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For reasons of economy, this document is printed in a limited number. Delegates are 

kindly asked to bring their copies to meetings and not to request additional copies.

INTERNATIONAL MARITIME ORGANIZATION

IMO

E

MARINE ENVIRONMENT PROTECTION 

COMMITTEE

56th session 

Agenda item 2

MEPC 56/2/3

6 April 2007

Original: ENGLISH

HARMFUL AQUATIC ORGANISMS IN BALLAST WATER

Basic Approval of Active Substances used by Resource Ballast Technologies System

(Cavitation combined with Ozone and Sodium Hypochlorite treatment)

Submitted by South Africa 

SUMMARY

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

Approval of Active Substances used by Resource Ballast

Technologies System (Cavitation combined with Ozone and Sodium 

Hypochlorite treatment) 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). The 

relevant documents and application dossier will be provided to the 

Marine Environment Division of the Organization for review by the 

GESAMP – Ballast Water Working Group.

Action to be taken: Paragraph 6

Related documents: BWM /CONF/36; MEPC 53/24/Add.1 and MEPC 56/1

Introduction

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

and Sediments states in regulation D-3 that Ballast Water Management systems which make use 

of Active Substances to comply with the Convention shall be approved by the Organization, 

based on a procedure developed by the Organization.

2 The Procedure for approval of Ballast Water Management systems that make use of 

Active Substances (G9) was adopted by resolution MEPC.126(53). Procedure (G9) requests 

IMO to establish a Technical Group (the GESAMP – Ballast Water Working Group) to review 

proposals for Basic Approval submitted by Administrations, and report its findings to the 

Organization. Procedure (G9) details in Section 8 the methodology to be followed by an

Administration seeking Basic Approval of Active Substances.
MEPC 56/2/3 - 2 -

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3 MEPC 55 agreed to invite Members to submit application dossiers for Basic Approval of 

Active Substances. Documents for MEPC 56 containing more than 6 pages of text should be 

submitted by Friday, 6 April 2007 (MEPC 56/1).

4 South Africa hereby submits to the Organization, in the annex of this document, the 

non-confidential information related to the Resource Ballast Technologies System (cavitation 

combined with Ozone and Sodium Hypochlorite treatment). The introduction part of the annex 

describes the system’s ability to meet the performance criteria detailed in the Guidelines for 

approval of Ballast Water Management systems (G8) as per resolution MEPC.125(53), while 

remaining safe to ship, crew and environment.

5 The complete proposal for Basic Approval including application dossier and relevant 

documents will be submitted to the Marine Environment Division of the Organization to be 

reviewed by the GESAMP-BWWG in accordance with Procedure (G9).

Action requested of the Committee

6 The Committee is invited to consider the above proposal for Basic Approval and decide 

as appropriate.

*** 
MEPC 56/2/3

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ANNEX

INFORMATION FOR BASIC APPROVAL OF ACTIVE SUBSTANCES USED BY 

RESOURCE BALLAST TECHNOLOGIES (CAVITATION COMBINED WITH OZONE

AND SODIUM HYPOCHLORITE TREATMENT)

1 INTRODUCTION

1.1 Background

Resource Ballast Technologies (Pty) Ltd. has over the past 5 years developed a solution to treat 

ballast water that meets the IMO standards. With the initial guidelines in mind and the

subsequent IMO Guidelines (G8) and Procedure (G9), the solution was designed to achieve the 

desired results. 

Particular attention was taken to the environmental requirements using cavitation as a primary 

treatment with small amounts of Active Substances to assist the cavitation process. The Active 

Substances (Ozone and Sodium Hypochlorite) are used as an assistant for the cavitation. 

Test results taken from water treated directly after the Resource Ballast Treatment

solution as shows chlorine levels (free and total) – (Appendix 1) < 0.4mg/L and Boromoform 

at 19.6μg/L (Appendix 2). As a guideline, both these levels are within the recommended 

standards for drinking water (Appendix 3).

A full-scale land-based test facility has been built at Cape Town Harbour (for Type Approval), 

capable of testing the Resource Ballast Technologies (RBT) Systems for flow rates

of 200m3/hr to 1500m3/hr. Through traditional testing methods, and with the use of a FlowCAM, 

tests conducted to date show that the RBT system consistently meets Guidelines (G8)

requirement for Type Approval. 

The Type Approval testing process is currently under way, with assistance from the University of 

Stellenbosch, The Aquaculture Institute of South Africa (AISA) and The Marine and Coastal 

Management Department of the Ministry of Environmental Affairs and Tourism.

The process is being co-ordinated under the supervision of the Department of Transport and the 

South African Maritime Safety Authority.

1.2 System configuration

1.2.1 Resource Ballast Technologies BWT Reactor

The RBT Reactor is an efficient, cost effective system designed to meet the requirements of IMO 

resolution MEPC 53/24. Two models of the reactor are currently available to suit installation in 

vessels with 6-inch and 10-inch ballast water pipe systems respectively.

The Reactor combines the use of mechanical cavitation, disinfection and physical separation 

methods to provide a system that is equally efficient in both salt-water and freshwater

environments. In addition, this combination of methods means that it can handle diverse water 

conditions such as high turbidity and polluted water, including that containing high levels of

organic and mineral matter.
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The disinfectants employed are produced within the system and thus, no additional storage 

facilities are required.

A basic block diagram of a typical Ballast Water Management System (BWMS) is shown below 

in Figure 1 and a dual-reactor system for installation in a vessel with port and starboard ballast 

water pumps in Figure 2. A further option is to replace the bypass valves shown in the

illustrations with a separate Reactor thus ensuring that ballast water treatment operations can 

continue even in the event of main reactor failure. If fitted, this Reactor would be connected to 

the same Electrical Control Panel (ECP) as the main Reactor.

The disinfection and mechanical processes are carried out within the Reactor while the physical 

separation is done by the electric filter located after the ballast pump. In the block diagram the 

Reactor is shown before the ballast pump but can be located after the ballast pump if necessary. 

If required, the ECP can be installed remote from the Reactor.

The BWMS is an automatic system with the amount of ballast water that it can treat being 

dependent on model of reactor installed. For example, a 6-inch Reactor can treat up to 450 m3 of 

ballast water per hour whereas a 10-inch Reactor can treat up to 1400 m3 per hour. Its automatic 

operation and remote monitor units allow the ship’s crew to continue with their normal tasks 

while ballast water operations are in progress. In addition, the relatively small size makes the 

system suitable for retrofit operations.

The RBT Reactor operates on normal shipboard supply, i.e. 400 VAC, 60 Hz. Note that a 

basic 320 m3 system requires a 7 kW supply.

A combination of units can be installed into a manifold/pod, to upscale the output capacity of the 

Reactor to the Treatment Rate Capacity (TRC) to suit the capacity of the ballast pumps installed 

on board the particular vessel.

System controls and indicators are located on the RMU, two of which are supplied. Real-time 

data, salinity and pH sensor readings are recorded on a data logging PC connected to the ECP.
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Figure 1: RBT Reactor System Block Diagram
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Figure 2: RBT Dual-Reactor System Block Diagram

1.3 Process Description

The BWMS incorporates a number of water treatment technologies. The methods used are as 

follows:

• Cavitation

• Electro-chemical (Chlorine)

• Ozone

• Filtration

It should be noted that no additional chemicals to those listed above are employed to allow the 

reactor to operate effectively. As such the safety of the crew and vessel are not jeopardized. 

Chlorine levels and Ozone levels are kept within the limits as required by manufacturers and 

suppliers of ballast tank coatings and should not pose any stress on the integrity of the ballast 

pipe work/system or ballast tank.
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1.3.1 Cavitation

Cavitation can be defined as the rapid creation and collapse of bubbles in liquid. Within the RBT 

Reactor there are several cavitation chambers which mechanically produce the bubbles as the 

ballast water flows through the reactor. When the bubbles reach a critical mass, they implode 

producing a shock wave which kills the organisms within the ballast water. Note that both the 

electro-chemical and Ozone processes assist in increasing the cavitation effect (see

Electro-chemical and Ozone sections for details).

1.3.2 Electro-Chemical

Mounted within the RBT chambers are a number of electrodes. The purpose of these electrodes is 

as follows:

The electrolytic production of sodium hyper chlorite (chlorine) compound (at levels of less than 

1ppm) which occurs when direct current is applied to the electrodes. This assists with the 

sterilization process and helps to maintain a sterile environment within the ballast tanks of the 

vessel. The amount of Sodium Hyper chlorite produced by the electrodes has a half-life 

of 12 hours and does not result in any additional hazardous or harmful by-products.

To assist the cavitation effect that is achieved by means of the addition of gaseous bubbles to the 

ballast water flow which are produced when direct current is applied to the electrodes.

The electrical charge induced into the water while passing through the Reactor has a detrimental 

effect on certain organisms.

1.3.3 Ozone

The ECP contains two Ozone generators. The Ozone gas produced is infused into the ballast 

water by means of a Venturi injector that only becomes operational once the RBT Reactor is 

powered. The maximum level of Ozone is 0.001mg/lt.

Ozone has a very short life span in seawater; however the primary effects that the infusion of the 

Ozone gas causes are as follows:

• provide an effective method of killing Aquatic Nuisance Species (ANS).

• provide an effective method of treating ANS in both salt-water and freshwater. For 

example, Should a vessel take on ballast water in freshwater ports the electrolytic

production of chlorine (as described in 1.2.2.2) will either not occur or be greatly reduced, 

and therefore the Ozone gas produced by the Reactor system compensates for this.

• assist the cavitation effect by increasing the levels of dissolved gases within the ballast 

water being treated. 
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1.3.4 Filtration

In the BWMS filtration is carried out before the ballast water enters the ballast tanks. The filter is 

located after the ballast pump and incorporates both coarse and fine filter screens. The standard 

fine screen is a 40-micron screen.

Cleaning of both the coarse and fine screens is carried out automatically with the “cake” from the 

screens being fed directly overboard.

1.4 Environmental

The BWMS generates a number of oxidising biocides to destroy cells in the ballast water. The 

oxidising agents and their quantities that the system produces are a maximum of:

• Ozone (0.001mg/l)

• Sodium Hypochlorite (<1ppm)

No additional conditioning of the ballast water is required to remove these agents from the ballast 

water. This is due to the fact that such small amounts are employed coupled with the fact that 

Sodium Hyperchlorite has a half life of less than 10 hours within seawater and Ozone has a 

half-life of 5.3 seconds in seawater.

The process also produces other by-products such as Trihalomethanes and Bromoform in limited 

quantities, which are well within the limits allowed for international standards for potable water.

Waste streams are limited to that from the cleaning of the electric filter screen. It is

recommended that this stream is discharged directly back into the port or location from where the 

ballast water is being taken on board, thereby ensuring that any filtered organisms and

contamination will remain in the water of the area of origin, and not be transported to other 

destinations. Note that all discharges cease when ballast operations cease as the filter and RBT 

reactor are electronically linked directly to the ballast pump. 

2 IDENTIFICATION OF THE SUBSTANCE OR PREPARATION 

2.1 Preparations

Active Substances to be used for treatment of ballast water using the RBT Reactor include Ozone

which is produced by a generator provided on board and other disinfectants such as the hydroxyl 

radical which are introduced directly into the media using an electrochemical system. The 

electrochemical system also allows for direct oxidation of micro-organisms and other

contaminants on the electrode surface. Neither of these processes involves the use of commercial 

preparations using additives, etc., and as such are not described in this application form.

2.2 Active Substances

In this application form, Ozone and the hydroxyl radical OH, are defined as Active Substances. 

Ozone exists in oxygen (raw material) at a ratio of 6 to 12%. Therefore, when it is used for 

treating the ballast water, it is in a state of Ozone gas. Hydroxyl radicals are produced at the 

electrodes of the electrolytic cell. They are highly reactive and decay within a few nanoseconds. 

Relevant chemical identifiers and components of Ozone gas and the hydroxyl radical are

listed in Table 1.
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Table 1. Components and relevant details (chemical identifiers) for Ozone gas and the

hydroxyl radical

Name of

substance

IUPAC 

International 

Chemical 

Identifier

CAS number Molar 

mass

Empirical 

formula

Structural 

formula Ratio Stabilizers/ 

additives

Ozone InChI=1/O3/c1-3-2 10028-15-6 6 48.00 O3 O=O=O ~ 12v/v% None

Oxygen InChI=1/O2/c1-2 7782-44-7 80 32.00 O2 O=O ~ 88v/v% None

Nitrogen InChI=1/N2/c1-27727-37-9 2 28.01 N2 N=N ~ 3v/v% None

Argon InChI=1/Ar 7440-37-1 4 39.95 Ar Ar ~ 5v/v% None

Hydroxyl 

radical

InChI=1/HO/h1H 3352-57-6 17.01 O*H HO - None

Note that basic approval has been issued for use of all of these Active Substances by the 

GESAMP-Ballast Water Working Group (GESAMP-BWWG) (MEPC 55/2, 2006). Full details 

on the nature, toxicity and risks posed by these Active Substances is nonetheless provided in this 

application for completeness.

2.3 Relevant Chemicals

Ozone is a very unstable molecule and, after injection into raw water (e.g., natural seawater or 

freshwater), it decomposes very rapidly. The chemistry of the breakdown process in seawater, 

however, differs from that in freshwater because of the presence of bromide ion in seawater. 

Ballast water taken up by a vessel may include fresh and salt water and hence both are relevant 

here. In seawater, Ozone reacts with bromide ions to produce hypobromous hypobromous acid 

(HOBr) and and hypobromite (OBr–) which are in equilibrium with one another (von Gunten and

Oliveras 1998, von Gunten 2003a, b). These compounds have disinfection properties. 

Bromoform (CHBr3), a disinfection byproduct, is also formed by a reaction with natural organic 

matter in the water. In freshwater Ozone breaks down more slowly (minutes rather than seconds) 

into oxygen and water. The rate of decomposition increases with the presence of organic 

impurities and increasing pH. As pH increases, Ozone turns into the very short-lived 

(microseconds) hydroxyl radicals (OH) (Rice and Wilkes, 1992).

The electrochemical system developed by the applicant produces a number of Active Substances 

and relevant chemicals at detectable concentrations including hydroxyl radicals (OH), free active 

chlorine (Cl2) and hydrogen gas (H2). Hydroxyl radicals (OH) are the primary Active Substances 

to be produced in freshwater, and is a very reactive oxidative species with a half-life in the order 

of nanoseconds. In seawater, sma ll amounts of chlorine gas (Cl2) are also likely to form on 

the anode surface of electrochemical system due to the presence of chloride ions. Reactions 

with the cathode on the electrochemical system will also produce other free active chlorine 

species – HOCl and/or OCl- – depending on the pH. Chlorine gas (Cl2) and the free active 

chlorine species (HOCl and OCl-) will rapidly decay back into chloride ions. Trihalomethanes

(THMs) (trifluoromethane CHF3, chlorodifluoromethane CHClF2, trichloromethane CHCl3) may 

also be formed in the reactor due to the reaction of chlorine species with organic matter in the 

ballast water.
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In this application, Ozone, bromate ions, bromoform, hydroxyl radicals, chlorine gas (Cl2), free 

free active chlorine species (HOCl and ClO-), and hydrogen gas generated during treatment of 

the ballast water are defined as relevant chemicals. Relevant chemical identifiers of these 

substances are provided in Table 2.

Table 2. Physical and chemical properties of the preparations and Active 

Substances used in the RBT system

Chemical name 

of substance

Ozone Bromate ion 

(in the form 

of 

Potassium 

bromate)

Bromoform Hydro

xyl 

radical

Chlorine 

gas

Sodium 

hypochlorite

Total 

residual 

oxidants

Hydrogen 

gas

Treated 

ballast 

water

Liquid 

Concentration

1358g/L (at -

112 oC)

- 2880g/L (at 

20 oC)

- - -

CAS number 10028-15-6 7758-38-0 75-25-2 3352-

57-6

7782-50-5 7681-52-9 - 01333-74-0 -

UN number and 

shipping name

UN1484

Potassium 

bromate

UN2515

Bromoform

- UN1017

Chlorine 

UN1971

Sodium 

hypochlorite

- UN1049

Hydrogen

-

Active 

Substance (AS)/ 

stabilizer/inhibit

or/ solvent

AS AS AS AS AS AS AS AS -

Molecular 

weight

48 167 252.73 17.01 70.9 74.4 - 2.015 -

Empirical 

formula

O3 KBrO3 CHBr3 HO Cl2 NaClO - H2 -

Structural 

formula

O=O-O O*H Cl-Cl Na-OCl - H – H -

Purity1 Usually 5-15% 

solution

>99% -

Necessary 

stabilisers &

additives

N/A N/A N/A N/A N/A N/A N/A N/A -

Melting point -193oC 350oC 8.3 oC - N/A -20 to -30 oC -259 oC -

Boiling point -112oC 370oC 150 oC - N/A 96-120 oC - -253 oC -

Flammability 

(flash point) oC

Noncombustible 

but promotes 

burning of 

other 

substances

N/A >107 oC N/A NonflammableN/A N/A N/A -

Density (20oC) 3.27 g/m31.1 (relative 

density)

0.0899x10-

3

g/cm3

-

Vapour pressure 

(20oC)

>1atm 6.4hPa 5.85 x 

103mmHg

-

Vapour Density

(air=1)

1.6 5.8 8.7 0.0695 -

Water 

solubility/dissoci

ation constant

(pKa)

Definition 

for liquid; no 

relation with 

gas

8.62 -

Oxidation/reduct

ion potential

2.07V 2.06V 2.8V 1.5V 1.7V -

Corrosivity to

the materials or 

equipment of

normal ship

construction

Yes Yes Yes Yes Yes -

Autoignition 

temperature

oC

Noncombustible 

but promotes 

burning of 

other

substances

Forms 

explosive 

mixtures 

with

flammable 

gases and 

mixtures

565.5 -
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Chemical name 

of substance

Ozone Bromate ion 

(in the form 

of 

Potassium 

bromate)

Bromoform Hydro

xyl 

radical

Chlorine 

gas

Sodium 

hypochlorite

Total 

residual 

oxidants

Hydrogen 

gas

Treated 

ballast 

water

Explosive 

properties

May cause 

fire or 

explosion 

when heated 

or coming 

into contact 

with a 

combustible 

material 

(alkene, 

ether)

Anhydrous 

sodium 

hypochlorite is 

explosive

Extremely 

especially at 

high 

temperatures

-

Oxidizing 

properties

Yes Yes Yes Yes -

Surface tension 3.84 x 10-2

N/mm (at -

183oC)

- -

Viscosity 1.5 x 10-3

Pa.s (at -

183oC)

66.6-67.6 - 0.01Pa.s

Thermal stability 

and identity of 

relevant 

breakdown 

products

Oxygen -

Reactivity 

towards 

container 

material

Yes -

pH - - - - - - - - 5-8

Salinity - - - - - - - -

TOC, DOC, % 

particulate 

matter

- - - - - - - -

Other known 

relevant physical 

or chemical 

hazards

Nothing 

noteworthy

Incompatibility 

with Nitrogen 

compounds, 

ammonium salts, 

acids, methanol. 

Copper, Nickel 

and cobalt speed 

up decomposition 

of NaOCl

Nothing 

notewort

hy

Analytical 

methods at 

environmentally 

relevant 

concentrations

2.4 Other chemicals 

No other relevant chemicals are produced by the RBT reactor.
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3 DATA ON EFFECTS ON AQUATIC PLANTS, INVERTEBRATES AND FISH, 

AND OTHER BIOTA, INCLUDING SENSITIVE AND REPRESENTATIVE

ORGANISMS

3.1 Ozone (Active Substance)

Ozone is an unstable gas that cannot be stored. In pure (fresh) water Ozone has a half life 

of 10-30 minutes. In seawater the half life is reduced to 5.3 seconds. Ozone decomposition rate 

increases in accordance with the increase of temperature and pH. The rate increases fast in the 

neutral to alkaline range at any temperature. This tendency accelerates with the increase of

temperature. The pH value of ballast water is generally between 5 and 8, in which range the 

decomposition of Ozone progresses quickly. Therefore it is highly unlikely that Ozone will have 

an effect on any ecosystem by the time the ballast water is discharged.

Note that Basic Approval has been recommended by the GESAMP-Ballast Water Working 

Group (GESAMP-BWWG) (MEPC 55/2, 2006) for use of Ozone at concentrations greater than 

those produced by the RBT reactor. Full details on the nature, toxicity and risks posed by this 

compound is nonetheless provided in this report for completeness.

3.1.1 Acute aquatic toxicity

The PAN pesticides database was used to obtain data on the acute toxicity of Ozone to aquatic 

organisms. Table 3 shows the effects of Ozone on representatives of three taxonomic groups 

(fish, molluscs and crustaceans). The acute toxicity of Ozone (LC50) used as an Active 

Substance for this system is 8.1μg/L in freshwater and 50μg/L in seawater.

Table 3. Effects of Ozone on representatives of two taxonomic groups (fish and 

molluscs)

Test 

water 

substance

Organism Scientfic/Common 

name

Stage Endpoint Effect Effect 

Measurement

Duration

Exp. 

Type

Concentr

ation as

Ozone

(μg/L)

Reference

Lepomis 

macrochirus

Bluegill

3.82g LC50 Mortality Mortality 24 hrs 60.0 Paller and

Heidinger 

(1979)

Morone saxatilis

Striped bass

Larvae, 

20mm

LC50 Mortality Mortality 6 hrs 150.0 Hall et al.

(1981)

Fish

Pimephales 

promelas

Fathead minnow

Larvae LC50 Mortality Mortality 0.03 hrs 100.0 Asbury and

Coler (1980)

Ozone

Molluscs Dreissena 

polymorpha

Zebra Mussel

Adult LC50 Mortality Mortality 5.78 hrs 520.0-

540.0

Harrington et 

al. (1997)

There is limited data on the chronic aquatic toxicity of Ozone. The concentration of Ozone will 

break down to <11 μg/L (NOEC for Daphnia magna, Leynan et al. 1997) within 40 seconds in 

seawater and within 3.5 hours in freshwater, and to <0.14 μg/L (natural background levels) 

within 75 seconds in seawater and 6.5 hours in freshwater. Thus, it is supposed that Ozone has 

no chronic aquatic toxicity.
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3.1.2 Endocrine disruption

There have been no documented studies on the endocrine disruptive properties of Ozone. Due to 

its rapid dissolution (see paragraph 3.2), it is considered not to be an endocrine disruptor. 

3.1.3 Sediment toxicity

The decomposition speed of Ozone is high enough so that there is no concern of toxicity to 

benthic organisms (see paragraph 3.2). 

3.1.4 Bioavailability/biomagnification/bioconcentration

Ozone decomposes very rapidly in natural water (see paragraph 2.2.1.1). Therefore there is no 

risk that Ozone may become concentrated in organisms.

3.1.5 Food web/population effects

Ozone does not persist or concentrate in organisms therefore there is no concern of effect on any 

animal high up the food chain.

3.1.6 Data on mammalian toxicity

The toxicity of Ozone to mammals is based on its strong oxidizing property. Ozone causes 

irritation to the eyes and to the pharynx, trachea, bronchi and bronchiole when inhaled. 

3.1.6.1 Acute toxicity

Acute toxicity data for Ozone is available from test conducted on mice (Cheminfo by Canadian 

Centre for Occupational Health and Safety). Data has been submitted for inhalation only and not 

for oral and dermal toxicity as Ozone is a gas and thus inhalation is the main exposure route of 

concern. The acute toxicity of Ozone (4 hours, LD50) is 5.9-6.8ppm.

3.1.6.2 Effects on skin and eye

Ozone gives no effect to the skin but causes irritation to the eyes at levels of 2 ppm or more when 

exposed for several minutes.

3.1.6.3 Repeated-dose toxicity

See chronic toxicity.

3.1.6.4 Chronic toxicity

In a series of studies, mice and rats exposed to 0.01-0.02 mg/kg bw/day for 105 to 130 weeks 

displayed increased incidence of non-carcinogenic lesions of the nose and lungs (NTP, 1994). 

Several studies also examined the effects of long-term exposure to monkeys. Exposures ranging 

from 0.003-0.013 mg/kg bw/day for 3-18 months consistently showed significant structural

alterations to lungs. Many of the changes seemed irreversible six months after exposure

had stopped.
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3.1.6.5 Developmental and reproductive toxicity

A study on offspring of rats continuously exposed to 0.020 or 0.03 mg/kg bw for four days 

during middle or late pregnancy produced reduced growth rates after birth and delayed

behavioural development. Maternal toxicity was not reported.

Another study reported a decrease in fetal body weight gain in the offspring of mice exposed 

to 0.024 but not to 0.008 or 0.016mg/kg bw, on days 7 to 17 of pregnancy. Signs of maternal 

toxicity were observed (Tox. Applied Pharmac. 1979).

Embryo toxicity in the form of increased resorption was observed in rats exposed to 0.03 

and 0.04 mg/kg bw, but not 0.013-0.025 mg/kg bw. Maternal toxicity was not reported

(COSHH).

Continuous exposure of mice from six days prior to mating to postnatal day 22 resulted in 

reduced body weight and slight effects in neurobehaviour development of the offspring. 

Maternal toxicity was not evaluated. No effects on reproductive performance (proportion of 

successful pregnancies, litter size, offspring viability and sex ratio) were noted (Arch.

Toxicology, 1995).

3.1.6.6 Carcinogenicity

From a study with rats and mice exposed to 0.0021, 0.01 and 0.02 mg/kg bw of Ozone

for 105-130 weeks, there was no evidence of carcinogenicity in male and female rats,

inconclusive evidence in male mice and some evidence in female mice. Ozone showed no 

tumour promoter properties in these studies (NTP, 1994).

3.1.6.7 Mutagenicity/genotoxicity

There are a number of studies which examine the potential for mutagenicity of Ozone in humans 

but due to some deficiencies not all of them seem to be conclusive.

However cytogenetic aberrations have been observed in the lymphocytes of hamsters exposed 

to 0.0048-0.086 mg/kg bw for 5 hours and in the macrophages of female rats

exposed 0.0024-0.016 mg/kg bw for 6 hours. Several studies have also shown that Ozone is 

mutagenetic in bacteria and in human and mammalian cells in vitro following inhalation

exposure (NTP, 1994; Mutation Research, 1992).

3.1.6.8 Toxicokinetics

Ozone is absorbed in both the upper and lower respiratory tract. It is a potent oxidant that reacts 

with protein and lipids, particularly within biological membranes. A small amount of Ozone is 

absorbed into the blood. The extreme reactivity of Ozone limits its ability to accumulate.
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3.1.7 Data on environmental fate and effect under aerobic and anaerobic conditions

Ozone reacts with both organic and inorganic compounds when injected into ballast water. 

The Ozone molecule is an unstable substance and its decomposition in water is promoted by 

higher temperatures and higher pH. In seawater, Ozone depredates with a half life of

between 5 and 30 seconds (Haag et al. 1983). It is finally decomposed to oxygen and water in 

the water.

Some of the main reactions when Ozone is injected into seawater are as follows:

1. O3 + Br ‡ O2 + OBr

2. O3 + OBr ‡ 2O3 + Br

3. 2O3 + OBr ‡ 2O2 + BrO3 

–

4. Br- + O3 fl‡ OBr

5. OBr- + H+ fl‡ HOBr

6. HOBr + Organic Matter ‡ CHBr3

7. HOBr + NH3 fl‡ NH2Br

Reactions 6 and 7 do not occur in water with a pH higher than 8 or in water with high contents of 

bromium compounds.

3.1.7.1 Modes of degradation (biotic; abiotic)

Ozone breaks down in an abiotic process into oxygen (O2).

3.1.7.2 Bioaccumulation, octanol/water partition coefficient

Bioaccumulation is a general term for the accumulation of substances, such as pesticides or other 

organic chemicals in an organism or part of an organism. The accumulation process involves the 

biological sequestering of substances that enter the organism through respiration, food intake, 

epidermal (skin) contact with the substance, and/or other means. The sequestering results in the 

organism having a higher concentration of the substance than the concentration in the organism’s 

surrounding environment. 

The level at which a given substance is bioaccumulated depends on the rate of uptake, the mode 

of uptake (e.g. through the gills of a fish, ingested along with food, contact with epidermis), how 

quickly the substance is eliminated from the organism, transformation of the substance by

metabolic processes, the lipid (fat) content of the organism, the hydrophobicity of the substance, 

environmental factors, and other biological and physical factors. As a general rule the more 

hydrophobic a substance is the more likely it is to bioaccumulate in organisms, such as fish. 

Another way of saying this is that bioaccumulation of a substance is correlated to the

octanol-water partition coefficient (KOW) of the substance. Increasing hydrophobicity

(lipophilicity) leads to an increasing propensity to bioaccumulate.

Bioccumulation data for Ozone shows the octanol/water partition coefficient to be less than 1 for 

Ozone. This means that it has a low propensity to bioaccumulate.
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3.1.7.3 Reaction with organic matter

Cyclo addition (Criegee mechanism)

Consequentially to its dipolar structure, an Ozone molecule can undergo a 1-3 dipolar cyclo 

addition with saturised compounds (double or triple bonds). This leads to the formation of a 

compound called ozonide (Figure 3).

Figure 3. Dipolar cyclo addition (Lenntech database)

In a protonic solution, such as water, primary ozonide disintegrates into an aldehyde, a keton or a 

zwitter ion (Figure 4). The zwitter ion will eventually be disintegrated further into hydrogen 

peroxide and carboxyl compounds.

Figure 4. Disintegration of ozonide (Lenntech database)

Electrophilic reactions

Electrophilic reactions occur in molecular solutions that have a high electronic density and 

mainly in solutions that contain a high level of aromatic compounds. Aromatic compounds that 

are substituted by electron donors (such as OH and NH2), have a high electronic density on the 

carbon compounds in ortho and para position. Consequentially, in these positions aromatic 

compounds react actively with Ozone. Figure 5 is an example of a reaction between Ozone and 

Phenol. Phenol groups react with Ozone relatively quickly.

Figure 5. Reaction between phenol and Ozone (Lenntech database)
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Nucleophilic reactions

Nucleophilic reactions mainly take place where there is a shortage of electrons and particularly at 

carbon compounds that contain electron-retreating groups, such as –COOH and -NO2. For 

electron-retreating groups, the reaction speed is much lower.

From the above-mentioned data, it appears that direct oxidation of organic matter by Ozone is a 

selective reaction mechanism, during which Ozone reacts quickly with organic matter that 

contains double bonds, activated aromatic groups or amines. It is also stated that Ozone reacts 

quicker with ionized and dissociated organic compounds than with the neutral (non-dissociated) 

type.

For most inorganic compounds in drinking water, the reaction speed is relatively high. The main 

reaction mechanism for oxidation of inorganic compounds is determined by transfer of the extra 

oxygen atom of Ozone to the inorganic compounds. For inorganic compounds, reaction speed is 

also higher for ionized and dissociated compounds.

In summary, Ozone oxidizes organic compounds selectively and partly. A large number of 

inorganic compounds are oxidized fast and completely.

3.1.7.4 Potential physical effects on wildlife and benthic habitats

As the half life of Ozone is 5.8 seconds in seawater and 30 minutes in fresh water, it decomposes 

too quickly for the treated ballast water to have any potential effects on wildlife and benthic 

habitats.

3.1.7.5 Potential residues in seafood

As Ozone is not accumulated, there will be no risk of residue in seafood.

3.1.7.6 Any known interactive effects

Ozone produces oxygen when decomposed in water. As a result it increases the amount of 

oxygen dissolved in the water which helps aquatic organisms. In a closed system, such as a 

seawater aquaculture system, Ozone removes nitrogen in the form of ammonia that is discharged 

from fish. 

3.2 Bromate Ion (Related Chemical)

Ozone reacts with bromide in seawater to form the bromate ion (BrO3

-

). The half life of the 

bromate ion is approximately 12 hours. Freshwater typically contains a very low concentration 

of the bromide ion and therefore the production of the bromate ion does not occur in freshwater.

Note that bromate ions are formed through reaction of Ozone with compounds in seawater and 

that Basic Approval has been recommended by the GESAMP-Ballast Water Working Group 

(GESAMP-BWWG) (MEPC 55/2, 2006) for use of Ozone at concentrations greater than those 

produced by the RBT reactor. Full details on the nature, toxicity and risks posed by this 

compound is nonetheless provided in this report for completeness.
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3.2.1 Acute aquatic toxicity

The PAN pesticides database was used to obtain data on the acute toxicity of bromate to aquatic 

organisms. Effects of bromate on representatives of three taxonomic groups (fish, molluscs, and 

crustaceans) are summarized in Table 4.

Table 4. Effects of bromate on three taxonomic groups (fish, molluscs and crustaceans)

Test water

substance

Organisms Scientfic/ 

Common

Name

Stage Toxicity 

Endpoint

Effect Effect 

Measurement

Duration

Exp. 

Type

Toxic 

dose 

(μg/L)

Reference

Cymatogaster 

aggregater

Shiner Perch

2.5-6cm LC100 Mortality Mortality 72 hrs 880,000 Crecelius 

(1979)

Fish

Oncorhynchus

Keta

Chum salmon

Juvenile

3cm

LC50 Mortality Mortality 96 hrs 512,000 Crecelius 

(1979)

Crassostrea 

gigas

Pacific oyster

Larvae EC50 Develop

ment

Development

al changes

48 hrs 30,000 Crecelius, 

1979

Macoma 

inquinata

Bent-nosed 

clam

2-3cm LC100 Mortality Mortality 72 hrs 880,000 Crecelius 

(1979)

Protothaca 

staminea

Littleneck 

clam

2-5cm LC100 Mortality Mortality 72 hrs 880,000 Crecelius 

(1979)

Molluscs

Crassostrea 

virginica

American 

oyster

Fertilized 

eggs

NR Mortality Mortality 48 hrs 1,000 Stewart et 

al. (1979)

Pandalus 

danae

Coon stripe

shrimp

4-5cm LC100 Mortality Mortality 72 hrs 880 000 Crecelius 

(1979)

Sewater

Bromate

Crustaceans

Neomysis 

awatschnsis

Opossum 

shrimp

Adult 

1.5-3.0g

LC50 Mortality Mortality 24 hrs 176 000 Crecelius 

(1979)

Freshwater 

Bromate

Not 

applicable

- - - - - - - -

3.2.2 Endocrine disruption

No instances have been reported for the endocrine disruptive properties of bromate ions.

3.2.3 Sediment toxicity

Soil absorption factor of bromate ion is estimated as follows from the relation with the

octanol/water partition coefficient, Pow:

 Koc = 0.41 x log Pow (-7.18)8 = 2.7 x 10-8 L/kg

This estimate of Koc: 2.7 x 10-8 L/kg is below the value of anticipated toxicity to benthic 

organisms and there is therefore no risk of toxicity to benthic organisms.
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3.2.4 Bioavailability/biomagnification/bioconcentration

The octanol/water partition coefficient log value of bromate ion is -7.18 and is therefore

considered not to pose a risk of concentration in organisms.

3.2.5 Food web/population effects

The bromate ion does not accumulate and there will therefore be no affect on organisms high in 

the food chain.

3.2.6 Data on mammalian toxicity

The toxicity of the bromate ion to mammals is based on its strong oxidizing properties. Bromate 

ions may effect the skin and eyes by exposure and cause coughing, pharynx pain, nausea, 

vomiting, abdominal pain, diarrhea or central nervous system disturbance if taken orally.

3.2.6.1 Acute toxicity

Experiments on rats have shown a single dose of Potassium bromate of concentration

LD50 321 mg/kg given orally is lethal (Sinochem chemical data sheet).

3.2.6.2 Effects on skin and eye

Bromate ions will cause skin and eye inflammation and pain.

3.2.6.3 Repeated-dose toxicity

The exposure of rats to bromate for 15 weeks demonstrated a No Observed Adverse Effect Level 

(NOAEL) of 30 mg/kg bw/day.

3.2.6.4 Chronic toxicity

The half life period of the bromate ion in seawater is approximately 12 hours longer than Ozone. 

Although the acute toxicity is relatively weak (approximately 1/1000 of that of Ozone) it is 

expected that the chronic effects are more likely due to the fact that it takes longer to decompose.

The carcinogenicity and chronic toxicity of potassium bromate (KBrO3) was studied in male 

B6C3F1 mice and F344/N rats to confirm and extend the results of previous work. Mice were 

treated with 0, 0.08, 0.4, or 0.8 g/L KBrO3 in the drinking water for up to 100 wk, and rats were 

provided with 0, 0.02, 0.1, 0.2, or 0.4 g/L KBrO3. Animals were euthanatized, necropsied, and 

subjected to a complete macroscopic examination. Selected tissues and gross lesions were 

processed by routine methods for light microscopic examination. The present study showed that 

KBrO3 is carcinogenic in the rat kidney, thyroid, and mesothelium and is a renal carcinogen in 

the male mouse, KBrO3 was carcinogenic in rodents at water concentrations as low as 0.02 g/L 

(De Angelo, 1998).
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3.2.6.5 Developmental and reproductive toxicity

Limited data are available on the reproductive or developmental effects of bromate by the oral 

route. Only one screening-level study (Wolf and Kaiser, 1996 in EPA/635/R-01/002, 2001) 

evaluates reproductive effects in rats. Although this study reports that pups were evaluated on 

postnatal day 5, no information on developmental endpoints is provided. No reliable

multigenerational studies are available. Another study showed several multigenerational studies 

in which rats or mice were fed bread made from flour treated with potassium bromate

(Kurokawa et al., 1986 in EPA/635/R-01/002, 2001), however, because most potassium

bromate added to flour is converted to bromide during the bread baking process it is unlikely 

that the animals in these multigenerational studies were actually exposed to bromate. No data 

are available evaluating reproductive or developmental effects by the inhalation route

(EPA/635/R-01/002, 2001).

In a study conducted for NTP, the potential reproductive and developmental toxicity of sodium 

bromate in Sprague-Dawley rats was evaluated following oral administration in the drinking 

water at concentrations of 0.25 ppm (2.6 mg/kg-day), 80 ppm (9.0 mg/kg-day), or 250 ppm

(25.6 mg/kg-day) over a 35-day period. (Equivalent bromate ion doses are 2.2, 7.7, and 22 mg 

BrO3 -/kg-day). (Wolf and Kaiser 1996 in EPA/635/R-01/002, 2001). Two groups of female rats 

were treated. Group A females (10/group) were dosed from study day 1 to 34 to test for effects 

during conception and early gestation. Group B females (13/group) were dosed from gestation 

day 6 to postnatal day 1 to test for effects during late gestation and birth. Male rats (10/group) 

were cohabited with Group B females for 5 days before dosing (study days 1-5) and were then 

dosed from study day 6 to day 34/35. Endpoints evaluated in males included clinical pathology, 

organ weight, sperm analysis, and histopathology. Endpoints evaluated in females included 

maternal body weight, number and weight of pups, and number of uterine implantations. 

Females in Group B were allowed to litter, and the pups were observed through postnatal day 5. 

However, there is no indication of the developmental endpoints that were evaluated in these pups 

or if any effects were observed. Treated males in the 250-ppm dose group demonstrated a 

statistically significant decrease (18%) in epididymal sperm density. All other endpoints

evaluated were comparable between controls and treated groups. Female reproductive function 

was not adversely affected. There were no treatment-related gross or microscopic changes in the 

kidney, liver, spleen, testis, or epididymis. These results indicated that sodium bromate treatment 

did not produce any adverse signs of general toxicity in any of the dose levels tested; a MTD was 

not reached. On the basis of changes in sperm density, this study identifies a NOAEL of 80 ppm 

(7.7 mg BrO3 -/kg-day) and a LOAEL of 250 ppm (22 mg BrO3 -/kg-day). (Taken directly from 

EPA/635/R-01/002, 2001).

3.2.6.6 Mutagenicity/genotoxicity

The carcinogenicity of KBrO to newborn rats and mice has been investigated. Male and female 

newborn F344 rats and ICR mice (24 hours old) were given single subcutaneous injections 

of 9.6, 19, 38, 77, or 154 mg BrO3 -/kg. Another group of newborn rats and mice received four 

weekly injections of 9.6, 19, 38, 77, or 154 mg BrO3 -/kg until weaning. Control animals 

received injections of olive oil. Rats were killed at 82 weeks, mice were killed at 78 weeks, and 

organs were examined histologically. No significant differences in the incidence of tumors in 

male or female rats or mice were observed. Under the conditions of the study, potassium

bromate had no potential for carcinogenicity in newborn male or female rats or mice

(Matsushima et al., 1986 in EPA/635/R-01/002, 2001).
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Another study tested the tumor initiation potential of bromate in a 104-week study in which male 

F344/NCr rats (29 or 39 per group) were given an intragastric dose of 300 mg KBrO3/kg (231 mg 

BrO3 -/kg), the maximum tolerated single dose. The rats were administered bromate alone, 

bromate followed by 4,000 ppm sodium barbital in the animal diet as a promoter, or sodium 

barbital in the diet alone. Sodium barbital was added to the die t starting 2 weeks after the 

animals were dosed with potassium bromate. Rats were examined at 30, 52, and 104 weeks for

nephropathy. At 30 weeks, renal damage (dysplastic tubular foci) was evident in the rats 

exposed to potassium bromate followed by sodium barbital and in rats exposed to sodium 

barbital, but not in those exposed to potassium bromate alone. The results indicated that a single 

oral dose of 300 mg KBrO3/kg (231 mg BrO3 -/kg) administered to rats does not initiate renal 

tumors within a 104-week observation period (Kurata et al. 1992 in EPA/635/R-01/002, 2001).

Groups of 8, 14, 20 and 26 male F344 rats were supplied with water containing 500 mg BrO3 -/L 

for up to 104 weeks to assess the time-course of renal cell tumor induction. The average daily 

consumption of potassium bromate was 41.9 mg/kg (32.3 mg BrO3 -/kg). At 104 weeks, the 

surviving animals were killed and examined histopathologically for dysplastic foci, renal

adenomas and adenocarcinomas, thyroid follicular cell tumors, and peritoneal mesotheliomas. 

All were significantly increased with continuous treatment. Dysplastic foci and renal adenomas 

were first observed following 26 weeks of continuous treatment. Renal dysplastic foci and 

adenomas were each significantly increased over controls by 52 weeks of treatment (mean 

number of renal cell tumors/rat was 0.81 vs. 0 in the controls). Continuous potassium bromate 

administration over 104 weeks resulted in renal adenocarcinomas in 3/20 (15%) and renal

adenomas in 6/20 (30%) rats. At 104 weeks the mean number of renal cell tumors/rat

was 1.25 compared with 0 in the controls. The combined incidence of follicular adenomas and 

adenocarcinomas of the thyroid was increased significantly (7/20 [35%]; p < 0.01) in rats 

receiving treatment for 104 weeks. The authors concluded that the minimum induction time for 

renal adenoma development was 26 weeks (Kurokawa et al.1987 in EPA/635/R-01/002, 2001).

The genotoxic potential of potassium bromate was examined in a variety of tests

with V79 Chinese hamster cells, including cytotoxicity, micronucleus, chromosome aberration, 

HPRT gene mutation, and comet assays. In addition, analysis was conducted on the HPRT 

mutations and for 8-oxodeoxyguanosine. Bromate was cytotoxic, increased the frequency of 

cells with micronuclei, increased the number of chromosome aberrations, and increased DNA 

migration in the alkaline comet assay. The majority of chromosome aberrations observed were 

chromatid breaks and chromatid exchanges. High-pressure liquid chromatography analysis 

revealed significantly increased levels of 8-oxodeoxyguanosine after potassium bromate

treatment. Furthermore, potassium bromate clearly induced gene mutations at the HPRT locus. 

Molecular analysis of potassium bromate-induced mutations indicated a high proportion of

deletion mutations. Three out of four point mutations were G-to-T transversions, which typically 

arise after replication of 8-oxoguanine. These results are consistent with oxidative damage 

induced by bromine radicals (Speit et al.1999 in EPA/635/R-01/002, 2001).

3.2.6.7 Toxicokinetics 

Bromate may be converted into hypobromic acid by hypochloric acid in the stomach. Liver and 

kidney tissues may degrade bromate to bromide by a process involving glutathione, although 

only a small amount appears to be reduced in this way. Bromate is excreted mainly by urine as 

bromate and bromide and some may also be eliminated by faeces. Bromate concentrations in 

urine peak at about 1 hour, and bromate is not detectable in plasma after 2 hours.
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In anaerobic conditions, the bromate ion is decomposed by anaerobic bacteria such as

methanogen.

3.2.7 Data on environmental fate and effects under aerobic and anaerobic conditions

3.2.7.1 Modes of degradation (biotic; abiotic)

Bromine is reportedly removed from seawater by several mechanisms (Perrins et al. 2006). 

HOBr/OBr_ reacts with natural organic matter to form bromoform (CHBr3) by the haloform 

reaction. In the presence of ammonia, HOBr/OBr- will react rapidly to form monobromamine 

which can subsequently disproportionate to NHBr2 and NH3 or with excess HOBr/OBrit can 

react further to form N2 and bromide. The rate of these reactions varies light and salinity 

concentration.

3.2.7.2 Bioaccumulation, octanol/water partition coefficient

Small amounts of bromine (1–2 ppm) were detected in the adipose tissue of mice, but not of rats, 

fed bread treated with potassium bromate in a lifetime study (Kurokawa et al., 1990 in

EPA/635/R-01/002, 2001). 

3.2.7.3 Reaction with organic matter

Bromate does not volatilize and is only slightly adsorbed onto soil or sediment. Because it is a 

strong oxidant, its most likely fate is reaction with organic matter, leading to the formation of 

bromide ion (WHO, 2005). Potassium bromide is also reportedly harmful if ingested in large 

amounts and it can cause skin and eye irritations.

3.2.7.4 Potential physical effects on wildlife and benthic habitats

The half life of the bromate ion in seawater is fairly short (~12 hours) and its estimated 

absorption coefficient is very low (2.7kg x 10-8 L/kg), there is no potential of effects on benthic 

organisms. The bromate ion is not accumulated and therefore will not affect high-order 

organisms in a food chain. 

3.2.7.5 Potential residues in seafood

The bromate ion is not accumulated and therefore there will be no potential residues in seafood.

3.2.7.6 Any known interactive effects

Under normal environmental conditions, it is difficult for the bromate ion to be reduced. 

However, it may be reduced to the bromide ion where ferrous ions, activiated carbon or other 

carbonaceous substances exist.

3.3 Bromoform (Tribromethane) – (Related Chemical)

Note that bromoform is produced through the reaction of Ozone with bromide ions in seawater 

and that Basic Approval has been recommended by the GESAMP-Ballast Water Working Group 

(GESAMP-BWWG) (MEPC 55/2, 2006) for use of the Ozone at concentrations greater than 

those produced by the RBT reactor. Full details on the nature, toxicity and risks posed by this 
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compound is nonetheless provided in this report for completeness.

3.3.1 Acute aquatic toxicity

The PAN pesticides database was used to obtain data on the acute toxicity of bromoform to 

aquatic organisms. Table 5 shows the effects of Bromoform on representatives of four

taxonomic groups (fish, molluscs, crustaceans and phytoplankton).

Table 5. Effects of bromoform on representatives of four taxonomic groups (fish, 

molluscs, crustaceans and phytoplankton)

Test water

substance

Organisms Scientfic

Name

Common 

Name

Stage Endpoint Effect Effect 

Measurement

Duration

Exp. 

Type

Minimum 

Toxic 

dose 

(μg/L)

Reference

Brevoortia 

tyrannus

Atlantic 

menhaden

NR LC50 Mortality Mortality 96 hrs 9,000 Anderson 

(1979)

Cyprinodon 

variegates

Sheepshead 

minnow

8-

15mm, 

14-28 

days

LC50 Mortality Mortality 48 hrs 16,000 Heitmuller 

et al.

(1981)

Fish

Lepomis 

macrochirus

Blue Gill

Juvenile, 

0.32-

1.2g

LC50 Mortality Mortality 24 hrs 33,000 Buccafusco 

et al.

(1981)

Crassostrea 

virginica

American 

oyster

75g NR Mortality Mortality 96 hrs 40,000 Gibson et 

al. (1981)

Molluscs

Mercenaria 

mercenaria

Hard clam

141g NR Mortality Mortality 96 hrs 140,000 Gibson et 

al. (1981)

Crustaceans Penaeus 

aztecus

Brown shrimp

3.3g LC50 Mort ality Mortality 96 hrs 20,000 Gibson et 

al. 1981

Selenastrum 

capricornutum

Green algae

NR EC50 Biochemistry Chlorophyll 24 hrs 18,700 US EPA,

1978

Bromoform

Phtyoplankton

Selenastrum 

capricornutum

Green algae

NR EC50 Population Population 

changes, 

general

96 hrs 28,100 US EPA,

1978

NR=Not recorded

3.3.2 Endocrine disruption

No information is available on disruption of endocrine functions by bromoform.

3.3.3 Sediment toxicity

Bromoform and dibromochloromethane have a minor tendency to be adsorbed by soils and 

sediments. Calculated and measured values of Koc (the organic carbon/water partition

coefficient, an index of the relative mobility of a material in water-soil systems) for bromoform 

range from 62 to 126 (Hassett et al. 1983; Hutzler et al. 1986; Mabey et al. 1982 in U.S. Agency 
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for Toxic Substances and Disease Registry, 2005). These relatively low values imply that 

bromoform will exhibit only a minor affinity for soil materials and will tend to be highly mobile 

(Roy and Griffin 1985 in U.S. Agency for Toxic Substances and Disease Registry, 2005). This 

low tendency for adsorption to soil has been confirmed in laboratory studies (Curtis et al. 1986 in 

U.S. Agency for Toxic Substances and Disease Registry, 2005) and in field studies by (Roberts 

et al.1986 in U.S. Agency for Toxic Substances and Disease Registry, 2005).

3.3.4 Bioavailability/biomagnification/bioconcentration

Bioaccumulation potential of the trihalomethanes appears to be low, compared to many

chlorinated organic compounds. 28 day uptake and depuration tests were conducted on five 

commercially and recreationally important species. These included three species of Penaeid 

shrimp and one species of fish (Gibson et al 1979 in UK Marine Special Areas of Conservation 

Database). The authors found that both uptake and depuration were rapid, with an equilibrium 

reached after 24 hours. Bioconcentration factors were relatively low (between <1 and 10 times 

the water concentration). Experiments using the marine oyster Crassostrea virginica have shown

that exposure to 90 µg l-1 bromoform for 24 hours resulted in a bioconcentration factor 

of 7.6. Uptake and depuration of bromoform were both rapid, both being essentially complete 

in 24-48 hours. However, it was concluded that the rate of uptake and depuration was dependent 

on the individual, the species and the concentration of bromoform in the water.

3.3.5 Food web/population effects

There is inconclusive evidence as to whether bromoform is concentrated up the food chain but it 

appears unlikely that bromoform persists in organisms.

3.3.6 Data on mammalian toxicity

Bromoform has been considered to be a moderately toxic chemical that can be absorbed

through the lungs, gastrointestinal tract, and skin. The oral LD50 value for tribromomethane 

is 1,400 and 1,550 mg/kg in male and female ICR Swiss mice (Bowman et al., 1978

in Melnick, 1989) and 1,388 and 1,147 mg/kg in male and female Sprague Dawley rats (Chu 

et al., 1980 in Melnick, 1989). Tribromomethane was slightly less acutely toxic than chloroform, 

bromodichloromethane, or chlorodibromomethane in rats and mice. In male rats, the

intraperitoneal LD50 value for tribromomethane is 414 yl/kg (1,196 mg/kg) (Agarwal and

Mehendale, 1983 in Melnick, 1989). Exposure to bromoform vapors may cause irritation to the 

respiratory tract, lacrimation, and liver damage (von Oettingen, 1955 in Melnick, 1989). 

The liver and kidney have been identified as target organs of trihalomethane toxicity in single 

exposure and short-term studies. Liver changes, described as variation in size of hepatocytes and 

vesiculation of biliary epithelial nuclei, were observed in female Sprague Dawley rats that 

survived a single oral dose of tribromomethane (1,071 mg/kg or higher) (Chu et al., 1982 in 

Melnick, 1989). Kidney changes were observed in Sprague Dawley rats that survived single oral 

doses of chloroform, bromodichloromethane, or chlorodibromomethane; however, these changes 

were not observed in rats exposed to tribromomethane. No pathologic changes were observed in 

Sprague Dawley rats exposed to tribromomethane at 5,50, or 500 ppm (equivalent to 0.13, 1.5, 

and 14 mg per rat per day, respectively) in drinking water for 28 days (Melnick, 1989).
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3.3.6.1 Acute toxicity

Oral LD50 values for bromoform are 1388 and 1147 mg/kg for male and female rats, respectively 

(Chu et al., 1980 in Faust, 1995) and 1400 and 1550 mg/kg for male and female mice,

respectively (Bowman et al. 1978 in Faust, 1995). The principal cause of death in laboratory 

animals following acute oral exposure is CNS depression. Clinical signs recorded in rats 

included piloerection, sedation, flaccid muscle tone, ataxia, prostration, and hypothermia. 

Enlargement of the livers and kidneys was also observed (Chu et al. 1980). At doses

of 1000 mg/kg, ataxia, sedation, and anesthesia occurred in mice within 60 minutes, with

sedation persisting for about 4 hours (Bowman et al., 1978 in Faust, 1995). In rats, a single 

gavage dose of 1000 mg/kg produced reductions in liver cytochrome P-450 content and 

aminolevulinic acid-dehydratase activity and increases in porphyrin content, suggesting

disturbances in hepatic heme metabolism (Moody and Smuckler, 1986 in Faust, 1995).

3.3.6.2 Effects on skin and eye

Direct contact with bromoform in liquid form causes redness and pain and may also be absorbed.

3.3.6.3 Repeated-dose toxicity

In a gavage study, F344/N rats and B6C3F1 mice were treated 5 times weekly for 13 weeks with 

bromoform at doses of 0, 12, 25, 50, 100, or 200 mg/kg (rats) or 0, 25, 50, 100, 200,

or 400 mg/kg (mice) (NTP, 1989 in Faust, 1995). All male rats treated with 100 or 200 mg/kg 

and all female rats treated with 200 mg/kg were lethargic. Dose-related increases of cytoplasmic 

vacuolization of hepatocytes were observed in males of both species, but not in females. 

Bromoform was administered to male and female mice by gavage at daily doses of 50, 125, 

or 250 mg/kg/day for 14 days. Several indices of humoral and cellular immunity were depressed 

in male but not in female mice exposed to the highest dose. In addition, liver weights and serum 

glutamate oxaloacetate transaminase (SGOT) levels were increased and serum glucose and blood 

urea nitrogen (BUN) levels were decreased in the high-dose animals (Munson et al. 1982 in 

Faust, 1995). In a similar study,72, 145, or 289 mg/kg/day of bromoform was fed by gavage to 

CD-1 mice for 14 days. BUN levels and serum creatinine values were not altered, but serum 

glutamate-pyruvate transaminase (SGPT) levels were elevated in high-dose animals. 

Histological changes were seen in the kidneys and liver in the midand high-dose groups and 

included hyperplasia of tubular epithelial cells, and hypertrophy and degenerative changes of the 

glomeruli in the kidney, and centrilobular cytoplasmic pallor and slight focal inflammation of the 

liver (Condie et al. 1983 in Fasut, 1995).

3.3.6.4 Chronic toxicity

Sprague Dawley rats were exposed to tribromomethane at 5,50, 500, or 2,500 ppm in drinking 

water for 90 days (Chu et al., 1982 in Melnick, 1989). Liver lesions were observed and the 

severity was increased in male rats dosed with 2,500 ppm tribromomethane and in female rats 

dosed with 500 or 2,500 ppm tribromomethane.

Tribromomethane was fed by gavage to CD-1 mice for 14 days at doses of 0, 72, 145,

or 289 mg/kg. Blood urea nitrogen (BUN) and serum creatinine levels were not altered;

however, active uptake of p-aminohippurate into renal cortical slices was reduced, and serum 
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glutamate-pyruvate transaminase (SGPT) levels were elevated in the high dose animals. Similar 

effects were observed in animals administered chloroform, bromodichloromethane, or

chlorodibromomethane. Histopathologic changes in the kidney (hyperplasia of tubular epithelial 

cells and hypertrophy and degenerative changes in the glomerular mesangium) and liver

(centrilobular cytoplasmic pallor and slight focal inflammation) were observed in the mid dose 

and high dose groups (Condie et al. 1983 in Melnick , 1989).

3.3.6.5 Developmental and reproductive toxicity

Teratology studies of organic concentrates were prepared from the drinking water of five U.S. 

cities. In addition, because low molecular weight organohalides may be lost during the

concentration procedure, a synthetic mixture was prepared based on the EPA monitoring survey 

of the concentrations of these compounds in 110 U.S. cities. The latter mixture

contained 68.9% chloroform, 16.4% bromodichloromethane, 10.0% chlorodibromomethane, 

and 3.6% tribromomethane. Each of these preparations, dissolved in dimethyl sulfoxide, was 

administered by gavage to groups of pregnant CD-1 mice on gestation days 7-14 at dose levels 

equivalent to 300, 1,000, and 3,000 times the anticipated human exposure. The mice that were 

administered the synthetic mixture at 3,000 times the human exposure level received 10.3 mg 

organohalide/kg per day (the tribromomethane dose level was 0.37 mg/kg per day). No effects 

on fetal weight, mortality, or the occurrence of skeletal or visceral anomalies were observed in 

any of the exposed groups (Kavlock et al. 1979 in Melnick, 1989).

Chloroform was administered to pregnant Sprague Dawley rats by gavage from day 6 to day 15 

of gestation at doses of 100, 200, or 400 mg/kg and tribromomethane, bromodichloromethane, 

and chlorodibromomethane at doses of 50,100, or 200 mg/kg. Corn oil was used as the vehicle 

for all studies. Only tribromomethane did not have an effect on maternal body weight gain. No 

histopathologic changes were observed for any of the four trihalomethanes in any of the dams or 

fetuses, nor were there any changes in the number of resorption sites, number of fetuses per dam, 

average fetal weight, or occurrence of visceral anomalies (Ruddick et al. 1983 in Melnick, 1989).

3.3.6.6 Mutagenicity/genotoxicity

Human data are considered inadequate in providing evidence of cancer by exposure 

to bromoform, while animal data indicate that long-term oral exposure can cause liver and 

intestinal tumors. Bromoform has been classified as a Group B2, probable human carcinogen 

(US EPA, 2000).

3.3.6.7 Toxicokinetics 

Bromoform and dibromochloromethane can be absorbed by inhalation ingestion, and dermal 

routes of exposure. In humans and laboratory animals, bromoform is generally absorbed quickly 

(Backer et al. 2000 in U.S. Agency for Toxic Substances and Disease Registry, 2005). Although 

bromoform and dibromochloromethane are lipophilic, they do not appear to accumulate in

adipose tissue (Stanley 1986 in U.S. Agency for Toxic Substances and Disease Registry, 2005). 

Bromoform and dibromochloromethane are thought to be metabolized by at least two

route-independent pathways: oxidation by cytochrome P-450 mixed function oxidase system

(Ahmed et al. 1977; Anders et al. 1978 in U.S. Agency for Toxic Substances and Disease 

Registry, 2005) and conjugation via glutathione S-transferase (DeMarini et al. 1997; Pegram 

et al. 1977 in U.S. Agency for Toxic Substances and Disease Registry, 2005). Bromoform is 

primarily excreted via exhalation as the parent compound or carbon dioxide (Mink et al. 1986 in 
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U.S. Agency for Toxic Substances and Disease Registry, 2005).

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

3.3.7.1 Modes of degradation (biotic; abiotic)

Bromoform tends to volatilize from water when exposed to the air, where it is relatively stable 

with a half-life of 1-2 months (ATSDR, 1990). Most measurements of the concentration of

bromoform in air indicate that levels are quite low (<10 ppt). 

3.3.7.2 Bioaccumulation, octanol/water partition coefficient

Bromoform may be slightly bioconcentrated by aquatic organisms. The octanol/water partition 

coefficient (Kow) (an index of the partitioning of a compound between octanol and water) is 

approximately 2.38 for bromoform (Mabey et al. 1982 in U.S. Agency for Toxic Substances and 

Disease Registry, 2005). The magnitudes of these values suggest that the chemicals will tend to 

partition to fat tissues of aquatic organisms (U.S. Agency for Toxic Substances and Disease 

Registry, 2005).

3.3.7.3 Reaction with organic matter

Trihalomethanes such as bromoform are formed as a byproduct when chlorine or bromine are 

used to treat ballast water. They result from the reaction of chlorine and/or bromine with organic 

matter in the water being treated. However, once the bromoform is formed it does not appear to 

have any further reactions with organic matter.

3.3.7.4 Potential physical effects on wildlife and benthic habitats

No information is available on the effects of bromoform on wildlife or benthic habitats.

3.3.7.5 Potential residues in seafood

No information is available on bromoform residues in seafood.

3.4 Free active chlorine (Active Substance)

The following compounds are all treated under this heading:

- Chlorine gas (Cl2)

- HOCl and ClO- (Sodium hypochlorite)

- Total Residual Oxidants (TRO)

Note that Basic Approval has been recommended by the GESAMP-Ballast Water Working 

Group (GESAMP-BWWG) (MEPC 55/2, 2006) for use of the chlorine compounds produced 

through electrochemical reaction for treatment of ballast water at concentrations greater than 

those produced by the RBT reactor. Full details on the nature, toxicity and risks posed by this 

compound is nonetheless provided in this report for completeness.
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3.4.1 Acute aquatic toxicity

The US EPA database was used to obtain data on the acute toxicity of chlorine to aquatic 

organisms. Effects of chlorine on representatives of four taxonomic groups (fish, molluscs, 

crustaceans and phytoplankton) is reported in Table 6.

Table 6. Effects of chlorine on representatives of four taxonomic groups (fish,

molluscs, crustaceans and phytoplankton)

Test 

water 

substance

Organisms Scientfic

Name

Common 

Name

Stage Toxicity 

Endpoint

Effect Effect 

Measurement

Durati

on

Exp. 

Concentrat

ion (mg/L)

Reference

Salvelinus 

fontinalis

Brook trout

11-15cm LC100 Mortality Mortality 9 hrs 350.0 Dandy, 

(1972)

Fish

Morone 

saxatilis

Striped bass

Fry, 1g LC50 Mortality Mortality 6 hrs 610.0 Bills et al. 

(1992)

Crassostrea 

gigas

Pacific 

oyster

Veliger LC50 Mortality Mortality 1 hr 556.0 Chien and

Chow, 1989

Molluscs

Mercenaria 

mercenaria

Hard Clam

Larvae LC50 Mortality Mortality 48 hrs 5.0 Bellanca 

and Bailey,

1977

Asellus 

aquaticus

Aquatic 

sowbug

Mature, 

nonreproducin

g

LC50 Mortality Mortality 24 hrs 754.0 KaniewskaPrus, 1982Crustaceans

Callinectus 

sapidus

Blue crab

Adult LC50 Mortality Mortality 48 hrs 750.0 Vreenegoor 

et al. 1977

Chlorine 

gas (Cl2)

Algae Chlorophyce

ae

Green Algae

8 species NR Populatio

n

Abundance 24 hrs

Static 

system

100.0 Toetz et al. 

1977

Fish Clupea 

pallasii

Pacific 

herring

Juvenile LC50 Mortality Mortality 96 hrs 65.0 Thatcher, 

1978

Lepomis 

macrochirus

Bluegill

Juvenile LC50 Mortality Mortality 96 hrs 580.0 Office of

pesticide 

programs, 

2000

Dreissena 

polymorpha

Zebra mussel

Adult LT95 Mortality Mortality 17.7 

hrs

90.0 Harrington 

et al . 1997

Crassostrea 

virginica

American 

oyster

Larvae (7

days)

LC50 Mortality Mortality 0.5 hrs 120.0 Capuzzo, 

1979

Clibanarius 

humilis

Hermit crab

NR LC50 Mortality Mortality 96 hrs 2,500.0 Best, 1991

Sodium 

hypochlor

ite

Molluscs

Hemigrapsus 

nudus

Shore crab

Adult LC50 Mortality Mortality 96 hrs 1,418.0 Thatcher, 

1978
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Test 

water 

substance

Organisms Scientfic

Name

Common 

Name

Stage Toxicity 

Endpoint

Effect Effect 

Measurement

Durati

on

Exp. 

Concentrat

ion (mg/L)

Reference

Chlorella 

sorokiniana

Green algae

225 

cells/ml

NR Mortality Mortality 20 hrs 200.0 Kott and

Edlis, 1969

Crustaceans

Plankton Chaetocero

s, Gracilis,

Dunaliella

LC50 Mortality Mortality 96 hrs 90.0 Best, 1991

3.4.2 Endocrine disruption

No information is available on endocrine disruption by chlorine

3.4.3 Sediment toxicity

Chlorine may react with soil and sediment components to form chlorides, which, depending on 

their water solubility, are easily washed out. (Seiler et al. 1988 from US EPA database).

3.4.4 Bioavailability/biomagnification/bioconcentration

There is no potential for the bioaccumulation or bioconcentration of chlorine (HSDB, 1994).

3.4.5 Food web/population effects

As there is no potential for bioconcentration of chlorine, animals high in the food chain will not 

be affected.

3.4.6 Data on mammalian toxicity

Sodium hypochlorite solution causes moderate mucosal irritation, the extent of which depends on 

the volume ingested, the viscosity and concentration of the preparation and the duration of the 

contact. When swallowed it may cause gastrointestinal irritation, with nausea, vomiting and 

diarrhea. Haematemesis may occur with concentrated solutions.

3.4.6.1 Acute toxicity

In humans, oral doses of 2.5 mg chlorine/day, administered to 10 men for 12 weeks, had no 

adverse effects (U.S. EPA 1990). No adverse effects were noted in persons ingesting water 

containing 50-90 ppm of chlorine (~1.4 to 2.6 mg Cl/kg/day) for a short period of time (U.S. 

EPA 1989). Drinking water concentrations of >90 ppm chlorine caused irritation of membranes 

of throat and mouth (U.S. EPA 1989). Concentrations of chlorine in the drinking water of 

greater than 25 ppm make the drinking water unpalatable (U.S. EPA, 1989).

Chlorine is considered a primary irritant to the mucous membranes of the eyes, nose, and throat 

and to the linings of the entire respiratory tract (Stokinger 1982). The extent of acute injury to 

humans depends on the concentration and duration of exposure as well as the water content of the 

tissue involved and the presence of underlying cardiopulmonary disease (HSDB 1994). The 

estimated clinical effects of varying concentrations of chlorine are as follows: mild mucous 

membrane irritation at 1-3 ppm; moderate irritation of the upper respiratory tract at 5-15 ppm; 

immediate chest pain, vomiting, dyspnea, and cough at 30 ppm; toxic pneumonitis and
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pulmonary edema at 40-60 ppm; death at 430 ppm for 30 minutes or 1000 ppm for a few minutes 

(HSDB 1994). Seventy-six individuals, exposed during a football game when

approximately 1,100 pounds of chlorine gas were released from a plant, suffered no serious or 

prolonged incapacitation due to the release (HSDB 1994). If one survives acute exposure to 

chlorine, recovery is usually complete and rapid (U.S.EPA 1989).

In animals - LC50 values for rats and mice are estimated to be 293 ppm for 1 h and 137 ppm 

for 1 h, respectively (HSDB 1994). LCLo values for other species range from 330 ppm for 7 h 

(guinea pigs) to 660 ppm for 4 h (cats and rabbits) (U.S. EPA 1989). Mice and rats exposed to 

chlorine at the RD50 concentration (9-11 ppm, 6 h/day for 1, 3, or 5 days) developed degeneration 

of olfactory sensory cells in the olfactory mucosa, loss of cilia of the respiratory epithelium, and 

cellular exfoliation, primarily of the naso- and maxilloturbinates (HSDB 1994). Signs and 

symptoms of the acute oral toxicity of chlorine in rats include decreased blood glutathione 

(30 minutes after 0.2 mg chlorine/kg administered as HOCl); decreased hypothalamic

norepinephrine levels and increases in normetanephrine levels (3 and 24 hours after intubation 

of 250 mg/kg free chlorine as HOCl); morphological and biochemical liver changes

(within 2 days of dosing with 142.9 mg/kg free chlorine as NaOCl); kidney enlargement (200 

mg/kg/day available chlorine for 14 days) (U.S. EPA 1989); and dose-related increase in liver 

and kidney weights (210 mg dietary chlorine/kg body weight/day for 28 days) (U.S. EPA 1987). 

C57Bl/6N mice given chlorine (25-30 ppm) in the drinking water for one to three weeks had 

significant decreases in the number of peritoneal exudate macrophages, and decreased in vitro 

cytotoxicity against mouse melanoma (B16) and fibrosarcoma (UV-112) target cells

(U.S. EPA 1989).

3.4.6.2 Effects on skin and eye

Free active chlorine can cause mild skin irritation to corrosive injury depending on the duration 

of the contact, concentration and pH of the solution. An 8% sodium hypochlorite solution has 

been shown to not cause skin irritation. Mild eye irritation to corrosive injury can also be caused 

depending on the concentration and pH of the solution and the duration of contact. 

3.4.6.3 Repeated-dose toxicity

See chronic toxicity.

3.4.6.4 Chronic toxicity

The major target organs for the subchronic/chronic toxicity of chlorine in humans are the 

respiratory tract and the blood. The major target organs for the subchronic/chronic toxicity of 

chlorine in animals are the immune system, the blood, the cardiovascular system and the

respiratory tract. The US EPA has derived an oral RfD (reference dose) of 0.1 mg/kg/day for 

chlorine, based on a no-observed-adverse-effect level of 14.4 mg/kg/day in a chronic drinking 

water study in rats.

Fifty-five workers exposed to about 1.0 ppm of chlorine, 8 h/day for at least 90 days exhibited 

asthma, chronic bronchitis, tuberculosis, and emphysema (U.S. EPA 1987). The concentration 

of 1 ppm is roughly equivalent to 0.415 mg/kg/day. In one case study, exposure to 0.015 mg/L 

of chlorine, 8 h/day for 6 years resulted in dyspnea, marked emphysema of both lower lung 

lobes, and reduced respiratory mobility (U.S. EPA 1987). Fifteen male workers exhibited 

decreased residual levels of maximal mid-expiratory flow rates and FEV/FVC after exposure 

to 0.18 ppm chlorine, 8 h/day, 5 days/week for 8.9 years (U.S. EPA 1990). Workers
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in 25 chlor-alkali plants (332 males), exposed to chlorine concentrations of 0.006 to 1.42 ppm 

(8-h TWAs) for about 10.9 years showed no dose-related correlation between chlorine exposure 

and the prevalence of colds, dyspnea, palpitation, chest pain, or permanent lung damage

(544 exposed workers had chest x-rays) (Stokinger 1982 in US EPA, 1994). 

Animals - Groups of 70 F344/N male and female rats were given drinking water containing up 

to 275 ppm of chlorine (14.4 mg/kg/day) for 2 years. No hematologic abnormalities were 

detected at interim sacrifices (14 and 66 weeks) and no non neoplastic abnormalities were 

observed in extensive gross and microscopic examinations at the end of the study (NTP 1992). 

The EPA used the no-observed-adverse-effect level, 14.4 mg/kg/day, to calculate a chronic oral 

RfD of 0.1 mg/kg/day for chlorine (U.S. EPA 1994).

Sprague-Dawley rats, given 5, 15, or 30 ppm chlorine in drinking water from weaning to 

12 weeks of age exhibited significantly reduced spleen weights, suppressed delayed-type 

hypersensitivity reactions, and decreased oxidative metabolism by macrophages at the highest 

dose; no effects were noted for the other doses or on other parameters of immunotoxicity

(NTP 1992). F344 rats given doses of chlorine up to 60 mg/kg/day for 92 days exhibited no 

histopathology in major organs (U.S. EPA 1989). Other species, exposed subchronically to 

chlorine exhibited the following: mice had no adverse effects on weight gain, food or water 

consumption, histological parameters (12.5 mg/kg/day for 50 days or 25 mg/kg/day for 33 days) 

(U.S. EPA 1989); New Zealand rabbits had increased hydroxyproline levels in heart tissue 

(1.6 mg chlorine/kg/day for 3 months; no effect at 0.1 mg/kg/day) (U.S. EPA 1989); Carneau 

pigeons exhibited cardiovascular effects (10 mg chlorine/kg/day in drinking water for 9 months) 

(U.S. EPA, 1989).

In various studies, Sprague Dawley and F344 rats treated with chlorine orally for 12-24 months 

at doses ranging from 0.14 to 22 mg/kg/day exhibited one or more of the following symptoms: 

significant decreases in red blood cell count and hematocrit (reversed at 6 months), increased 

osmotic fragility, increased mean corpuscular hemoglobin, significant decreases in body and 

liver weights, decreased brain and heart weights (p<0.05), and decreased salivary gland and 

kidney weights (U.S. EPA 1989), decreased spleen weight, and decreased thyroid weight

(U.S. EPA, 1987).

Rhesus monkeys (4/sex/dose) exposed to ó2.3 ppm of chlorine 6 h/day, 5 days/week for 1 year 

experienced ocular irritation, conjunctival irritation, hyperplasia of the nasal mucosa, and, in 

some females, epithelial hyperplasia of the trachea with minimal evidence of early

nonkeratinizing squamous metaplasia (U.S. EPA, 1990).

3.4.6.5 Deve lopmental and reproductive toxicity

No conclusion on the developmental/reproductive toxicity of chlorine can be made based on the 

limited information available from human and animal studies. 

Humans – No information was found in the secondary sources searched to indicate that chlorine 

is a developmental/reproductive toxicant in humans.

Animals – Female Sprague-Dawley rats were given chlorine concentrations of 0, 1.0, 10,

or 100 mg/L in the drinking water (as HOCL) for 2.5 months prior to conception and throughout 

gestation, were killed on gestation day 20, and the fetuses were examined (NTP 1992 in

U.S. EPA, 1994). Resorption was not increased at any concentration; however, fetuses in
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the 100 mg/L group had soft tissue defects, including improper orientation of the heart and 

adrenal agenesis, and a slightly increased incidence of skeletal variants, such as incompletely 

ossified or missing sternebrae or rudimentary ribs. Statistical analyses were not available. 

In other studies, chlorine administered to pregnant mice was negative for reproductive and 

teratogenic effects when given in drinking water as 10-13 ppm of sodium hypochlorite and 

hydrochloric acid (to maintain water pH of 2.5) or when given in heavily chlorinated municipal 

drinking water (U.S. EPA, 1989). 

Sperm head abnormalities were observed in B6C3F1 mice given 1.6 and 4.0 mg/kg/day of

chlorine as OCl-, but not at 8.0 mg/kg or when given as HOCl (U.S. EPA 1994). BDII rats 

(236 total males and females) given 10 mg/kg/day of free residual chlorine in the drinking water 

throughout 7 generations had no adverse effects on weight gain, food consumption, water 

consumption, fertility, lifespan, growth pattern, hematology, histology (liver, spleen, kidney or 

other organs) (U.S. EPA, 1989).

3.4.6.6 Mutagenicity/genotoxicity

Chlorine was mutagenic in Salmonella typhimurium strains TA1530 and TA100, without

metabolic activation; produced chromosome aberrations in human lymphocytes and other

mammalian cells (ò20 ppm); interacted with DNA in E. coli polA test (as sodium hypochlorite); 

and was negative for the induction of erythrocyte micronuclei or chromosome aberrations of 

bone marrow cells of Swiss CD-1 mice (up to 8 mg/kg/day of NaOCl) for up to 5 days 

(U.S. EPA, 1989).

3.4.6.7 Toxicokinetics 

No additional information is available on toxicokinetics for chlorine.

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

3.4.7.1 Modes of degradation (biotic; abiotic)

Chlorine hydrolyzes very rapidly in water (rate constants range from 1.5 x 10-4 at 0øC 

to 4.0 x 10-4 at 25øC; half-life in natural waters, 0.005 s) (U.S. EPA 1989). In fresh and 

wastewaters at pH >6, complete hydrolysis occurs with the formation of hypochlorous acid 

(HOCl) and chloride ion (Cl-). The hypochlorous acid ionizes to hydrogen ion (H+) and 

hypochlorite ion (OCl-). At pH values >5, OCl- predominates; at pH values <5, HOCl

predominates (U.S. EPA 1989). Free chlorine (Cl2, HOCl, and OCl-) reacts rapidly with 

inorganics such as bromide and more slowly with organic material present in natural waters. 

These reactions yield chloride, oxidized organics, chloroganics (including trihalomethanes),

oxygen, nitrogen, chlorate, bromate and bromoorganics.

3.4.7.2 Bioaccumulation, octanol/water partition coefficient

There is no potential for the bioaccumulation or bioconcentration of chlorine (HSDB 1994).

3.4.7.3 Reaction with organic matter

Chlorine reacts slowly with organic material present in natural waters. These reactions yield 

chloride, oxidized organics, chloroganics (including trihalomethanes), oxygen, nitrogen, chlorate, 

bromate and bromoorganics.
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3.4.7.4 Potential physical effects on wildlife and benthic habitats

Chlorine has been shown to have high acute toxicity to many organisms (U.S. EPA, 1994). Low 

level chlorination (0.05 to 0.15 mg/L) results in significant shifts in the species composition of 

marine phytoplankton communities (HSDB 1994 in U.S. EPA, 1994). Chlorine is phytotoxic but 

is also essential to plant growth; crops need around 5 pounds or more of chlorine per acre. 

Acute toxicity to plants is characterized by defoliation with no leaf symptoms and, in higher 

plant forms, by spotting of the leaves (at 1.5 mg/m3) and marginal and interveinal injury

(at 150-300 mg/m3) (Seiler et al. 1988 in U.S. EPA, 1994). No data were found regarding the 

toxicity of chlorine to terrestrial animals; however, the data from experimental studies indicate 

that injury to animals would occur only in the presence of high concentrations of chlorine, either 

in drinking water or the ambient atmosphere (U.S. EPA, 1994).

As chlorine and chlorine compounds do not persist in sediments it is not expected to affect 

benthic habitats unless directly applied in high concentrations.

Potential residues in seafood

As there is no potential for the bioaccumulation or bioconcentration of chlorine there is no risk of 

potential residues in seafood.

3.5 Hydrogen (Related Chemical)

Note that hydrogen gas is produced in the electrochemical cell of the RBT reactor as a byproduct 

of hydroxyl radicals. Basic Approval has been recommended by the GESAMP-Ballast Water 

Working Group (GESAMP-BWWG) (MEPC 55/2, 2006) for use of similar electrochemical 

systems designed for the treatment of ballast water that also produce hydrogen gas. Full details 

on the nature, toxicity and risks posed by this compound is nonetheless provided in this report for 

completeness.

3.5.1 Acute aquatic toxicity

There is no data on acute aquatic toxicity of hydrogen.

3.5.2 Endocrine disruption

None of the available data indicate toxicity for exposures of any duration.

3.5.3 Sediment toxicity

There is no data on sediemnt toxicity of hydrogen.
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3.5.4 Bioavailability/biomagnification/bioconcentration

Hydrogen does not bioconcentrate in the tissues of organisms.

3.5.5 Food web/population effects

Hydrogen does not bioconcentrate or accumulate in the tissues of organisms therefore there is no 

risk to organisms up the food chain.

3.5.6 Data on mammalian toxicity 

None of the available data indicate toxicity for exposures of any duration. Hydrogen is not listed 

by NTP, OSHA or IARC.

3.5.6.1 Acute toxicity

High concentrations of hydrogen in the air can cause a deficiency of oxygen with the risk of 

unconsciousness or death. Ingestion is not an observed route of exposure to gaseous hazardous 

materials. Exposure to moderate concentrations may cause dizziness, headache, nausea and 

unconsciousness.

3.5.6.2 Effects on skin and eye

No detrimental effects of skin or eye contact has been reported. Hydrogen only poses a risk of 

thermal burns if ignited.

3.5.6.3 Repeated-dose toxicity

None of the available data indicate toxicity for exposures of any duration.

3.5.6.4 Chronic toxicity

None of the available data indicate toxicity for exposures of any duration.

3.5.6.5 Developmental and reproductive toxicity

None of the available data indicate toxicity for exposures of any duration.

3.5.6.6 Mutagenicity/genotoxicity

None of the available data indicate toxicity for exposures of any duration.

3.5.6.7 Toxicokinetics 

None of the available data indicate toxicity for exposures of any duration.
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3.5.7 Data on environmental fate and effect under aerobic and anaerobic conditions

3.5.7.1 Modes of degradation (biotic; abiotic)

Hydrogen exists naturally in the atmosphere and will be dissipated rapidly in well ventilated 

areas.

3.5.7.2 Bioaccumulation, octanol/water partition coefficient

Hydrogen rapidly dissipates so there is no bioaccumulation.

3.5.7.3 Reaction with organic matter

Hydrogen is not known to react with organic matter.

3.5.7.4 Potential physical effects on wildlife and benthic habitats

No adverse ecological effects are expected. Hydrogen does not contain any Class I or Class II 

Ozone depleting chemicals (40 CFR Part 82). Hydrogen is not listed as a marine pollutant by 

DOT (49 CFR Part 171).

3.5.7.5 Potential residues in seafood

Hydrogen does not bioaccumulate so there is no risk of hydrogen residues in seafood.

4 PHYSICAL AND CHEMICAL PROPERTIES FOR THE ACTIVE SUBSTANCES 

AND PREPARATIONS AND TREATED BALLAST WATER

Data on the physical and chemical properties of the Active Substances, preparations and treated 

ballast water are provided in Table 2. 

5 USE OF THE ACTIVE SUBSTANCE OR THE PREPARATION

5.1 Active Substance Preparation

The RBT reactor employs the use of two Active Substances in its working principals. These 

substances namely; Ozone and sodium hypochlorite, are generated on board the vessel from 

natural sources such as air from the atmosphere for Ozone production, and sodium chloride or 

other electrolyte substance found in the ballast water being pumped.

The main reason for the addition of these substances is to assist with the cavitation that forms the 

basis of the reactor; also these chemicals have the additional advantage of maintaining a sterile 

environment within the ballast tanks on board a ship.

Both Ozone and sodium Hypochlorite have been used to disinfect drinking water for many 

decades. The use of these chemical compounds for potable water treatment is well documented.

These chemical substances are added into the ballast water during ballasting operations and as 

such do not need to be handled by the crew at any stage. 
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Levels of these chemical are kept to a minimum i.e. 0.001mg/l for the O3 gas and <1.0ppm for 

the sodium Hypochlorite.

No additional preparation methods or handling of these chemicals is required. The RBT Reactor 

is supplied pre-calibrated for the specific ballast flow rate as determined by the individual vessel 

requirements.

5.2 The RBT “Coronatech” Ozone generator

Ozone gas that is produced and subsequently infused into the ballast water treatment system is 

generated by the corona method.

The corona discharge generator utilizes a high frequency transformer (typically 16-20KHz) This 

method is favoured because greater Ozone production can be achieved with less electrode surface 

area and less electrical consumption (0.75 amps).

The RBT Ozone discharge generator accelerates electrons so as to give them sufficient energy to 

split the oxygen-oxygen double bond upon impact with another oxygen molecule. The two 

oxygen atoms, which are produced by the collision, react with other diatomic oxygen molecules 

to form Ozone. Ozone is produced as a result of an electrical discharge.

Various factors that affect the production of Ozone gas via the generator have been taken into 

account i.e., temperature, humidity and oxygen supply. In order to maintain the efficient working 

temperature for the effective production of Ozone gas, a cooling system is integrated into the 

equipment. Filtered atmospheric air is cooled via a chiller; the chiller also acts to cool the corona 

discharge chamber. Ozone produced via the generator is approximately 2%.

5.2.1 Risks to ship safety and crew

The Ozone generator that forms part of the RBT ballast water treatment system is purpose built, 

baring in mind the safety of the ship its crew and the environment.

Specific consideration was given to the assurance that no Ozone leaks could or would take place 

during the normal operation of the O3 generator.

Safety features

Ozone is produced from the surrounding air, and is drawn into the ballast water by means of a 

venturi system. (Vacuum) As such the O3 generator will not produce any additional O3 gas in 

the event of a zero flow of air.

Two one-way / non-return, check valves are installed. One check valve on the Ozone delivery 

line and one check valve on the air intake of the Ozone generator. The purpose of these check 

valves is to ensure a one directional flow of air through the O3 generator and also that no 

Ozone gas can be dissipated into the surrounding air. In the most unlikely event that the

check valves should fail, ballast water would be passed back into the corona tubes, thereby 

rendering the Ozone generator incapable of producing any O3 gas. An 5 milli-amp fuse protects 

the O3 generator.
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Corrosion

Due to the fact that the RBT reactor makes use of only 0.0001 ppm of Ozone gas in its working 

principals no noticeable increase in corrosion of the ballast pipe work or tanks will occur. Surface 

coatings within the ballast tanks offer additional protection from any residual Ozone gas. 

Venting

In the unlikely event of any Ozone gas build up within the ballast tank, any free Ozone gas that is 

not absorbed into the ballast water will be vented via the balla st tank venting system. At no time 

will the free Ozone reach any harmful or dangerous levels.

System failure

The Ozone generator has no moving parts and as such is maintenance free. In the event of Ozone

system failure, warning signals are transmitted to the bridge and ballast control room.

5.3 Electro Chemical Production

Installed into the electrical control panel is an electrical rectifier that supplies a current to the 

electrodes that form part of the RBT reactor. Passing an electrical potential through a cathode and 

an anode produces Electro chemical production of chemical compounds such as Sodium

Hypochlorite and gases. The dissolved salts and compounds within ballast water, namely Na Cl 

serve as an electrolyte in the process, produce compounds such as Hydrogen, Oxygen and 

Sodium Hypochlorite. The electrodes that form part of the RBT Reactor are selected from the 

group VIII metals on the periodic table – Ruthenium, Titanium.

Low concentrations of Sodium Hypochlorite are produced at the surface of the electrodes 

(< 1 ppm) Residual chlorine content assists in maintaining a sterile environment within the 

ballast tank. Other useful chemicals produced by the electrodes that are harmful or lethal to 

marine organisms include, Bromine, Hypobromous acid, Chlorine Dioxide, Chlorine,

Hypobromite, Hydroxyl radical. These chemicals degrade over a period of time and would not be 

harmful to the environment when the ship de-ballasts.

Chlorine residuals are affected by temperature and pH of the water being treated, the 

effectiveness of chlorine decreases with an increase of pH above 8.0. For human consumption 

chlorine residuals of 1.2 to 1.5 ppm are acceptable. It is important to maintain chlorine (NaOCl) 

limits within the prescribed limits for human consumption, as no particular limits and standards 

are currently available for the treatment of seawater. The levels of NaOCl produced by the RBT 

reactor are less than 1 ppm.

Sodium Hypochlorite levels fall within the specifications of the paint manufacturers responsible

for the manufacture and application of ballast tank paint protection systems

5.3.1 Risks to ship safety and crew

The rectifiers installed into the electrical control panel of the RBT reactor supplies a DC current 

directly to the electrodes of the reactor.
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As with all electrical component that make up the treatment process of the equipment, ship and 

crew safety are taken into account. Where necessary the electrical equipment installed would be 

supplied with the necessary certification and build to ATEX Standards, should the equipment 

need to be installed into a hazardous area on board a vessel.

Safety features

Certain chemicals predominantly “sodium hypochlorite,” are produced inside of the RBT reactor 

directly from the seawater, when the ballast water is being pumped into the vessel. The ship crew 

requires no additional handling of any chemicals.

Circuit breakers and fuses are installed into the ECP that would trip in the event of any direct 

short circuit of the rectifiers.

Corrosion

Chemicals produc ed by the electro chemical components of the RBT reactor can be potentially 

corrosive, however, levels of these chemicals and gases are low and will not increase the 

corrosion rate of the ballast piping and tanks.

Venting

Any un-dissolved gases such as chlorine gas and hydrogen will be vented through the ships 

ballast tank vents. Hydrogen gas levels would never reach dangerous levels (4%).

System failure

In the unlikely event of a rectifier or electrode failure, aural and visual alarm warnings are 

transmitted to the ballast control room as well as the bridge. Two rectifiers are installed to ensure 

that ballasting operations would not be affected in the event of a rectifier failure.

6 RISK ASSESSMENT

6.1 Risk to safety of ship

There is an increased risk of corrosion arising form the oxidizing properties of Ozone. However, 

because Ozone has such a short half-life (< 6 seconds in seawater), it will only exist for a very 

short time in the ballast tank. 

Mitigation required will be to ensure that the machinery producing the Ozone and the piping 

leading into the ballast water is coated with a ceramic coating and/or constructed of anticorrosive material such as stainless steel. Ozone is the most corrosive of the Active Substances 

applied directly to the ballast water and therefore any measures taken to prevent corrosion by 

Ozone will be sufficient to prevent corrosion by the other Active Substances. Hydrogen poses a 

flammability risk but quantities produced will be so small as to be of no concern. Hydroxyl 

radicals degradate within nanoseconds and are therefore of no concern with regards to corrosion.

There are no risks associated with the handling of active chemical as the Active Substances and 

the relevant chemicals are produced in situ and are therefore not handled.
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Ozone Ship Risk Summary

Risk of substance: Medium

Certainty: High

Risk after mitigation: Very Low

Certainty: High

Bromate ion Ship Risk Summary

Risk of substance: Low

Certainty: High

Risk after mitigation: Very Low

Certainty: High

Bromoform Ship Risk Summary

Risk of substance: Low

Certainty: High

Risk after mitigation: Very Low

Certainty: High

Sodium hypochlorite (free active chlorine) Ship Risk Summary

Risk of substance: Medium

Certainty: High

Risk after mitigation: Very Low

Certainty: High

Hydrogen Ship Risk Summary

Risk of substance: Medium

Certainty: High

Risk after mitigation: None

Certainty: High

Hydroxyl radical Ship Risk Summary

Risk of substance: None

Certainty: High

Risk after mitigation: None

Certainty: High
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6.2 Risks to human health

6.2.1 Ozone

Ozone is very toxic by inhalation route and there is also a potential for Ozone to cause 

mutagenicity after oral exposure. Therefore strict mitigation measures will have to be applied to 

avoid human exposure. 

Mitigation: The Ozone generator is fabricated in such a way as to ensure that no Ozone gas can 

escape into the surrounding air. When the ballast pump is incited the Ozone generator is turned 

on automatically, and the Ozone gas that is generated is sucked directly into the ballast water 

being treated.

A non-return/one way valve, situated onto the corona reactor ensures that no Ozone gas escapes. 

Should there be no air flow through the corona reactor, no Ozone gas is produced thereby

ensuring that the equipment is safe for the ship and its crew. Even in the event of accidental or 

purposely turning on of the Ozone generator it would be impossible for the Ozone generator to 

produce Ozone gas without an airflow through the corona reactor. The air flow required is 

created by a venturi that ensures that all of the Ozone gas is infused into the ballast water. 

In addition, with regard to the health of the ship crew, placards relating to the general hazards of 

Ozone inhalation should be placed onboard to promote general awareness.

Ozone Human Health Risk Summary

Risk of substance: Low

Certainty: High

Risk after mitigation: Very Low

Certainty: High

6.2.2 Bromate ions

Several studies have indicated high potential for mutagenicity and carcinogenicity in humans. 

The current MCL (Maximum Contaminant Level) in the United States is 0.010mg/L and the 

MCL goal is zero because of the possibility that bromate may function as a genotoxic carcinogen. 

Therefore human exposure should be totally avoided.

Mitigation: Bromate ions will form in the ballast water which is pumped into the ship’s ballast 

tanks mechanically and therefore there will be no human contact on board the ship with treated 

ballast water. Providing the treated water is released more than 12 hours (the half life of a 

bromate ion) after it was treated, bromate ions will pose no threat to human health outside of the 

ship either.

Bromate ion Human Health Risk Summary

Risk of substance: Low

Certainty: High

Risk after mitigation: Very Low

Certainty: High
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6.2.3 Bromoform

Bromoform is a highly reactive compound capable of bioacumulating. Exposure to bromoform 

vapors may cause irritation to the respiratory tract, lacrimation, and liver damage. Bromoform 

has also been classified as a Group B2, probable human carcinogen (US EPA, 2000). Exposure 

should therefore be minimized.

Mitigation: According to tests conducted on water that was treated using Resource Ballast 

Technologies (Pty) Ltd., the concentration of all trihalomethanes (which was made up almost 

entirely of bromoform) was 19.6μg/L. The acceptable concentration level of total

trihalomethanes in the United States for water used by humans is 80.0μg/L. Therefore the 

concentration levels of bromoform produced by this methodology are unlikely to pose a health 

risk to humans. However, further testing is recommended with seawater from a variety

of sources.

Bromoform Human Health Risk Summary

Risk of substance: Low

Certainty: High

Risk after mitigation: Low

Certainty: High

6.2.4 Free active chlorine

Swallowing sodium hypochlorite can cause irritation, pain and inflammation of mucoses. In 

severe cases it can cause ulceration and perforation of the gastro intestinal tract. Vapours are not 

easily formed although under certain conditions, high concentration solutions in high pH mixed 

with acids, may produce chlorine gas which causes mild irritation of the nose and throat. 

Mitigation: The sodium hypochlorite will be produced in situ and will be pumped directly into 

the ballast water. Therefore there will be no potential risk of the crew being exposed to chlorine 

in any form. Chlorine has a rapid half life (0.005) and does not bioaccumulate. Therefore it poses 

no risk to humans once after the treated ballast water has been released.

Free active chlorine human health risk summary

Risk of substance: Medium

Certainty: High

Risk after mitigation: None

Certainty: High
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6.2.5 Hydrogen

Hydrogen is not toxic but if released in large enough quantities it may displace oxygen leading to 

unconsciousness or asphyxiation. It is also highly explosive in high concentrations.

Mitigation: The amount of hydrogen produced by the electro-chemical electrodes is miniscule 

and would not reach any dangerous levels, any excess that is not already absorbed/dissolved into 

the ballast water would be vented into the atmosphere via the vents in the ballast tanks.

Hydrogen human health risk summary

Risk of substance: Medium

Certainty: High

Risk after mitigation: Very Low

Certainty: High

6.2.6 Hydroxyl radicals

Hydroxyl radicals have an extremely raid half life (nanoseconds) and do not persist or

bioaccumulate. They therefore do not pose a risk to human health.

7 RISKS TO THE AQUATIC ENVIRONMENT

7.1 Screening for persistence, bioaccumulation and toxicity

Active Substances and relevant chemicals produced or introduced by the RBT reactor for

treatment of ballast water include the following:

• Ozone,

• bromate ions,

• bromoform,

• hydroxyl radicals,

• chlorine gas (Cl2),

• free active chlorine species (HOCl and ClO-), and

• hydrogen gas.

Of these, Ozone, hydroxyl radicals and chlorine compounds (chlorine gas and free active

chlorine species) are extremely short lived and have very little or no potential for persistence or 

for bioaccumulation (see data presented in the preceding sections). Thus, although their toxicity 

to marine life may be high (which is the reason for their use in the RBT reactor) risks posed to 

the environment through the release of treated ballast water is considered negligible.

Bromate ions are only likely to be formed in seawater but have a longer half life than Ozone, 

hydroxyl radicals and the chlorine compounds mentioned above (approximately 12 hours). 

The octanol/water particial coefficient log value (Pow) for bromate is -7.18 and such it is not 

considered to pose a risk of concentration in marine organisms or to animals higher up the 

food chain (PAN Pesticides Database). Acute toxicity of bromate is also low

(approximately 1/1000 of that of Ozone) and concentrations in ballast water treated with the RBT 

reactor are very low relative to concentrations at which toxic effects have been demonstrated 

(see data presented in the preceding sections).
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Bromoform has an octanol/water partition coefficient (Pow) of approximately 2.38 which suggests 

that it will tend to partition to fat tissues of aquatic organisms, and hence may be slightly

bioconcentrated by aquatic organisms. The concentration of bromoform in ballast water treated 

with the RBT reactor is very low (<20 μg/l) relative to concentrations at which toxic effects have 

been detected (9 000-140 000 μg/l, see preceding sections).

In conclusion, therefore it is clear that none of the Active Substances or relevant chemicals 

produced by the RBT reactor can be considered as PBT substances (Table 7).

Table 7. Risk characterization for Active Substances and relevant chemicals 

produced or introduced by the RBT reactor

Substance Persistence

(Half-life: > 60 days in marine 

water/> 40 days in freshwater, or > 

180 days in marine sediment, or > 

120 days in freshwater sediment

Bioaccumulation 

(Log Pow >3)

Toxicity (Chronic 

NOEC

< 0.01 mg/l)

Ozone No No Yes

Bromate ions No No Yes

Bromoform, Yes No Yes

Hydroxyl radicals No No Yes

Chlorine gas (Cl2) No No Yes

Free active chlorine

species (HOCl and ClO-)

No No Yes

Hydrogen gas No No No

7.2 Evaluation of the treated ballast water

Toxicity test has not yet been undertaken on samples of treated ballast water due to time 

constraints but it is the intention of the proponents to undertake relevant toxicity tests as required 

by the GESAMP-Ballast Water Working Group (GESAMP-BWWG) (MEPC 55/2, 2006). 

7.3 Aquatic toxicity of Active Substance & Relevant Chemical

7.3.1 Acute aquatic toxicity

An overview of acute toxicity data (lowest short-term LC50 test values) for up to three taxa (fish, 

crustacean, mollusc, algae) where available are presented in Table 8.

It can be concluded from these data that acute toxicity to Ozone can be seen at >500 μg/L, 

bromate ions at >176 000 μg/L, bromoform at >16 000 μg/L, chlorine gas at >600 μg/L, and 

sodium hypochlorite at around 100 μg/L. The concentration of bromoform and chlorine in 

ballast water treated with the RBT reactor are low (<20 μg/l, and 80-320 μg/l, resepctively) 

relative to levels at which acute toxicity can be expected.
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Table 8. Overview of acute toxicity data (lowe st short-term LC50 test values)

Test

Substance

F

C

A

Species Effect Value (μg/L)

F Lepomis macrochirus 24h LC50 60

M Dreissena polymorpha 5.8h LC50 520

Ozone

A - - -

F Oncorhynchus keta 96h LC50 512 000

C Neomysis awatschnsis 24h LC50 176 000

Bromate

Ion

A - - -

F Cyprinodon variegates 48h LC50 16 000

C Peneus aztecus 96h LC50 20 000

Bromoform

A - - -

F Morone saxatilis 6h LC50 610

C Asellus aquaticus 24h LC50 754

Chlorine gas 

(Cl2)

A - - -

Sodium F Clupea pallasii 96h LC50 65

hypochlorite M Crassotrea virginica 0.5 LC50 120

 F = Fish, C = Crustacea, A = Algae, M = Molluscs

7.3.2 Chronic aquatic toxicity

An overview of chronic toxicity data (lowest long-term LC50 test values) for up to three taxa 

(fish, crustacean, mollusc, algae) where available are presented in Table 9. It can be concluded 

from these data that chronic toxicity to Ozone and free active chlorine can both be expected 

at >5 μg/L. Considering the short half lives of these substances, they are not expected to be 

released into the environment above these levels. 

Table 9. Overview of acute toxicity data (lowest long-term NOEC test values)

Test

Substance

F

C

A

Species Effect Value (μg/L)

F Oncorhynchus mykiss 90d NOEC 5

C - - -

Ozone

A - - -

F - - -

C - - -

Bromate

Ion

A Skeletonema costatum 7d NOEC 0.125

-

F Menidia penensulae eggs 28d NOEC 40

C Crassostrea virginica &

Rangia cuneata

15d NOEC 7

Free active 

chlorine

A Phytoplankton 21d effect 1

 F = Fish, C = Crustacea, A = Algae, M = Molluscs
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7.3.3 Derivation of the Predicted No Effect Concentration (PNEC)

According to the GESAMP-Ballast Water Working Group (GESAMP-BWWG) (MEPC 55/2,

2006), PNEC for Active Substances and relevant chemicals should be derived by dividing

the lowest available effect concentration with an appropriate assessment factor, as provided in 

Table 10.

Table 10. Effect assessment for deriving PNECs for freshwater and saltwater 

(MEPC 55/2)

Assessment Factor

Data set PNEC 

long

PNEC

short

Freshwater assessment

Lowest short-term L(E)C50 from fresh water species 

representing three trophic levels

1000 10-100

Lowest chronic NOEC from three freshwater or saltwater 

species representing three trophic levels

10

Saltwater assessment

Lowest short-term L(E)C50 from marine species

representing three trophic levels

1000 10-100

Lowest chronic NOEC from three freshwater or saltwater 

species representing three trophic levels 

100

Lowest chronic NOEC from three saltwater species 

representing three trophic level

100

Lowest chronic NOEC from three freshwater or saltwater 

species representing three trophic levels + at least two 

chronic NOECs from additional marine taxonomic 

groups

10

Table 11. Predicted concentrations of Active Substance and relevant chemical in 

treated ballast water produced or introduced by the RBT reactor

Active 

Substance/ 

chemical

P

N

E

C

Concentration 

immediately 

after treatment

(μg/L)

Concentr

ation 

after 2 h

(μg/L)

Concentr

ation 

after 4h

(μg/L)

Concent

ration 

after 8h

(μg/L)

Concentra

tion after 

12h

(μg/L)

Ozone

(freshwater)

1 000 nd nd nd nd

Ozone

(seawater)

1 000 62.5 3.9 0.015 5.9 x 10-5

Bromoform 

(seawater)

19.6 19.6 19.6 19.6 19.6

Chlorine gas 

(freshwater)

0.32 nd nd nd nd

 nd = not detectable.
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It is only relevant to evaluate PNEC values for Ozone in freshwater and bromoform in seawater 

for this study (the remaining Active Substances are either created in negligible concentrations in 

the other medium or decay to rapidly to be of consequence).

For Ozone there is only one chronic value available. An assessment factor of 100 is applied to 

this value resulting in a PNECchronic = 0.05 μg/L. There are 2 values available for acute data, 

the lowest of which is 60 μg/L. Apply a factor of 1000 to this yields a PNECacute = 0.06 μg/L. 

Of these two data the lowest value is taken as the resulting PNEC: PNEC = 0.05 μg/L as Ozone. 

In the case of Ozone introduced to freshwater a total time of at least 8 hours is required before 

the ballast water can safely be discharged.

For bromoform there is one chronic value available. An assessment factor of 100 is applied to 

this value resulting in a PNECchronic = 48 μg/L and 3 for the acute data, the lowest of which 

is 7.1 mg/L. Using an assessment factor of 1000 the PNECacute is established at 7.1 μg/L. Of 

these two data the lowest value is taken as the resulting PNEC: PNEC = 7.1 μg/L as bromoform. 

The half life of bromoform is in the order of 1-2 month and delaying release of ballast water is 

not considered feasible. Concentration in the treated ballast water (19.6 μg/L) are only

marginally higher than the PNEC value (7.1 μg/L) and hence not considred to pose a major risk 

to the environment.

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Vreenegoor, S.M., R.M. Block, J.C. Rhoderick, and S.R. Gullans. 1977. The Effects of

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* * *
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APPENDIX 1
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APPENDIX 2
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_______________