemically-produced hydroxyl radicals has been estimated as 5.8x10-14 cm3/molecule-sec at 

25 °C using a structure estimation method. This corresponds to an atmospheric half life of about 

280 days at an atmospheric concentration of 5x105 hydroxyl radicals per cm3. (HSDB,(2006)) 

Same as tribromomethane, this compound hardly undergoes aerobic biodegradation but is easily 

biodegraded anaerobically. In an anaerobically experiment with methanogenic mixed culture, 

initial concentration of 19, 25 and 205 ug/l of dibromochloromethane were degraded to less than 

detection limit after 2 weeks incubation (Bouwer, E.J. et al. (1981)). 

(4) 2,2-dibromoacetic acid 

Haloacid dehalogenase (EC3.8.1.3) has been found in many kind of bacteria such as Alcaligenes

sp., Arthrobacter sp., Moraxella sp., Pseudomonas sp. or Xanthobacter sp., which are widely 

distributed in environment (soil, inland water, seawater). The enzymes degrade halogen (Cl or 
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Br or F)-substituted short-chain fatty acid (IUBMB (2006)). After 10 days aerobic cultivation 

of Xanthobacter authotrophicus GJ10, 2,2-dibromoacetic acid was degraded and released 

8.8mM bromine ion from initial concentration of 5mM of 2,2-dibromoacetic acid. (Janssen, 

D.B. et al. (1985)). 

(5) 2,2,2-tribromoacetic acid 

Like 2,2,2-dibromoacetic acid, 2,2,2-tribromoacetic acid is degraded by haloacid dehalogenase 

(EC3.8.1.3). An enzyme activities assay of haloacid dehalogenase, whish purified from 

Rhizobium sp., was carried out in Tris buffer (pH7.5). It is reported that the catalytic efficiency 

(=Kcat/Km) of 2,2,2-tribromoacetic acid was 0.64 x 104 /M/sec, this value is lower than that of 

2,2-dibromoacetic acid (1.64 x 104

 /M/sec)(Huyop, F.Z. (2004)). 

2.4.2 Bioaccumulation, partition coefficient 

2.4.2.1 Free active chlorine

As the calculated Log Pow value of hypochlorous acid is -0.87 (that of sodium hypochlorite 

is -3.42), which is smaller than the rough indication value for bioaccumulation potential of Log 

Pow=3, free active chlorine is not considered to have high bioaccumulation potential. Therefore 

the possibility of accumulation to the higher-level predator in the food web is low. 

Also, the Koc value of hypochlorous acid is 14.3l/kg (estimated by EPI Suite TM) (that of sodium 

hypochlorite is 14.3(estimated by EPI Suite TM)). Because Koc is smaller than 500l/kg, it is 

considered that soil adsorption potential of free active chlorine is low. Therefore, free active 

chlorine is considered to have low sediment toxicity. 

2.4.2.2 Relevant chemicals 

(1) Monochloramine 

As the calculated Log Pow value of monochloramine is –1.19, which is smaller than the rough 

indication value for bioaccumulation potential of Log Pow=3, monochloramine is not considered 

to have high bioaccumulation potential. Therefore the possibility of accumulation to the 

higher-level predator in the food web is low. 

Also, the Koc value of monochloramine is 14.3l/kg (estimated by EPI Suite TM). Because Koc is 

smaller than 500l/kg, it is considered that soil adsorption potential of monochloramine is low. 

Therefore, free active chlorine is considered to have low sediment toxicity. 

(2) Tribromomethane 

As the Log Pow value of tribromomethane is 2.4(observed), which is smaller than the rough 

indication value for bioaccumulation potential of Log Pow=3, tribromomethane is not considered 

to have high bioaccumulation potential. Therefore the possibility of accumulation to the 

higher-level predator in the food web is low. 

Also, the Koc value of tribromomethane is 218.8l/kg (observed, DiToro et al. (1991)). Because 

Koc is smaller than 500l/kg, it is considered that soil adsorption potential of tribromomethane is 

relatively low. Therefore, free active chlorine is considered to have low sediment toxicity. 
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(3) Dibromochloromethane 

As the Log Pow value of dibromochloromethane is 2.16 (observed), which is smaller than the 

rough indication value for bioaccumulation potential of Log Pow=3, dibromochloromethane is 

not considered to have high bioaccumulation potential. Therefore the possibility of accumulation 

to the higher-level predator in the food web is low. 

Also, the Koc value of dibromochloromethane is 84l/kg (ATSDR (2005)). Because Koc is 

smaller than 500l/kg, it is considered that soil adsorption potential of dibromochloromethane is 

relatively low. Therefore, free active chlorine is considered to have low sediment toxicity. 

(4) 2,2-dibromoacetic acid 

As the calculated Log Pow value of 2,2-dibromoacetic acid is 1.22, which is smaller than the 

rough indication value for bioaccumulation potential of Log Pow=3, 2,2-dibromoacetic acid is 

not considered to have high bioaccumulation potential. Therefore the possibility of accumulation 

to the higher-level predator in the food web is low. 

Also, the Koc value of 2,2-dibromoacetic acid is 1.90l/kg (estimated by EPI Suite TM). Because 

Koc is smaller than 500l/kg, it is considered that soil adsorption potential of 2,2-dibromoacetic 

acid is relatively low. Therefore, free active chlorine is considered to have low sediment toxicity. 

(5) 2,2,2-tribromoacetic acid 

As the calculated Log Pow value of 2,2,2-tribromoacetic acid is 2.07, which is smaller than the 

rough indication value for bioaccumulation potential of Log Pow=3, 2,2,2-tribromoacetic acid is 

not considered to have high bioaccumulation potential. Therefore the possibility of accumulation 

to the higher-level predator in the food web is low. 

Also, the Koc value of 2,2,2-tribromoacetic acid is 2.74l/kg (estimated by EPI Suite TM). Because 

Koc is smaller than 500l/kg, it is considered that soil adsorption potential of 2,2,2-tribromoacetic 

acid is relatively low. Therefore, free active chlorine is considered to have low sediment toxicity. 

2.4.3 Main metabolites 

2.4.3.1 Free active chlorine 

 

The metabolites of free active chlorine are H+

, Cland O2, and no persistent substance is formed. 

2.4.3.2 Relevant chemicals 

(1) Monochloramine 

The metabolites of monochloramine are H+, Cl-, NH3 and N2, and no persistent substance is 

formed. 

(2) Tribromomethane 

The metabolites of tribromomethane are H+

, Br- and CO2, and no persistent substance is formed. 
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(3) Dibromochloromethane 

The metabolites of monochloramine are H+

, Br-, Cl- and CO2, and no persistent substance is 

formed. 

(4) 2,2-dibromoacetic acid 

The metabolites of 2,2-dibromoacetic acid are H+

, Br-, CH3COOH and CO2, and no persistent 

substance is formed. 

(5) 2,2,2-tribromoacetic acid 

The metabolites of 2,2,2-triibromoacetic acid are H+, Br-, CH3COOH and CO2, and no persistent 

substance is formed. 

2.4.4 Reaction with organic matter 

2.4.4.1 Free active chlorine 

It is known that when free active chlorine reacts with organic matters in water, DBPs such as 

trihalomethane and halogenated acetic acids are formed. In this application, 4 substances 

(tribromomethane, dibromochloromethane, 2,2-dibromoacetic acid and 2,2,2-tribromoacetic 

acid) detected by preliminary experiments are designated as by-products from the ballast water 

management system. As to by-products resulted from disinfection of drinking water by chlorine, 

presence of various substances has been reported due to concern about the influence on the health 

of humans. However, most of the DBPs in drinking water are present in a very small amount. 

Moreover, presence of non-identified compounds may be possible. Thus, there have been 

obtained no sufficient data on the toxicity and the amount of formation of all the DBPs 

(see paragraph 2.1.3.2). 

2.4.4.2 Relevant chemicals 

(1) Monochloramine 

Trihalomethanes are formed by the reaction of monochloramine with an organic matter, but the 

amount of formation is very small compared with that formed by the reaction of hypochlorous 

acid. Rick Baugh, J.F. et al. carried out a test using the water of the Ohio River. As a result, the 

amount of trihalomethanes formed by monochloramine treatment is reduced by 90.7 to 99.9% 

compared with the case where the water is treated with the same amount of chlorine 

(Rickabaugh, J.F. et al. (1978)). 

(2) Tribromomethane 

No reports on the reaction of tribromomethane with organic matters are available. 

(3) Dibromochloromethane 

No reports on the reaction of dibromochloromethane with organic matters are available. 
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(4) 2,2-dibromoacetic acid 

No reports on the reaction of 2,2-dibromoacetic acid with organic matters are available. 

(5) 2,2,2-tribromoacetic acid 

No reports on the reaction of 2,2,2-tribromoacetic acid with organic matters are available. 

2.4.5 Potential physical effects on wildlife and benthic habitats 

2.4.5.1 Free active chlorine

Free active chlorine is highly soluble in water (IUCLID (2000)) and does not have a property of 

floating on the surface or sedimenting to the bottom. So, the compound is not the subject of 

evaluation of potential physical effects on wildlife and benthic habitants under GESAMP hazard 

evaluation (GESAMP (2002)). 

2.4.5.2 Relevant chemicals 

(1) Monochloramine 

Monochloramine is highly soluble in water and does not have a property of floating on the 

surface or sedimenting to the bottom. So, the compound is not the subject of evaluation of 

potential physical effects on wildlife and benthic habitants under GESAMP hazard evaluation 

(GESAMP (2002)). 

(2) Tribromomethane 

Tribromomethane has a higher specific gravity than seawater (2.899 (20°C)) and a low solubility 

(3.1g/l (20°C)). Therefore, according to evaluation based on GESAMP hazard evaluation 

(GESAMP (2002)), the compound is classified as Rating S (substances having a potential effect 

on benthic habitats). 

(3) Dibromochloromethane 

Dibromochloromethane has a higher specific gravity than seawater (2.451 (20°C)) and a low 

solubility (2.7g/l (20°C)). Therefore, according to evaluation based on GESAMP hazard 

evaluation (GESAMP (2002)), the compound is classified as Rating S (substances having a 

potential effect on benthic habitats). 

(4) 2,2-dibromoacetic acid 

2,2-dibromoacetic acid is highly soluble in water (2100g/l) and does not have a property of 

floating on the surface or sedimenting to the bottom. So, the compound is not the subject of 

evaluation of potential physical effects on wildlife and benthic habitants under GESAMP hazard 

evaluation (GESAMP (2002)). 
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(5) 2,2,2-tribromoacetic acid 

2,2,2-tribromoacetic acid is highly soluble in water (2000g/l) and does not have a property of 

floating on the surface or sedimenting to the bottom. So, the compound is not the subject of 

evaluation of potential physical effects on wildlife and benthic habitants under GESAMP hazard 

evaluation (GESAMP (2002)). 

2.4.6 Potential residuals in seafood 

2.4.6.1 Free active chlorine 

No report concerning persistence of free active chlorine in seafood is available. As free active 

chlorine is considered to have low bioaccumulation potential, its persistence in seafood is 

speculated to be low. 

2.4.6.2 Relevant chemicals 

(1) Monochloramine 

No report concerning persistence of monochloramine in seafood is available. As 

monochloramine is considered to have low bioaccumulation potential, its persistence in seafood 

is speculated to be low. 

(2) Tribromomethane 

As tribromomethane is considered to have low bioaccumulation potential, its persistence in 

seafood is speculated to be low. According to the report of Gotoh, M. et al. (1992), 

tribromomethane was not detected in oysters, clam and the sediment of the Ariho River and the 

Yoshinaga River. 

(3) Dibromochloromethane 

As dibromochloromethane is considered to have low bioaccumulation potential, its persistence in 

seafood is al speculated to be low. According to the report of Gotoh, M. et al. (1992), 

dibromochloromethane was not detected in oysters, clam and the sediment of the Ariho River 

and the Yoshinaga River. 

(4) 2,2-dibromoacetic acid 

No report concerning persistence of 2,2-dibromoacetic acid in seafood is available. 

As 2,2-dibromoacetic acid is considered to have low bioaccumulation potential, its persistence in 

seafood is speculated to be low. 

(5) 2,2,2-tribromoacetic acid 

No report concerning persistence of 2,2,2-triibromoacetic acid in seafood is available. 

As 2,2,2-tribromoacetic acid is considered to have low bioaccumulation potential, its persistence 

in seafood is speculated to be low. 
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2.4.7 Any known interactive effects 

2.4.7.1 Free active chlorine 

Free active chlorine may generate corrosive gas including gaseous chlorine under high 

temperature or low pH condition (<pH4). 

2.5 Physical and chemical properties (G9: 4.2.1.4) 

As the physical and chemical properties for free active chlorine, property values of HClO, 

Cl2 and NaClO are shown in Table 6. Property values concerning HClO have not been reported 

almost at all because HClO itself is an unstable substance. 

Table 6. Physical and chemical properties for free active chlorine 

Properties Value Reference 

Melting point (°C) -101 (Cl2) Weast, R. C. (1988-1989) 

Boiling point (°C) -34.6 (Cl2) Weast, R. C. (1988-1989) 

Flammability 

 (flash point for liquids; °C) 

Nonflammable (Cl2) HSDB 

Density (20°C;kg/m 3.214 (Cl2, 0°C and 101.3kPa) Weast, R. C. (1988-1989) 3) 

1.21x103 (NaClO: 14%-aqueous 

solution) 

HSDB 

7.77 x105 Vapor pressure (20 °C; Pa) (Cl2, 25 °C) HSDB 

17.4 - 20 x102

 (NaClO) IUCLID (2000) 

Vapor density (air = 1) 2.5 (Cl2,-34.6°C) HSDB 

14.6 (Cl2, 0 °C) 

5.7 (Cl2, 30°C) 

Weast, R. C. (1988-1989) 

Weast, R. C. (1988-1989) 

Water solubility 

 (temp.; effect of pH; g/l) 

293 (NaClO, 0 °C) HSDB 

Dissociation constant (pKa) 7.5 (HClO, 25°C) Morris (1966) 

3.4 (Cl2, 25°C) Morris (1978) 

Autoignition temperature 

(°C) 

NA 

Surface tension NA 

Viscosity NA 

2.6 Analytical methods at environmentally relevant concentrations (G9: 4.2.1.5) 

2.6.1 Free active chlorine 

Analytical methods of free active chlorine is described in American Public Health Association 

(APHA)’s Standard Methods for the Examination of Water and Wastewater 19th, 4500-Cl 

Chlorine (Residual). Typical analytical methods are as follows (APHA (1995)): 

(1) DPD/Spectrophotometric colorimetry (APHA Standard method 4500-Cl G) 

According to this method, pinkish red color developed by the reaction of free active chlorine or 

total residual chlorine with N, N-diethyl-p-phenylene diamine (DPD) is measured, and free active 

chlorine or total residual chlorine is quantitatively determined by comparison with standard 

colorimetric specimen. 
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The determination limit is 0.01mg FAC/l (or mg TRC/l) under ideal measurement conditions, but 

is higher under ordinary operation conditions. 

i) Measurement of free active chlorine concentration 

To a test tube to which 0.5 ml of phosphate buffer and 0.5 ml of a DPD solution (1 g/l DPD 

oxalate, 1.5 g/l DPD sulfate pentahydrate or 1.1 g/l anhydrous DPD sulfate) are pipetted is added 

10 ml of sample with mixing. Thereafter, red color developed is measured by a 

spetctrophotometer, and the concentration of free active chlorine is obtained from the calibration 

curve preliminarily prepared using standard specimen. 

ii) Measurement of total residual chlorine concentration 

To the solution undergoing the color development in i) above is added 0.1 g of potassium iodide 

to be dissolved. After the mixture is kept standing still for 2 minutes, red color developed is 

measured using a spectrophotometer, and the concentration of total residual chlorine is obtained 

from the calibration curve preliminarily prepared using standard materials. 

This method is generally used for the measurement of residual chlorine concentration in drinking 

water because its measurement range is 0.05 to 2.0 mg TRC/l and the apparatus for analysis is 

small. 

(2) Iodometry (APHA Standard method 4500-Cl B) 

According to this method, total residual chlorine is quantitatively determined by titrating iodine 

liberated by the reaction of total residual chlorine with potassium iodide using sodium 

thiosulfate. 

Water is added to an appropriate amount of a sample to make the volume of 500 ml, followed by 

the addition of 5 ml of acetic acid to adjust the pH in the range 3-4. To the resulting solution is 

added 1 g of potassium iodide with mixing. The liberated iodine is titrated with 10 mmol/l 

sodium thiosulfate solution and the concentration of total residual chlorine in water is calculated 

from the volume (ml) of sodium thiosulfate required for the titration. 

 

 total residual chlorine (mg TRC/l)=(d-a) x f x test water (ml)/1000 x 0.3545 

 d:titer of sodium thiosulfate (ml) 

 a:titer of sodium thiosulfate for blank test (water) (ml) 

 f:factor of sodium thiosulfate 

Although the detection limit is 0.04 mg TRC/l according to this method, because the precision of 

values below 1 mg/l is low, this method is used for the measurement of the concentration of high 

concentration total residual chlorine. 

(3) Amperometry/ Titration (APHA Standard method 4500-Cl D) 

When iodine is liberated by the reaction of free active chlorine or total residual chlorine with 

potassium iodide, direct current electricity flows through the solution. By titrating the water with 

a reducing agent, iodine is reduced and the current value goes down. The point at which the 

current value no more goes down is the end point of titration. The concentration of free active 

chlorine or total residual chlorine is calculated from the amount of the reducing agent required 

for the titration. 
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i) Measurement of free active chlorine concentration 

To an appropriate amount of sample is added 1 ml of phosphate buffer (pH 7), and titration is 

carried out with 0.00564mol/l phenylarsenoxide solution using an amperometric titrator. The 

concentration of free active chlorine sample is calculated from the volume (ml) of 

phenylarsenoxide solution (0.00564mol/l) (d) according to the following formula: 

Free active chlorine (mg FAC/l) = d x 0.2 x 1000/sample volume (ml) 

ii) Measurement of total residual chlorine concentration 

After adding 1 ml of potassium iodide solution (5w/v%) and 1 ml of phosphate buffer (pH4) to 

an appropriate amount of sample the concentration of total residual chlorine in the test water is 

calculated through similar operations as in i) above using an amperometric titrator. 

2.6.2 Relevant chemicals 

(1) Monochloramine 

As in the case of free active chlorine, monochloramine can be analyzed as combined chlorine 

according to the DPD method (APHA Method 4500-Cl G). 

In the DPD method, total chlorine (free active chlorine plus combined chlorine) is measured by 

the addition of potassium iodide in a similar manner as in the measurement of free active 

chlorine, and the amount of combined chlorine (amount of chloramines) is calculated by 

subtracting the amount of free active chlorine. 

(2) Tribromomethane 

Analytical method of tribromomethane is described in METHOD 551 of U.S. EPA (1990). 

A sample (35 ml) is extracted with 2 ml of methyl-tert-butyl ether (MTBE), and 2 μl of the 

extraction solution is injected to GC provided with a silica glass capillary column and an electron 

capture detector (ECD). Standard samples can be analyzed in 40 to 50 minutes using a column 

used for this method. Detected substances can be identified using a separate column or GC-MS. 

(3) Dibromochloromethane 

Dibromochloromethane can be analyzed using GC/ECD or GC/MS according to METHOD 551 

of U.S. EPA (1990) as same as tribromomethane. 

(4) 2,2-dibromoacetic acid 

Analytical method of halogenated acetic acids including 2,2-dibromoacetic acid is described in 

METHOD 552.3 of U.S. EPA (2003). 

A sample (40 ml) is adjusted to lower pH value than 0.5 and extracted with 4 ml of 

methyl-tert-butyl ether (MTBE) or tert-amyl methyl ether containing internal standard. To the 

extracted halogenated acetic acid is added methanol, followed by heating for 2 hours for 

methyl-esterification. The mixture is then dehydrated and neutralized to be used for analysis. 

Halogenated acetic acids are identified and quantitatively determined using GC provided with a 

capillary column and ECD. 
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(5) 2,2,2-tribromoacetic acid 

2,2,2-tribromoacetic acid can be analyzed according to METHOD 552.3 of U.S. EPA (2003) 

using GC/ECD as same as in the case of 2,2-tribromoacetic acid. 

3 USE OF THE ACTIVE SUBSTANCE 

The following describes in this section, the operation method for the seawater electrolytic 

process. “mg FAC(t)/l” means the theoretical concentration of free active chlorine without 

consideration of initial decay after mixing electrolyzed seawater and untreated seawater. 

“mg TRC/l” means the measured concentration of total residual chlorine. 

3.1 Seawater Electrolytic Process on Hybrid Ballast Water Management System 

The ballast water management system applied is a hybrid management system composed of a 

mechanical treatment process and seawater electrolytic process (Fig. 2 shows the treatment flow 

in the case of seawater intake). The mechanical treatment process treats mainly large organisms 

(minimum dimension: 50 μm or more) using mechanical treatment apparatus such as strainers to 

remove of impurities, filters to remove or deactivate large organisms, etc. The seawater 

electrolytic process is installed in the stage immediately following mechanical treatment in order 

to treat small organisms (the minimum dimension: less than 50 μm), bacteria, etc. that elude the 

mechanical treatment. The free active chlorine generated in the seawater electrolytic process 

derives its bactericidal effects from the chlorine ion, a main component of seawater generated via 

seawater electrolysis. 

The seawater electrolysis equipment consists mainly of an electrolytic cell with built-in 

electrodes, a DC power supply unit, and current control equipment. Together these components 

are installed in intake/discharge lines of the ballast water. The system can be applied during 

intake or discharge of ballast water or during navigation (part of ballast water is circulated in the 

seawater electrolytic process). As a rule, however, the treatment is conducted during ballast water 

intake. 

The allowable concentration range of FAC and TRC is summarized in Table 7. 

Seawater

Electrolytic

Cell

Ballast

Water

Tanks

P

P

Discharged

Ballast

Water

Ballast

Strainer Pump

DC Power Supply Unit

and

Control Equipment 

FI

02

FI

01

V-1

V-6

V-2

V-7

V-4

V-5

CI

01

V-8

V-3

V-9

Mechanical

Treatment

Process

Hybrid Ballast Water Management System

Seawater Electrolysis

Process

V-10 V-11

Seawater

Electrolytic

Cell

Ballast

Water

Tanks

P

P

Discharged

Ballast

Water

Ballast

Strainer Pump

DC Power Supply Unit

and

Control Equipment 

FI

02

FI

01

V-1

V-6

V-2

V-7

V-4

V-5

CI

01

V-8

V-3

V-9

Mechanical

Treatment

Process

Hybrid Ballast Water Management System

Seawater Electrolysis

Process

V-10 V-11

Fig.2. Flow diagram of Hybrid Ballast Water Management System (at Intaking) 
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Table 7. Allowable FAC and TRC concentration range of 

Hybrid Ballast Water Management System 

Allowable concentration range 

Item 

Concentration* Deversion ratio of treated 

seawater 

16 mg FAC(t)/l 

(minimum) 30% of intake seawater Efflent of Electrolytic Cell 

1,500 mg FAC(t)/l 

(maximum) 0.33% of intake seawater 

Efflent of Seawater 

Electrolysis Process 5.0 mg FAC(t)/l - 

Discharged ballast water 0.1-3.0 mg TRC/l - 

* mg FAC(t)/l : The theoretical concentration of free active chlorine without consideration of initial decay. 

 mg TRC/l : The measured concentration of total residual chlorine . 

3.2 Active Substance generation mechanism by seawater electrolysis 

The Active Substance is generated by electrochemical reactions in the seawater electrolytic 

process. The details are described below. 

3.2.1 Anode reaction 

If the water containing chlorine ion such as seawater, blackish water and etc. is electrolyzed, the 

following reactions progress normally on the anode surface: 

 

2Cl-

 → Cl2 + 2e- (E0 = 1.359V at 25°C) (11) 

2H2O → O2 + 4H+

 + 4e- (E0 = 1.229V at 25°C) (12) 

This seawater electrolysis system, however, uses catalyst-coated electrodes that suppress oxygen 

generation. Thus, the reaction of Equation (12) hardly occurs under high Cl ion concentration 

conditions such as those of seawater, and the chlorine can be produced selectively. 

3.2.2 Cathode reaction 

The following reaction occurs on the cathode surface: 

2H+

 + 2 e- → H2 (E0 = 0V at 25°C) (13) 

2H2O + 2e- → H2 + 2OH- (E0 = -0.828V at 25°C) (14) 

If we assume that chlorine of 1 mg FAC(t)/l is produced by the electrolysis, then 0.028 mg-H2/l 

(0.315 ml-H2/l) of hydrogen (H2) is generated on the cathode. 

3.3 Existence form of Active Substance in seawater 

Cl2 gas is generated by the anode reaction. Cl2 gas is thought as highly soluble compound (0.64 

ml/ml-H2O). Cl2 gas rapidly dissolves into the seawater and becomes hypochlorous acid (HClO) 

(Equation (15)). 1 mole of hypochlorous acid (HClO) is generated from 1 mole of chlorine gas. 
MEPC 56/2 

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Additionally, hypochlorous acid (HClO) is hydrolyzed and hypochlorite ion (ClO-) is generated 

(Equation (16). Chlorine gas (Cl2) /hypochlorous acid (HClO)/hypochlorite ion (ClO-

) are in 

equilibrium and the existence forms depend on the pH. The mixture of hypochlorous acid (HClO) 

/hypochlorite ion (ClO-) is called “free active chlorine”. 

Cl2 + H2O ↔ HClO + H+ + Cl- (15) 

HClO ↔ H+

 + ClO- (16) 

As natural seawater is normally of pH 8, the dissolved chlorine takes the form of hypochlorous 

acid (HClO) or hypochlorite ion (ClO-

). 

Fig.3. Simulated variation in composition of a chlorine solution with degree of acidity or 

alkalinity for 0.1 M Cl2 in water at standard temperature and pressure (AISE (1997)). 

As shown in Equation (11), 2 moles of electron are required for 1 mole of chlorine gas 

generation. As shown in Equation (15) and (16), 1 mole of free active chlorine (the mixture of 

hypochlorous acid (HClO) /hypochlorite ion (ClO-

)) is generated from 1 mole of chlorine 

gas (Cl2). The quantity of electric charge of 1 mole of electron is 96500 coulomb. When 1 A of 

current is applied during 1 second, the quantity of electric charge is defined as 1 coulomb. Then, 

theoretical free active chlorine (FAC) generation is expressed in Equation (17). 

Theoretical FAC generation[mol] 

 = Applied current[A] x applied time[sec] / 96500[A·sec/mol] / 2 (17) 

Theoretical FAC generation at 1 A current applied during 1 hour (3600second) is calculated 

using Equation(18). 
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Theoretical FAC generation[mol] = 1 [A] x 3600 [sec] / 96500 [A·sec/mol] / 2 

= 1.87 x 10-2 [mol] (18) 

Theoretical FAC generation per unit current and time is expressed in Equation (19) using 

the result of Equation (18). 

Theoretical FAC generation[mol/A/h] = 1.87 x 10-2 [mol/A/h] (19) 

Current efficiency(η) means generation efficiency of FAC per applied current and it is 

defined as Equation (20). 

Current efficiency(η)[%] 

 = actual amount of FAC generation[mol]/theoretical amount of FAC generation[mol] x 100

 (20) 

3.4 Safety of the seawater electrolysis system 

The seawater electrolytic process does not require the loading or storage of the Active Substance 

on board. This eliminates all hazards entailed in the handling of chemicals by the ship and the 

crew (poisonings, burns, fires, etc.). 

In this system, the amount of electrolytic chlorine generation is controlled by the applied current. 

Then, no excess chlorine is generated at normal operating condition. If the emergency condition 

(power failure, electrolytic leakage etc) occurs, current applying to electrolytic cell is turned off. 

When the flow rate of injection seawater to electrolytic cell comes down below the preset value, 

the electrolytic cell is turned off automatically to prevent excess chlorine generation. The flow 

rate of injection seawater to electrolytic cell is monitored using flow meters. 

4 MATERIAL SAFETY DATA SHEET (G9:4.2.7) 

Material Safety Data Sheet (MSDS) in conformity with JIS Z 7250 (2005) is described 

(APPENDIX 2). JIS Z 7250 is a Japanese Industrial Standard established based on part 1 of the 

ISO 11014-1 Safety data sheet for chemical products. The Content and order of the section were 

published as the first edition in 1994 with modifications of the technical contents for 

harmonization with “GHS, Part 1, Chapter 1.5 Hazard communication: Safety data sheet” 

(implemented by resolution of the United Nations Economic and Social Council in July 2003). 
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5 RISK CHARACTERIZATION 

5.1 Screening for persistence, bioaccumulation and toxicity (G9: 5.1) 

5.1.1 PBT criteria 

The criteria of PBT characteristics defined by the Procedure (G9) are as follows (Table 8): 

Table 8. PBT criteria 

Criterion PBT criteria 

Persistence Half-life: 

 > 60 days in marine water 

 > 40 days in freshwater* 

 > 180 days in marine sediment 

 > 120 days in freshwater sediment* 

Bioaccumulation Experimentally determined BCF > 2,000, or if no 

experimentally BCF has been determined, Log Pow≥3 

Toxicity Chronic toxicity NOEC <0.01mg/l 

*For the purpose of marine environmental risk assessment half-life data in freshwater and freshwater 

sediment can be overruled by data obtained under marine conditions. 

5.1.2 PBT character of Active Substance and relevant chemicals 

5.1.2.1 Free active chlorine 

i) Persistence 

As free active chlorine is unstable substance and is easily decomposed by light, heat or reaction 

with organic compound, it is considered that it does not possess persistence. 

Hypochlorous acid is an oxidizer and a disinfectant and, is primarily an inorganic substance. 

Therefore, it is said that it is not proper to discuss its biodegradability (IUCLID (2000)). 

Also, the Koc value of hypochlorous acid is 14.3l/kg (estimated by EPI Suite TM) (that of sodium 

hypochlorite is 14.3(estimated by EPI Suite TM)). Because Koc is smaller than 500l/kg, it is 

considered that soil adsorption potential of free active chlorine is low. Therefore, free active 

chlorine is considered to have low sediment toxicity. 

ii) Bioaccumulation 

Log Pow of hypochlorous acid is -0.87 (estimated) (that of sodium hypochlorite -3.42 

(estimated)) and this value is smaller than PBT criteria (Log Pow≥3). In addition, it is easily 

decomposable inorganic substance. It is speculated that this chemical is not high 

bioaccumulation potential compound. 

iii) Toxicity 

As the chronic aquatic toxicity value of free active chlorine is presumed to be 7d NOEC=0.0027 

mg TRC/l from the results of chronic aquatic toxicity test for algae microcosm, it is evaluated 

based on PBT criteria (NOEC<0.01mg/l) that free active chlorine has some toxicities. 
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5.1.2.2 Relevant chemicals 

(1) Monochloramine 

i) Persistence 

As the half-life of monochloramine by hydrolysis is 10 h (Margerum et al. (1978)), it is 

considered that there is no persistence in the environment. 

Koc calculated from the structure of monochloramine with calculation program (EPI SuiteTM) of 

U.S. EPA based on QSAR is 14.3l/kg, and it is believed that the adsorption amount to soil/sludge 

is small. 

There is no report on biodegradation of monochloramine. 

ii) Bioaccumulation 

The data on Log Pow and BCF of monochloramine have not been reported. As the calculation 

results by EPI SuiteTM, Log Pow of monochloramine is -1.19 and is smaller than PBT criteria 

(Log Pow≥3). Therefore, the bioaccumulation is considered low. 

Furthermore, the calculation result of BCF is BCF=3.2, and is sufficiently low value in 

comparison with the PBT criteria (BCF > 2,000). 

iii) Toxicity 

Since the evaluation as single substance is difficult, the toxicity of monochloramine has not been 

clarified. 

(2) Tribromomethane 

i) Persistence 

Though the half-life of tribromomethane in the water calculated from hydrolysis rate constant 

(3.2x10-11/sec) is 686 years and tribromomethane is relatively stable compound in the water 

(Mabey, W. et al. (1978)). The half-life by volatilization is calculated as 1h (riffle)-581h (pool) 

(Kaczmar, S.W. et al. (1984). 

As described in paragraph 2.4.1.2, aerobic biodegradation of tribromomethane is limitative, 

however, it is reported that tribromomethane is easily degraded anaerobically, for example, by 

methanogenic bacteria or denitrifying bacteria. 

Koc of tribromomethane is 218.8l/kg (observed), and the adsorption to soil/sediment is 

considered to be small (DiToro et al. (1991)). 

ii) Bioaccumulation 

Log Pow of tribromomethane is 2.4 (observed) and is smaller than PBT criteria (Log Pow≥3). 

Therefore, the bioaccumulation is considered to be low. 
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Though there is no report on BCF, the calculation result by BCF calculation program of U.S. 

EPA (EPI SuiteTM) based on QSAR is BCF=14, and it is a sufficiently low value in comparison 

with the PBT criteria (BCF > 2,000). 

iii) Toxicity 

From the report that NOEC (28 days) to Cyprinodon variegates was 4.8 mg/l (Ward et. al. 

(1981)), it is evaluated based on PBT criteria (NOEC<0.01mg/l) that tribromomethane has no 

toxicity. 

(3) Dibromochloromethane 

i) Persistence 

Though the half-life of dibromochloromethane in the water calculated from the hydrolysis rate 

constant (8.0x10-11/sec) is 686 years and dibromochloromethane is relatively stable compound in 

the water (Mabey, W. et al. (1978)). The half-life by volatilization is tentatively calculated 

as 0.7h(riffle)-398h (pool) (Kaczmar, S.W. et al. (1984). 

As described in paragraph 2.4.1.2, aerobic biodegradation of dibromochloromethane is limitative, 

however, it is reported that dibromochloromethane is easily degraded anaerobically. 

Koc of dibromochloromethane is 84l/kg (observed), and the adsorption amount to soil/sludge is 

considered to be small (HSDB (2006b)). 

ii) Bioaccumulation 

Log Pow of dibromochloromethane is 2.16 (observed) and is smaller than PBT criteria (Log 

Pow≥3). Therefore, the bioaccumulation is considered to be low. 

Though there is not a report on BCF, the calculation result by BCF calculation program of U.S. 

EPA (EPI SuiteTM) based on the QSAR is BCF=9, and it is a sufficiently low value in 

comparison with the PBT criteria (BCF > 2,000). 

iii) Toxicity 

From the report (NITE (2006)) that NOEC (21 days) to daphnia magna was 0.063mg/l and that to 

Oryzias latipes was 3.2 mg/l (NITE (2006)), it is evaluated based on the PBT criteria 

(NOEC<0.01mg/l) that dibromochloromethane has no toxicity. 

(4) 2,2-dibromoacetic acid 

i) Persistence 

As 2,2-dibromoacetic acid is easily subjected to biodegradation in the environment, it is 

considered that the persistence is not shown. 

As described in paragraph 2.4.1.2, biodegradations by haloacid dehalogenase of aerobic bacteria 

are reported. 
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Also, the Koc value of 2,2-dibromoacetic acid is 1.90l/kg (estimated by EPI Suite TM). Because 

Koc is smaller than 500l/kg, it is considered that soil adsorption potential of 2,2-dibromoacetic 

acid is relatively low. Therefore, free active chlorine is considered to have low sediment toxicity. 

ii) Bioaccumulation 

Log Pow of 2,2-dibromoacetic acid is 1.22 (estimated value) and is smaller than PBT criteria 

(Log Pow≥3). Thus, the bioaccumulation is considered to be low. 

Though there is no report on the BCF, the calculation result by BCF calculation program of U.S. 

EPA (EPI SuiteTM) based on QSAR is BCF=3.2, and it is a sufficiently low value in comparison 

with the PBT criteria (BCF > 2,000). 

iii) Toxicity 

There is no report on the toxicity of 2,2-dibromoacetic acid, and the toxicity evaluation is still 

uncertain. 

(5) 2,2,2-tribromoacetic acid 

i) Persistence 

As 2,2-dibromoacetic acid is readily subjected to biodegradation in the environment, it is 

supposed that the persistence is not shown. 

As described in paragraph 2.4.1.2, biodegradations by haloacid dehalogenase of aerobic bacteria 

are reported. 

Also, the Koc value of 2,2,2-tribromoacetic acid is 2.74l/kg (estimated by EPI Suite TM). Because 

Koc is smaller than 500l/kg, it is considered that soil adsorption potential of 2,2,2-tribromoacetic 

acid is relatively low. Therefore, free active chlorine is considered to have low sediment toxicity. 

ii) Bioaccumulation 

Log Pow of 2,2,2-tribromoacetic acid is 1.71 (estimated value) and is smaller than PBT criteria 

(Log Pow≥3). Thus, the bioaccumulation is considered to be low. 

Though there is no report on the BCF, the calculation result by BCF calculation program of U.S. 

EPA (EPI SuiteTM) based on QSAR is BCF=3.2, and it is a sufficiently low value in comparison 

with the PBT criteria (BCF > 2,000). 

iii) Toxicity 

There is no report on the toxicity of 2,2,2-tribromoacetic acid, and the toxicity evaluation is still 

uncertain. 

5.1.3 Summary of PBT evaluation 

The persistence and bioaccumulation of hypochlorous acid, an Active Substance, satisfy the PBT 

criteria. The toxicity, on the other hand, fails to satisfy the PBT criteria (NOEC<0.01 mg/l). The 

hypochlorous acid must therefore be assumed to be toxic. 
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But as shown by the toxicity evaluation test of the treated ballast water (Section 5.2) and the risk 

evaluation of the discharge from that water (Section 5.3), the free active chlorine acting within 

this seawater electrolysis system is not toxic under actual operating conditions. The toxicity is 

nullified by the rapid dilution and decomposition of the free active chlorine after the discharge of 

the free active chlorine together with the treated ballast water. 

Out of the relevant chemicals, the persistence and bioaccumulation of monochloramine satisfy 

PBT criteria by margins comparable to those of free active chlorine. The difficulty in evaluating 

monochloramine as a single substance precludes conclusive evaluations of its toxicity. 

Tribromomethane and dibromochloromethane satisfy all the PBT criteria and are considered to 

have very small effects on the environment. 

2,2-dibromoacetic acid and 2,2,2-tribromoacetic acid satisfy the PBT criteria for persistence and 

bioaccumulation. A lack of data makes it difficult to clearly evaluate their toxicity. 

5.2 Toxicity evaluation of the treated ballast water (G9:5.2) 

Seawater electrolysis may very well generate substances other than free active chlorine, 

monochloramine, tribromomethane, dibromochloromethane, 2,2-dibromoacetic acid and 

2,2,2-tribromoacetic acid (listed in Section 2) in water. It would be very difficult, however, to 

identify all of the relevant chemicals, in light of their minute quantities and widely variable types. 

Section 5.2 of the Procedure (G9) (MEPC 53/24/Add.1) requires a toxicity test of discharge 

ballast water after treatment. Owing to this, the possibility of interaction of the Active Substance 

can be evaluated integrally together with by-products. 

The chronic toxicity for the test organisms was therefore evaluated in a seawater chlorinated by a 

simulated ballast water management system, using a small device fitted with the same types of 

electrodes used for the actual seawater electrolytic process. IDEA Consultants, Inc. carried out 

the toxicity test in accordance with GLP Criteria of the OECD (OECD Principles of Good 

Laboratory Practice, ENV/MC/CHEM (98)17, 1997) (IDEA Consultants, Inc., Early life stage 

toxicity test for the electrolyte-chlorinated seawater using Java medaka, Oryzias javanicus, 

BWF-0601 (2006), IDEA Consultants, Inc., Chronic toxicity test for the electrolyte-chlorinated 

seawater using marine Gammarid, Hyale barbicorins, BWG-0601 (2006), IDEA Consultants, 

Inc., Growth inhibition test for the electrolyte-chlorinated seawater using marine diatom, 

Skeletonema costatum, BWA-0601 (2006)). 

5.2.1 Test method and conditions 

(1) Preparation of test seawater 

Natural seawater filtered with 10 μm pore diameter filter was electrolyzed, and electrolyzed 

seawater at 50±3 mg FAC/l was produced. The unit (mg FAC/l) means concentration of free 

active chlorine. FAC of the electrolyzed seawater and the test seawater, treated seawater held for 

2 days, were analyzed by iodometry and DPD/Spectrophotometric colorimetry, respectively. 

Then, the electrolyzed seawater was added to untreated filtered seawater to prepare treated 

seawater, active chlorine concentration of 5.0 mg FAC/l. This treated seawater was put into a 

glass container and was held in darkness at 25°C for two days, then, it was used for the exposure 

of test organism. The test seawater, treated seawater held for 2 days, was gradually diluted with 

dilution seawater (natural seawater filtered by activated carbon filter) to 1/1 (no dilution), 1/3.2, 

1/10, 1/32, 1/100, and 1/320, and of each was applied to the exposure in this study. 
MEPC 56/2 

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(2) Early life stage toxicity test for the treated seawater using Java medaka, Oryzias 

javanicus

This study was conducted in accordance with the OECD guideline for testing of chemicals 

No.210, “Fish early-life stage toxicity test”, 1992. 

Java medaka, Oryzias javanicus, was used for this study as test species. The exposure of test 

organism, Oryzias javanicus, was conducted under condition shown below. During the exposure 

duration, hatchability and the number of days to hatching in the exposed fertilized eggs, and the 

post-hatch mortality, were measured. Also, total length and body weight of all survived animals 

were measured at the completion of exposure. For each parameter, the data set of calculated 

values was checked for homogeneity of variances across control and treatment groups by 

Bartlett’s test. The differences between control group and treatment groups were determined 

using one-way analysis of variance (ANOVA) followed by Dunnett's multiple comparison tests 

when homogeneity was observed, or by the nonparametric Kruskal-Wallis test followed by 

Welch’s t-test with Bonferroni-Holm’s adjustment when no homogeneity was observed. 

The residual chlorine concentration, as an Active Substance concentration, was measured twice a 

week in the newly prepared test solution, and was measured once a week in test solution 

immediately prior to the renewal (after a day from previous replacement). 

Type of exposure : Semi-static, whole amount renewal every 24 hours 

Exposure duration : From embryo stage at 1 day post-fertilization to 28 days 

post-hatch (40 days) 

Number of treatment : 6 treatment groups (1/1, 1/3.2, 1/10, 1/32, 1/100 and 1/320

group), 

and a control group 

Number of replicates : 3 replicates per each treatment and 3 replicates for control group

Volume of test solution : 100ml/vessel in embryo phase and 500ml/vessel in post-hatch 

phase 

Test organism : Fertilized egg 1 day post-fertilization of Java medaka, Oryzias 

javanicus

Number of animals : 60 animals/group (20 animals per replicate vessel) 

Temperature : 26±1 oC 

Illumination : Cool-white type fluorescent bulbs, 12 hours light/12 hours dark 

Feeding (pos-hatch 

phase) 

: Brine shrimp nauplii once daily 

(3) Chronic toxicity test for the treated seawater using marine Gammarid, Hyale barbicorins

This study was conducted in accordance with the test method reported by Anasco et al. using 

marine gammarid, Hyale barbicorins, as a test organism. In this study, cumulative mortality, 

molting frequency, head length and body weight of the survived animals at the completion of the 

exposure were applied for endpoints, instead of cumulative mortality and body length. 

The exposure of test organism, Hyale barbicorins, was conducted under condition shown below. 

During the exposure duration, mortality and the frequency of molting were measured. Also, the 

head length and body weight (dry weight) of all survived animals were measured at the 

completion of the 21 days of exposure. 
MEPC 56/2 

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The differences between the treatment groups and the control group were determined by 

chi-squared test, with Bonferroni-Holm adjustment, for cumulative mortality and molting 

frequency: the data set of surviving number and cumulative number of dead animals at the 

completion of exposure, and the cumulative molting frequency for surviving animals was 

applied, respectively. The homogeneity of variance across the groups for the data set for head 

length and body weight of surviving animals were observed by Bartlett’s test, and thus the 

differences between the treatment groups and the control group were determined by one-way 

analysis of variance (ANOVA) , followed by Dunnett’s multiple comparison test. 

The residual chlorine concentration, as an Active Substance concentration, was measured twice a 

week in the newly prepared test solution, and was measured once a week in test solution 

immediately prior to the renewal (after a day from previous replacement). 

Type of exposure : Semi-static, whole amount renewal every 24 hours 

Exposure duration : 21 days 

Number of treatment : 6 treatment groups (1/1, 1/3.2, 1/10, 1/32, 1/100 and 1/320 group),

and a control group 

Number of replicates : 20 replicates per treatment group and 20 replicates for control 

group 

Volume test solution : 10ml/vessel 

Test animal : Marine Gammarid, Hyale barbicorins, within 24 hours post-hatch

Number of animals : 20 animals/group (1 animal per vessel) 

Temperature : 24±1 oC 

Illumination : Cool-white type fluorescent bulbs, 12 hours light/12 hours dark 

Feeding : Artificial flak food, TetraMarine® , < 0.5mm crushed pieces, 

once daily 

(4) Growth inhibition test for the treated seawater using marine diatom, Skeletonema 

costatum

This study was conducted in accordance with the International standard ISO 10253: “Water 

quality -Marine algae growth inhibition test with Skeletonema costatum and Phaeodactylum 

tricornutum”, 1995. 

Marine diatom, Skeletonema costatum, was used for this study as test species. The exposure of 

test organism, Skeletonema costatum, was conducted under condition shown below. The cell 

density in each test vessel was measured at 24, 48 and 72 hours after the start of exposure, and 

area under the growth curve and the growth rate over the exposure duration was calculated. For 

each parameter, the data set of calculated values was checked for homogeneity of variances 

across control and treatment groups by Bartlett’s test. The differences between control group and 

treatment groups were determined using one-way analysis of variance (ANOVA) followed by 

Dunnett’s multiple comparison tests when homogeneity was observed, or by the nonparametric 

Kruskal-Wallis test followed by Welch’s t-test with Bonferroni-Holm’s adjustment when no 

homogeneity was observed. 

The residual chlorine concentration, as an Active Substance concentration, in test solution was 

measured in each treatment group at the beginning and the completion of the exposure. 

Type of exposure : Static, shaking at 100 rpm 

Exposure duration : 72 hours 
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Number of treatment : 6 treatment groups (1/1, 1/3.2, 1/10, 1/32, 1/100 and 1/320

group), and a control group 

Number of replicates : 3 replicates per each treatment and 6 replicates for control 

Volume of test solution : 30 ml/vessel 

Initial cell density : 1 x 104 cells/ml 

Temperature : 20±2 oC 

Illumination : Cool-white type fluorescent bulbs, continuous at 7,000 Lux ±

20% 

pH adjustment of test 

solution 

: None 

5.2.2 Results and conclusions 

(1) Early life stage toxicity test for the treated seawater using Java medaka, Oryzias javanicus

The cumulative hatchability of exposed eggs and the post-hatch cumulative mortality in control 

group were 95% and 3.5%, respectively, satisfying the validity criteria in this study (more 

than 70% in the hatchability, and less than 30 % in the mortality). In addition, the test conditions 

(water temperature, salinity, pH value, and dissolved oxygen concentration of test solution) had 

been maintained at an adequate level throughout the exposure duration, and thus there was no 

factor, which may have influenced the reliability of the results of this study. 

The free active chlorine (FAC) concentrations in the newly prepared test solutions were 

3.7 - 3.9 mg FAC/l in 1/1 group, and 0.39 - 0.89 mg FAC/l in 1/3.2 group, whereas the 

FAC concentrations were lower than determination limit of 0.05 mg FAC/l (ND) in other 

treatment groups and control group at all measurement days. The FAC in the test solution just 

before the replacement were 1.9 - 2.4 mg FAC/l in 1/1 group, ND - 0.07 mg FAC/l 

in 1/3.2 group, and ND at all measurement days in other treatment groups and control group. 

In regard to the cumulative hatchability of fertilized eggs, 1/1 group was 0%, showing a 

significant decrease compared to the control group at p<0.05. As for the cumulative post-hatch 

mortality, 1/3.2 group resulted in 100%, and a significant increase compared to the control group 

at p<0.05 was observed. No significant effect was observed on the cumulative hatchability, the 

days to hatching, and the cumulative post-hatch mortality, in other treatment groups. A statistical 

significant difference was observed for the total length of survived animals at completion of the 

exposure of 1/100 group compared to control group at p<0.05. However, it is considered that the 

total length in 1/100 group was a contingent alteration with no relationship with the toxicity of 

test seawater, because no clear tendency was observed in average of total length between 1/10 

and 1/320 group. Also, no significant difference on the body weight of the survived animals was 

statistically observed in all treatment groups, compared to the control group. 

From the results of this study, the lethal or sub-lethal effect of test seawater to the early life stage 

Java medaka, Oryzias javanicus, which was treated at 5.0 mg FAC/l and held in the darkness for 

two days, was concluded as follows. 

No observed effect dilution ratio: 1/10 

Lowest observed effect dilution ratio: 1/3.2 
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(2) Chronic toxicity test for the treated seawater using marine Gammarid, Hyale barbicorins

The cumulative mortality in control group was 5% at the completion of exposure, satisfying the 

validity criterion of this study (less than 30% at the completion of exposure). In addition, the test 

conditions (water temperature, salinity, pH value, and dissolved oxygen concentration of the test 

solution) had been maintained at an adequate level throughout the exposure duration, and thus 

there was no factor, which may have influenced the reliability of the results of this study. 

The FAC concentrations in the newly prepared test solutions were 3.6 mg FAC/ml in 1/1 group, 

which was measured only once, and 0.39-0.50 mg FAC/l in 1/3.2 group, whereas, the FAC were 

lower than determination limit of 0.05 mg FAC/ml (ND: lower than 0.05 mg FAC/ml) in other 

treatment and control groups at all measurement days. In addition, the FAC of the test solution 

just before the replacement were 2.0 mg FAC/l in 1/1 group, which was measured only once, and 

ND at all measurement days in other treatment and control groups. 

The cumulative mortality at the completion of the exposure was 100% in 1/1 and 1/3.2 group, 

and a significant increase, compared to control group, was observed for these groups at p<0.05. 

The cumulative mortality for groups 1/10, 1/32, 1/100, and 1/320 was 5% or below, and no 

statistical significance was observed between the control group. In regards to the cumulative 

frequency of molting the completion of exposure, no statistical significance was statistically 

observed in each treatment group compared to control group. Also, no statistical significant 

difference was observed between each treatment group and control group for both the head 

length and the body weight of the survived animals at the completion of the exposure. 

From the results of this study, the lethal or sub-lethal effect of test seawater, which was treated 

at 5.0 mg FAC/l and held in the darkness for two days, to the marine Gammarid, Hyale 

barbicorins, was concluded as follows. 

No observed effect dilution ratio: 1/10 

Lowest observed effect dilution ratio: 1/3.2 

(3) Growth inhibition test for the treated seawater using marine diatom, Skeletonema 

costatum

The average cell density in control group at the end of the exposure was 57.6×104

 cells/mL, 

satisfying the validity criteria in this study (more than 16 times the initial cell density in 

72 hours). In addition, the environmental condition had been maintained at an adequate level 

throughout the exposure duration, and thus there was no factor, which may have influenced the 

reliability of the results of this study. 

The FAC in test solution was 2.4 mg FAC/l in 1/1 group, whereas, the FAC was lower than 

determination limit of 0.05 mg FAC/l in all of other treatment groups and control, at beginning of 

the exposure. The TRC at the completion of exposure was lower than determination limit in all 

treatment and control groups. 

In the area under the growth curve over exposure duration (0 to 72 hours), a clear declining trend 

which depend on the dilution ratio of test seawater was observed, and a significant difference, or 

a significant reduction of biomass, was statistically observed at 1/10, 1/3.2, and 1/1 group, 

compared with control group at p<0.05. A similar tendency was observed in the growth rate 

from 0 to 72 hours, and likewise, a significant difference from control group, or a significant 
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decline in growth rate, was observed at 1/1, 1/3.2, and 1/10 group at p<0.05. Neither the 

significant reduces of growth rate, nor the area under the growth curve, was observed in 

treatment groups with dilution rate of 1/32 or below. 

From the results of this study, the influence of test seawater to the growth of marine diatom 

Skeletonema costatum, which was treated at 5.0mg/ FAC/l and held in the darkness for two days, 

was concluded as follows: 

No observed effect dilution ratio: 1/32 

Lowest observed effect dilution ratio: 1/10 

5.2.3 Conclusion of toxicity test of the treated ballast water 

The toxicity was evaluated on the test organisms in the seawater chlorinated with the method 

simulating the ballast water management system, with a small device using the electrodes of the 

same type as those of the seawater electrolytic process. IDEA Consultants, Inc. carried out 

the toxicity test in accordance with the test plan and standard operation procedure (SOP), and 

GLP Criteria of OECD (OECD Principles of Good Laboratory Practice, 

ENV/MC/CHEM (98) 17, 1997). 

The results of the toxicity test of the treated ballast water are summarized below (Table 9). 

Dilution ratio (treated ballast water/natural seawater) was used for No Observed Effect 

Concentration (NOEC) and Lowest Observed Effect Concentration (LOEC) of treated ballast 

water. From these results, the results of the growth inhibition test with skeletonema costatum

were adopted as the highest no observable effect concentration and the lowest observable effect 

concentration of the treated ballast water, which were determined to be NOEC = 3.1% (v/v) and 

LOEC = 10%(v/v), respectively. 

Table 9. Results of toxicity evaluation of the treated ballast water 

Species NOEC* LOEC* 

Oryzias javanicus 

(fish, 28d) 10%(v/v) 31%(v/v) 

Hyale barbicorins 

(crustaceans, 21d) 10%(v/v) 31%(v/v) 

Skeletonema costatum 

(algae, 72h) 3.1%(v/v) 10%(v/v) 

* Dilution rate with treated ballast water and dilution seawater. 

5.3 Risk assessment of treated ballast water discharges 

It is necessary to understand the effect of the treated ballast water discharges on marine 

organism. In this section, the short- and long-term (for 1 year) risks of the treated ballast water 

discharges have been assessed. 

The short-term risk of the treated ballast water discharges has been assessed with the treated 

ballast water to estimate the effect of free active chlorine and relevant chemicals in parallel. 

Dilution ratio (treated ballast water/natural seawater) has been used for No Observed Effect 

Concentration (NOEC) of the treated ballast water, and NOEC = 3.1% (v/v). The results of the 

chronic toxicity tests (fish, crustacean, algae) of the treated ballast water have been applied for 

the NOEC (section 5.2). Acute toxicity value is usually applied in short-term risk assessment, but 

the chronic toxicity value has been adopted because the chronic toxicity value is mostly lower 

than the acute toxicity value resulting in the safe side evaluation. Degradation of the treated 
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ballast water has not been considered due to the same reason as above. Therefore, assessment 

factor has not been considered. The time period when dilution ratio of the treated ballast water 

had reached 3.1%(v/v) has been estimated in the short-term risk assessment. 

The long-term risk of the treated ballast water discharges has been assessed with 

tribromomethane. The long-term risk should be assessed with the treated ballast water under 

normal circumstances. However, the half-life value of the treated ballast water can not be defined 

because the treated ballast water contains varied components (e.g., free active chlorine, 

tribromomethane, etc.). And the treated ballast water must continue to be accumulated in natural 

seawater. Accordingly, the long-term risk can not be assessed with reasonable accuracy without 

considering the half-life value. Therefore, the risk assessment for tribromomethane is conducted 

because it has the highest concentration among relevant chemicals in the treated ballast water and 

its accumulation in natural seawater has to be considered due to low degradation rate. The 

long-term risk of free active chlorine, which has very low half-life value, is considered to be very 

low, so it hasn’t been assessed. The concentration of tribromomethane was 0.16 mg/l as the 

analytical result (section 2.1.3.2). 96h NOEC = 2.9 mg/l (Cyprinodon variegates/fish) was 

applied to the NOEC of tribromomethane (section 2.2.6). The NOEC is valid acute toxicity data. 

Although chronic toxicity data should be applied to long-term risk assessment, the acute toxicity 

data was applied to the NOEC so that it was lower than the chronic toxicity data (28d NOEC 

(juvenile mortality) = 4.8-8.5 mg/l (Cyprinodon variegates/fish)) (section 2.2.2.2). Evaluation by 

the acute toxicity data is on the safe side. Assessment factor should be 100 due to applying the 

valid acute toxicity data to the NOEC, but 10 was applied to the assessment factor. Because the 

acute toxicity data was lower than the chronic toxicity data. PNEC of tribromomethane 

was NOEC/10 = 0.29mg/l. 

Then, the behaviors of the discharge from the treated ballast water and residual chemical 

components must be properly understood in order to assess the potential risks they pose after 

discharge to the marine environment. For this investigation the applicant developed a 

high-resolution hydrodynamic model of Tokyo Bay using HYDROMAP (Zigic et al.(2003)), a 

computerized system from Applied Science Associates. The hydrodynamic simulations were 

linked to a comprehensive chemical dispersion model known as CHEMMAP (French 

McCay, 2001; French McCay and Isaji, 2004; French McCay et al., 2006), another application 

from Applied Science Associates, in order to quantify the fate and dispersion of the discharge 

and tribromomethane within Tokyo Bay. 

Exposure assessments were carried out by expert marine and freshwater modelers from 

Asia-Pacific Applied Science Associates (APASA). Effect assessments were conducted by 

Science and Technology Co., Ltd. (SAT), a company with expertise and research experience in 

assessing the effects of antifouling paints (Science and Technology Co., Ltd. and Asia-Pacific 

Applied Science Associates. “Risk evaluation of discharge treated ballast water in Yokohama 

Port (2006)). 

5.3.1 Environmental information 

The effect of bathymetry, tides, salinities and water temperatures, all play a role in the fate of any 

ballast water release. Historical measurements of these parameters in the Yokohama Port were 

used as input data into the simulation models to determine the range of possible concentrations, 

which might result under the influence of all these factors. 

In particular, water currents within the region are tidally driven as shown in Fig. 3 and were 

included into the study to account for their dynamic nature, since these tidal currents are 

time-varying. These tidal currents were created using a detailed high-resolution model of Tokyo 

Bay. Fig. 3 demonstrates that the tidal range in Yokohama Port is < 2 m during spring tides. 
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The tides demonstrate a diurnal inequality (that is, tidal ranges during the day can be significantly 

less than the tidal range at night). During neap tides, the tides change only once a day 

with a range < 1 m. 

-1.0

-0.5

-0.0

0.5

-0.10

-0.05

0.00

0.05

0.10

0.000

0.025

0.050

0.075

1 Aug

Aug 2006

8 Tue 15 Tue 22 Tue 1 Sep 8 Fri 15 Fri 22 Fri 1 Oct

Oceanographic Conditions at Discharge Location 

Ele.(m) Stick(kt) Speed(kt)

Date-Time

Fig.3. Example currents within Yokohama Port from a hydrodynamic model of Tokyo Bay 

demonstrating the range of tidal conditions possible for Yokohama Port. 

Publicly available water quality data for Yokohama Port also show that water temperatures are 

known to range between 10 - 28 oC and that salinities are known to range from 18 ppt to 31 ppt. 

5.3.2 Treated Ballast Water Release Information 

Shipping statistics for Yokohama Port were examined to quantify the amount of ballast water 

brought into the port on an annual basis. From these statistics, two case studies or scenarios were 

developed for the modelling study being: 

(1) In the short-term risk assessment, the distribution and short-term fate of treated ballast 

water discharged from one ship in Yokohama Port (least-case and worst-case rates and volumes) 

were simulated. From the shipping statistics, the least-case discharge volume from one ship 

is 3,000 m3

 over 6 hours (discharge rate being 500 m3/hour) while the worst-case discharge 

volume from one ship is 72,000 m3 over 12 hours (discharge rate being 6,000 m3/hour). 

(2) In the long-term risk assessment, the potential for the accumulation of tribromomethane 

concentration in the treated ballast water discharged at a rate of 212,329 m3

/day for 365 days 

representing the total possible volume from all ships in Yokohama Port over a one-year period 

was simulated. Statistical data of ship arrivals at Yokohama Port (2004) and estimated annual 

amounts of ballast water discharged in Yokohama Port, used for the long-term evaluation, are as 

follows: 
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Statistical data of ship arrivals at Yokohama Port (2004) 

Number of incoming ships: 11,214/annum, 31/day 

Total gross tonnage: 193,647,519 GT/annum, 530,541 GT/day 

Percentage of total gross tonnage: Full container ship: 56.3% 

 Car carrier: 14.6% 

 Tanker: 12.2% 

 General cargo ship: 9.5% 

 Others: 7.4% 

Table 10. Condition of long-term risk evaluation at Yokohama Port 

(1) Since Japan is a country importing fossil fuels, such as crude oil, etc., it is assumed that 

all the tankers are inward ships (which do not discharge ballast water), the total of gross 

tonnage was deducted from the statistical data (2004). 

(2) Ballast water amount was estimated from class of ship and gross tonnage. 

Further, in order to determine the ‘worst-case’ risk to marine organisms from in-water 

concentrations of discharged the treated ballast water in Yokohama Port, three inner harbour 

locations were selected in order to find a ‘worst-case’ location in terms of dilution efficiency. 

These three test locations are shown in Fig. 4. Consequently, the CHEMMAP modelling 

simulated scenario 1 at these three locations until discharge dilutions were reduced to below the 

NOEC (that is 3.1% (v/v) of the treated ballast water in Port Waters). The NOEC is dilution rate 

with treated ballast water and dilution seawater. For scenario 2, only one location was selected 

as a ‘worst-case’ assumption and the CHEMMAP model simulated the discharge of the treated 

ballast water from all ships over a one year period at this location and calculated 

tribromomethane concentrations from an initial concentration of 0.16 mg/L before discharge to 

below PNEC (that is 0.29 mg/L assuming an assessment factor of 10) for the long-term 

simulation. 

Annual Daily Annual Daily Annual Daily

Full Container Ship 5,500 15 110,000,000 301,370 55,000,000 150,684

Car Carrier 1,500 4 37,500,000 102,740 7,500,000 20,548

General Cargo Ship 3,000 8 30,000,000 82,192 15,000,000 41,096

Total 10,000 27 177,500,000 486,302 77,500,000 212,328

Ship Type

Number of

Ships Gross Tonnage[t] Amount of Ballast

Water[t]
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Fig.4. Location map showing the simulated inner-harbour discharge locations used in the 

CHEMMAP modelling. 

5.3.2.1 Short-Term modelling 

For the short-term case study, the results of the modelling, given different combinations of the 

tides, release volume (least-case and worst-case) and release location (1, 2 and 3), were analysed 

to determine the time taken for treated ballast water to completely dilute to less than the NOEC 

(that is 3.1% (v/v) of the treated ballast water in Port Waters) for each different scenario tested 

(detail in section 5.3). These results are shown in Table 11. 

From Table 11 it can be concluded that volume is the most significant variable in determining the 

time frame for discharge dilution ratio to naturally disperse below NOEC while the effect of 

location and tidal strength demonstrated only a slight influence. Consequently, the longest 

period of time taken for discharged calculations to fall below NOEC was estimated by the model 

to be 24 hours after discharge ceases, that is, Test Number 7, being a worst-case discharge 

volume at Location 2 during neap tides. Fig. 5 shows the expected concentration distribution 

after 36 hours given a 12 hours discharge from a single ship. 

It is important to note that the calculated timeframes (Time period) in Table 11 do not include the 

period of discharge, being 12 hours for the worst-case volume and 6 hours for the least-case 

volume. 

The NOEC (that is the dilution ratio (3.1% (v/v)) with treated ballast water and dilution seawater) 

is 72h NOEC (algae) of the chronic toxicity tests (section 5.2) of the treated ballast water. It is 

showed that the value of PEC/NOEC reached less than 1 at 24 hours after discharge (at 36 hours 

after discharge start time). 
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Table 11. Model calculated time period for a discharge of treated ballast water 

from a single ship to completely dilute to levels below NOEC in Yokohama Port 

after discharge stops. 

Test 

Number Location Tides Volume 

(m3) 

Discharge 

period 

(hours) 

Time period (hours) 

1 1 Neap 3,000 6 1.25 

2 1 Spring 3,000 6 1.00 

3 2 Neap 3,000 6 1.50 

4 2 Spring 3,000 6 1.25 

5 3 Neap 3,000 6 1.50 

6 1 Neap 72,000 12 23.00 

7 2 Neap 72,000 12 24.00 

8 3 Neap 72,000 12 23.00 

9 3 Spring 72,000 12 21.50 

Fig.5. The expected concentration distribution after 36 hours given a 12 hours discharge from a 

single ship (Test Number 7). 

5.3.2.2 Long-Term modelling 

Given that the short-term results above show no exceedance of NOEC from a single discharge of 

the treated ballast water after 24 hours, the only other consideration was to investigate the effect 

of all ships discharging treated ballast water on a daily basis to see if there is the potential for 

multi-dose accumulation of tribromomethane. Multiple dosing occurs when subsequent 

discharge occurs at the same location as previous discharge and before the previous discharge 

have completely diluted. 
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Fig. 6 shows an example of the effect of this multiple dosing when assuming that all ships 

discharge at the one location, which is a worst-case assumption. The long-term risk of the treated 

ballast water discharges has been assessed with tribromomethane (initial concentration of 

0.16 mg/L and PNEC = 0.29mg/l, detail in section 5.3). The behaviors of tribromomethane 

concentration in natural seawater were considered for Henry’s law (volatile) and degradation rate 

that is k = 0.00978 (day-1) = 0.693/t1/2 (decay) set in the database of CHEMMAP (Science and 

technology Co., Ltd. and Asia-Pacific Applied Science Associates (2006),APPENDIX B). In 

Fig.6, it can be seen that from all ships discharging over 12 months, the distribution of 

tribromomethane concentrations do not exceed PNEC at any time during that period. The time 

series graph in Fig. 6 shows the peak concentrations of tribromomethane will initially increase 

from background levels, but this increase in concentration is limited due to its volatility and 

decay. The fluctuations in Hazard Quotient over time in Fig. 6 also demonstrate the influence of 

current speed on dilution; during spring tides mixing increases and dilution is maximised while 

during neap tides, mixing decreases and concentrations reach there peak at this time. 

Consequently, in conclusion, the CHEMMAP model results, shown in Fig. 6, demonstrate that 

this ‘worst-case’ scenario did not produce any accumulation that exceeded PNEC even with an 

assessment factor of 10 and all possible tidal regimes. 

Fig.6. The expected concentration distribution for a long-term simulation of a discharge of 

treated ballast water showing that accumulation is limited and that tribromomethane 

concentrations do not exceed PNEC even if all ships discharge at one location over a 12 month 

period. Insert time-series graph shows example concentrations 100m from discharge location. 
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6 RISK ASSESMENT 

6.1 Risk to safety of ship 

6.1.1 General 

The system is subject to the risks of excessive production of Active Substance, leaks from the 

apparatus resulting from system runaways caused by accidents or failures of the system. 

In this system, the amount of electrolytic chlorine generation is controlled by the applied current. 

Then, no excess chlorine is generated at normal operating condition. If the emergency condition 

(power failures, electrolytic leakage etc) occurs, current applying to electrolytic cell turns off. 

When the flow rate of injection seawater to electrolytic cell comes down below preset value, the 

electrolytic cell is turned off automatically to prevent excess chlorine generation. The flow rate 

of injection seawater to electrolytic cell is monitored using flow meters. 

6.1.2 Corrosion 

Sodium hypochlorite has chemical properties similar to those of the Active Substance and is 

corrosive to metals. It can therefore be assumed to increase the risk of corrosion of the piping or 

ballast tank. 

The intake/discharge line and ballast tank for the ballast water are normally protected by plating, 

paint, polymer linings, etc. to safeguard against corrosion. Direct contact between metal materials 

and the Active Substance is considered low. There are few risk of corrosion, however, only a low 

concentration (5.0 mg FAC/l) of the Active Substance is measured during treatment of this 

system. 

The polyethylene-lined steel pipe, FRP pipe, rubber lining steel pipe, etc. used for the electrolysis 

cell and piping around also reduce the risk of corrosion by conferring resistance against 

hypochlorous acid with high concentrations of the Active Substance (≤1,500 mg FAC/l). These 

piping materials have a long history of use in land-used MGPS. 

6.1.3 Generation of hydrogen gas 

As described in Section 3.2.2, the following reactions occur on the cathode surface during the 

generation of the Active Substance by the seawater electrolysis. This leads to a risk of explosion 

by accumulation of the resulting hydrogen gas. 

2H+

 + 2 e- → H2 (21) 

2H2O + 2e- → H2 + 2OH- (22) 

If the theoretical amount of hydrogen gas is assumed to be generated in this seawater electrolysis 

system, hydrogen gas of 0.14 mg-H2/l (1.58 ml-H2/l) will be generated against chlorine of 5.0 mg 

FAC/l, the maximum amount required for typical seawater treatment. This is very small in 

comparison with the solubility of hydrogen in water (1.62 mg-H2/l-H2O; freshwater, 21°C, 1 atm) 

(HSDB, 2006), hence most of the generated hydrogen gas is thought to be dissolved in the 

seawater. 
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The hydrogen gas in the ballast water treatment equipment is also unlikely to accumulate, as the 

seawater electrolysis system uses a flowing type electrolytic cell without a hold-up portion for 

liquid/gas. 

Furthermore, only low concentration of the hydrogen gas shifts to the gas phase. The hydrogen 

gas is discharged from the ventilation hole of the ballast tank.

6.2 Risk to human health 

Details on the handling of the electrolyzed seawater containing the Active Substance are 

described in the MSDS attached as Appendix 2. 

Human contact with the electrolyzed seawater and with the chloride gas generated from 

hypochlorous acid, an Active Substance, are assumed to be very rare. The possibility of contact is 

very low under normal operation conditions and operation works. There have been no 

reported cases of disasters of this nature with affects on human health in the service history of 

MGPS® for ships. 

This seawater electrolysis system produces the Active Substance on board. Its adoption 

eliminates the need to load and store chemicals, as well as the risks related thereto. The Active 

Substance is produced inside sealed equipment, eliminating the danger of direct contact with 

personnel directly under normal operating conditions and operation works. 

The acute aquatic toxicity value of the electrolyzed seawater (Rats; Oral LD50=850 mg/kg, see 

Appendix 2) is low even in the worst case (leak of electrolyzed seawater from the electrolytic 

cell, ≤1500 mg FAC/L). The seawater has no chronic aquatic toxicity, mutagenicity/genotoxicity, 

carcinogenicity, developmental/reproduction toxicity, or endocrine disturbance effect. 

In the unlikely event that the treatment water leaks, the safety of the crew can be ensured by 

sufficiently ventilating the room and washing the site of the leak with ample water while wearing 

protective equipment (goggles, rubber gloves, masks for halogens, etc.). 

The concentration of Active Substance of treatment water in the ballast tank is lower (0.1-3.0 mg 

TRC/l) than the drinking water guideline of WHO (5mg TRC/l). Therefore, it is speculated that 

the hazard of the treatment water may near level to that of chlorinated drinking water. However, 

chronic toxicities of some of relevant chemicals are not evaluated. Then, at the time of a periodic 

inspection, it is preferable that the worker puts on personal protective equipment (goggles, rubber 

gloves, masks for halogens, etc.) to prevent direct contact with treatment water. 

The chlorine gas poses a higher risk to health than the electrolyzed seawater, but the conditions 

leading to chlorine gas generation (rise of temperature, decrease of pH, etc.) differ from normal 

operation conditions and the risk of generation are low. 

Thus, the methods commonly used to prevent oxygen deficiency (ventilation fan, compressed air, 

etc.) during the routine inspection of the ballast water tank are thought to secure the safety of 

the crew. 
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6.3 Risk to the aquatic environment 

As this system produces the Active Substance on board using seawater, there is no need to stow 

harmful chemicals on the ship. The amount of Active Substance produced can be controlled by 

the electric power applied to the electrolysis cell. And the electrolysis equipment is automatically 

shut down by the automatic safety devices, halting the production of Active Substance, in the 

rare event of an accident involving the system or ship. These safeguards ensure that Active 

Substance will not be released in high concentrations into the aquatic environment or cause 

adverse effects. 

The discharge of the ballast water treated with this system poses no hazard to the aquatic 

environment. As already described in the section on risk assessment (section 5.3), the discharge 

is rapidly diluted, rapidly diffuses, and it will not accumulate. This satisfies the provisions 

stipulated in the related regulations. 

7 ASSESMENT REPORT (G9:4.3) 

The persistence, bioaccumulation, and toxicity were assessed based on reliable bibliographic data 

on the physicochemical properties and environmental toxicity of the Active Substance generated 

with seawater electrolysis process and the relevant chemicals generated from ballast water 

treatment by the Active Substance. 

Neither the Active Substance nor relevant the chemical has persistence or bioaccumulation. 

On the other hand, the data indicate that hypochlorous acid/hypochlorite ion, both Active 

Substances, has toxicity. Furthermore, reliable data have yet to be reported on 2,2-dibromoacetic 

acid and 2,2,2-tribromoacetic acid, and neither of these brominated acetic acids could be 

definitively evaluated for toxicity. Notwithstanding, their toxicity in the electrolyzed seawater is 

much lower than the concentrations measured in documented cases of toxicity. The other relevant 

chemicals were found not to be toxic. 

Given the Active Substance has toxicity and that the toxicity of several of the other chemicals 

cannot be determined, the applicant executed a toxicity evaluation test and risk assessment of the 

treated ballast water discharges for the treated ballast water under the conditions of actual use. 

 

The NOEC of the treated ballast water has been determined to be 3.1% (v/v), based on the results 

of the chronic toxicity tests of the treated ballast water, water that had been chlorinated by a 

method simulating the ballast water treatment system according to the OECD test to evaluate 

toxicity for fishes, crustacean, and algae in the aquatic environment. Dilution ratio (treated ballast 

water/natural seawater) has been used for the NOEC of the treated ballast water. 

The transport, diffusion and fate of the discharge of ballast water treated by this treatment system 

were predicted using NOEC (reported by the toxicity tests), the high-resolution flow model 

(HYDROMAP), and the chemical compounds diffusion model (CHEMSAP). 

In the short-term risk assessment of the treated ballast water discharges, the estimation of the 

time required for the toxicity to fall below the NOEC (3.1% (v/v) as dilution ratio) presupposed 

different conditions of the discharge point, tide, and discharge amount. The time required for 

elimination of the risk was 1.00 - 1.25 hours for a ship with a ballast tank capacity of 3,000 m3

and 21.50 -24.00 hours for a ship with a ballast tank capacity of 72,000 m3. 
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In the long-term risk assessment, the applicant carried out a long-term simulation assuming the 

worst case, all ships anchored in Yokohama Port discharge ballast water at one point, using 

tribromomethane, the substance considered to have the highest persistence in the treated ballast 

water, as an indicator. The simulation estimated a tribromomethane concentration below 

PNEC (0.29 mg/l; assessment factor =10) all year. 

The evaluations of the ballast water management system, including the seawater electrolytic 

process, indicate that the system can satisfy the provisions stipulated in the related regulations, 

and further, that the system in no way poses risks to ships, human, the aquatic environment, or 

marine resources. 

The data used in this application concerning the seawater electrolytic process and Active 

Substance are based mainly on the results obtained by the laboratory test and from small 

pilot-scale test equipment. This raises unanswered questions about the scale-up effect, the 

fluctuation of seawater properties, etc. in relation to the current data and its certainty (G9:6.4.3). 

Plans are in place to continuously survey these effects in land-based tests and shipboard tests 

with the goal of developing systems to be approved in the future. 

8 REFERENCE 

Abdel-Rahman, M.S., D.M. Waldron and R.J. Bull. (1983) A comparative kinetics study of 

monochloramine and hypochlorous acid in rat. J. Appl. Toxicol. 3(4): 175-179 

AISE (1997) Benefits and Safety Aspects of Hypochlorite Formulated in Domestic Products 

APHA (1995) Part 4000 INORGANIC NONMETALLIC CONSTITUENTS 4500-Cl Chlorine 

(Residual), in: Standard Methods for the Examination of Water and Wastewater 19th, 4-36-4-47 

Arthur J.W., and Eaton J.G. (1971) Chloramine Toxicity to the Amphipod Gammarus 

pseudolimnaeus and the Fathead Minnow (Pimephales promelas) J.Fish.Res.Board Can. 28(12), 

1841-1845 

ATSDR (2005) Toxicological profile for bromoform and dibromochloromethane. Agency for 

Toxic Substances and Disease Registry, U.S. DEPARTMENT OF HEALTH AND HUMAN 

SERVICES. 

Bouwer E.J., Rittman B.E., McCarty P.L. (1981) Anaerobic degradation of halogenated l- and 

2-carbon organic compounds. Environ Sci Technol 15,596-599. 

Bowman F.J., Borzelleca J.F., and Munson A.E. (1978) The toxicity of some halomethanes in 

mice. Toxicol Appl Pharmacol. 44, 213-215. 

Cairns J. Jr., Niederlehner B.R. and Pratt J.R. (1990) Evaluation of joint toxicity of chlorine and 

ammonia to aquatic communities Aquatic Toxicology, 16(2), 87-100 

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9 ABBREVIATION 

ACGIH American Conference of Governmental Industrial Hygienists 

AF Assessment Factor 

 AISE Association Internationale de la Savonnerie, de la Détergence et des Produits 

d’Entretien 

ATSDR Agency for Toxic Substances and Disease Registry 

CPO Chlorine Produced Oxidant 

DBP Disinfection By-Product 

BCF Bioconcentration Factor 

DOC Dissolved Organic Carbon 

EC50 Median Effective Concentration 

FAC Free active chlorine 

GHS The Globally Harmonized System of Classification and Labelling of Chemicals 

GLP Good Laboratory Practices 

HSDB Hazard Substances Data Bank 

IARC International Agency for Research on Cancer 
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IC50 Median Inhibition Concentration 

IMO International Maritime Organization 

IUCLID International Uniform ChemicaL Information Database 

Koc adsorption coefficient 

LC50 Median Lethal Concentration 

LD50 Median Lethal Dose 

LOEC Lowest Observed Effect Concentration 

NA Not Availabel 

ND Not Determined 

NITE National Institute of Technology and Evaluation, Japan 

NTP National Toxicology Program 

NOAEL No Observed Adverse Effect Level 

NOEC No Observed Effect Concentration 

NOEL No Observed Effect Level 

OECD Organization for Economic Cooperation and Development 

PBT Persistence, Bioaccumulation, Toxicity 

PEC Predicted Environmental Concentration 

PNEC Predicted No Effect Concentration 

POC Particulate Organic Carbon 

Pow octanol/water coefficient 

PSU Practical Salinity Units 

QSAR Quantitative Structure-Activity Relationship 

THMs Trihalomethanes 

TOC Total Organic carbon 

TRC Total Residual Chlorine 

TRO Total Residual oxidant 

U.S.EPA United States Environmental Protection Agency 

WHO World Health Organization 

____________