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

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I:\MEPC\58\2-2.doc 

INTERNATIONAL MARITIME ORGANIZATION

IMO 

E

MARINE ENVIRONMENT PROTECTION 

COMMITTEE 

58th session 

Agenda item 2 

MEPC 58/2/2

20 March 2008

 Original: ENGLISH

HARMFUL AQUATIC ORGANISMS IN BALLAST WATER

Application for Basic Approval of the EcochlorÆ Ballast Water Treatment System 

Submitted by Germany 

SUMMARY

Executive summary: This document contains the non-confidential information related to 

the application for Basic Approval of the EcochlorÆ Ballast Water 

Treatment System 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) 

Strategic direction: 7.1 

High-level action: 7.1.2 

Planned output: 7.1.2.4 

Action to be taken: Paragraph 5 

Related documents: BWM/CONF/36, MEPC 53/24/Add.1 and BWM.2/Circ.12 

Introduction 

1 Regulation D-3.2 of the International Convention for the Control and Management of 

Shipsí Ballast Water and Sediments stipulates that ballast water management systems that make 

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

2 The Procedure for approval of ballast water management systems that make use of 

Active Substances (G9) stipulates the required information (MEPC 53/24/Add.1, annex 4, 

paragraph 4.2.1) and provisions for risk characterization and analysis (MEPC 53/24/Add.1, annex 4, 

paragraph 5.3), which, according to section 6 of Procedure (G9), should be evaluated by the 

Organization. 

3 The receiving competent authority in Germany has verified the application dossier 

and believes it to satisfy the data requirements of Procedure (G9) adopted by 

resolution MEPC.126(53). 
MEPC 58/2/2 - 2 - 

I:\MEPC\58\2-2.doc 

4 In accordance with BWM.2/Circ.12, Germany therefore submits the non-confidential part 

of the manufacturerís application dossier in the annex to this document. The complete dossier 

will be made available to the experts of the GESAMP-BWWG with the understanding of 

confidential treatment. 

Action requested of the Committee 

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

***
1

1.0 INTRODUCTION 

The Ecochlor®

 Ballast Water Treatment System (BWTS) applies established chlorine dioxide 

technology to oxidize and disinfect aquatic invasive species (AIS). Chlorine dioxide has a long 

history (50+ years) of being applied safely and economically for the control of microorganisms 

in industrial and municipal waters. What is unique about chlorine dioxide is its ability to be 

effective against a wide range of troublesome organisms and in a broad range of water quality 

conditions. A second unique feature of the chlorine dioxide generated with the Ecochlor®

BWTS compared to other oxidants (such as chlorine) is the minimization of unwanted

by-products. 

Chlorine dioxide is believed to be a superior candidate for ballast water treatment for the 

following reasons: 

• Chlorine dioxide oxidation is well documented in drinking water applications; 

• Chlorine dioxide kinetics of bacterial disinfection are fast; 

• Chlorine dioxide inactivates organisms at low dosages (a favorable C x t); 

• Chlorine dioxide generated with the Ecochlor® BWTS does not produce chlorinated

by-products;

• Chlorine dioxide does not significantly increase corrosion rates at the concentration used 

 with the Ecochlor®

 BWTS; 

• Chorine dioxide is documented as an effective biocide against known pathogens that 

 demonstrate resistance (i.e. Cryptosporidium, anthrax, etc.); 

• Chlorine dioxide can be safely and economically produced onboard ship; 

• Chlorine dioxide is uniquely effective in preventing and neutralizing biofilm; and 

• Chlorine dioxide typically decays to below detection levels in a relatively short time 

period. 

Ecochlor is applying for Basic Approval of the Purate®

 chlorine dioxide generation method 

utilized with the Ecochlor®

 BWTS in accordance with the International Maritime Organization 

(IMO) Guideline 9 (resolution MEPC.126(53)). This application was compiled using the

guidance and format provided in the Draft Methodology (MEPC 55/2/16, annex 4).

1.0.1 Technology Overview 

The Ecochlor®

 BWTS generates chlorine-free chlorine dioxide using the Eka Chemicals Purate®

technology, a patent-protected chlorine dioxide generation method. Eka’s Purate®

 technology is 

a chlorate-based chlorine dioxide generation process. This method differs from other 

conventional chlorine dioxide generation methods that involve use of aqueous or gaseous 

chlorine, making the chlorine-free Purate®

 method environmentally superior. Additionally, 

Eka’s Purate®

 technology produces chlorine dioxide efficiently, thereby controlling the required 

input of precursor chemicals and eliminating production of unwanted by-products. 

To further explain the chemistry, chlorine dioxide can be generated using differing methods, and 

a number of chlorate ion reduction processes exist to produce chlorine dioxide. Some of these 

methods can also produce chlorine as a generation intermediate or by-product (e.g., Mathieson, 

Solvay, R2 and R3/SVP processes). To avooid the chlorine by-product in these traditional 

methods, a new process was developed where hydrogen peroxide is the reducing agent and 
2

hydrochloric acid is replaced by sulfuric acid. This newer process, utilized in the patentprotected Eka Chemicals Purate®

 technology employed with the Ecochlor® Ballast Water 

Treatment System (BWTS), does not involve or create free available chlorine (FAC). 

Additionally, it is important to note that chlorine dioxide and chlorine act very different 

chemically. For instance, chlorine dioxide is an oxidant, yet it does not chlorinate. In contrast, 

FAC is both an oxidant and a chlorinating agent. Because FAC is not present in any detectable 

concentration, the application of chlorine-free chlorine dioxide results in oxidation without the 

direct formation of organic by-products such as trihalomethanes (THM’s), and other unwanted 

by-products such as haloacetic acids (HAA’s) are minimized. 

To support the above statement regarding halogenated by-products, Ecochlor presents theoretical 

discussion of the chlorine-free Purate® chlorine dioxide methodology as well as chemical 

analysis of treated ballast water from San Francisco Bay that demonstrates that chlorine dioxide 

does not directly form THM’s. 

Using the preparation chemicals, the Ecochlor®

 BWTS generates and injects a dilute solution of 

chlorine-free chlorine dioxide directly into ballast water as it is loaded onboard. Treatment of 

ballast water occurs during uptake only. The chlorine dioxide solution is not stored onboard as a 

concentrated chemical at any time. It is generated on demand based on the amount of ballast 

water being pumped onboard. After injection into the incoming ballast water, chlorine dioxide 

remains effective in the ballast water tanks for a short period (2 – 20 hours) in order to neutralize 

ballast tank biofilm that can cause bacterial re-growth. Over time, the chlorine dioxide continues 

to react and/or decay in the ballast tanks so that at the time of discharge the ballast water contains

an undetectable concentration of chlorine dioxide. Operational specifics of the Ecochlor® BWTS 

are discussed in detail in Section 3.0.1, Manner of Application. 

Since 2001, several bench scale experiments have been conducted on the use of chlorine-free 

chlorine dioxide to control aquatic invasive species. The success of the bench scale studies and 

the proven effectiveness of chlorine dioxide in numerous land-based water disinfection 

applications indicated that the technology was ready for land-based efficacy testing. However, 

because there were no land-based testing facilities available in the world, Ecochlor proceeded 

directly to installing a full-scale system on the Atlantic Compass in 2004 for efficacy testing. A 

second prototype system was installed on the M/V Moku Pahu in 2005. Testing of these systems 

is ongoing to demonstrate and verify the efficacy of the Ecochlor®

 BWTS. Shipboard testing is 

being conducted by scientists at the University Of Rhode Island, Graduate School of 

Oceanography (URI) who are using a testing protocol approved by the United States Coast 

Guard (USCG). Ballast water treated with the Ecochlor® BWTS will comply with the 

performance standards in Regulation D-2 of the International Convention for the Control and 

Management of Ship’s Ballast Water and Sediments, as well as standards proposed in the United 

States Ballast Water Management Act of 2005 (Senate Bill S.363). 

The Ecochlor® BWTS is viable for all ballast water capacity ranges, and is distinguished by the 

system’s capability to treat at high ballast water flow rates. The Ecochlor® BWTS can be 

installed as a retrofit on existing vessels or during a new construction, with the latter being the 
3

most straightforward and cost effective. Additionally, Ecochlor’s treatment system can be easily 

incorporated into a land-based system to treat ballast water land-side. 

2.0 IDENTIFICATION OF PREPARATIONS, ACTIVE SUBSTANCES AND 

RELEVANT CHEMICALS (G9: 4.1) 

Based on the definitions of Preparations, Active Substances and Relevant Chemicals in the G9 

procedure (Resolution MEPC.126(53)), Ecochlor classifies the substances involved in the 

Ecochlor® BWTS process as follows: 

Preparations: There are two preparation substances used with the Ecochlor® BWTS: 

1) Purate® (a proprietary formulation from Eka Chemicals containing 40% by 

weight sodium chlorate (NaCl03) and 8% by weight hydrogen peroxide 

(H2O2); and 

2) Sulfuric acid (78% by weight). 

These two preparation substances are used to generate the active substance (chlorine-free 

chlorine dioxide) onboard and are not themselves active substances. 

Purate®

 is discussed in more detail in Section 2.0.1.1 and sulfuric acid is discussed further in 

Section 2.0.1.2 below. 

Active Substance: Chlorine-free chlorine dioxide is the active substance that is generated 

onboard and has “...specific action on or against harmful aquatic organisms and pathogens” 

(Guideline 9, 2.1.1). Additional information regarding chlorine dioxide is presented in Section 

2.0.2.1 below. 

Relevant Chemicals: Ecochlor discusses the following two substances as Relevant Chemicals in 

Section 2.0.3: 

1) Sulfate ion (as sodium sulfate or sulfuric acid); and 

2) Chlorite ion (as sodium chlorite). 

Based on the G9 definition of relevant chemicals, both of these substances are “...transformation 

or reaction products that are produced during the treatment process...” (Guideline 9, 2.1.4). 

Sulfate ions are discussed as a relevant chemical because a slight excess of sulfuric acid is used 

during the chlorine dioxide generation process. This is done to ensure high chlorine dioxide 

production efficiency. As such, additional sulfate ions (19 mg/L) may be added to ballast water 

treated with chlorine dioxide. Although the addition of sulfate ions to sea water as a result of 

treatment with the Ecochlor® BWTS is inconsequential, Ecochlor presents justifications to fully 

explain the chemistry associated with the treatment process. Section 2.0.3.1 of the application 

provides further information regarding sulfate ions that clearly demonstrates that sulfate ions are 

not added to treated ballast water at environmentally relevant concentrations. 

As the primary reaction by-product in ballast water after disinfection with chlorine-free chlorine 

dioxide, Ecochlor classifies chlorite ion (ClO2

-

), or sodium chlorite (NaClO2) as a relevant 

chemical. Detailed information on chlorite ion is presented in Section 2.0.3.2 below. 
4

Chemical analysis and known chemical principles of disinfection using chlorine dioxide that is 

generated in the chlorine-free method used with the Ecochlor® BWTS indicate that no other 

reaction by-products are present at environmentally relevant concentrations. However, biocide 

treatment of water can raise questions regarding the formation of THM’s and/or HAA’s. 

Chemical data and justifications regarding these substances are located in Sections 1.0.1 (above) 

and 2.0.3.3. 

Table T2.1 below provides an overview of the chemicals involved in the Ecochlor®

 BWTS and 

descriptions of each chemical follow the table. 

Table T2.1 – Overview of Chemical Identification 

Ingredient 

(IUPAC Name) 

Identification 

Numbers 

Chemical 

Formula 

Structural 

Formula 

Molecular 

Weight 

Percentage 

(by weight) 

Applied 

Concentration 

Preparation Chemicals 

1. Purate®

a. Hydrogen 

Peroxide 

b. Sodium 

Chlorate 

a. CAS # 7722-84-1 

b. CAS # 7775-09-9 

 a. H2O2

b. NaClO3

a. 

b. a. 34.01 

b. 106.44 

a. <8% 

b. 40% 

a. 0.05-2.9 M 

b. 0.5-3.2 M 

2. Sulfuric Acid CAS# 7664-93-9 H2SO4 98.08 78% 0.75-4M 

Active Substance in Ballast Water 

 Chlorine dioxide CAS# 10049-04-4 ClO2 67.45 -- 

< 5 mg/L 

in ballast 

water 

Relevant Chemicals in Ballast Water

1. Sulfate ion 

 (as sodium 

 sulfate or 

 sulfuric acid) 

CAS # 7757-82-6 

or 

CAS# 7664-93-9 

Na2SO4

or 

H2SO4

or 

142.04 

or 

98.08 

By-product < 20 mg/L 

2. Sodium Chlorite 

 (present as 

 chlorite ion) 

CAS # 7758-19-2 NaClO2 90.45 By-product < 5 mg/L 

2.0.1 Preparations 

In order to generate chlorine dioxide onboard Ecochlor® is utilizing a two precursor chemical 

approach. The two preparation chemicals, Purate®

 and sulfuric acid, are mixed under controlled 

conditions to generate chlorine dioxide, which is then injected into the ballast water stream. The 

preparation chemicals are not added to the ballast water directly, and are not the active 

substance. 
5

2.0.1.1 Purate® 

Purate® is a proprietary formulation from Eka Chemicals containing 40% by weight sodium 

chlorate (NaCl03) and 8% by weight hydrogen peroxide (H2O2). Therefore, the Ecochlor®

BWTS utilizes chlorate-based chlorine dioxide generation technology. For comparison purposes 

only, the USEPA specifies that chlorate ion generators used in drinking water applications 

operate at 95% efficiency. This means that at a minimum, 95% of the sodium chlorate in 

Purate® is converted to chlorine dioxide. Efficiency is the amount of chlorine dioxide formed, 

divided by the sum of all possible oxychlorine compounds that could form. Hydrogen peroxide 

is not a part of the efficiency calculation. 

 x 100

H O [ClO ] [ + ClO ] [ + ClO ]

[ClO ]

Efficiency =

2 2 2 2 3

2

− −

[ ] +

%

Although the Ecochlor® BWTS is not treating drinking water, the system’s chlorine dioxide 

generator is operated to achieve a minimum 95% efficiency. This high efficiency reduces the 

potential for the preparation chemicals to be present as residual substances in treated ballast 

water. The individual components of Purate® (hydrogen peroxide and sodium chlorate) are 

discussed in more detail below to explain why they are not considered relevant residual 

chemicals. 

It should also be recognized that the Purate® solution acts as a precursor to the active substance 

and is consumed during chlorine dioxide generation. It is not the active substance itself. 

Therefore, Ecochlor is not submitting comprehensive toxicity data for the Purate® chemicals in 

this application as it is not relevant to an evaluation of treated ballast water. However, data on 

the individual components of Purate® (hydrogen peroxide and sodium chlorate) are provided 

where pertinent to human health and/or ship safety.

Hydrogen Peroxide: 

The presence of hydrogen peroxide in the Purate® solution is designed to chemically reduce 

chlorate ion (+5 oxidation state) to chlorine dioxide (+4 oxidation state). Thus, it is reasonable 

to presume that a slight stoichiometric excess of hydrogen peroxide may be present in the 

chlorine dioxide solution. This being the case, it is important to understand what happens to any 

excess hydrogen peroxide that may be present in the chlorine dioxide solution generated by the 

Ecochlor® BWTS. 

Chlorine dioxide reacts with hydrogen peroxide in acidic solution to slowly form chloride ion. 

In basic solution, chlorine dioxide reacts rapidly (minutes time scale) with hydrogen peroxide to 

form chlorite ion. Thus, any excess hydrogen peroxide that might be present in the acidic mixing 

chamber (where chlorine dioxide generation occurs in the Ecochlor® BWTS) is likely to react 

with chlorine dioxide and form chloride ion, which is ubiquitous in the marine environment. 

Alternatively, if any excess hydrogen peroxide were to be carried over into the ballast water 

which is slightly basic, it will react with chlorine dioxide to form chlorite ion. Ultimately, the 

eventual fate of any residual hydrogen peroxide from Purate® is to form oxygen and water, and 

its reducing effect on chlorine dioxide is to form either chloride ion or chlorite ion. 
6

Purate® contains 8% hydrogen peroxide. At a chlorine dioxide treatment dose of 5.0 mg/L, the 

maximum initial concentration of hydrogen peroxide in the chlorine dioxide solution at 95% 

reaction efficiency is 0.35 mg/L. As discussed above, this low level residual will react with 

chlorine dioxide to form either chloride ion or chlorite ion and will not persist in treated ballast 

water. As such, Ecochlor does not consider hydrogen peroxide a relevant chemical applicable to 

an evaluation of the Ecochlor® BWTS. 

Sodium Chlorate: 

Although the major degradation by-product of disinfection with chlorine-free chlorine dioxide is 

chlorite ion, some chlorate ion can also be produced. However, residual chlorate ion from the 

chlorine dioxide generation process is expected in low concentrations due to the small excess 

sulfuric acid applied to the Purate® solution during the chlorine dioxide generation process. As 

mentioned above, the chlorine dioxide generator is operated at a minimum 95% efficiency to 

ensure complete conversion of sodium chlorate and efficient chlorine dioxide generation. 

Based on a 5.0 mg/L applied dose of chlorine dioxide, a calculated chlorate ion concentration on 

the order of 0.2 to 0.49 mg/L may be present in the treated ballast water. These concentrations 

of chlorate ion in treated ballast water have been confirmed by ion chromatographic analysis 

(See Figures F2.1 through F2.3, Tables T2.2 through T2.4, T2.8). Again, for comparison 

purposes, these concentrations of chlorate ion are well within the reported range of chlorate ion 

measured in drinking water systems (United States) that use chlorine dioxide to treat water for 

human consumption. Because there is no US standard for chlorate ion in drinking water and the 

fact that the measured chlorate ion concentration is within the range presented in USEPA 

published documents for drinking water, Ecochlor does not consider it a chemical of concern in 

treated ballast water. Therefore, Ecochlor does not consider chlorate ion a relevant chemical 

applicable to an evaluation of the Ecochlor® BWTS. 

2.0.1.2 Sulfuric Acid 

The sulfuric acid (H2S04) used to generate chlorine-free chlorine dioxide is industrial grade 78% 

by weight. A slight excess of sulfuric acid is added to Purate®

 to increase the efficiency of the 

chlorine dioxide generation reaction. Thus, a low concentration of sulfuric acid remains (as 

sulfate ion) after the generation of chlorine dioxide and can be measured in treated ballast water. 

As such, Ecochlor further discusses sulfuric acid below in Section 2.0.3, Relevant Chemicals. 

Analytical data (sulfate ion concentration and pH) from treated ballast water is presented in 

Table T2.8 of Section 2.0.3.3. 

2.0.2 Active Substance 

2.0.2.1 Chlorine Dioxide 

The active substance generated by the reaction of the two precursor chemicals is chlorine-free 

chlorine dioxide (ClO2). Chlorine dioxide is generated on demand and immediately injected into 

the ballast water based on the amount of ballast water being pumped onboard. The preparation 

chemicals are not added to the ballast water directly. Chlorine dioxide treatment occurs only 

during uptake of ballast water. Chlorine dioxide is not stored onboard as a concentrated 

chemical at any time.
7

When used to treat ballast water, chlorine dioxide will rapidly react (oxidize / disinfect) with 

susceptible organisms and certain chemical components over time. This continuing consumption 

of chlorine dioxide is described as the chlorine dioxide demand. The concept of demand is 

widely used in water purification to help determine the dose and contact time (C x t) needed for 

effective disinfection of a specific water source. In practice this means that when a 5.0 mg/L 

dose of chlorine dioxide is added to ballast water, there is typically a rapid decrease in the 

chlorine dioxide concentration followed by a continuing reaction of the remaining chlorine 

dioxide until the demand of the water is met. After meeting the demand, the chlorine dioxide 

will maintain a residual concentration and continue to react with components in the ballast water. 

This results in a slow decrease in concentration over time until the concentration of chlorine 

dioxide falls to a level that is undetectable by available analytical methods. 

In the significant number of tests Ecochlor has conducted, ballast water treated with 5.0 mg/L 

chlorine dioxide has a typical decay of less than 24 hours. The chlorine dioxide demand/decay 

of a specific water sample will vary depending on factors such as water temperature and amount 

of organic matter present. To isolate the effect of temperature on chlorine dioxide demand, 

testing was performed in a laboratory setting where temperature was controlled. A whole water 

sample from Newark, New Jersey was sent to NovaChem Laboratories for testing. Figures F2.1, 

F2.2, and F2.3 show the chlorine dioxide demand of the New Jersey water at 4°C, 12°C and 

24°C, respectively. Data Tables T2.2, T2.3 and T2.4 correspond to these demand study curves. 

Figure F2.1 – Example of Chlorine Dioxide Demand Curve, 4°C 

 Note: Demand testing on raw water samples performed by NovaChem Laboratories 
8

Table T2.2 – Ecochlor Chlorine Dioxide Demand Study, 4oC 

Ecochlor Ballast Water Chlorine Dioxide Decay Study

 

Source Water New Jersey Ballast Water 

ClO2 Dose 5.06 mg/L 

Water Temp 4 oC 

 

Time after ClO2

treatment 

(minutes) 

Chlorine 

Dioxide 

ClO2 (mg/L) 

Chlorite Ion 

ClO2

-

 (mg/L) 

Chlorate Ion 

ClO3

-

 (mg/L) 

0 5.06 ND ND 

5 3.50 0.742 0.001 

30 2.80 0.855 0.055 

60 1.90 1.285 0.110 

180 1.40 1.727 0.169 

300 1.10 -- -- 

480 0.21 -- -- 

660 0.00 1.796 0.282 

 Note: Demand testing on raw water samples performed by NovaChem Laboratories 

 ND = not detected, “--“ = not measured 

Figure F2.2 – Example of Chlorine Dioxide Demand Curve, 12°C 

 Note: Demand testing on raw water samples performed by NovaChem Laboratories 
9

Table T2.3 – Ecochlor Chlorine Dioxide Demand Study, 12oC 

Ecochlor Ballast Water Chlorine Dioxide Decay Study

 

Source Water New Jersey Ballast Water 

ClO2 Dose 5.01 mg/L 

Water Temp 12 oC 

 

Time after ClO2

treatment 

(minutes) 

Chlorine Dioxide 

ClO2 (mg/L) 

Chlorite Ion 

ClO2

-

 (mg/L) 

Chlorate Ion 

ClO3

-

 (mg/L) 

0 5.01 ND ND 

5 3.30 0.747 0.046 

30 2.30 1.105 0.161 

60 1.30 1.520 0.184 

120 0.71 2.200 -- 

180 0.43 2.203 -- 

240 0.20 2.075 0.265 

300 0.12 1.912 -- 

360 0.02 1.902 0.285 

 Note: Demand testing on raw water samples performed by NovaChem Laboratories 

 ND = not detected, “--“ = not measured 

Figure F2.3 – Example of Chlorine Dioxide Demand Curve, 24°C 

 Note: Demand testing on raw water samples performed by NovaChem Laboratories 
10

Table T2.4 – Ecochlor Chlorine Dioxide Demand Study, 24oC

Ecochlor Ballast Water Chlorine Dioxide Decay Study

 

Source Water New Jersey Ballast Water 

ClO2 Dose 5.05 mg/L 

Water Temp 24 oC 

 

Time after ClO2

treatment 

(minutes) 

Chlorine Dioxide 

ClO2 (mg/L) 

Chlorite Ion 

ClO2

-

 (mg/L) 

Chlorate Ion 

ClO3

-

 (mg/L) 

0 5.05 ND ND 

5 -- 1.225 0.110 

15 2.20 1.533 0.140 

30 1.52 1.956 0.178 

50 0.83 --` 0.236 

60 0.73 2.229 0.227 

120 0.19 2.351 0.245 

150 0.04 2.369 0.243 

 Note: Demand testing on raw water samples performed by NovaChem Laboratories 

 ND = not detected, “--“ = not measured 

As the figures depict, the chlorine dioxide demand / decay proceeds as anticipated with an initial 

rapid decrease in chlorine dioxide concentration until the demand of the water is met, and then a 

residual concentration decays over time. The figures also demonstrate that the chlorine dioxide 

decay rate can decrease in colder water and increase in warmer water. 

Because of the known decay behavior and chemical properties, it is unlikely that chlorine 

dioxide will be present in treated ballast water at the time of discharge. Additionally, the 

Ecochlor® BWTS employs a methodology that treats ballast water during uptake rather than 

prior to discharge, which further ensures sufficient holding time to reach undetectable levels of 

chlorine dioxide. Although unlikely, Ecochlor recognizes that there is potential for the discharge 

of treated ballast water containing minimal amounts of chlorine dioxide. In light of this, chlorine 

dioxide toxicity data is presented in this application for review. It should also be noted that one 

could reasonably anticipate that any discharged chlorine dioxide would quickly react (decay) 

upon introduction to the receiving water. 

2.0.3 Relevant Chemicals 

2.0.3.1 Sulfate Ion and Sulfuric Acid 

During the generation of chlorine-free chlorine dioxide, conversion of sodium chlorate to 

chlorine dioxide involves the use of sulfuric acid. To ensure high chlorine dioxide production 

efficiency, an excess of acid is typically added to the Purate®

 solution. Thus, the applied 

chlorine dioxide solution is slightly acidic and sulfate ion (SO4

2-), as sulfuric acid or sodium 

sulfate, is produced as a by-product. 

The stoichiometric equation for the chlorine dioxide generation process is: 

2ClO3

-

 + 2H2O2 + 2H2SO4 → 2ClO2 + O2 + SO4

-2 + 2H2O 

In water, sulfuric acid is totally miscible and readily dissociates to form hydrogen ion (H+) and 

sulfate ions (SO4

2-). The reaction stoichiometry indicates that for every mole of chlorine dioxide 

produced, 0.5 moles of sulfate ion is produced. Thus, if 5.0 mg/L ClO2 is added to the ballast 
11

water it is accompanied by less than 4.0 mg/L SO4

2-. Further, due to the slight excess of acid 

needed for reaction efficiency, at a chlorine dioxide dose of 5.0 mg/L a maximum of 15.0 mg/L 

additional sulfate ion might be added to the ballast water. Thus, a maximum total of 19.0 mg/L 

of sulfate ion may be added along with a small amount of acidity. This added acidity is easily 

buffered by the dissolved carbon dioxide (CO2) naturally present in seawater. Analysis of 

treated ballast water shows that the effect of the excess sulfuric acid on pH is nominal. Table 

T2.8 presents that control tank ballast water had a pH of 7.6, and chlorine dioxide treated ballast 

water had a pH of 7.3. 

Because sulfate ion is one the major ions naturally present in seawater, the addition of sulfate ion 

from the BWTS is not considered environmentally relevant. Chemical analysis of treated ballast 

water from the San Francisco Bay area (Richmond, CA) confirms this statement. Table T2.8 

below presents analytical data in which the sulfate ion concentration in the control ballast tank 

(no chlorine dioxide treatment) was 1,902 mg/L, while the chlorine dioxide treated ballast tank 

had a sulfate ion concentration of 1,826 mg/L (measured 8 days after treatment). These numbers 

support the theoretical conclusion that sulfate ion will not be added to treated ballast water at 

environmentally relevant concentrations. 

Further, at environmentally relevant concentrations, sulfuric acid is completely dissociated and 

sulfate ion is at or below natural levels. Complete ionization also implies that sulfuric acid itself

will not adsorb on particulate matter and will not accumulate in living tissues1. Therefore, the 

known chemical properties of sulfuric acid, along with the chemical analysis of treated ballast 

water, provide justification that it will not be of concern to the aquatic environment or humans 

when discharged in treated ballast water. As such, aquatic toxicity data for sulfate ions is not 

presented in this application. However, data on sulfuric acid is provided where pertinent to 

human health and/or ship safety. 

2.0.3.2 Chlorite Ion 

Based on the above discussion, the primary reaction by-product in the ballast water after 

disinfection and/or decay of chlorine dioxide is chlorite ion (ClO2

-

), or sodium chlorite 

(NaClO2). When chlorine dioxide reacts it loses an electron and forms chlorite ion, which is also 

a low level biocide. 

ClO2 → ClO2

-

 + eThe concentration of chlorite ion at the time of ballast water discharge will vary depending upon 

the source of the ballast water, the treatment dose, and the hold time in the ballast tanks. In 

water, chlorite ion decomposes to chloride ion. Light, microorganisms, enzymes, and metals 

(such as iron) in the water contribute to the decomposition of chlorite ion. Thus, in a way similar 

to chlorine dioxide, chlorite ion will in many cases have an observable demand. Over time the 

chlorite ion concentration decreases through continuing reactions with humic or other labile 

substances in the ballast water, resulting in an increase of chloride ion (Cl-). 

In addition to the chlorite ion data presented in Section 2.0.2.1 above, the chlorite ion demand of 

water from Newark, New Jersey was determined and the observed curve is depicted in Figure 

F2.4. 

 

1

 OECD SIDS SIAR, SIAM 11 (January 2001), UNEP Publications. 
12

Figure F2.4 – Example of Chlorite Ion Demand Curve 

Newark, NJ Water 

Ballast Water Chlorite Ion Demand

1.94 mg/L, 20 C

0.00

0.50

1.00

1.50

2.00

2.50

0 10 20 30 40 50 60 70 80

Time (Hr)

Concentration (mg/L)

 Note: Demand testing on raw water samples performed by NovaChem Laboratories 

Table T2.5 – Ecochlor Chlorite Ion Demand Study, 20oC

Ecochlor Ballast Water Chlorite Ion Demand Study

 

Source Water New Jersey Ballast Water 

Chlorite Dose 1.94 mg/L 

Water Temp 20 oC 

 

Time after ClO2

-

treatment (hour) 

Chlorite Ion

ClO2

-

 (mg/L) 

0 1.94 

1 0.88 

18 0.30 

42 0.36 

69 0.19 

Note: Demand testing on raw water samples performed by NovaChem Laboratories 

It is important to note that the above figure and data table depicts a laboratory setting where the 

water sample is static. Once the demand of the water has been met, the chlorite ion 

concentration becomes stable in the closed system. However, in an actual onboard chlorine 

dioxide treatment scenario the treated ballast water will be discharged. Once the ballast water is 

discharged, two forces act on the remaining chlorite ion. The first is the dilution of the ballast 

water with the receiving water and the second is the chlorite demand of the receiving water. 

Because the chlorite ion reaction by-product may persist in chlorine dioxide treated ballast water 

at the time of discharge, chlorite toxicity data is presented in this application for review. 

However, Ecochlor does not believe that the low concentration of chlorite ion that may be 

present in treated ballast water poses unacceptable risks. Additionally, any chlorite ion present at 

the time treated ballast water is discharged into the marine environment will continue to decrease 

in concentration based on the chlorite ion demand discussed above and dilution effects upon 

discharge. Toxicological data verifying that treated ballast water that may contain low levels of 

chlorite ion does not present unacceptable risks are presented in Sections 5.1 and 5.2. 
13

2.0.3.3 Trihalomethanes and Haloacetic Acid By-Products 

The Ecochlor® BWTS generates chlorine-free chlorine dioxide using the Eka Chemicals Purate®

technology, a patent-protected chlorine dioxide generation method. Eka’s Purate®

 technology is 

a chlorate-based chlorine dioxide generation process. This method differs from other 

conventional chlorine dioxide generation methods that involve use of aqueous or gaseous 

chlorine, making the chlorine-free Purate®

 method environmentally superior. Additionally, 

Eka’s Purate® technology produces chlorine dioxide efficiently, thereby controlling the required 

input of precursor chemicals and eliminating production of unwanted by-products. 

To further explain the chemistry, chlorine dioxide can be generated using differing methods, and 

a number of chlorate ion reduction processes exist to produce chlorine dioxide. Some of these 

methods can also produce chlorine as a generation intermediate or by-product (e.g., Mathieson, 

Solvay, R2 and R3/SVP processes). To avoid the chlorine by-product in these traditional 

methods, a new process was developed where hydrogen peroxide is the reducing agent and 

hydrochloric acid is replaced by sulfuric acid. This newer process, utilized in the patentprotected Eka Chemicals Purate®

 technology employed with the Ecochlor® Ballast Water 

Treatment System (BWTS), does not involve or create free available chlorine (FAC). 

Additionally, it is important to note that chlorine dioxide and chlorine act very different 

chemically. For instance, chlorine dioxide is an oxidant, yet it does not chlorinate. In contrast, 

FAC is both an oxidant and a chlorinating agent. Chlorine dioxide disinfection is the result of a 

1e- transfer mechanism resulting in the formation of chlorite ion (ClO2

-

) 

ClO2 → ClO2

-

 + eBecause FAC is not present in any detectable concentration, the application of chlorine-free 

chlorine dioxide results in oxidation without the formation of organic by-products such as 

THM’s, and other unwanted by-products such as HAA’s are minimized. 

Chemical analysis of ballast water treated with chlorine-free chlorine dioxide presented in Table 

T2.8 confirms that THM’s are not directly formed and that HAA’s are not present at 

environmentally relevant concentrations. The data show that, similar to the untreated ballast 

water (control), FAC is not measurable (<0.05 m/L) (EPA Standard Method 4500-Cl F, DPD) in 

treated ballast water when measured on Day 3 following treatment. Further, a chlorine dioxide 

residual is not observed (Palintest Lissamine Green-B method), indicating that the entire 5.0 

mg/L dose of chlorine dioxide has been reacted. 

The data in Table T2.8 shows no formation of THM’s (<1 μg/L) after treatment of ballast water 

with chlorine dioxide from the Ecochlor®

 BWTS. The table also shows the low level (12 μg/L) 

presence of a single haloacetic acid (dibromoacetic acid (DBAA)). These data are consistent 

with chemistry of chlorine dioxide as an oxidant. The drinking water standard in the United 

States is <80 μg/L total THM’s and <60 μg/L total HAA. Both of these standard levels are 

achieved in the ballast water treated with chlorine-free chlorine dioxide. Based on the chemical 

analysis and the G9 definition of relevant chemicals under 2.1.4 of the Guideline, Ecochlor does 

not consider THM’s or HAA’s as relevant chemicals or applicable to an evaluation of the 

Ecochlor® BWTS. 
14

Table T2.8 – Analysis of Ballast Water Treated Onboard the M/V Moku Pahu, 

San Francisco Bay Area (Richmond, CA)

Parameter 

Control Ballast 

Water 

Ballast Water 

Treated Onboard 

+ 3 Day 

13 Feb 2008 

Ballast Water 

Treated Onboard 

+ 5 Day 

15 Feb 2008 

pH 7.6 7.3 7.3 

FAC <0.05 mg/L <0.05 mg/L -- 

ClO2 -- <0.05 mg/L <0.05 mg/L 

ClO2

-

 <0.05 mg/L 0.91 mg/L 0.24 mg/L 

ClO3

-

 <0.10 mg/L 0.49 mg/L 0.49 mg/L 

Br - 50 mg/L -- -- 

BrO3

-

<0.02 mg/L -- <0.02 mg/L 

(+11 Day) 

SO4

-2

1902 mg/L -- 1826 mg/L 

(+ Day 8) 

THM’s 

Bromdichloromethane 

Bromoform 

Chloroform 

Dibromochloromethane 

<1 μg/L 

<1 μg/L 

<1 μg/L 

<1 μg/L 

-- 

<1 μg/L 

<1 μg/L 

<1 μg/L 

<1 μg/L 

HAA’s 

Dibromoacetic Acid 

Dichloroacetic Acid 

Bromoacetic Acid 

Monochloroacetic Acid 

Trichloroacetic Acid 

<1 μg/L 

<1 μg/L 

<1 μg/L 

<1 μg/L 

<1 μg/L 

-- 

12 μg/L 

<1 μg/L 

<1 μg/L 

<1 μg/L 

<1 μg/L 

 Note: Demand testing on raw water samples performed by NovaChem Laboratories 

 “--“ = not measured 

2.1 DATA ON EFFECTS ON AQUATIC PLANTS, INVERTEBRATES AND FISH, 

AND OTHER BIOTA, INCLUDING SENSITIVE AND REPRESENTATIVE 

ORGANISMS (G9: 4.2.1.1) 

The toxicology data presented in this application varies by topic and is selective by design. To 

clarify, the toxicology data set required by Guideline 9 involves several categories; 1) aquatic 

toxicity, 2) mammalian toxicity and 3) environmental fate and effect. It is Ecochlor’s opinion 

that these categories relate to the Ecochlor process at different phases of treatment and potential 

exposure to the substances associated with the Ecochlor®

 BWTS is not the same for each 

category. As such, each toxicological category was evaluated to determine where a potential 

exposure existed and what chemicals were of potential concern throughout the treatment process. 

For example, the acute and chronic aquatic toxicity data submitted is intended to provide a reallife scenario of what chemicals may be present when treated ballast water is discharged. 

Because Purate®

 and sulfuric acid are converted into chlorine-free chlorine dioxide and are not 

present at significant concentrations in treated ballast water, aquatic toxicity data is not provided 

for these chemicals. However, because treated ballast water may contain chlorine dioxide (this 

should not happen if the system is used as directed) and chlorite ion (the primary by-product of 

disinfection with chlorine dioxide), aquatic toxicity data is provided for these chemicals. 

Similarly, because Purate® and sulfuric acid are stored onboard and a potential for human 

exposure (crew or technicians) exists, mammalian toxicity data is provided for these chemicals. 

However, because treated ballast water is not typically handled by crew or technicians, Ecochlor 
15

did not provide mammalian toxicity data on chlorite ion as this does not seem relevant. Even in 

a situation where human contact with treated ballast water could occur, (i.e. water sample 

collection) the chemicals that may be present have been determined analytically to be at 

concentrations that are not of concern to humans. 

Toxicity testing with THM’s and HAA’s was not considered because chemical analysis of 

treated ballast water indicates that these substances are not relevant to an evaluation of ballast 

water disinfected with chlorine-free chlorine dioxide (see also Sections 1.0.1, 2.0.3.3 and 5.3). 

Additionally, whole effluent testing of the treated ballast water includes the sum of all substances 

formed in the treatment process. In Ecochlor’s opinion, aquatic toxicity testing on treated ballast 

water reflects the most accurate information on the potential toxicological effects of the treated 

water a ship will discharge. Toxicity testing on the precursor chemicals and/or intermediate 

substances is informative, but may not reflect the most realistic toxicological evaluation of 

treated ballast water. 

Toxicity tests for chlorine dioxide were performed by Nautilus Environmental and end-points are 

based on measured concentrations of chlorine dioxide at the start of the exposure periods. Acute 

toxicity tests were static and chronic tests were static renewal with a daily renewal of test 

solutions, with the exception of tests with Macrocystis pyrifera, Mytilus sp. and Skeletonema 

costatum, which were static, and the 96 hr test with Clupea pallasi in which the solution was 

renewed only after 48 hr of exposure. All tests were conducted according to USEPA guidelines 

for conducting short term acute and chronic toxicity tests (USEPA 1995, 2002), with the 

exception of the tests with Skeletonema costatum, which followed ASTM (1998) methodology, 

and tests with Clupea pallasi, which were based on methodology developed by Dr. Paul Dinnel 

from the Shannon Point Marine Center. 

Toxicity tests for chlorite were static, with the exception of 7 day tests with Mysidposis bahia

and Atherinops affinis, which were static renewal, with daily renewal of solutions. All tests were 

conducted according to USEPA guidelines for conducting short term acute and chronic toxicity 

tests (USEPA 1995, 2002). 

According to 3.2.1.2 of the Draft Methodology (MEPC 55/2/16, Annex 4), “In the case of whole 

effluent testing, EPA, or equivalent, short term methods for estimating the acute toxicity of 

substances and discharge provide acceptable alternatives.” 

2.1.1 Acute Aquatic Toxicity 

2.1.1.1 Chlorine Dioxide 

Acute toxicity data (LC50 or EC50) are presented in Table T2.9 for survival of the crustacean 

Mysidposis bahia and the larval fish Menidia beryllina (inland silverside), as well as spore 

germination of the giant kelp (Macrocystis pyrifera). EC50 values for these species were ~0.4, 

>0.4 and 0.2 mg/L, respectively. Additional data are presented for survival of a second fish, the 

Pacific herring (Clupea pallasi). 

2.1.1.2 Chlorite Ion 

Acute toxicity data (LC50 or EC50) are presented in Table T2.9 for survival of the crustacean 

Mysidopsis bahia and the larval fish Cyprinidon variegatus (sheepshead minnow), as well as 
16

spore germination of the giant kelp (Macrocystis pyrifera). EC50 values for these species were 

0.58, 75.0 and >15.4 mg/L, respectively. 

2.1.1.3 Treated Ballast Water 

Acute toxicity data (LC50 or EC50) are presented in Table T2.9 for survival of the crustacean 

Mysidopsis bahia in ballast water treated with chlorine-free chlorine dioxide. EC50 values for 

these species were 38.7% and 37.7%. 

 

Table T2.9 – Overview of Acute Aquatic Toxicity 

Test 

Substance 

F

C

A

Species Test Type EC50 

mg/L 

NOEC 

mg/L 

Reference/ 

comments 

Preparations 

1. Purate® -- -- -- -- 

See Section 2.0.1.1 

for justification of not 

providing data 

2. Sulfuric Acid -- -- -- -- 

See Section 2.0.3.1 

for justification of not 

providing data 

Active Substance 

Chlorine Dioxide 

F Menidia beryllina 96 hr survivala>0.4 0.4 Nautilus Env. 2005 

F Clupea pallasi 96 hr survival 0.35 0.22 Nautilus Env. 2005 

C Mysidopsis bahia 48 hr survivala

~ 0.4 0.04b Nautilus Env. 2005 

A Macrocystis pyrifera 48 hr 

germination 0.20 0.14 Nautilus Env. 2006 

Relevant Chemicals 

1. Sulfate Ion/ 

 Sulfuric Acid -- -- -- -- 

See Section 2.0.3 for 

justification of not 

providing data 

2. Chlorite Ion 

 (Sodium chlorite) 

F Cyprinidon variegatus 96 hr survival 75.0 13.9 Env. Sci. Eng. 1994b 

C Mysidopsis bahia 96 hr survival 0.58 NR Env. Sci. Eng. 1994a 

A Macrocystis pyrifera 48 hr germ. >15.4 15.4 Nautilus Env. 2007 

Treated Ballast Water 

5.0 mg/L dose of 

ClO2

C Mysidopsis bahia 48 hr survival 38.7% 25% Nautilus Env. 2006 

C Mysidopsis bahia 48 hr survival 37.7% 25% Nautilus Env. 2006 

 F = Fish, C = Crustacean, A = Algae, NR = Not Reported 

 a Calculated on the basis of data from the chronic toxicity test with this species. 

 b Reported NOEC is highly conservative because the next concentration tested was 10-times higher (see discussion in Section 

 2.1.2.1). 

2.1.2 Chronic Aquatic Toxicity 

2.1.2.1 Chlorine Dioxide 

Chronic toxicity data in Table T2.10 include data for a fish (survival and growth of larval 

Menidia beryllina), an invertebrate (survival and growth of a mysid, Mysidopsis bahia) and an 

algae (germination and growth of giant [Macrocystis pyrifera] kelp spores), as well as for two 

additional species (larval development for a mollusc [Mytilus sp.] and population growth for a 

diatom [Skeletonema costatum]). The most sensitive test species was Mytilus sp., which 

exhibited a chronic NOEC of 0.09 mg/L and an EC50 of 0.22 mg/L on the basis of a larval 

development test. 
17

It should be noted that the chlorine dioxide NOEC of 0.04 mg/L reported in Table T2.10 for 

Mysidopsis bahia is likely overly conservative and resulted from the ten-fold dilution series 

employed in this test. A partial effect was observed at 0.4 mg/L chlorine dioxide with this 

species, and no effect at the next lower concentration of 0.04 mg/L. Based on acute tests, the 

bivalve larval development test using Mytilus sp. was clearly more sensitive than M. bahia and, 

consequently, a definitive test was conducted using the bivalve larval development test with a 

narrower (two-fold) dilution series. Thus, although the NOEC reported for Mytilus sp. of 0.09 

mg/L appears to be higher than the NOEC for M. bahia, this is largely an artifact associated with 

the concentrations which were tested. Consequently, it is appropriate to consider the test using 

Mytilus sp. to be the most sensitive test, and therefore the most sensitive NOEC should be the 

one reported for this test (0.09 mg/L). 

2.1.2.2 Chlorite Ion 

Table T2.10 includes chronic toxicity data for a fish (survival and growth of larval topsmelt, 

Atherinops affinis), an invertebrate (survival and growth of a mysid, Mysidopsis bahia) and an 

alga (germination and growth of giant kelp [Macrocystis pyrifera] spores), as well as for two 

additional species (larval development for a mollusc, Crassostria virginica and an echinoderm, 

Strongylocentrotus purpuratus). The most sensitive test species was Mysidopsis bahia, which 

exhibited a chronic NOEC of 0.18 mg/L and an EC50 of 0.25 mg/L on the basis of a 7-day 

survival and growth test. 

2.1.2.3 Chlorine Dioxide 

Chronic toxicity testing on the mollusk Mytilus sp. was performed on ballast water disinfected 

with chlorine-free chlorine dioxide. An EC50 of >81% and 84% was exhibited. Chronic NOEC 

values of 11.7% and 12% for the crustacean Mysidopsis bahia were calculated based on the acute 

toxicity results. 

Table T2.10 – Overview of Chronic Aquatic Toxicity 

Test 

Substance 

F

C

A

M

Species Test Type EC50 

mg/L 

NOEC 

mg/L 

Reference/ 

comments 

Preparations 

1. Purate® -- -- -- -- 

See Section 2.0.1.1 for 

justification of not 

providing data 

2. Sulfuric Acid -- -- -- -- 

See Section 2.0.3.1 for 

justification of not 

providing data 

Active Substance 

Chlorine Dioxide 

F Menidia beryllina 7 day 

surv/growth >0.4 0.4 Nautilus Env. 2005 

F Clupea pallasi 18 day embryo 

devpt >0.33 0.33 Nautilus Env. 2005 

C Mysidopsis bahia 7 day 

surv/growth ~ 0.4 0.04a Nautilus Env. 2005 

A Macrocystis pyrifera 48 hr 

germination 0.20 0.14 Nautilus Env. 2006 

D Skeletonema costatum 96 hr growth 3.09 2.09 Nautilus Env. 2006 

M Mytilus edulis 48 hr 

development 0.22 0.09 Nautilus Env. 2005 
18

Test 

Substance 

F

C

A

M

Species Test Type EC50 

mg/L 

NOEC 

mg/L 

Reference/ 

comments 

Relevant Chemicals 

1. Sulfate Ion/ 

 Sulfuric Acid 

-- 

-- -- -- 

See Section 2.0.3.1 for 

justification of not 

providing data 

2. Chlorite Ion 

 (Sodium chlorite) 

F Atherinops affinis 7 day 

surv/growth >13.8 6.9 Nautilus Env. 2007 

C Mysidopsis bahia 7 day 

surv/growth 0.25 0.18 Nautilus Env. 2007 

A Macrocystis pyrifera 48 hr germ. >15.4 15.4 Nautilus Env. 2007 

E Strongylocentrotus 

purpuratus Development 10.4 5.0 Nautilus Env. 2007 

M Crassostrea virginica Development 21.4 14.3 Env. Sci. Eng. 1994c 

Treated Ballast Water 

5.0 mg/L dose of 

ClO2

M Mytilus sp. Development >81% 81% Nautilus Env. 2006 

M Mytilus sp. Development >84% 84% Nautilus Env. 2006 

C Mysidopsis bahia 48 hr survival -- 12%b

 Nautilus Env. 2006 

C Mysidopsis bahia 48 hr survival -- 11.7%b

 Nautilus Env. 2006 

 F = Fish, C = Crustacean, A = Algae, D = Diatom, M = Mollusk, E = Echinoderm 

 

a

 Reported NOEC is highly conservative because the next concentration (NOEC) tested was 10-times higher. 

 

b

 Chronic NOEC calculated using acute-to-chronic ratio of 3.22 

2.1.3 Endocrine Disruption 

There is no evidence to suggest that Purate®

 or sulfuric acid would result in endocrine disruption. 

There is no evidence to suggest that chlorine dioxide or chlorite would result in endocrine 

disruption2

. 

2.1.4 Sediment Toxicity 

2.1.4.1 Preparations 

The sodium chlorate and hydrogen peroxide components of Purate®

 are both non-organic and 

soluble in water. The chemical properties of both components indicate that they would not be 

expected to accumulate in sediments. 

2.1.4.2 Active Substance 

Chlorine dioxide is not persistent as a result of its rapid degradation pathway to chlorite, and is 

not expected to bioaccumulate since it is non-organic and does not have hydrophobic or 

lipophilic properties. This chemical would not be expected to accumulate in sediments2

. 

2.1.4.3 Relevant Chemicals 

In water, sulfuric acid is totally miscible and readily dissociates to form hydrogen ion (H+) and 

sulfate ions (SO4

2-). At environmentally relevant concentrations, sulfuric acid is completely 

dissociated and sulfate ion is at or below natural concentrations. Complete ionization also 

implies that sulfuric acid itself will not adsorb on particulate matter and will not accumulate in 

living tissues1

. 

Chlorite ion is not persistent as a result of its degradation pathway to chloride ion in both water 

and soils, and is not expected to bioaccumulate since it is non-organic and does not have 

 

2

 Review of the Environmental Fate and Effects of Chlorine Dioxide and Chlorite, Nautilus Environmental, 2007. 
19

hydrophobic or lipophilic properties2. Therefore, chlorite would not be expected to accumulate 

in sediments. 

2.1.4.4 Treated Ballast Water 

The potential substances present in treated ballast water at the time of discharge are chlorine 

dioxide and chlorite ion. The capability of these constituents to accumulate in sediments is 

discussed above. 

2.1.5 Bioavailability/Biomagnification/Bioconcentration and Food Web/Population 

Effects 

The active substance and relevant chemical (chlorine dioxide and chlorite, respectively) are the 

only constituents potentially present in treated ballast water that will be discharged to the 

environment. Both substances are highly water soluble and are not organic in nature. Neither of 

these chemicals would be expected to exhibit biomagnification or bioconcentration, and 

consequently, would not be expected to persist in the food web2. 

2.2 DATA ON MAMMALIAN TOXICITY (G9: 4.2.1.2) 

Test reports used in this application were from a variety of sources, including, but not limited to, 

OECD SIDS, Eka Chemicals (performed by independent laboratories), independent research, 

USEPA, and the National Toxicology Program. The reports were evaluated to ensure that the 

data presented was generated by accredited laboratories using accepted standard methodologies 

and laboratory practices. Additional discussion on data quality is presented in Section 6.5.2. 

The studies and documents referenced are attached to this application. 

Potential for human exposure to Ecochlor® BWTS chemicals are limited to Purate®, sulfuric acid 

and chlorine dioxide. Chlorite ion is a low-level degradation by-product that will only be present 

in treated ballast water. Because treated ballast water is not handled by technicians or ship’s 

crew, no potential for exposure exists. Therefore, mammalian toxicity data is presented for 

Purate®

, sulfuric acid and chlorine dioxide in this section. Section 2.1 provides additional 

justification for the selection of toxicity data presented. 

The toxicity data presented in this section has been gathered through literature review of 

available data. The various forms in which the chemicals have been evaluated (gas, liquid, or 

solid phases at differing concentrations) do not necessarily reflect the actual form of the 

substance utilized in the Ecochlor® BWTS or the potential route of exposure. Mammalian 

toxicity data is presented for informational purposes using data previously established by others. 

The quality of the data used is presented in Section 6.5, Assessment Report of this application. 
20

2.2.1 Acute Mammalian Toxicity 

Table T2.11 – Acute Mammalian Toxicity Data 

Test Substance Exposure 

Route Species Value range Reference/ comments 

Preparations 

Purate®

 Sodium Chlorate a. Acute Oral LD50 

b. Inhalation LC50 

a. Rat 

b. Rat 

a. >5000 mg/kg 

b. 5.6 mg/L/4hr 

Purate® MSDS, 

Eka Chemicals 

 Hydrogen Peroxide (10%) a. Acute Oral LD50 

b. Inhalation LC50

a. Rat 

b. Rat 

a.1500 - >5000 mg/kg 

b. 122 mg/L/4hr 

Purate®

 MSDS, 

Eka Chemicals 

Sulfuric Acid a. Acute Oral LD50 

b. Inhalation LC50 

a. Rat 

b. Rat 

a. 2140 mg/kg 

b. 0.375 mg/L/4hr 

OECD SIDS 

SIAR, SIAM 11 

(January 2001), 

UNEP 

Publications1

Active Substance 

Chlorine Dioxide 

a. Acute Oral LD50 

 (EPA OPPTS 

 Method 

 870.1100) 

b. Inhalation (nose) 

 LC50 

a. Rat 

b. Rat 

a. 292 mg/kg (males) 

 340 mg/kg (females) 

b. 32 mg/L (90 

 mg/m3

)/4hr 

a. USEPA RED 

for Chlorine 

Dioxide and 

Sodium chlorite3

b. Schorsch 

(1995) cited in 

IPCS Chlorine 

Dioxide (Gas) 

2002) CICADS 

37.4 

2.2.2 Effects on Skin and Eye 

Table T2.12 – Skin, Eye and Dermal Effects 

Test Substance Skin Eye Sensitization Reference/ 

comments 

Preparations 

Purate®

 Sodium Chlorate Not irritating to rabbits Mildly irritating to 

rabbits 

Not sensitizing to 

guinea pigs. 

Purate® MSDS, 

Eka Chemicals 

 Hydrogen Peroxide 

At concentrations 

<35%, not a skin 

irritant

Highly corrosive/ 

irritating at 

concentrations>10% 

Not sensitizing to 

guinea pigs at 6% 

concentration 

Purate® MSDS, 

Eka Chemicals 

Sulfuric Acid Severely irritating to 

contaminated tissue Severe irritant Not known to be a sensitizer 

Sulfuric acid 

MSDS, Basic 

Chemical 

Solutions 

Active Substance 

Chlorine Dioxide Irritant Strong irritant Not located 

Chlorine Dioxide 

MSDS, 

Eka Chemicals 

 

3

 USEPA Reregistration Eligibility Decision (RED) for Chlorine Dioxide and Sodium Chlorite (Case 4023), August 2006. 

4

 Concise International Chemical Assessment Document (CICADS) 37, Chlorine Dioxide (Gas), 2002. 
21

2.2.3 Repeated-dose Toxicity 

Table T2.13 – Repeated-Dose Toxicity 

Test Substance Exposure 

Route Species Value range Reference/ comments 

Preparations 

Purate®

 Sodium Chlorate 

a. Oral, 90-day 

subchronic 

b. Oral, 90-day 

subchronic 

a. Rodent 

b. Dog 

a. NOAEL 100 

mg/kg/day 

b. NOAEL 360 

mg/kg/day 

EKA Study 86-

3112 EPA 

Guideline 82-1 

(1987)5

EKA Study 86-

3114 EPA 

Guideline 82-1 

(1987)6

 Hydrogen Peroxide (10%) 

a. Oral, 90-day 

subchronic 

b. Oral, 90-day 

subchronic

a. Rodent 

b. Other 

mammal 

a. NOEL 30-56.2 

mg/kg 

b. Not located 

Ito et al. 1976 

and Kawasaki et 

al., 1969, cited 

by SCCP7

Sulfuric Acid 28 day, inhalation 

(nose only) Rat NOEL/NOAEL not indentified 

OECD SIDS 

SIAR, SIAM 11 

(January 2001), 

UNEP 

Publications1

Active Substance 

Chlorine Dioxide 

a. Inhalation, 60-day 

b. Oral, 90-day 

subchronic

a. Rat 

b. Rat 

a. LOAEL – 1 mg/L 

(2.8 mg/m3

) 

b. 2-15 mg/kg in 

drinking water. No 

treatment related 

deaths, clinical signs 

or effects on 

hematology, clinical 

chemistry or organ 

weights. Dose-related 

decrease in water 

consumption and food 

consumption in high 

dose only. Nasal 

cavity was identified as 

the target tissue with 

hyperplasia, 

squamous metaplasia 

and inflammatory 

responses 

USEPA Tox. 

Review of 

Chlorine Dioxide 

and Chlorite, 

20008

 

Daniel, 1990, 

cited in IPCS 

Chlorine Dioxide 

(Gas) 2002) 

CICADS 374

 

5

 Barrett, D.S. (1987) A Subchronic (3 Month) Oral Toxicity Study of Sodium Chlorate in the Rat via Gavage. 

6

 Barrett, D.S. (1987) A Subchronic (3 Month) Oral Toxicity Study in the Dog via Gavage Administration with Sodium Chlorate. 

7

 Scientific Committee on Consumer Products (SCCP), Opinion on Hydrogen Peroxide in Tooth Whitening Products, 2005 

 (SCCP/0844/04). 

8

 USEPA Toxicological Review of Chlorine Dioxide and Chlorite, September 2000 
22

2.2.4 Chronic Toxicity 

Table T2.14 – Chronic Mammalian Toxicity 

Test Substance Exposure 

Route Species Value range Reference/ comments 

Preparations 

Purate®

 Sodium Chlorate 

a. Oral, 2 year 

b. --

a. Rodent 

b. Other 

mammal 

a. NOAEL < ~5 

mg/kg/day for 2 years. 

Thyroid hyperplasia 

was observed in all 

groups of males in an 

NTP 2-year cancer 

bioassay. Survival, 

water consumption, 

and body weights were 

similar to controls. No 

clinical findings were 

attributed to sodium 

chlorate exposure. 

b. Not located 

National 

Toxicology 

Program (2005) 

Technical 

Report on the 

Toxicology and 

Carcinogenesis 

Studies of 

Sodium 

Chlorate.9 

 Hydrogen Peroxide (10%) 

a. minimum 12 

month study 

b. minimum 12 

month study

a. Rodent 

b. Other 

mammal 

a. None located 

b. None located 

SEE 

PARAGRAPH 

BELOW TABLE 

Sulfuric Acid -- -- 

Long term studies 

have focused on portal 

of entry effects as 

systemic effects are 

considered unlikely. 

OECD SIDS 

SIAR, SIAM 11 

(January 2001), 

UNEP 

Publications1

Active Substance 

Chlorine Dioxide 

a. Oral, 2-year 

chronic 

b. minimum 12 

month study

a. Rat 

b.Other 

mammal 

a. NOAEL: 10 mg/L 

b. Not located 

USEPA Tox. 

Review of 

Chlorine Dioxide 

and Chlorite, 

20008

Although not general toxicology studies, hydrogen peroxide has been extensively evaluated as an 

aid to oral hygiene in humans. “Daily use of a ... or a 1.5% hydrogen peroxide-containing 

mouth rinse for 18 months or 2 years resulted in no reported adverse effects on oral health.”7 

2.2.5 Developmental and Reproductive Toxicity 

The sodium chlorate component of Purate®

 was not teratogenic to rats at doses up to 1,000 

mg/kg-day during 6-15 days of gestation. Sufficient data is not available for the hydrogen 

peroxide component of Purate® (See Purate® MSDS in GESAMP submission). 

Hydrogen peroxide was not deemed to cause any concern for reproductive effects by the 

European Chemicals Bureau10. Sulfuric acid is not reported to cause teratogenic or reproductive 

toxicity effects in humans (See sulfuric acid MSDS in GESAMP submission). Additionally, 

from the OECD SIDS Initial Assessment Report1

: 

 

9

 NTP Technical Report on the Toxicology and Carcinogenesis Studies of Sodium Chlorate in F344/N Rats and B6C3F1 Mice 

 (Drinking Water Studies), 2005. NTP TR 517, NIH Publication No. 06-4457. 

10 European Chemicals Bureau (2003) Hydrogen Peroxide Summary Risk Assessment Report. Special Publication I.03.148. 
23

“...due to irritant/corrosive effects of H2SO4, oral and dermal routes are not appropriate for testing toxicity 

to reproduction. In addition, H2SO4 is a direct-acting toxicant. The acid as such, is not expected to be 

absorbed or distributed throughout the body. Therefore, it is not likely that it will reach male and female 

reproductive organs following exposures by any route.” 

In a study by Carlton et al. (1991), an NOAEL of 10 mg/kg-day for reproductive effects in rats 

receiving gavage doses (0, 2.5, 5, or 10 mg/kg chlorine dioxide in deionized water) was 

identified8

. 

2.2.6 Carcinogenicity 

The sodium chlorate and hydrogen peroxide components of Purate® are not considered 

carcinogenic. Additionally, IARC, OSHA and ACGIH do not list hydrogen peroxide as a 

carcinogen and animal experiments did not show clear carcinogenic evidence in different 

species. (See Purate® MSDS in GESAMP submission). 

Sulfuric acid is not considered to be, nor suspected to be, a cancer-causing agent. (See sulfuric 

acid MSDS in GESAMP submission). 

Chlorine dioxide has not been assessed for carcinogenic potential. The available dermal 

carcinogenicity studies do not definitively characterize the carcinogenicity of chlorine dioxide3. 

2.2.7 Mutagenicity/Genotoxicity 

Sodium chlorate is not considered mutagenic. In vitro studies indicate that without metabolic 

activation, hydrogen peroxide is mutagenic and generally not mutagenic with metabolic 

activation. No mutagenic effects were observed with in vivo studies after oral administration. 

(See Purate® MSDS in GESAMP submission). 

Sulfuric acid is not reported to produce mutagenic effects in humans (sulfuric acid MSDS in 

GESAMP submission). 

From the USEPA Toxicological Review of Chlorine Dioxide and Chlorite8: 

“Both positive and negative results have been found in genotoxicity studies of chlorine dioxide. Exposure 

to chlorine dioxide did not induce chromosomal aberrations in vitro, but it did increase occurrence of

reverse mutations (Ishidate et al., 1984). In vivo assays did not find increases in micronucleus induction, 

chromosomal aberrations, or sperm-head abnormalities following oral exposure (Meier et al., 1985), but

they did find increases in micronuclei induction after intraperitoneal injection (Hayashi et al., 1988).” 

2.2.8 Toxicokinetics 

When sodium chlorate was administered on a carrier by capsule in steers, the apparent 

radiochlorine absorption was approximately 65%. Urine was the primary route of elimination 

where 65-100% of the radiolabeled material was the parent chlorate. Chloride was the only 

radiochlorine labeled metabolite detected11

. 

 

11 Smith, D.J., Anderson, R. C., Ellig, E.A., and Larsen, G.L. (2005) Tissue Distribution, Elimination, and Metabolism of Dietary 

 Sodium [36Cl} Chlorate in Beef Cattle. 
24

From the European Chemicals Bureau Summary Risk Assessment Report10 on hydrogen 

peroxide: 

“The toxicokinetic evaluation of H2O2 suggests that only under conditions of very high exposure rates the 

substance might enter the systemic circulation. When accidental swallowing is excluded, it is unlikely that 

such high exposures could be reached in any realistic scenario of occupational or consumer exposure. It is 

especially unlikely that the substance deposited on the skin is systemically absorbed to a meaningful 

degree. Results from animal studies also suggest that local toxicity at the point of contact and no systemic 

effect as the primary mode of action.” 

Sulfuric acid is not expected to be absorbed or distributed throughout the body1. 

Seventy two hours after administration of chlorine dioxide in water to rats12, 75% of the 

recovered dose had been in urine and 25% feces. Chloride ion was the major metabolite 

accounting for approximately 84% of the administered dose. 

From the USEPA Toxicological Review of Chlorine Dioxide and Chlorite8: 

“Chlorine dioxide and chlorite are rapidly absorbed from the gastrointestinal tract and slowly cleared from 

the blood. Chlorine dioxide and chlorite, primarily in the form of chloride, are widely distributed 

throughout the body and predominantly excreted in the urine. Chloride is the major urinary “metabolite” 

for both chlorine dioxide and chlorite.” 

2.3 DATA ON ENVIRONMENTAL FATE AND EFFECT UNDER AEROBIC AND 

ANAEROBIC CONDITIONS (G9: 4.2.1.3) 

The active substance and relevant chemical (chlorine dioxide and chlorite, respectively) are the only 

constituents potentially present at environmentally relevant concentrations in treated ballast water 

that may be discharged to the environment. Therefore, environmental fate is evaluated for these 

substances only. 

2.3.1 Modes of Degradation (Biotic, Abiotic) 

Degradation of chlorine dioxide occurs by abiotic mechanisms and results from oxidative 

reactions with target organisms and some organic constituents. Degradation also occurs from 

thermal decomposition, disproportionation, and is enhanced by ultra-violet (UV) light2. Chlorine 

does not hydrolyze to an appreciable extent but remains in solution as a dissolved gas13. 

Chlorite is more stable in aqueous solution than chlorine dioxide; however, in a similar manner 

to chlorine dioxide, chlorite also degrades in aqueous solution as a result of oxidative reactions. 

In treated ballast water that is discharged, residual chlorite will decrease through reactions with 

organic matter to form chloride, which is non-toxic at the concentrations of interest. Chlorite is 

not persistent as a result of its degradation pathway to chloride2

. 

2.3.2 Bioaccumulation, Partition Coefficient, Octanol/Water Partition Coefficient 

The water solubility of chlorine dioxide and sodium chlorite is 3.0 g/L and 390 g/L, respectively. 

These physical properties indicate that bioaccumulation is not likely. Additionally, the Kow

 

12 Abdel-Rahman, M.S., Couri, D., and Bull, R.J. (1982) Metabolism and Pharmacokinetics of Alternate Drinking Water 

 Disinfectants. Environmental Health Perspectives, v46, pp19-23. 

13 EPA Guidance Manual, Alternative Disinfectants and Oxidants, Chlorine Dioxide, 1999. 
25

values of chlorine dioxide and chlorite are -3.22 and -7.173, respectively. Also see Sections 2.1.5 

and 5.1.4. 

2.3.3 Reaction with Organic Matter 

Chlorine dioxide is an oxidizing agent. Chlorine dioxide does not chlorinate organic matter, thus 

its use does not promote the formation of trihalomethanes (THMs), which are a concern with 

respect to toxicity and carcinogenicity2. 

In addition, data collected for the drinking water industry shows that the use of chlorine dioxide 

results in a reduction of the observed concentration of organic contaminant species (e.g., THMs, 

haloacetic acids (HAAs), haloaldehydes, haloketones, halocarboxylic acids and other potentially 

harmful organic residues). Similarly, the reaction of chlorite ion with organic matter does not 

produce harmful organic chemical species and typically results in a chemical reduction of 

chlorite ion to chloride ion, which is ubiquitous in the marine environment. Therefore, the 

production of harmful organic by-products is not anticipated. 

2.3.4 Potential Physical Effects on Wildlife and Benthic Habitats 

The chemical and physical properties of the preparation chemicals, active substance, and relevant 

chemicals (Table T2-15) indicate that physical effects on wildlife and benthic habitats as 

described and rated in GESAMP Reports and Studies No. 64 would not be expected to occur. 

Also see Section 2.1.4. 

2.3.5 Potential Residues in Seafood 

No potential for residues in seafood are known or anticipated. 

2.3.6 Any Known Interactive Effects 

No other known or expected interactive effects. 

2.4 PHYSICAL AND CHEMICAL PROPERTIES FOR THE PREPARATIONS, 

ACTIVE SUBSTANCE, AND TREATED BALLAST WATER (G9: 4.2.1.4) 

Table T2.15 – Physical and Chemical Properties 

Physical/Chemical 

Property 

(with units & reference)

Preparations

 1. Purate® 

 2. Sulfuric Acid 

 (78% by weight)

Active Substance 

Chlorine Dioxide 

(solution)

Relevant Chemical

Sodium Chlorite

Treated Ballast 

Water 

Melting point (oC) 1. -29 

2. -11.3 

Same as water 

(0 oC) 

Boiling point (oC) 1. 111 

2. 193 

Same as water 

(100 oC) 

Flammability 

(flash point for liquids; oC)

1. Non flammablea

2. Non flammable 

Not applicable 

Density (20oC; kg/m3) 1. 1370 ca. 

2. 1708 

1000 - 1035 ca (for 

dilute sol’n in sea 

water) 

Vapor pressure 1. 6700 Pa (40oC, 40% 

sodium chlorate sol’n) 

2. <133.32 Pa (37.8oC) 

399.9 Pa (30 oC)

Vapor density (air=1) 1. Similar to waterb 

2. 3.4 @ boiling 2.3 
26

Physical/Chemical 

Property 

(with units & reference)

Preparations

 1. Purate® 

 2. Sulfuric Acid 

 (78% by weight)

Active Substance 

Chlorine Dioxide 

(solution)

Relevant Chemical

Sodium Chlorite

Treated Ballast 

Water 

 point 

Water solubility 

(temp; effect of pH; mg/L) 3.0 g/L @ 25oC and 

34 mmHg 

39 g/100 ml at 17°C 

(from solid form) 

pH in solution 1. 2 ca 

2. <1 (1% aq.sol’n) ca 6.7 - 7.6 

Dissociation constant 

(pKa) 1.72i 1.72i 

Oxidation-reduction 

potential 

1. Strong Oxidizer 

2. Strong Oxidizer 0.95 V @ pH 4-7 ca 100 – 700 mVk 

Corrosivity to material or 

equipment 

1. See notec 

2. Corrosive 

Produced in situ and 

delivered to ballast 

tanks with materials 

designed for ClO2. 

Similar to untreated 

ballast water (see 

Section 6.1.2) 

Similar to 

untreated ballast 

water (see 

Section 6.1.2) 

Reactivity to container 

material 

1. Yesd 

2. Yese

Produced in situ, not 

stored 

Autoignition temperature 

(oC) 

1. Not applicable 

2. No Data 

 Available 

Not applicable 

Explosive properties Stable as an 

aqueous sol’nj 

Oxidizing properties 1. Strong oxidizerf  

2. Strong oxidizerg 

Intended for use as 

disinfectant/oxidizer 

Surface tension 1. See noteh 

2. Not Available 

Similar to intake 

water

Viscosity (20oC) 1. 1.8 mPa.s 

2. 26.7 mPa.s Same as treated 

sea water 

The low 

concentration will 

not affect typical 

sea water viscosity 

1060 cP (20oC) 

(same as sea 

water) 

Thermal stability and 

identity of breakdown 

products 

Avoid elevated 

temps to 

avoid/reduce 

evolution of ClO2 

gas. 

Other physical or 

chemical properties 

1. Liquid slight blue color 

w/ slightly pungent odor. 

2. Dense, viscous, 

colorless, odorless liquid 

Pale green/yellow 

solution with an odor 

similar to chlorine. 

-- -- 

Salinity 23.8 – 24.7 ppt 

TOC/DOC, 

% Particulate Matter 

3271 μg/l (TOC) 

3073 μg/l (DOC)

6.05%l 

Shaded cells = data not required 

a

 Contact with organic materials e.g. textiles, wood or leather may cause fire, if allowed to dry. Contamination from various metals 

 or organic materials may cause rapid decomposition, resulting in oxygen gas release and pressure build-up if not properly vented. 

b Purate®

 is a solution of sodium chlorate and hydrogen peroxide containing 52% water. The only relevant vapor present is water 

 vapor. 

c Purate®

 is corrosive to carbon steel, copper, and brass. Stainless steel 316 and 316L are suitable. Non-metal materials such as 

 CPVC, PVDF, PTFE, ECTFE, and vinyl ester resins offer excellent performance. Polyethylene and polypropylene offer good 

 performance, typically for storage tanks.

d

 Materials to Avoid: Incompatible materials and chemicals such as organic materials, alkaline substances, strong acids, 

 phosphorus, sulphur, sulphides, sulphites, and metal/ammonium salts. Contaminated organic materials ignite readily if allowed to 

 dry. Decomposes in contact with certain metals and alkalis, which generates oxygen gas. Risk of explosion. 

e Do not store near bases, halides, sulfides, picrates, nitrates, chlorates, carbides, fulminates, cyanides, and reducing agents. Do 
27

 not allow water to enter containers. Sulfuric acid may be safely stored in properly designed bulk storage tanks. 

f

 Contamination from various metals or organic materials may cause rapid decomposition, resulting in oxygen gas release. Assists 

 combustion. Contaminated clothing will become highly combustible if allowed to dry, and may be ignited by friction or heat. 

g

 Sulfuric acid is not flammable or combustible. However, it is highly reactive. Concentrated sulfuric acid is a strong oxidizer 

 capable of igniting combustible materials on contact. 

h No test data is available. Expect it to be similar to a water solution of ionic salts, like sodium chloride.

i The pKa for chlorous acid (HClO2) is 1.72. HClO2 ↔ ClO2-

 + H+ 

j BWTS chlorine dioxide solution (5 mg/L) is >99.5+% water and is generally water-like. Highly concentrated solutions (>8000 mg/L) 

 can be explosive.

k At higher end of range immediately after chlorine dioxide treatment, then decreases to values similar to untreated ballast water. 

l

 % Particulate matter calculated as follows: 100*(TOC-DOC)/TOC 

2.5 ANALYTICAL METHODS AT ENVIRONMENTALLY RELEVANT 

CONCENTRATIONS (G9: 4.2.1.5) 

Chemistries that have been tested and verified by the USEPA are used to analyze the chlorine 

dioxide treated ballast water produced by the Ecochlor®

 BWTS. Chlorine dioxide residuals are 

measured using the lissamine green B (LGB) chemistry (USEPA Method 327). Chlorite ion 

residuals are measured by ion chromatography (IC) (USEPA method 300.1). 

Chlorine dioxide measurements are performed using the Palintest 1000 Chlordiox-Duo 

Photometer with prepackaged reagent kits to measure chlorine dioxide in the 0.1 to 20 mg/L 

concentration range. The LGB detection chemistry is highly selective for chlorine dioxide in the 

presence of chlorite ion. The prepared reagents establish the proper pH to minimize any 

potential reaction with chlorite ion. The reagent kit also includes a chemical mask to react with 

chlorine if it is present in the sample. Under the measurement conditions, studies indicate that 

the seawater matrix does not create interference issues that might lead to inaccurate 

measurements. The recommended operating range is 0 – 40oC, and the test reagents are 

calibrated for use at 15 - 25oC. For lower or higher sample temperatures equilibration of a 

particular sample to ambient temperature is recommended. 

The sensitivity of the Palintest LGB analytical method provides field verification of the expected 

decay of chlorine dioxide in treated ballast water at levels below environmentally relevant 

concentrations. 

Chlorite ion is measured using USEPA Method 300.1. This method uses a sodium carbonate eluent 

to separate and measure common anions (F-

, Cl, NO2

-

, Br-, NO3

-

, HPO4

2- and SO42-) as well as 

chlorite, chlorate and bromate ions. Typically, the sample (25 to 1,000 μL) is injected into the 

eluent at 1.0 mL/min. The sample passes through a metal free column to remove dissolved metals 

and a guard column before separation on the analytical column. An anion suppressor is used with a 

weak acid regenerant solution (newer IC systems might use electrochemical suppression which is 

equally effective). Detection is by conductivity. 

 

Method 300.1 may be used to routinely measure chlorite and chlorate ions from 5.0 μg/L to 

concentrations in excess of 5.0 mg/L. Measurement at lower concentrations can be made by 

increasing the sample loop volume. Higher concentrations require a dilution to bring the sample 

concentration to a level inside the calibration range of concentrations. 

The sensitivity of USEPA Method 300.1 provides verification of the chlorite ion concentration in 

chlorine dioxide treated ballast water at levels below environmentally relevant concentrations. 
28

2.6 QUALITY CONTROL/QUALITY ASSURANCE (G9: 4.2.4) 

2.6.1 Chemical Quality Control 

Purate®

 is a proprietary chemical formulation manufactured by Eka Chemicals. An outline of 

the procedure Eka follows to ensure quality of their product is included in GESAMP submission. 

Sulfuric acid is obtained from different suppliers depending on the location where chemical resupply may occur. Each sulfuric acid supplier provides batch control or certificate of analysis 

documentation. Examples of these documents are included in GESAMP submission. 

Chlorine dioxide is generated on demand and quality is assured through preparation chemical 

quality. Additionally, the operational parameters of the system that are controlled automatically 

(discussed in Section 3.0) ensure efficiency of chlorine dioxide production. Routine BWTS 

maintenance also ensures system efficiency and quality of the active substance. 

2.6.2 Test Data Quality Control 

Nautilus Environmental has performed toxicity tests for evaluation of the Ecochlor®

 BWTS. 

Quality assurance documentation is included in GESAMP submission. 

NovaChem Laboratories, Inc. has performed chemical analysis for Ecochlor. Quality assurance 

documentation is included in GESAMP submission. 

Data quality is also discussed in Section 6.5.2. 

3.0 USE OF THE ACTIVE SUBSTANCE 

3.0.1 Manner of Application (G9: 4.2.6) 

As described in Section 1.0, Ecochlor is utilizing a two precursor chemical approach to generate 

chlorine-free chlorine dioxide onboard. The two precursor chemicals are Purate® and sulfuric 

acid. Purate®, a proprietary chemical from Eka Chemicals, is a mixture containing 40% by 

weight (NaCl03) sodium chlorate and 8% by weight (H2O2) hydrogen peroxide. The sulfuric 

acid is industrial grade 78% by weight (H2S04) acid solution. 

The Ecochlor® BWTS generates and injects a dilute solution of chlorine-free chlorine dioxide 

(5.0 mg/L final concentration) into ballast water as it is loaded onboard. Chlorine dioxide is 

generated on demand based on the volume of ballast water being brought onboard and is injected 

immediately. Chlorine dioxide is not stored onboard as a concentrated substance at any time. 

The mechanism of action of chlorine dioxide on organisms is not entirely deciphered. However, 

a study by Aieta and Berg (1986) reported that permeability of the outer membrane is disrupted 

by chlorine dioxide13. Additional studies supported the findings that outer membrane proteins 

and lipids were altered by chlorine dioxide13

. 

During Ecochlor’s early investigations with chlorine-free chlorine dioxide the target dosage 

found to be effective on the widest array of organisms in various water samples was 5.0 mg/L. 

This target dosage was established by examining the efficacy of chlorine dioxide treated water 
29

(20°C) at 1.0, 5.0, 10 and 20 mg/L dosages in a laboratory setting. In developing the target dose, 

the desired concentration had to be high enough to meet the initial chlorine dioxide demand of a 

water sample (demand is discussed in Section 2.0.2), and then a residual concentration of 

chlorine dioxide had to remain in the water sample long enough to be effective on biofilms 

and/or AIS in ballast tank sediments. These trials indicated that at a treatment of 1.0 mg/L 

chlorine dioxide, the chlorine dioxide was quickly consumed and therefore, a residual 

concentration was not available for disinfection. While chlorine dioxide dosages of 10 and 20 

mg/L were effective biocidal treatment, the residual concentration persisted longer than 

necessary and was considered an excessive use of chlorine dioxide. 

Therefore, the study demonstrated that chlorine dioxide applied at a dose of 5.0 mg/L is safe, 

effective, and economical. Treatment at 5.0 mg/L neutralizes all forms of AIS and then remains 

effective to neutralize any biofilm or AIS that might be present in the ballast system and ballast 

tanks. 

In the significant number of tests that Ecochlor has conducted on treated ballast water, the typical 

time required for chlorine dioxide to decay to a non-detectable concentration is less than 24 

hours. In waters that are colder or warmer, or have lower or higher levels of organic matter, 

decay rates may decrease or increase. The 5.0 mg/L target dosage and subsequent residual 

concentration time (i.e. holding time) ensures effective removal of AIS and a zero concentration 

of chlorine dioxide in treated ballast water at the time of discharge. 

3.0.2 Operational Overview & Process Description 

The Ecochlor®

 BWTS consists of two self-contained chemical storage modules, two separate 

precursor chemical pumps, a chlorine dioxide generation module (housing for the reactor 

column), a booster pump, a programmable logic controller (PLC), an operator interface terminal 

(OIT), a system status/start-up panel, and piping to inject chlorine dioxide solution into the 

ballast water line. Ancillary equipment includes pipelines for chemical vents and re-supply, and 

in-line sampling valves. For demonstration, an engineered drawing of a full scale Ecochlor®

BWTS is included in GESAMP submission. Figure F3.1 provides a photograph of the 

Ecochlor® BWTS and F3.2 outlines the Ecochlor® BWTS process. 
30

Motive Water 

Figure F3.1 – Photo of Full Scale Ecochlor®

 BWTS 

Figure F3.2 – Ecochlor® BWTS Process Flow Diagram 

 

FT = Flow Transmitter, PT = Pressure Transmitter, PLC = Programmable Logic Controller 

With Eka’s SVP-Pure® chlorine dioxide generator, individual chemical pumps transfer the 

Purate® and sulfuric acid to the reactor column within the chlorine dioxide generation module. 

The reactor column is under vacuum and is continuously monitored using a pressure transmitter 

to ensure the generation of chlorine dioxide is under sub-atmospheric conditions. Loss of 

vacuum for any reason (loss of water flow, power, etc.) will automatically shut down the system 

and stop chlorine dioxide production. Inside the reactor column, the chemicals react to form 

To Ballast Tanks 

Venturi Eductor 
31

chlorine dioxide, oxygen, sodium sulfate and water. (Refer to Section 2.0 for a detailed 

discussion of the chemistry.) 

At no time during the production or injection of chlorine dioxide are any chemicals open to the 

atmosphere. All chemicals are completely contained in appropriate storage vessels or pipelines 

during the entire treatment process. All aspects of the treatment process take place under 

conditions that are highly controlled and monitored automatically at all times. Chlorine dioxide 

is generated on demand based on the volume of ballast water being brought onboard and is 

injected immediately. Chlorine dioxide is not stored onboard at any time. 

3.0.3 System Monitoring & Control, Crew Interaction 

The Ecochlor® BWTS is designed to provide a safe, economical and completely effective 

solution to the problem of AIS in ballast water. It is also designed to minimize impacts to 

existing cargo and ballasting operations, crew activities, and demands of the vessel (power, 

water, etc.). The Ecochlor® BWTS is fully automated and, depending on how automated the 

ships’ ballast water system is, typically requires no additional actions by the crew or alteration of 

current ballasting procedures. However, more “manual” ballast water systems that do not have 

electronic monitoring capabilities may require slight alterations in current ballasting procedures 

to avoid conditions that the Ecochlor® BWTS could falsely recognize as unacceptable. Minor 

modifications to ballasting procedures, if any, are ship specific and carefully considered during 

system engineering and installation. 

If at any time during the ballasting operation the parameters required for safe operation are not 

met, the BWTS automatically stops production of chlorine dioxide. An alarm is given and the 

condition resulting in the alarm is displayed on the OIT. A list of system alarms and the 

appropriate response for each are provided during Ecochlor’s training of ship’s crew and are kept 

with the system. Should an alarm condition occur, reactivating the system requires that the 

condition be recognized. Once addressed, the alarm is reset on the OIT. Once reset, the PLC 

will again perform the series of run permissives and resume chlorine dioxide production. Further 

discussion on the BWTS alarms and safety capabilities can be found in Section 3.0.7. The 

reliability of Eka’s chlorine dioxide generators is discussed in Section 3.0.5. 

3.0.4 System Requirements 

Power Requirements: The power requirements for the Ecochlor®

 BWTS are quite small. These 

are: 480 VAC, 3-phase, 60 Hz, rated at 16 FLA. The PLC panel requires 1-phase, 60Hz, 220 

VAC rated at 2 FLA. 

Water Requirements: As discussed above, a small amount of motive water flow (approximately 

53 L/min) is required for a system treating 2,500 m3/hour of ballast water. The water can be 

fresh or sea water, and is utilized to create a vacuum in the reactor column. This vacuum draws 

the chlorine dioxide into solution for delivery to the ballast water system. 

Space Requirements: The Ecochlor® BWTS can be completely enclosed within the dimensions 

of a standard shipping container, or a custom design can be developed to accommodate a specific 

vessel’s requirements. One of the two systems currently installed is fully enclosed in a container 

with dimensions of 5.03 m x 1.98 m x 2.34 m. The other system was designed to meet the 
32

requirements of the space and is not fully enclosed, with a small footprint measuring 

approximately 7.5 m2. 

Personnel Requirements: The Ecochlor®

 BWTS was designed to require minimal input from 

technicians and/or crew members. In most installations, the system is kept in an “enabled” or 

idle state until the PLC detects a ballasting operation. The crew member performs the ballasting 

procedure as normal (gravity, pump, etc,) and the Ecochlor®

 BWTS automatically treats 

incoming ballast water. The BWTS also determines when ballasting has stopped and conducts a 

pre-determined shut-down procedure to flush residual chlorine dioxide from the reactor column 

and injection piping. The BWTS returns to an idle state until the next ballasting operation is 

detected by the PLC. 

For installations on ships with a more manual ballasting system that is not capable of electronic 

signals, a crew member may be required to push a ‘start’ button or switch on a control panel after 

the ballasting operation has been initiated. The BWTS will then operate and control chlorine 

dioxide production automatically as described above. No further crew member action is required 

to stop chlorine dioxide production as the PLC will recognize when the ballasting operation has 

terminated, perform the shut-down procedure and return to the idle status. 

Maintenance Requirements: The chlorine dioxide generator requires approximately 6 hours of 

preventative maintenance per year. Ecochlor technicians will conduct this service during routine 

technical service visits. The scheduled maintenance can easily be accomplished during a typical 

port call and will be conducted when the BWTS is not needed for treatment of ballast water. 

Maintenance that involves chemical inventory or re-supply will always be handled by Ecochlor 

technicians, and never ships’ crew. 

3.0.5 System Locations, Considerations and Limitations 

Locations and Considerations: The most important factor in the safe operation of the Ecochlor®

BWTS is to first determine a suitable location. Some of the factors that must be considered for 

placement of the Ecochlor® BWTS are: 

• General space limitations – what engineering will be required to fit the system in the 

desired location? 

• Is there a location available that does not interfere with normal cargo operations or 

required crew activities? 

• Can motive water and electricity be provided in a safe and practical manner? 

• Can chlorine dioxide solution piping be routed to the injection point in a safe and 

practical manner? 

• Can the precursor chemicals be re-supplied easily or can the chemical storage units be 

easily removed and re-supplied land based? 

• Is the area’s cleanliness acceptable? The area around the Ecochlor® system should be 

clean and free of debris. 

The Ecochlor®

 BWTS can be located in any suitable and convenient location dependant on the 

ship’s design. Ecochlor’s naval architects look for placement opportunities close to the main 

ballast water pumps to minimize the length of piping needed for any given installation. 
33

Limitations: Incoming or Raw water 

Chlorine dioxide was selected for treatment of ballast water because of its ability to work 

effectively under extremely varied water quality conditions. Ecochlor is confident that the 

various water conditions found around the world are well within the operational parameters of 

the BWTS and chlorine dioxide effectiveness. For example, chlorine dioxide is effective in brine 

water (deep oil well applications), high solids applications (paper mill thick stock, 5 % by 

weight) and high color / high organic loading applications (paper mill, drinking water pretreatment)14

. 

The Ecochlor® BWTS requires no pretreatment of the ballast water to be effective. This means 

that high solids or color need not be filtered or removed for the chlorine dioxide to be effective 

against potential AIS. Also, the Ecochlor® BWTS can easily handle the temperature variations 

likely encountered in ballast water at different ports world wide, which are mild compared to 

many other applications where chlorine dioxide technology is successful. 

3.0.6 BWTS Operational Safety Features and Alarms 

Safety Valve Isolation of the BWTS from the Ship’s Ballast System: The Ecochlor® BWTS and 

the ships ballasting system are interconnected only by the delivery line/injection quill for 

injecting the chlorine dioxide solution into the ballast water and, in the case where the ballast 

water is used as motive water, the incoming water line from the ballast system to the Ecochlor®

BWTS. These lines are fitted with safety valves that separate the BWTS from the ship’s systems 

in case of an emergency. These safety valves, together with the failsafe measures in the PLC that 

shut down the BWTS in the event that all run-permissive criteria are not met, protects the ship’s 

integrity and assures safe operating conditions. These safety valves have the appropriate 

approvals by the ship’s classification society and are constructed of materials appropriate for the 

application. Additional discussion regarding safety is included in Section 6.2. 

System Parameter Alarms: The single most important driving factor in all of Ecochlor’s design, 

manufacturing, and installation decisions of any Ecochlor®

 BWTS is safety. In light of this, the 

Ecochlor®

 BWTS requires multiple and redundant system parameters to be met prior to the 

activation of the system and subsequent production of chlorine dioxide. Should any of the 

parameters not be met, the system will not function and chlorine dioxide will not be generated. 

 

The Ecochlor®

 BWTS will provide alarms and indicate which parameter is not to specification. 

Technicians and/or the ships’ crew can be alerted to an alarm condition in a variety of ways 

depending upon the specific needs of each crew and vessel. For instance, the alarm can be sent 

to a lighted control panel in the engine room, displayed on an OIT, or an audible signal can be 

sent to the crew radio communication system. Corrective action may be taken by shipboard 

personnel if it falls within the guidelines established by Ecochlor, or Ecochlor will service the 

installation on-site should it be necessary. 

3.0.7 Precursor Chemical Storage, Handling and Delivery 

Ecochlor’s team has accumulated over 100 years of industrial and municipal experience in 

storing, feeding and re-supplying these and many other chemicals. This experience is utilized in 

the design, fabrication and installation of the Ecochlor®

 BWTS. Ecochlor also utilizes a team of 

 

14 Simpson, G.D., Miller, R.F., Laxton, G.D., Clements, W.R., A Focus on Chlorine Dioxide: The “Ideal” Biocide. 
34

Naval Architects and Marine Engineers from Seaworthy Systems, Inc. to assist with the specifics 

of shipboard installation and environments. 

3.0.8.1 Chemical Storage 

The two precursor chemicals (Purate® and sulfuric acid) are stored onboard in tanks designed 

specifically for this service. Exact tank specifications such as size and location are determined 

according to conditions specific to each ship. The amount of the preparation chemicals kept on 

board will depend on the ballast water capacity of the vessel. Ecochlor designs the system and 

performs calculations so that enough chemicals are kept onboard to ensure effective ballast water 

treatment and achieve a re-supply schedule of two to three times per year. For the two Ecochlor 

systems currently installed, the tanks are designed to hold a maximum of approximately 1.14 m3

of each preparation chemical. Future systems may have higher or lower chemical volumes 

depending on the nature of the specific ballast water requirements and refill capabilities. 

The Purate® is stored in a stainless steel tank designed for this application. Purate® can be safely 

stored in a vented stainless steel tank for extended periods of time. Tanks for Purate® storage are 

constructed of 316L stainless steel that is passivated prior to the introduction of Purate®

. 

The sulfuric acid is stored in a steel tank lined with Halar (ECTFE) to a minimum thickness of 

1.5 mm. This coating is recommended for this application by the coatings manufacturer15. It is 

important to note that sulfuric acid is the world’s most commonly utilized commodity chemical. 

Sulfuric acid is often referred to as the “king of chemicals”, and is produced in greater amounts 

than any other chemical besides water16. Many applications have utilized this material safely for 

many years, often delivering the acid via ocean freight. 

 

The chemical storage tanks are designed with secondary containment that has a capacity of 130% 

of the tanks volume, assuming a 30 degree vessel list, and are approved by each ship’s 

classification society (Lloyd’s & ABS). Each Ecochlor® BWTS will be equipped with the 

appropriate spill containment supplies in the unlikely event of a chemical release. 

Chlorine dioxide is generated on demand, is never transported to the ship, and is never stored 

onboard. 

3.0.8.2 Chemical Handling 

Re-supply of the precursor chemicals will be the only time these chemicals are ever “handled” 

during the use of the Ecochlor® BWTS. The logistical details involved will vary based on a 

variety of factors for each specific ship such as the type of vessel, the geographic location where 

re-supply will occur, and where the fill station is installed on the vessel. Ecochlor is capable of 

conducting chemical re-supply operations at port facilities world wide. ONLY Ecochlor 

technical representatives or highly qualified contractors trained by Ecochlor will perform resupply operations. Ships’ crew, longshoremen, stevedores, and any other port facility workers 

will never be required to handle the precursor chemicals at any time. 

 

15 Mosser, Mark L., Sermatech International Inc., September 15, 2005 

16 The Sulphur Institute Online, Glossary of Terms, (http://www.sulphurinstitute.org/webarticles/anmviewer.asp?a=109&z=30) 
35

The Ecochlor system does not give off fumes or gases during normal operation. However, a 

small amount of fumes may be displaced when the chemical storage tanks are refilled, and 

sufficient ventilation is necessary during these operations. For this reason, the chemical tanks 

are equipped with vent lines. Each Ecochlor® BWTS installation considers proper chemical 

storage tank ventilation, preferably to atmospheric conditions such as the weather deck or 

overboard. The locations of the chemical tank vent lines are placed to ensure that technicians, 

ship or port crews are not at risk of inhalation dangers during chemical re-supply operations. 

For an installation where venting the chemical tanks to the atmosphere is not possible, placement 

of the Ecochlor® BWTS in a suitable location where proper ventilation can be achieved is 

necessary. To be more specific, proper ventilation would ensure that the occupational exposure 

limits for Purate® and sulfuric acid in air are not exceeded (MSDS sheets in GESAMP 

submission) include exposure limits for each chemical). The flow rate to ensure these limits are 

not exceeded is dependent upon the engineering specifics the installation (size of the space where 

the tanks are located, volume of chemical vapors displaced, etc.). Therefore, it is not practical to 

provide an exact air flow rate that may be required for a particular installation. However, the 

ventilation rate would ensure the occupational limits are not exceeded. 

Most important for an installation where venting the chemical tanks to the atmosphere is not 

possible, is selection of a suitable location on the ship where existing ventilation mechanisms are 

in place. An example is a Ro-Ro deck. The cargo operations that take place normally on Ro-Ro 

decks can produce harmful vapors. As such, the existing ventilation equipment is in place to 

comply with the occupational exposure limits of a large volume of potentially harmful vapors. 

The rate of air exchange required for such cargo operations will exceed the necessary air 

exchange rate for the small amount of chemical vapors that might be displaced during a chemical 

refill operation. 

To summarize, Ecochlor’s preferred method for chemical tank ventilation is to the atmosphere, 

in a location that will not create inhalation dangers for technicians, ship or port crews. Should 

ventilation to the atmosphere not be possible, placement of the system where existing ventilation 

methods are already in place will ensure the occupational exposure limits are not exceeded. It is 

also important to note that vapor displacement from the chemical tanks is not continual. Vapors 

will only be displaced from the chemical tanks during refill operations, which are anticipated to 

occur at a frequency of two - three times per year.

The unloading of foreign materials into the Ecochlor

®

 BWTS chemical storage tanks could cause 

a dangerous event. The chemical fill lines are placed away from other lines for 

loading/unloading, are clearly labeled, and secured (locked) to minimize the chance for misdelivery of material. Additionally, the chemical fill line fittings for Purate®

 are unique and 

different from those of the sulfuric acid fill line fittings. 

The unloading practices and safeguards are outlined by the manufacturer’s MSDS of the two 

precursor chemicals. The Purate® and sulfuric acid MSDS sheets, as well at the Purate®

Technical Bulletin provided by Eka Chemicals / Akzo Nobel, are included in GESAMP 

submission. 
36

Only highly trained Ecochlor technicians or representatives will conduct re-supply of precursor 

chemicals. This will ensure the proper procedures are followed at all times. No crew assistance 

is needed in the chemical handling procedures, but proper notification and scheduling is 

mandatory. 

For general safety, awareness training of the ship’s crew is required and performed by Ecochlor 

or its trained representatives. Additional health and safety discussion is included in Section 6.2. 

3.0.8.3 Chemical Delivery 

The piping used for delivery of the sulfuric acid to the chlorine dioxide generation module is 

HastelloyTM (C22 and C276), while the pipe for delivering the Purate® to the generation module 

is 316 stainless steel. The pipe used to carry the motive water to the Ecochlor® BWTS is 

typically a 2” BondstrandTM pipe. This is the same type of pipe used to carry the chlorine 

dioxide solution to the injection point. BondstrandTM pipe has been approved for this service by 

both ABS and Lloyds. 

3.0.8 Various Procedures and Management Measures 

3.0.8.1 Fire 

As with any fire, human exposure to fire, smoke, fumes or combustion products will be 

prevented by utilization of proper personal protective equipment (PPE). Also, non-essential 

personnel will be required to evacuate the fire area. 

Purate® is non-flammable in solution; however, organic materials (e.g. textiles, wood, or leather) 

saturated with Purate®

 may increase the potential for fire if allowed to dry, and a heat or ignition 

source is applied. A fire involving Purate® is to be extinguished with water or a water spray. 

The use of dry foam, powder or carbon dioxide type extinguishers is to be avoided. Purate®

 will 

sustain combustion due to release of oxygen upon thermal decomposition. Refer to the Purate®

Material Safety Data Sheet (MSDS) that is included in GESAMP submission for complete fire 

procedures. 

Sulfuric acid is not flammable or combustible and is not sensitive to static discharge or 

mechanical impact. However, it is highly reactive and concentrated sulfuric acid is a strong 

oxidizer capable of igniting combustible materials. A fire involving sulfuric acid is to be 

extinguished with dry chemical, carbon dioxide or foam extinguishing agents. A fire area may 

be flooded with water, or fire-exposed containers may be kept cool with a water spray, but water 

shall not be allowed to enter containers of sulfuric acid. Decomposition of sulfuric acid under 

fire conditions will produce sulfur oxides. Refer to the sulfuric acid MSDS that is included in 

GESAMP submission for complete fire procedures. 

3.0.8.2 Accidental Release Measures 

Ecochlor technicians and ship’s crew will be sufficiently trained to respond to a chemical spill 

situation. Training will include, but may not be limited to, familiarization of the chemical 

properties and reactivity, exposure hazards, and correct donning of PPE. Proper PPE will 

include respiratory protection equipment, eye and face protection (goggles and/or face shield), 

chemical resistant gloves and boots (or boot covers), and chemical resistant clothing. 

 
37

Any accidental chemical release requires isolation of the spill area and evacuation of nonessential personnel. Proper PPE is to be worn, good industrial hygiene practices will be 

maintained and adequate ventilation will be used in any area of accidental release. 

For both Purate® and sulfuric acid, suitable dry, inert materials that are not combustible (sand, 

earth) or sorbents that are designed for use with these chemicals will be used to absorb spills. 

Chemical spill containment kits and PPE are kept near the BWTS in the event of a chemical 

release. Used absorbent materials will be placed in appropriate chemical waste containers for 

proper disposal. 

3.0.8.3 Marine Environment Release 

The preparations, although they should not be allowed to freely enter the marine environment, 

will not create surface impacts such as oil slicks or thick sludges because both substances are 

ionizable in water. Should a marine environment release occur the proper agencies/authorities 

will be notified. 

If contained, a Purate®

 spill can be handled and disposed of as a chemical waste. If released into 

the marine environment, the Purate® will readily dissipate as the solution is totally miscible in 

water. No practical methods of decontamination in a marine water body are available. 

Neutralization of sulfuric acid can be achieved with sodium bicarbonate, crushed limestone or 

agricultural lime. This product does not contain any components which are designated by the US 

Department of Transportation to be Marine Pollutants (49 CFR 172.101). 

3.0.8.4 Active Substance Waste Management, Reuse, Recycling, Neutralization 

Because the active substance is generated on demand and applied in situ, no active substance 

waste stream is created during the treatment process. 

 

3.0.8.5 Conditions for Controlled Discharge 

Because the active substance is generated on demand and not stored on board, a situation where 

unwanted chlorine dioxide needs to be discharged is not anticipated. 

In the very unlikely event that the precursor (preparation) chemicals need to be removed from 

the vessel, the necessary chemical transfer pumps, discharge piping and vessel-specific protocols 

will be onboard the vessel. 

3.0.10 Evaluation of Management Measures 

Preventing exposures and emergency situations begins with proper engineering and construction 

of systems that are designed for use onboard ships. The measures utilized in managing the 

chemicals associated with the Ecochlor®

 BWTS consider system placement, proper training, and 

substance handling that will avoid uncontrolled or emergency situations. The management 

measures discussed in Section 3.0.9 above are considered adequate to properly manage the 

Ecochlor® BWTS chemicals in a safe manner. 
38

4.0 HAZARD CLASSIFICATION & MATERIAL SAFETY DATA SHEETS (G9: 

4.2.7) 

The hazard classifications presented in this section reflect hazards only and do not consider 

actual potential for exposure. 

4.0.1 Purate®

The hazard classification presented below for Purate

®

 is according to the European Union 

directive on classification of hazardous preparations (1999/45/EC). Complete information is 

included on the Purate®

 MSDS provided in GESAMP submission. 

R-phrases: R9, R22, R36, R51/53 

S-phrases: S3/4, S36/37/39, S46, S61 

4.0.2 Sulfuric Acid 

The hazard classification presented below for sulfuric acid data from International Chemical 

Safety Cards (ICSC #0362). Additional information is provided on the sulfuric acid MSDS 

provided in GESAMP submission. 

R-phrases: R35 

S-phrases: S1/2, S26, S30, S45 

4.0.3 Chlorine Dioxide 

The hazard classification presented below for chlorine dioxide solution generated with the SVPPure®

 technology is according to the European Union directive on classification of hazardous 

preparations (2001/59/EC). Additional information is included on the chlorine dioxide MSDS 

provided in GESAMP submission. 

R-phrases: R20, R36/37/38 

S-phrases: S24/25, S26, S36/37/39 

4.0.4 Sodium Chlorite 

Utilizing a typical MSDS sheet for sodium chlorite solution for hazard classification does not 

accurately represent the potential hazards at the low concentration of chlorite ion that may be 

present in treated ballast water. Thus, hazard classification is not provided for chlorite ion, but 

toxicology data is presented in this application. 

5.0 RISK CHARACTERIZATION 

5.1 SCREENING FOR PERSISTENCE, BIOACCUMULATION, & TOXICITY (G9: 

5.1) 

Biocide treatment of water can raise questions regarding the formation of THM’s and/or HAA’s. 

Chemical analysis and known chemical principles of disinfection using chlorine dioxide that is 

generated in the chlorine-free method used with the Ecochlor®

 BWTS indicate that these reaction 

by-products are not present at environmentally relevant concentrations. As such, THM’s and 

HAA’s are not evaluated in regards to persistence, bioaccumulation and toxicity in this 

application. Chemical data and justifications regarding these substances are located in Sections 

1.0.1 and 2.0.3.3. 
39

5.1.1 Persistence (G9: 5.1.1.1) 

Chlorine dioxide and chlorite ion demand/decay data presented in Section 2.0 demonstrate that 

these constituents do not persist for extended periods of time in water. These findings are 

supported by the physical and chemical properties (i.e. high solubility, non-organic) associated 

with these substances as well as studies conducted by others. 

For chlorine dioxide, Cooper et al. (2007) demonstrated that chlorine dioxide degradation is 

photochemically-enhanced2

. Fisher and Burton (1993) reported that at 25°C, 60% of chlorine 

dioxide decays to chlorite within 15 minutes, and decayed completely within four hours2. 

Chlorite is more stable in aqueous solution than chlorine dioxide; however, in a similar manner 

to chlorine dioxide, chlorite also degrades in aqueous solution as a result of oxidative reactions. 

Residual chlorite ion in treated ballast water will decrease through reactions with organic matter 

to form chloride, which is non-toxic at the concentrations of interest. Chlorite is not persistent as

a result of its degradation pathway to chloride2. 

5.1.2 Bioaccumulation (G9: 5.1.1.2) 

The estimated log Kow of chlorine dioxide is -3.22 and for sodium chlorite is -7.173. These 

values along with the chemical properties (i.e. high solubility, non-organic) of chlorine dioxide 

and chlorite indicate that bioaccumulation is not expected. 

5.1.3 Toxicity (G9: 5.1.2.3) 

5.1.4 PBT Criteria - Active Substance (G9: Table 1) 

Table T5.1 – PBT Criteria for Chlorine Dioxide & Chlorite Ion 

Substance 

Persistence (P)

Half-life: 

>60 days in marine water, or 

>40 days in freshwater, or 

>180 days in marine 

 sediment 

>120 days in freshwater 

 sediment

Bioaccumulation (B)

BCF >2,000 or Log Kow

≥3 

Toxicity (T)

Chronic NOEC 

<0.01mg/L 

Chlorine dioxide 

3.9 minutes, clear freshwater 

at 5 meters2

Criteria fulfilled - No 

-3.223

Criteria fulfilled - No 

Lowest chronic 

NOEC = 0.09 mg/L 

(see Table T2.5) 

Criteria fulfilled - No 

Chlorite Ion 

<1 hour in saltwater 

(See Figure F2.4) 

Criteria Fulfilled – No 

-7.173

(as sodium chlorite) 

Criteria fulfilled - No 

Lowest chronic 

NOEC = 0.18 mg/L 

(See Table T2.5) 

Criteria Fulfilled - No 

It is important to note that the half-life of chlorite ion reported is based on laboratory analysis 

with a raw sea water sample. The decay rate in another water sample may be shorter or longer, 

depending on the organic matter present and water temperature. However, this analysis is 

consistent with the well-documented decay behavior of chlorite ion indicating that persistence 

>60 days in sea water would not be expected. 
40

The estimated log Kow values for chlorine dioxide and chlorite, the physical and chemical 

characteristics (i.e. highly soluble, non-organic), along with well-documented degradation 

behavior, indicate that chlorine dioxide and chlorite ion will not bioaccumulate. Additionally, 

neither chemical meets the criteria to be classified as PBT substances. 

5.2 EVALUATION OF THE TREATED BALLAST WATER 

5.2.1 Determination of Holding Time 

5.2.1.1 Toxicity and Dilution of Treated Ballast Water 

Nautilus Environmental performed toxicity testing on treated ballast water2 (See Tables T2.9 and 

T2.10). Mytilus sp. bivalve larval development and Mysidopsis bahia acute toxicity tests were 

selected because these species were identified as being the most sensitive to chlorine dioxide and 

chlorite, respectively. An acute toxicity test was selected for M. bahia due to the small 

difference in the acute test EC50 (0.58 mg/L) and the chronic test NOEC for chlorite (0.18 

mg/L). Thus, the acute-to-chronic ratio (acute LC50 divided by chronic NOEC) for M. bahia for 

chlorite was 3.222. 

Results of toxicity tests with treated ballast water using Mytilus sp. (chronic) and Mysidopsis 

bahia (acute) are presented on the basis of percent by volume (% v/v) of treated water. 

No chronic toxicity was observed with the Mytilus edulis larval development test for treated 

ballast water; the EC50 was greater than the highest test concentration in each of two tests 

(>81% and >84% v/v). 

Acute toxicity with M. bahia resulted in EC50 values of 38.7% and 37.7% (v/v) and the NOEC 

for both tests was 25% sample. Thus, a three-fold dilution was necessary to reach a 

concentration less than the EC50 and a four-fold dilution was necessary to result in no acute 

toxicity with M. bahia. Because M. bahia was the most sensitive species to chlorite by a 

significant margin, these data can be considered appropriate to evaluate safe concentrations for 

aquatic organisms. 

Although chronic toxicity tests were not conducted with treated ballast water using M. bahia, 

evaluation of the dilution necessary to result in a chronic toxicity NOEC was calculated. Based 

on acute EC50 values (38.7% and 37.7%) and an acute-to-chronic ratio of 3.22, the NOEC for 

chronic effects is calculated to be 12% and 11.7% (EC50 value divided by 3.22 ratio). Thus, a 

dilution to approximately 12% (v/v) would achieve no chronic toxicity to M. bahia, which has 

been demonstrated to be the most sensitive species by a significant margin in the tests 

performed2

. Further, the next most sensitive species (A. affinis, chronic NOEC 13.8 mg/L) was 

almost two orders of magnitude less sensitive to chlorite. Consequently, application of a 10-fold 

safety margin is likely highly conservative2 and protective of aquatic organisms. 

5.2.1.2 Factors Influencing Holding Time 

As presented in Section 3.0.1, the 5.0 mg/L target dosage and subsequent residual concentration 

time (i.e. holding time) ensures effective removal of AIS and an undetectable concentration of 

chlorine dioxide in treated ballast water at the time of discharge. This target dose of chlorine 

dioxide treatment was developed to use the smallest concentration possible for safe and 

economical treatment of ballast water. 
41

Shipboard testing of chlorine dioxide demand has included seasonal changes in North America 

(North East, Pacific North West, Gulf Coast), Central America (Pacific), Sweden, and North 

Africa. The conclusion is that temperature is the most critical factor in determining the length of 

time for the chlorine dioxide residual to decay to undetectable concentrations in ballast water 

tanks. However, through extensive shipboard testing and laboratory analysis, chlorine dioxide 

decay is predictable. 

In the significant number of tests that Ecochlor has conducted on treated ballast water, the typical 

time required for chlorine dioxide to decay to a non-detectable concentration is less than 24 

hours. In waters that are colder or warmer, or have lower or higher levels of organic matter, 

decay rates may decrease or increase. Decay rates (i.e. demand) of chlorine dioxide in various 

waters at differing temperatures are presented in Section 2.0.2. Ecochlor has found that lower 

temperatures can lengthen the time required to reach an undetectable level of chlorine dioxide, 

while higher temperatures typically increase the decay rate. Ecochlor takes this into account in 

developing and applying the treatment methodology. 

One significant advantage of chlorine dioxide treatment is its ability to remain effective in a 

broad range of pH values. The lack of any significant reaction of chlorine dioxide with water is 

partly responsible for retention of biocidal effectiveness over a wide pH range14. The typical pH 

ranges found in various natural waters will not affect the anticipated decay rates or the holding 

time for effective chlorine dioxide treatment. 

Based on laboratory and shipboard tests, salinity does not interfere with chlorine dioxide’s 

oxidative properties or alter the effectiveness of chlorine dioxide treatment. Ecochlor has found 

that the decay rate of chlorine dioxide in fresh water can be slower that that of salt water. 

However, the chlorine dioxide demand of a particular water sample is more related to the amount 

of organic matter and/or AIS present in the water rather than salinity. 

Another advantage to chlorine dioxide treatment is its ability to disinfect without a need for 

filtration. Sediment loading does not alter the effectiveness of chlorine dioxide treatment of 

ballast water. However, sediment loading may have an effect on the chlorine dioxide demand of 

a particular water sample. 

Although the chlorine dioxide demand of various waters may change, the overall effectiveness 

and holding time required for chlorine dioxide treatment of ballast water remain stable. Ecochlor 

is confident in the holding time (less than 24 hours) that has been developed for effective 

treatment of AIS in ballast water. 

5.3 RISK CHARACTERIZATION & ANALYSIS 

5.3.1 Reaction with Organic Matter (G9: 4.2.1.3) 

Chlorine dioxide is an oxidizing agent. Chlorine dioxide does not chlorinate organic matter, thus 

its use does not promote the formation of trihalomethanes (THMs), which are a concern with 

respect to toxicity and carcinogenicity2

. 
42

In addition, data collected for the drinking water industry shows that the use of chlorine dioxide 

results in a reduction of the observed concentration of organic contaminant species (e.g., THMs, 

haloacetic acids (HAAs), haloaldehydes, haloketones, halocarboxylic acids and other potentially 

harmful organic residues). 

Similarly, the reaction of chlorite ion with organic matter does not produce harmful organic 

chemical species and typically results in a chemical reduction of chlorite ion to chloride ion, 

which is ubiquitous in the marine environment. Therefore, the production of harmful organic byproducts is not anticipated. 

5.3.2 Characterization of Degradation Route & Rate (G9: 5.3.5) 

Chlorine dioxide degrades rapidly in marine and fresh waters, predominantly forming chlorite 

ion as a degradation by-product2. Degradation is by abiotic mechanisms and is typically a result 

of oxidative reactions with target organisms and some organic constituents. Section 2.0.2.1 has 

figures that demonstrate the decay rate of chlorine dioxide at different temperatures. Based on 

these laboratory studies, in a static water sample at 24°C treated with 5.05 mg/L of chlorine 

dioxide had an undetectable concentration within approximately 150 minutes (2.5 hours). 

Chlorite ion also degrades in aqueous solution as a result of oxidative reactions. The rate at 

which chlorite ion degrades depends on the demand of the water. Figures in Section 2.0.3.2 

depict laboratory studies on the decay rate of chlorite ion. In a static water sample at 20°C dosed 

with 1.94 mg/L of chlorite solution, the concentration of chlorite decayed to 0.19 mg/L in 69 

hours. It is important to note that in a laboratory setting where the water sample is in a closed 

system the chlorite ion concentration becomes stable once demand of the water has been met. 

5.3.3 Prediction of Discharge & Environmental Concentrations (G9: 5.3.8) 

When the Ecochlor® BWTS is utilized as directed by Ecochlor, the concentration of chlorine 

dioxide is expected to be at undetectable levels when treated ballast water is discharged. Thus, 

the predicted environmental concentration (PEC) for chlorine dioxide is 0 mg/L. 

Figures F2.1 through F2.3 clearly depict the laboratory-derived concentrations of the active 

substance and relevant chemicals over time with approximately 5.0 mg/L treatment of chlorine 

dioxide at three different temperatures. Repeated testing of this type indicates that the curves are 

predictable. Additionally, ion chromatographic analyses of ballast water treated with 5.0 mg/L 

of chlorine dioxide have measured chlorite ion concentrations ranging from <0.1 g/L to 2.37 

mg/L (see Tables T2.2, T2.3, T2.4, T2.5, T2.6 and T2.7). Therefore, the PEC for chlorite ion is 

<0.1 mg/L to 2.37 mg/L. This range is a result of the varied chlorite ion demand of different 

waters and factors such as organic load, pH and temperature that affect the decay rate. Section 

2.0.3.2 discusses chlorite ion demand /decay in greater detail. 

The data in Table T2.8 shows no formation of THM’s (<1 μg/L) after treatment of ballast water 

with chlorine-free chlorine dioxide from the Ecochlor

®

 BWTS. The table also shows <1 μg/L of 

HAA’s with the exception of a single haloacetic acid (dibromoacetic acid (DBAA), which was 

present at a low level (12 μg/L). These data are consistent with the chemistry of chlorine-free 

chlorine dioxide as an oxidant. The drinking water standard in the United States is <80 μg/L 

total THM’s and <60 μg/L total HAA. Therefore, the analysis of treated ballast water 
43

demonstrates that THM’s and HAA’s are present at levels well below US drinking water 

standards, with a PEC’s of <1 μg/L and <1 μg/L to 12 μg/L, respectively. Based on chemical 

analysis and the G9 definition of relevant chemicals under 2.1.4 of the Guideline, Ecochlor does 

not consider THM’s or HAA’s as relevant chemicals applicable to an evaluation of the 

Ecochlor® BWTS. 

5.3.4 Assessment of Potential for Bioaccumulation (G9: 5.3.7) 

Because the substances utilized with the Ecochlor® BWTS do not have characteristics that would 

indicate a potential for bioaccumulation, no bioaccumulation effects are anticipated. 

5.3.5 Effects Assessment 

Acute and chronic toxicity test data for chlorine dioxide and chlorite are presented in Tables T2.9 

and T2.10, respectively. 

5.3.5.1 Chlorine Dioxide 

From the Review of the Environmental Fate and Effects of Chlorine Dioxide and Chlorite2

: 

“It should be noted that because of the rapid dissipation rate of chlorine dioxide, it is somewhat difficult to 

interpret the results of toxicity tests with this chemical since, unless the system is continually dosed in a 

flow-through manner, the test organisms will typically be exposed to a concentration of chlorine dioxide 

which is diminishing over time, and a concentration of chlorite which is initially increasing (as a breakdown product of chlorine dioxide) and then itself decreasing. Thus, any exposure to chlorine dioxide is 

actually an exposure to both chlorine dioxide and its breakdown product, chlorite, and the extent to which 

each of these toxicants is the cause for any observed effect is somewhat difficult to determine. However, 

such would be the case in an environment in which a non-continuous discharge containing chlorine dioxide 

occurs and, consequently, data from static and static renewal tests with chlorine dioxide appear to be

appropriate for this evaluation.” 

With respect to risk, toxicity to aquatic organisms appears to be the most significant potential 

exposure for chlorine dioxide because it is not persistent in the environment and is not expected 

to bioaccumulate or adsorb to sediments2. An effects assessment of secondary poisoning is not 

relevant. Therefore, the acute and chronic aquatic toxicity results presented in Section 2.1 for 

chlorine dioxide provide the most appropriate evaluation of the potential for adverse effects to 

aquatic organisms. 

Acute toxicity data (LC50 or EC50) are presented in Table T2.9 for survival of the crustacean 

Mysidposis bahia and the larval fish Menidia beryllina (inland silverside), as well as spore 

germination of the giant kelp (Macrocystis pyrifera). EC50 values for these species were ~0.4, 

>0.4 and 0.2 mg/L, respectively. Additional data are presented for survival of a second fish, the 

Pacific herring (Clupea pallasi). 

Chronic toxicity data in Table T2.10 include data for a fish (survival and growth of larval 

Menidia beryllina), an invertebrate (survival and growth of a mysid, Mysidopsis bahia) and an 

algae (germination and growth of giant [Macrocystis pyrifera] kelp spores), as well as for two 

additional species (larval development for a mollusc [Mytilus sp.] and population growth for a 

diatom [Skeletonema costatum]). The most sensitive test species was Mytilus sp., which 

exhibited a chronic NOEC of 0.09 mg/L and an EC50 of 0.22 mg/L on the basis of a larval 

development test. 
44

5.3.5.2 Chlorite Ion 

With respect to risk, toxicity to aquatic organisms appears to be the most significant potential 

exposure for chlorite because it is not persistent in the environment and is not expected to 

bioaccumulate or adsorb to sediments2. An effects assessment of secondary poisoning is not 

relevant. Therefore, the acute and chronic aquatic toxicity results presented in Section 2.1 for 

chlorite provide the most appropriate evaluation of the potential for adverse effects to aquatic 

organisms. 

Acute toxicity data (LC50 or EC50) are presented in Table T2.9 for survival of the crustacean 

Mysidopsis bahia and the larval fish Cyprinidon variegatus (sheepshead minnow), as well as 

spore germination of the giant kelp (Macrocystis pyrifera). EC50 values for these species were 

0.58, 75.0 and >15.4 mg/L, respectively. 

Table T2.10 includes chronic toxicity data for a fish (survival and growth of larval topsmelt, 

Atherinops affinis), an invertebrate (survival and growth of a mysid, Mysidopsis bahia) and an 

algae (germination and growth of giant kelp [Macrocystis pyrifera] spores), as well as for two 

additional species (larval development for a mollusc, Crassostria virginica and an echinoderm, 

Strongylocentrotus purpuratus). The most sensitive test species was Mysidopsis bahia, which 

exhibited a chronic NOEC of 0.18 mg/L and an EC50 of 0.25 mg/L on the basis of a 7-day 

survival and growth test.

5.3.6 Effects on Aquatic Organisms 

When the Ecochlor®

 BWTS is utilized as directed by Ecochlor, the concentration of chlorine 

dioxide is expected to be at undetectable levels when treated ballast water is discharged. 

However, a Probable No Effect Concentration (PNEC) for chlorine dioxide is presented. As 

defined by the International Maritime Organization (IMO), the PNEC is established at ten times 

lower than the lowest NOEC in cases where sufficient data are available. The data provided 

meet the requirements outlined by the IMO for use of a 10-fold assessment factor and, 

consequently, the PNEC for chlorine dioxide is established at 0.009 mg/L2

 (lowest chronic 

NOEC for Mytilus sp., 0.09 mg/L divided by 10). 

The long-term PNEC for chlorite, as defined by the IMO, is established at ten times lower than 

the lowest NOEC, in cases where sufficient data are available. The data provided meet the 

requirements outlined by the IMO for use of a 10-fold assessment factor and, consequently, the 

PNEC for chlorite is established on this basis at 0.018 mg/L (lowest chronic NOEC for M. bahia,

0.18 mg/L divided by 10). It should be noted that this PNEC is conservative, since a PNEC for 

chlorite has been reported on the basis of a species sensitivity distribution to be 0.135 mg/L by 

Fisher et al. (2003) on the basis of freshwater acute toxicity data2. 

5.3.7 Effects on Sediment 

Because the substances utilized with the Ecochlor®

 BWTS do not have characteristics that would 

indicate adsorption to sediment particles, no effects on sediments are anticipated. 

5.3.8 Comparison of Effect Assessment with Discharge Toxicity 

The relevant chemicals (chlorine dioxide and chlorite ion) potentially present in treated ballast 

water were evaluated in regards to discharge toxicity. No chronic toxicity was observed with the 
45

Mytilus edulis larval development test for treated ballast water (see Section 5.2.1.1). Therefore, 

discharge toxicity testing indicates that observed toxicity in treated ballast water can be 

attributed to the presence of chlorite. 

Samples of ballast water from two separate onboard treatments with 5.0 mg/L of chlorine 

dioxide were tested for toxicity. Chlorite ion was measured in these samples and was 2.35 mg/L 

and 0.41 mg/L, which represents both the high and low ends of the overall range of chlorite ion 

measured in treated ballast water. On the basis of measured chlorite ion and the EC50 values of 

38.7% and 37.7% by volume, the LC50 for the treated ballast water samples was 0.91 mg/L 

(2.35 mg/L chlorite multiplied by 38.7%) and 0.15 mg/L (0.41 mg/L chlorite multiplied by 

37.7%), respectively. Although these LC50 values are somewhat variable, their average (0.53 

mg/L) compares well with the reported LC50 for chlorite using Mysidopsis bahia of 0.58 mg/L 

(Table T2.9). The variability between these two numbers may have resulted from differences in 

sensitivity of different batches of test organisms, or variability in subsampling or analytical 

procedures2. 

Thus, the results are generally consistent with the conclusion that the toxicity to M. bahia

observed in treated ballast water was caused by residual chlorite and not by chlorine dioxide or 

additional contaminants. This conclusion is further supported by the fact that toxicity was 

observed using an acute test with M. bahia in both samples, and no toxicity was observed with a 

chronic test using Mytilus sp.. In general, a chronic toxicity test with Mytilus sp. would be 

expected to be more sensitive than an acute test with M. bahia in the vast majority of cases, with 

chlorite being unusual in this regard2

. 

6.0 RISK ASSESSMENT 

The risks presented by having the Ecochlor® BWTS onboard are discussed in Section 6.1, while 

risks to technicians and/or ships crew are discussed in Section 6.2. 

6.1 RISK TO SAFETY OF SHIP 

6.1.1 Ship Integrity and the BWTS 

The Ecochlor® BWTS and the ship’s ballasting system are interconnected only by the delivery 

line/injection quill for delivering the chlorine dioxide solution into the ballast water and, in the 

case where ballast water is used as motive water, the incoming water line from the ballast system 

to the Ecochlor® BWTS. These lines are fitted with safety valves that separate the BWTS from 

the ship’s systems in case of an emergency. These safety valves, together with the failsafe 

measures in the PLC that shut down the BWTS in the event that all run-permissive criteria are 

not met, protects the ship’s integrity and assures safe operating conditions. The safety valves 

have the appropriate approvals by the ship’s classification society and are constructed of 

materials appropriate for the application. 

Further, the Ecochlor®

 BWTS does not become an integral part of the existing ballast system 

upon installation. The ship’s ballast system will run unaffected if the BWTS is enabled/disabled, 

has power/no power, etc. and the only impact from shutting off the BWTS would be that 

incoming ballast water would not be treated. 
46

6.1.2 Corrosion 

Corrosion in natural waters, to include seawater and brackish harbor waters, is caused by the 

presence of dissolved oxygen, marine growth, and salts in the water. Most of the fundamental 

research on corrosion in natural waters was done in the early part of the 20th Century and is 

summarized in the 1948 Corrosion Handbook, edited by Professor H. H. Uhlig of MIT17. 

Extreme water pH values (below 4 or above 10) can also affect corrosion rates. 

Figure F6.1 shows the relationship between the salt content of water and corrosion rate. As the 

salt content increases to approximately 3% by weight, the rate of corrosion begins to decrease. 

This behavior was explained years ago, and is based on the principles of electrical conductivity. 

As the salt content increases, so does the electrical conductivity. Although increased 

conductivity increases corrosion rates, the increased conductivity is countered by a decrease in 

the solubility of other substances (such as oxygen) in the water. Because dissolved oxygen is the 

most common chemical to be reduced by the oxidation of iron17, increased salinity reduces the 

dissolved oxygen in the water, and therefore, reduces the corrosion rate. 

Figure F6.1 – Salt Content and Water Corrosivity17

1

Effect of Salt Content on Corrosivity of 

Water

Note: Redrawn from Uhlig Corrosion Handbook, page 131

Since the installation of the first full-scale Ecochlor® BWTS aboard the M/V Atlantic Compass 

in 2004, testing relating to corrosion has been conducted. Specifically, the pH and dissolved 

oxygen (DO) in dockside water as well as chlorine dioxide treated and untreated ballast water 

has been measured, and corrosion test coupons have been analyzed by an independent 

laboratory. The data presented in this section will demonstrate that the active substance 

(chlorine dioxide) being utilized by the Ecochlor® BWTS does not increase the rate of corrosion 

above that encountered under typical environmental conditions. 

Additionally, installation of the Ecochlor®

 BWTS results in no dissimilar metals being in contact 

with the existing ballast system or any other part of the ship. All parts in contact with the ship 

are mild steel. If necessary, Ecochlor can match a particular ship’s alloy piping or identify 

 

17 Heidersbach, Bob; Dr. Rust, Inc.; Ballast Water Corrosion Rates Using the Ecochlor Ballast Water Treatment System, May 2007 Relative Corrosion Rate

Concentration of NaCl, % wt. 
47

another appropriate material to ensure there is no elevated risk of corrosion due to use of 

dissimilar metals. 

6.1.2.1 Effect of pH and Elevated Dissolved Oxygen Concentration on Corrosion 

During a July 2005 investigation aboard the Atlantic Compass, DO and pH measurements were 

recorded. The background DO level was measured from a sample of Newark, NJ dockside water 

(FAPS Terminal) and found to be approximately 4.71 mg/L. After the ship completed a 

ballasting operation, the DO was measured in a control tank (not treated with chlorine dioxide) 

after the tank was filled (time, T=0). The measured DO concentration was 5.86 mg/L; a 1.15 

mg/L increase in DO compared to the dockside water. At the end of the test period of 96 hours, 

the DO concentration had dropped to 5.17 mg/L, possibly due to the presence of viable respiring 

organisms. 

In the same study, the DO level in a ballast tank that received 5.0 mg/L chlorine dioxide 

treatment was also measured after being filled (time, T=0). The measured DO concentration was 

6.57 mg/L; a 1.86 mg/L increase in DO compared to the dockside water. Compared to the 

control tank, this represents an increase in measured DO of approximately 12%. Over the test 

period of 96 hours, the DO concentration remained relatively stable and dropped to 6.47 mg/L, 

possibly due to the lack of respiring organisms. The results of this study are depicted in Figure 

F6.2. 

Figure F6.2 – Dissolved Oxygen and pH 

Dissolved O2 and pH

0

1

2

3

4

5

6

7

8

0 20 40 60 80 100

Time (h)

O2 (mg L-1) and pH

O2- C

pH- C

O2- T

pH- T

O2- F

pH- F

Incoming water

FAPS terninal

Incoming water

FAPS terninal

 Source: University of Rhode Island, Graduate School of Oceanography, 2005 

 O2 = Dissolved oxygen, C= control (untreated ballast water), T= treatment (treated ballast water) 

 F= Water sample location ID (FAPS Terminal)

Clearly, turbulence that occurs during loading of ballast water, either through a centrifugal pump 

or gravity, and the turbulent entry into an empty and vented ballast tank contributes to an 

increased DO level in the incoming ballast water. For a chlorine dioxide treated tank, some of 

the increase observed may also be due to the liberation of oxygen during the chlorine dioxide 
48

generation reaction (refer to the chemical equation in Section 2.0.3.1). Based on stoichiometry, 

when the hydrogen peroxide component of Purate® reacts with sulfuric acid (at a chlorine 

dioxide treatment dose of 5.0 mg/L) roughly 1.2 mg/L of oxygen is generated. This theoretical 

increase in DO is comparable with that observed during the study. Further, increased DO at 

these concentrations is not significantly greater than the increase observed during normal 

ballasting operations, and is not anticipated to create increased or unacceptable corrosion risk for 

the ship. 

The pH of dockside water (FAPS Terminal) as well as untreated and chlorine dioxide treated 

ballast water was concurrently measured during the DO investigation. During this study, the pH 

of the chlorine dioxide treated tank ranged from 6.61 to 6.82. As Figure F6.2 above 

demonstrates, the pH of the treated ballast water was not significantly decreased as a result of 

chlorine dioxide treatment, and remained stable over the duration of the test period. Further, 

corrosion rates of iron and steel are fairly uniform between pH’s of approximately 4 and 10. 

Any change of pH of the ballast tank water between the pH’s of 5 and 9 will not affect corrosion 

rates17. 

6.1.2.2 Corrosion Coupon Testing 

Corrosion tests have been conducted in ballast tanks treated by the Ecochlor®

 BWTS to verify 

the effect of chlorine dioxide treatment on ballast tank corrosion rates. Tests were conducted 

with C1010 mild steel corrosion test coupons and sent to Metal Samples Company, Inc. for 

analysis18. 

In July/August of 2005, corrosion test coupons were placed in one control (untreated) tank and 

one chlorine dioxide-treated tank that received ballast water from Newark, NJ. The treatment 

tank received a 5.0 mg/L dose of chlorine dioxide. Two test coupons were placed in each tank; 

one high (approximately 1.35 m from the bottom of a 1.8 m tank) and one low (approximately 

0.9 m from the bottom of a 1.8 m tank), and hung by nylon strings. Both sets of coupons 

remained in the respective tanks for 672 hours (28 days). 

In October/November of 2006 a similar test took place in a tank treated with approximately 4.0 

mg/L of chlorine dioxide. Two test coupons were placed in the tank; one high (approximately 

1.35 m from the bottom of a 1.8 m tank) and one low (approximately 0.9 m from the bottom of a 

1.8 m tank), and hung by nylon strings. Both coupons remained in the tank for 768 hours (32 

days). 

 

The results of this initial testing are presented in Table T6.1 below, and indicate no adverse 

effect on corrosion rates from chlorine dioxide treatment. Actually, when the July/Aug 2005 

study corrosion rates of test coupons from untreated and treated tanks are compared, a slight 

decrease in the corrosion rate was observed for test coupons in the treated tanks. 

 

18 Corrosion Analysis Data Report, Metal Samples, Co., 2005. 
49

Table T6.1 – Comparison of Corrosion Rates 

Sample Date ClO2 Dosage (mg/l) Exposure time (Hrs) Corrosion Rate (mpy)

Untreated tank (high) Jul/Aug 2005 0 672 9.8389

Untreated tank (low) Jul/Aug 2005 0 672 10.9133

Treated (high) Jul/Aug 2005 5 672 6.0879

Treated (low) Jul/Aug 2005 5 672 7.87

Treated (high) Oct/Nov 2006 4 768 5.0977

Corrosion by chlorine dioxide

Ecochlor’s statement that chlorine dioxide treatment will not adversely affect corrosion rates is 

supported by this data. Additional verification of these results with continued coupon corrosion 

studies is planned. Additionally, visual inspections of piping close to the chlorine dioxide 

injection point will be conducted as necessary during shipyard visits to ensure that there is no 

sign of excessive wastage. 

6.1.3 Fire and Explosion 

The fire and explosion risks associated with the Ecochlor®

 BWTS relate to the precursor 

chemicals stored onboard or electrical components that are part of the system. 

6.1.3.1 Preparation Chemicals 

As a solution, Purate® is non-flammable and does not have explosive properties19. Organic 

materials (i.e. wood, leather) that become contaminated with Purate® can ignite by a heat or 

friction source if they are allowed to dry. If evaporation of Purate® solution is allowed, solid 

sodium chlorate crystals could form. Solid sodium chlorate does not burn, but if exposed to fire 

it decomposes to give off oxygen, which can feed a fire. Decomposition of Purate® (in contact 

with certain metals or alkalis, or upon thermal decomposition) generates oxygen gas, and has the 

potential to increase explosion risk. 

Sulfuric acid is non-flammable. Although sulfuric acid is not flammable or combustible and is 

not sensitive to static discharge, it is a strong oxidizing agent and is highly reactive. 

Concentrated sulfuric acid is capable of igniting combustible materials, and contact with water or 

strong bases can result in a strong exothermic reaction. Contact with common metals can evolve 

flammable and potentially explosive hydrogen gas. Sulfur oxides may be produced under fire 

conditions. 

These risks are mitigated through proper training, system engineering, identification of a suitable 

location for the BWTS, the use of chemical storage tanks specifically designed for the chemicals 

they hold, and proper tank ventilation. Additionally, the space where the BWTS is located is 

kept clean and free of incompatible materials that can react with the precursor chemicals. 

Regular inspection and maintenance of the BWTS further reduce any potential risks. The 

mitigation measures and engineering controls in place for the precursor chemicals stored onboard 

make the risks of fire and/or explosion extremely low. 

 

19 Physical and Chemical Characteristics of Purate®

, Case Consulting Laboratories, 2000. 
50

6.1.3.2 Active Substance 

Gaseous chlorine dioxide can present explosion hazards under specific conditions. Concentrated 

vapors of chlorine dioxide gas can be explosive at temperatures >40oC and concentrations >10% 

v/v in air at 1 atmosphere20. However, under the highly controlled conditions that chlorine 

dioxide is generated with the Ecochlor® BWTS, the potential for explosion risk is very unlikely. 

Section 3.0.7 discusses the safety features of the BWTS that eliminate the possibility of chlorine 

dioxide production under unacceptable conditions. 

Once generated, the chlorine dioxide is immediately converted into a dilute aqueous solution 

under proper temperature and vacuum conditions in an enclosed system. In solution, chlorine 

dioxide is stable and does not present fire or explosion hazards. Additionally, chlorine dioxide is 

generated on demand, injected immediately, and never stored onboard. Therefore, the risk of fire 

and/or explosion presented by the active substance is extremely low. 

6.1.3.3 Other BWTS Components 

The electrical components of the Ecochlor®

 BWTS are intrinsically safe and there is no risk of 

fire associated with this aspect of the BWTS. 

6.1.4 Chemical Storage 

The precursor chemicals (preparations) are the only BWTS chemicals stored onboard at any 

time. While 78% sulfuric acid is IMDG Code classified, the BWTS is considered ship’s 

equipment and the chemicals are consumables rather than dangerous cargo. Therefore the 

provisions of the IMDG Code are not applicable (IMDG CODE 2006 Edition, Amendment 33-

06, Chapter VII, Part A. Regulation 2). 

The active substance, chlorine dioxide, is generated on-demand and is never stored onboard. 

Outside of the potential fire and explosion risks discussed in Section 6.1.3, other risks associated 

with storing chemicals onboard relate to improper storage containers. This can lead to 

unintended chemical release and chemical contact with incompatible materials, as well as 

exposure by direct chemical contact (skin/eye) and/or inhalation. 

Because proper storage containers designed and engineered specifically for Purate®

 and sulfuric 

acid are utilized with the Ecochlor®

 BWTS the potential for unintended release, contact with 

incompatible materials, or direct chemical exposure to occur is low. (Details of the chemical 

storage containers are located in Section 3.0.8). To further ensure proper chemical storage, 

temperature control device(s) can be installed if a BWTS is to be located in an area or on a ship 

where there is potential for temperature extremes. Additionally, proper training and 

implementation of standard operating procedures mitigate the potential risks of chemical storage 

onboard. Should a spill occur, chemical spill containment kits are kept onboard with the BWTS, 

as well as appropriate fire extinguishing methods. Additional discussion on accidental chemical 

release is presented below in Section 6.1.5 and the exposure risks to technicians, ship’s crew, 

and/or other personnel are addressed in Section 6.2.1 below. 

 

20 Chlorine Dioxide and Chlorite Toxicological Profile, Agency for Toxic Substances and Disease Registry 

 (http://www.atsdr.cdc.gov/toxprofiles/tp160-c4.pdf). 
51

6.1.5 Accidental Chemical Release 

The potential for unintended release of chemicals associated with the BWTS relate to storage 

tank failure, delivery pipe failure, and chemical re-supply operations. The areas for potential 

release are limited to the areas where the storage tanks are located, where pipelines traverse, and 

where chemical re-supply operations take place. 

6.1.5.1 Storage Tank Failure 

The risks to a ship of an unintentional release of Purate®

 or sulfuric acid from the chemical 

storage tanks are related to contact with incompatible materials that may create other hazards 

such as fire. A chemical release from the storage tanks is very unlikely, and only a catastrophic 

event on the vessel could result in tank failure and simultaneous secondary containment failure. 

As discussed above in Sections 3.0.8, 6.1.3 and 6.1.4, properly engineered and designed 

chemical storage tanks and secondary containment, along with proper placement and 

maintenance of the BWTS, make the risks to a ship from a storage tank failure extremely low. 

6.1.5.2 Delivery Pipeline Failure 

As with any installation where liquids are transported in a pipeline, potential exists for pipeline 

failure. Should a pipeline failure occur, the risks to a ship from chemical release include contact 

with incompatible materials. Although unlikely, this could increase risk of fire. 

Because the BWTS does not compromise the integrity of the ship’s ballast water system (Section 

6.1.1), there would be no risk to vessel stabiliy should a BWTS piping failure occur. In the event 

that a pipe failure occurred, emergency stop controls to shut down the BWTS are strategically 

located on the vessel. Additionally, a pipeline failure would create unacceptable conditions 

within the BWTS, which would be recognized by the PLC and production of chlorine dioxide 

would cease. 

One important factor in mitigating the potential for a pipeline failure is selection of proper 

BWTS construction materials. As presented in Section 3.0.8.3, the piping materials were 

specifically selected for application with the Ecochlor®

 BWTS to ensure that compatible and 

sturdy materials are utilized to deliver Purate®, sulfuric acid and chlorine dioxide. 

The risks for pipeline damage are further minimized by installing piping in less exposed areas, 

using proper labeling, and implementing other protective measures where prudent or required. 

For installations where the BWTS may be located in a cargo area, extra precautions are taken to 

eliminate risk of damage to piping. These may include, but are not confined to, installation of 

hard casings and/or protective barriers around the system where the potential for damage exists. 

Preventing exposures and emergency situations begins with proper engineering and construction 

of systems that are designed for use onboard ships. Implementation of appropriate mitigation 

measures ensure that unacceptable risks to a ship from chemical release do not result from a 

BWTS pipeline failure. 
52

6.2 RISK TO TECHNICIANS AND/OR SHIP’S CREW

6.2.1 System Interaction – Risks to Technicians and Crew 

The typical activities for operating and maintaining the Ecochlor®

 BWTS that present potential 

risks to technicians or other personnel are assessed in this section. These tasks include normal 

system operation, system maintenance and chemical refill operations. The areas for potential 

exposure are limited to the areas where the BWTS and chemical storage tanks are located, where 

pipelines traverse, and where chemical re-supply operations take place. 

In this section we refer to ‘technicians’, who are trained Ecochlor personnel or properly trained 

representatives from distributors or service companies used by Ecochlor. Technicians or 

properly trained Ecochlor representatives are the only individuals who will work within close 

proximity to the BWTS, perform maintenance, or handle chemicals related to the Ecochlor®

BWTS. As such, technicians are the population group that has the greatest potential for 

exposure. 

Occasionally, other individuals such as ship crew members, port staff, stevedores, or ship repair 

contractors may be working in the vicinity of the Ecochlor®

 BWTS. In this section, these 

persons are referred to as ‘other personnel’ or ‘ship’s crew’. The contact these personnel may 

have with the BWTS would be specific to the BWTS location on the vessel and the work 

activities taking place in that location (i.e. cargo space vs. engine room vs. deck house). For 

example, the BWTS may be located in a designated area of a cargo hold where various work 

tasks or cargo operations are performed. Simply working within proximity to the BWTS would 

not lead to direct contact with the BWTS or chemicals. Therefore, this subpopulation has a low 

potential for exposure and the BWTS does not pose unacceptable risks to ship’s crew or other 

personnel who may perform work tasks nearby. 

6.2.1.1 Normal System Operation 

Operation of the Ecochlor®

 BWTS does not require technician or ship’s crew involvement, 

unless the ship’s ballast system is manual in nature and is not capable of providing electronic 

signals regarding the ballast system status. Even in such an installation, a crew member would 

only be required to push a remote ‘start’ button and possibly adjust ballast system valves. In 

either case, the BWTS automatically delivers the preparation chemicals and the active substance, 

and no technicians or crew members are required to be at the location of the BWTS while in 

operation. The BWTS automatically starts, stops, and doses the correct amount of chlorine 

dioxide. At no time during the normal operation of the system are Ecochlor technicians or ship 

crew members required to handle chemicals. 

With the exception of the vent lines on the precursor chemical storage tanks, the BWTS is a 

closed system. Chemical tank vent lines are directed either to the atmosphere or to spaces with 

proper ventilation (also refer to the discussion in Section 3.0.8.2). The Ecochlor system does not 

give off fumes or gases during normal operation. However, a small amount of fumes may be 

displaced when the chemical storage tanks are refilled, and sufficient ventilation is necessary 

during these operations. See Section 6.2.1.2 below. 
53

The system does not generate a significant level of noise that would pose hearing damage risks to 

technicians or other personnel. 

6.3 RISKS TO HUMAN HEALTH 

6.3.1 Identification of Chemicals of Potential Concern and Sources 

The chemicals of potential concern (COPC) related to the Ecochlor® BWTS are Purate®, sulfuric 

acid, and chlorine dioxide. Purate® (40% by weight sodium chlorate and 8% by weight 

hydrogen peroxide) and sulfuric acid (78%) are preparation chemicals used to generate chlorine 

dioxide. 

Although low levels of chlorite ion may persist in treated ballast water, no sources of direct 

contact or exposure to the by-product exist for technicians or ship’s crew. Additionally, the 

chemical properties and modes of chlorite ion degradation indicate that it will not persist in the 

environment or have the potential to bioaccumulate (refer to Section 2.3). As such there is no 

mechanism of transport that would allow primary or secondary exposure risks for technicians, 

ships crew, persons at the coast or seafood consumers. Chlorite ion is not considered further in 

this human health risk assessment. 

6.3.2 Exposure Assessment 

An exposure pathway describes the course that COPC take from a source to an individual. A 

complete exposure pathway consists of the following: 

• A source of the chemical(s) of concern; 

• An environmental medium (i.e. air) containing the chemical(s) of concern; 

• An exposure point or direct contact point with the contaminated medium (i.e. direct 

contact with the chemical(s)) or a release mechanism for contact with a secondary 

medium (i.e. vaporization of chemicals); and 

• An exposure route for chemical intake by an individual (i.e. inhalation). 

The combination of all four components together makes a complete exposure pathway. If one or 

more of the components is missing, the exposure pathway is considered incomplete. Incomplete 

exposure pathways do not present potential human health hazards. 

Areas for potential exposure are defined as areas where both the COPC and human receptors 

may come in contact. The onboard areas, or sources of chemicals, with potential for exposure to 

Purate®

, sulfuric acid and chlorine dioxide are limited to the areas where the BWTS and 

chemical storage tanks are located, where pipelines traverse, and where chemical re-supply 

operations take place. 

The potential media for exposure relating to the Ecochlor® BWTS that have been identified are 

direct contact with chemicals and air containing volatiles of the COPC within enclosed ship 

spaces. Treated ballast water is not considered as a potential exposure medium to Purate® and 

sulfuric acid because these substances are consumed in the chlorine dioxide generation reaction. 

Further, chlorine dioxide degradation behavior indicates that chlorine dioxide will not persist in 

the environment, nor does it have the potential to bioaccumulate (refer to Section 2.3). Thus, 
54

there is no complete exposure pathway for contact with treated ballast water containing Purate®, 

sulfuric acid or chlorine dioxide for Ecochlor technicians, ships crew, persons at the coast, or 

seafood consumers. However, because chlorine dioxide in solution readily volatilizes, a 

potentially complete exposure pathway for inhalation of chlorine dioxide from treated ballast 

water exists. 

The populations with the greatest potential for exposure are Ecochlor technicians, and to a lesser 

extent, ships crew and/or other personnel (see explanation of those in this population group in 

Section 6.2.1). Technicians have a greater potential for exposure because they will work most 

closely with the BWTS (i.e. performing maintenance and chemical re-supply operations, etc.). 

Because ship’s crew will never be required to handle chemicals during operation of the BWTS or 

be directly involved in chemical-handling operations, the exposure potential for this population 

group is extremely low. To fulfill the components necessary for a complete exposure pathway, 

chemical exposure would only occur in the event of a pipeline or storage tank failure, or an 

emergency situation in the same space where ships crew may be working. In this unlikely event, 

the most probable exposure route would be inhalation rather than direct chemical contact. 

With the exception of the vent lines on the precursor chemical storage tanks, the chemicals used 

with the BWTS are in a closed system. Chemical tank vent lines are directed either to the 

atmosphere or to spaces with proper ventilation. Further, ballast tank vents are directed to 

atmospheric conditions outside a ship. Thus, chlorine dioxide that may volatilize from treated 

water within the ballast water tanks does not present a complete inhalation exposure pathway. 

As such, with the exception of an emergency situation, a complete exposure pathway for 

inhalation or direct chemical contact exposure routes does not exist while the BWTS is in normal 

operation. 

During routine system maintenance and chemical re-supply operations chlorine dioxide would 

not be generated. Thus, these operations would only involve potential exposure to Purate®

and/or sulfuric acid for Ecochlor technicians. Based on this evaluation, potential exposure to 

chlorine dioxide could only occur for technicians during an emergency situation (i.e. pipeline 

failure). For ships crew, potential exposure to Purate®, sulfuric acid and/or chlorine dioxide 

could only occur during an emergency situation involving the BWTS (i.e. storage tank or 

pipeline failure). 

Emergency situations onboard that are not related to the BWTS (i.e. ingress of water, fire on 

board) would not necessarily create completed chemical exposure pathways. For instance, if 

ingress of water onto the ship occurred, this would not necessarily alter the integrity of the 

chemical tanks and cause a tank or pipeline failure. Additionally, the BWTS is a closed system 

and water would not be able to enter the chemical tanks. Similarly, a fire onboard that is 

unrelated to the BWTS would not necessarily create a completed exposure pathway. This is 

because the chemical solutions are not flammable or explosive. Even if the fire is nearby 

causing the chemicals to heat, the vapors would be vented. 

Additionally, the standard operating procedures that would be implemented in an emergency 

situation that is not related to the Ecochlor®

 BWTS (i.e. ingress of water, fire onboard) are not

changed as a result of the system being onboard. 
55

6.3.3 Potential Exposure Health Risks 

The components of Purate® (sodium chlorate and hydrogen peroxide), as well as sulfuric acid, 

are considered non-carcinogenic substances. Insufficient data is available for classification of 

chlorine dioxide as a human carcinogen8

. 

Inhalation of Purate® vapors and/or mists is irritating to the mucous membranes, and may cause 

nausea, headache and/or weakness. Inhalation exposure can have an oxidizing effect, and 

oxidizes hemoglobin in the blood to methaemoglobinemia, causing a reduced ability to transport 

oxygen. This can lead to a lack of oxygen in body tissues. 

Inhalation of sulfuric acid mists or sprays can cause pulmonary irritation, irritation of the mucous 

membranes, coughing and sore throat. Inhalation of high concentrations may cause respiratory 

tissue damage, causing lung disorders (chemical pneumonitis and pulmonary edema) and erosion 

of tooth enamel. 

Chlorine dioxide is a strong, corrosive respiratory irritant, and the respiratory tract appears to the

primary target of toxicity in human and animal studies8. Reported symptoms include cough, 

wheezing, headache, nausea, pulmonary edema and shortness of breath. 

Direct chemical contact with Purate®

 may cause moderate irritation to the skin, and can cause 

severe eye irritation, tearing and blurred vision, with irreversible corneal damage and possible 

blindness in instances of overexposure. 

Direct chemical contact of sulfuric acid with the skin or eyes can cause severe irritation, burns 

and permanent tissue damage. Absorption through the skin is not anticipated to be a significant 

route of over-exposure. 

Direct dermal contact with chlorine dioxide solution may cause redness and skin burns, and may 

cause severe eye irritation, pain, blurred vision, tearing corneal injury and burns. 

6.3.4 Risk Characterization 

The exposure assessment identified potentially complete exposure pathways for Purate®

, sulfuric 

acid and chlorine dioxide with inhalation or direct chemical contact as the exposure routes. 

Exposure risks are present during system maintenance and chemical re-supply operations, or 

during emergency situations involving the BWTS. 

The Ecochlor® BWTS requires approximately 6 hours of preventative maintenance per year, and 

chemical re-supply operations will typically take place two - three times per year. Therefore, 

operations where potential exposure risks exist are limited in duration and frequency. 

Preventing exposures and emergency situations begins with proper engineering and construction 

of systems that are designed for use onboard ships. Thorough administrative measures, 

technician and crew training, engineering controls and standard operating procedures further 

mitigate potential exposures to the COPC. PPE worn by technicians greatly reduces the potential 

for the exposure pathways to be completed. For instance, during chemical re-supply operations, 

the required PPE consists of eye protection (chemical goggles), and/or a face shield, along with 

chemical resistant clothing and gloves designed for use with Purate®

 and sulfuric acid. These 
56

operations are only conducted in well-ventilated areas or with the use of appropriate engineering 

controls to prevent inhalation risks. However, in the event of an emergency situation where 

inhalation exposure may occur, respiratory protection devices would be added to the required 

PPE. 

6.4 RISKS TO THE AQUATIC ENVIRONMENT 

With respect to risk, toxicity to aquatic organisms appears to be the most significant potential 

exposure for chlorine dioxide because it is not persistent in the environment and is not expected 

to bioaccumulate or adsorb to sediments2. However, when the Ecochlor® BWTS is utilized as 

directed by Ecochlor, the treated ballast water discharge will contain undetectable concentrations 

of chlorine dioxide. Therefore, unacceptable risks to the aquatic environment from chlorine 

dioxide are not expected. 

With respect to risk, toxicity to aquatic organisms appears to be the most significant potential 

exposure for chlorite ion because it is not persistent in the environment and is not expected to 

bioaccumulate or adsorb to sediments2

. The chlorite ion measured in treated ballast water ranges 

from <0.1 mg/L to 2.37 mg/L. Because treated ballast water may contain residual chlorite ion 

when discharged, a dilution to approximately 12% has been calculated to achieve the chronic 

NOEC for M. bahia to chlorite ion (see Section 5.2.1.1). The calculated dilution to 12% was 

based on toxicity tests done with the upper range of chlorite ion measured in treated ballast water 

(2.35 mg/L), and with the chronic NOEC for M. bahia, which was identified as the species most 

sensitive to chlorite ion. 

Additionally, dilution to 12% (v/v) is considered conservative because none of the other species 

tested would require dilution of treated ballast water to reach the chronic chlorite NOEC. For 

instance, the next most sensitive species tested (A. affinis, chronic NOEC 13.8 mg/L) was almost 

two orders of magnitude less sensitive to chlorite. 

Therefore, dilution to 12% (v/v) is considered highly conservative and protective of aquatic 

organisms to ensure there are no unacceptable risks to the aquatic environment. 

6.5 ASSESSMENT REPORT (G9: 4.3) 

6.5.1 Overview of Data and Endpoints 

As constituents potentially present in ballast water treated with the Ecochlor®

 BWTS, chlorine 

dioxide and chlorite ion were evaluated in regards to persistence, bioaccumulation, and toxicity. 

In regards to persistence, chlorine dioxide was reported to have a half-life of 3.9 minutes in 

freshwater2, and the half-life of chlorite ion in sea water was measured as <1 hour. The 

estimated log Kow values for chlorine dioxide and chlorite are -3.22 and -7.173, respectively. 

These Kow values, the physical and chemical characteristics (i.e. highly soluble, non-organic), 

along with well-documented degradation behavior, indicate that chlorine dioxide and chlorite ion 

would not be expected to bioaccumulate. In regards to toxicity, the lowest chronic NOEC was 

0.09 mg/L and 0.18 mg/L for chlorine dioxide and chlorite ion, respectively. Therefore, chlorine 

dioxide and chlorite ion do not meet the criteria to be classified as PBT substances. 
57

In a toxicity evaluation of treated ballast water, the lowest acute LC50 was 37.7% (v/v) for 

Mysidopsis bahia and the lowest chronic EC50 was >81% (v/v) for Mytilus sp. (Tables T2.9 and 

T2.10). By calculation, these values compare well with the chlorite ion toxicity observed for M. 

bahia (Table T2.10 and Section 5.3.8). The evaluation of treated ballast water toxicity resulted 

in a calculated dilution to 12% (v/v) to achieve the chronic NOEC for M. bahia to chlorite ion. 

This dilution was derived using the upper limits of chlorite ion that may be present, as well as the 

most sensitive species in toxicity tests (see Section 6.4) to incorporate a sufficient safety margin. 

Ecochlor has conducted a significant number of tests on various waters to determine the holding 

time necessary, and evaluate the effects of differing water conditions (i.e. organic load, pH, 

salinity, temperature). Although additional studies are planned to increase the available data set 

for treated ballast water, Ecochlor is confident in the data that has been generated through 

laboratory analysis and onboard testing. 

 

As presented in Sections 2.3.3 and 5.3.1, both chlorine dioxide and chlorite ion are oxidizing 

agents that do not produce harmful organic by-products. Additionally, chlorine dioxide degrades 

rapidly in marine and fresh waters, predominantly forming chlorite ion as a degradation byproduct2

. Degradation of both substances is by abiotic mechanisms and is predominantly a result 

of oxidative reactions. 

When the Ecochlor® BWTS is utilized as directed by Ecochlor, the concentration of chlorine 

dioxide is expected to be at undetectable levels when treated ballast water is discharged. Thus, 

the predicted environmental concentration (PEC) for chlorine dioxide is 0 mg/L. Ion 

chromatographic analysis of ballast water treated with 5.0 mg/L of chlorine dioxide indicate 

chlorite ion concentrations ranging from <0.1 g/L to 2.37 mg/L. Therefore, the PEC for chlorite 

ion in treated ballast water is <0.1 mg/L to 2.37 mg/L. This range is a result of the varied 

chlorite ion demand of different waters and factors such as organic load, pH and temperature that 

affect the decay rate. Section 2.0.3.2 discusses chlorite ion demand / decay in greater detail. 

The Ecochlor® BWTS can safely and effectively treat ballast water for AIS to comply with the 

performance standards in Regulation D-2 of the International Convention for the Control and 

Management of Ship’s Ballast Water and Sediments, as well as standards proposed in the US 

Ballast Water Management Act of 2005 (Senate Bill S.363). Based on laboratory analysis and 

shipboard data of treated ballast water, no related adverse effects from the use of the Ecochlor®

BWTS to comply with the Convention can be reasonably anticipated. The level of uncertainty in 

the data supporting this opinion is low. Additional data continues to be collected on the 

Ecochlor® BWTS, further increasing the confidence in the results obtained through various 

analyses. 

The potential risks to the safety of ships, human health and the environment are mitigated by 

engineering and constructing systems that are designed for use onboard ships, proper chemical 

production, dosing, storage and handling, as well as thorough personnel training and use of PPE. 

The automatic dosing of chlorine dioxide treatment based on the amount of ballast water being 

brought onboard limits chlorine dioxide production, ensuring safe discharge of treated water to 

the environment. The substances used with the Ecochlor®

 BWTS are not expected to persist in 
58

the environment or bioaccumulate, thereby presenting no risks to resources (i.e. beaches, 

fisheries). 

The active substance is generated on demand, applied in situ, and is never stored onboard. After 

injection into the ballast water, the concentration of chlorine dioxide decays quickly (within than 

24 hours). When used as directed, the ballast water treated with Ecochlor® BWTS will have 

undetectable concentrations of chlorine dioxide at the time of discharge. Thus the PEC for 

chlorine dioxide is 0 mg/L. Therefore, a situation where the PEC/PNEC ratio is >1 at discharge 

is not anticipated. Further, no waste stream is created during the treatment process. 

6.5.2 Test Report Data Quality 

Test reports used in this application were from a variety of sources, including, but not limited to, 

OECD SIDS, Eka Chemicals (performed by independent laboratories), independent research, 

USEPA, and the National Toxicology Program. The reports were evaluated to ensure that the 

data presented was generated by accredited laboratories using accepted standard methodologies 

and laboratory practices. The data met acceptable confidence intervals (i.e. >95%), indicating a 

low level of uncertainty associated with the data. For example, the following is quoted text from 

one mammalian toxicity study used in the risk characterization (Eka Study 86-31125): 

“Results of the inspections made by the Quality Assurance Unit at BIO/dynamics, Inc. 

indicate that this study was conducted in compliance with applicable United States 

Environmental Protection Agency’s Good Laboratory Practice Standards and applicable 

Standard Operating Procedures. No significant deviates were noted. Minor deviations 

may be include in the raw data” 

The studies referenced in this application are listed in the “Reference Documents” portion of the 

Table of Contents and are included in a complete copy of the application. 

**** 

LIST OF TABLES 

Table T2.1 – Overview of Chemical Identification 

Table T2.2 – Ecochlor Chlorine Dioxide Demand Study, 4oC 

Table T2.3 – Ecochlor Chlorine Dioxide Demand Study, 12oC 

Table T2.4 – Ecochlor Chlorine Dioxide Demand Study, 24oC

Table T2.5 – Ecochlor Chlorite Ion Demand Study, 20oC 

Table T2.6 – Chlorite Ion Dilution / Demand Study, New Jersey Water 

Table T2.7 – Chlorite Ion Dilution / Demand Study, Maryland Water 

Table T2.8 – Analysis of Ballast Water Treated Onboard the M/V Moku Pahu 

Table T2.9 – Overview of Acute Aquatic Toxicity 

Table T2.10 – Overview of Chronic Aquatic Toxicity 

Table T2.11 – Acute Mammalian Toxicity Data 

Table T2.12 – Skin, Eye and Dermal Effects 

Table T2.13 – Repeated-Dose Toxicity 

Table T2.14 – Chronic Mammalian Toxicity 

Table T2.15 – Physical and Chemical Properties 

Table T3.1 – List of BWTS Monitoring & Control Devices 

Table T3.2 – Eka Chlorine Dioxide Generator Operational Reliability Data 

Table T5.1 – PBT Criteria for Chlorine Dioxide & Chlorite Ion 

Table T6.1 – Comparison of Corrosion Rates 
59

LIST OF FIGURES 

Figure F2.1 – Example of Chlorine Dioxide Demand Curve, 4°C 

Figure F2.2 – Example of Chlorine Dioxide Demand Curve, 12°C 

Figure F2.3 – Example of Chlorine Dioxide Demand Curve, 24°C 

Figure F2.4 – Example of Chlorite Ion Demand Curve, Newark, NJ Water 

Figure F2.5 – Chlorite Ion Dilution / Demand Study, New Jersey Water 

Figure F2.6 – Chlorite Ion Dilution / Demand Study, Maryland Water 

Figure F3.1 – Photo of Full Scale Ecochlor® BWTS 

Figure F3.2 – Ecochlor® BWTS Process Flow Diagram 

Figure F6.1 – Salt Content and Water Corrosivity 

Figure F6.2 – Dissolved Oxygen and pH 

REFERENCE DOCUMENTS 

1 OECD SIDS SIAR, SIAM 11 (January 2001), UNEP Publications. 

2 Review of the Environmental Fate and Effects of Chlorine Dioxide and Chlorite, Nautilus 

 Environmental, 2007. 

3 USEPA Reregistration Eligibility Decision (RED) for Chlorine Dioxide and Sodium Chlorite 

 (Case 4023), August 2006. 

4 Concise International Chemical Assessment Document (CICADS) 37, Chlorine Dioxide (Gas), 2002. 

5 Barrett, D.S. (1987) A Subchronic (3 Month) Oral Toxicity Study of Sodium Chlorate in the Rat via 

 Gavage. 

6 Barrett, D.S. (1987) A Subchronic (3 Month) Oral Toxicity Study in the Dog via Gavage 

 Administration with Sodium Chlorate. 

7 Scientific Committee on Consumer Products (SCCP), Opinion on Hydrogen Peroxide in Tooth 

 Whitening Products, 2005. 

8 USEPA Toxicological Review of Chlorine Dioxide and Chlorite, September 2000. 

9 NTP Technical Report on the Toxicology and Carcinogenesis Studies of Sodium Chlorate in F344/N 

 Rats and B6C3F1 Mice (Drinking Water Studies), 2005. NTP TR 517, NIH Publication No. 06-4457. 

10 European Chemicals Bureau (2003) Hydrogen Peroxide Summary Risk Assessment Report, 

 Special Publication I.03.148. 

11 Smith, D.J., Anderson, R. C., Ellig, E.A., and Larsen, G.L. (2005) Tissue Distribution, Elimination, 

 and Metabolism of Dietary Sodium [36Cl}Chlorate in Beef Cattle. 

12 Abdel-Rahman, M.S., Couri, D., and Bull, R.J. (1982) Metabolism and Pharmacokinetics of Alternate 

 Drinking Water Disinfectants. Environmental Health Perspectives, v46, pp19-23. 

13 EPA Guidance Manual, Alternative Disinfectants and Oxidants, Chlorine Dioxide, 1999 

 (http://www.epa.gov/safewater/mdbp/pdf/alter/chapt_4.pdf). 

14 Simpson, G.D., Miller, R.F., Laxton, G.D., Clements, W.R., A Focus on Chlorine Dioxide: 

 The “Ideal” Biocide. 

15 Mosser, Mark L., Sermatech International Inc., September 15, 2005. 

16 The Sulphur Institute Online, Glossary of Terms 

 (http://www.sulphurinstitute.org/webarticles/anmviewer.asp?a=109&z=30). 

17 Heidersbach, Bob; Dr. Rust, Inc.; Ballast Water Corrosion Rates Using the Ecochlor®

 Ballast 

 Water Treatment System, May 2007. 

18 Corrosion Analysis Data Report, Metal Samples, Co., 2005. 

19 Physical and Chemical Characteristics of Purate®

, Case Consulting Laboratories, 2000. 

20 Chlorine Dioxide and Chlorite Toxicological Profile, Agency for Toxic Substances and Disease 

 Registry (http://www.atsdr.cdc.gov/toxprofiles/tp160-c4.pdf). 

****