AC.2000.J33.0202.R02 Revision 0 3 April 2002

AMOG Consulting A.C.N. 065 475 818 Sea Technology House A.B.N. 12 065 475 818 Monash Business Park Telephone: + 61 3 9558 9077 19 Business Park Drive Facsimile: + 61 3 9558 9880 Notting Hill Victoria 3168 Email: amogmel@amog.com.au Australia Internet: www.amog.com.au



# Hull Fouling as a Vector for the Translocation of Marine Organisms



# PHASE 3 THE SIGNIFICANCE OF THE PROSPECTIVE BAN ON TRIBUTYLTIN ANTIFOULING PAINTS ON THE INTRODUCTION & TRANSLOCATION OF MARINE PESTS IN AUSTRALIA

Report No.2 April 2002

Submitted to: DEPT OF AGRICULTURE, FISHERIES

AND FORESTRY - AUSTRALIA Strategic Ballast Water R&D Program GPO Box 858 Canberra ACT 2601
Attention: Peter CassellsPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

Pests in Australia i

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r2000.j33.02.0.aw

DOCUMENT ISSUE AND DISTRIBUTION

Document Number AC.2000.J33.0202.R02 Document Title Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paings on the Introduction & Translocation of Marine Pests in Australia Client Dept. of Agriculture, Fisheries and Forestry (AFFA) Job Number AC.2000.J33 Job Title Hull Fouling Research Copy Number 1

Issue Date Issued Author Checked Authorised Revision 0 03.04.02 J. Lewis H. Houridis Dr A. Potts

DISTRIBUTION OF COPIES Number of Copies Location

1 AMOG Consulting (Melbourne office) 1 Marine Science & Ecology 1 AQIS/AFFA

REVISION REGISTER Page Revision Date CommentsPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

Pests in Australia ii

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r2000.j33.02.0.aw PREAMBLE
Hull Fouling as a Vector for the Translocation of Marine Organisms is a project initiated by the Australian Strategic Ballast Water Research and Development Program (Department of Agriculture, Fisheries and Forestry - Australia) to review the current state of knowledge concerned with the fouling of ships’ hulls and the potential for marine organisms to be transferred, both domestically and internationally, by this pathway. Further, the intent is to institute a strategy to develop and implement a hull fouling management module into the Australian Ballast Water Decision Support System. The ‘‘Hull Fouling’’ project is divided into four phases. Phase 1 toprepare a definitive report on the status ofresearch intohull fouling as apathway for the introduction of invasive marine species has been completed (AMOG Consulting, 2001). The mainobjectivesspecifiedforphasethreeoftheprojectweretoconductareviewofthelikely current and future significance of the proposed IMO ban on tributyltin (TBT) and consider the risk of vessels visiting Australian waters with depleted levels of antifoulant. The approach specified was to:

• Consult with paint companies and other organisations conducting research into this area in order to provide a review of possible alternatives to TBT and their relative costs and effectiveness.

• Consider the risk of introduction to Australianwaters of invasive marine speciesviavessels with depleted levels of antifoulant.

• Identify gaps in knowledge and therefore risk associated with the proposed TBT ban.

• Identify gaps in knowledge and make recommendations for future research. The purposes of the other two phases proposed for the project were to:

• Carry out a review of the data available for the Australian Port Surveys and other related research and evaluate whether hull type organisms present have resulted from the organisms likely to be on ships’ hulls (Phase 2); and

• Develop a strategy to develop an implement ahullmanagementmodule into theAustralian Ballast Water Decision Support System (Phase 4).Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw EXECUTIVE SUMMARY
The attachment and growth of marine organisms on the hulls of vessels imposes significant operational and economic costs on the vessel operator and antifouling measures are therefore needed. Sincethemid-18th century, antifoulingpaintshavebeentheprimarymethod ofcontrol fouling. These prevent fouling attachment by continuously releasing a biocide from the coating surface, which either kills or deters the settling spores or larvae. Up until the 1970s, most antifouling paintswerebased on copper, and the effective life of thesepaints rarely exceeded 24 months. At that time the vessel would need to be docked, the spent antifouling coating and attached fouling removed, and a new coating applied.
In the 1960s, organotin compounds were found to be highly effective antifouling biocides and subsequent developments led to the formulation of self-polishing copolymer (SPC) antifouling paints based on tributyltin (TBT) copolymers. These paint systems could provide effective antifouling performanceformorethan5years, andthe self-polishing effect generated additional operational and fuel savings. However, TBT released from antifouling paints hasbeen found to have adverse effects in the marine environment and the International Maritime Organization (IMO) recently adopted a new convention to globally ban the application of TBT antifouling paints form 1 January 2003. Hull foulinghasbeen recognised as a significantvector for the introduction ofmarine species to Australia and concerns have been expressed that the ban on TBT antifouling paints may heighten the risk of introduction if less effective antifouling systems are used. The available alternatives to TBT antifouling products are:

• Conventional copper-based (copper metal, cuprous oxide or cuprous thiocyanate) antifouling paints, often containing a secondary biocide such as diuron, chlorothalonil, thiram or zineb;

• ‘‘New technology’’ self-polishing copper-based antifoulingpaints, likely to contain a ‘‘new’’ secondary biocide such as zinc pyrithione, copper pyrithione or Sea-Nine 211;

• Silicone-based, ‘‘non-toxic’’ fouling-release coatings;

• Novel coatings based on new ‘‘natural’’ biocides, or having fibrous surfaces; and

• Physical, electronic and chemical deterrents. Conventional copper-based coatings do not provide the reliability or effective life of TBT, and antifouling protection only for periods up to 36 months is claimed. ‘‘New technology’’ copper-based systems have resin systems, which are claimed to self-polish in a similar manner to TBT SPC systems and to provide similar performance. Such systems are based on copper acrylate, zinc acrylate or silyl polymers. The results from trials and ship applications support these claims, and these products should provide antifouling protection matching that provided byTBTSPCpaints.The ‘‘newtechnology’’coatingsaremoreexpensivethatTBTorconventional coatings, but savings in performance should offset this initial expense.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Fouling release coatings do not prevent foulingby release of abiocide,but instead have surface characteristics that minimise the strength of adhesion of attaching organisms. They therefore pose no chemical threat to the environment. The most effective fouling release coatings found to date arebasedonsiliconecompounds.Foulingorganismswillattachandgrowonthesecoatings under staticconditions,but arerelativelyeasyto dislodge.Self-cleaninghasbeenseen onvessels which exceed 15knots.For slower,less activevessels,in-water cleaningisnecessaryifthehullis to be kept fouling-free for when it leaves port. If this is not done, there is a risk of organism translocation.
In many countries antifouling paints must be registered, and in Australia this role is performed by the National Registration Authority for Veterinary and Agricultural Chemicals (NRA). Every antifouling product that contains an ‘‘active’’ must be registered, and all ‘‘actives’’ must be approved to ensure they pose no risk to the environment or to public health. Ten actives are currently approved for use in antifouling formulations. The registration process can take up to 15 months or more if a new ‘‘active’’ is used in a formulation. Silicone and other fouling release coatings, fibrelock coatings and construction materials such as copper cladding do not require registration as they are not considered to contain an ‘‘active’’ antifouling agent. Only one of the ‘‘new technology’’ copper-based coatings, of which 17 or more are commercially-available for application overseas, is registered and therefore available for application to vessels docked in Australian shipyards.
In the short to medium term, ship owners will turn to copper-based coatings to replace TBT antifouling paints. ‘New technology’’ coatings are expected to provide the necessary performance and to be generally applied to vessels with long docking cycles. Vessels with shorter docking cycles (< 3 years) may utilise cheaper, conventional copper-based systems, but application of ‘‘new technology’’ products to these vessels would still provide operational and economic advantages and also reduce the risk of organism translocation. Cuprous oxidebased systems cannotbe safely applied to aluminiumhulls, and this sector ofthe maritime industry could be greatly affected by the TBT ban as TBT and cuprous oxide free coatings have an effective life of rarely more than two years. Silicone, fouling release coatings offer an alternative for this sector, and seem particularly suitable for high-speed catamarans. As more antifouling biocides come under scrutiny and are banned or restricted, as seen with the recent banning of diuron in the UK and the raising of concerns with respect to copper, fouling release coatings may become increasingly the most effective method of fouling control. The significant research gaps identified related to:

• The limited number of independent, comparative studies of antifouling efficacy and performance; and

• The limitednumber ofviable,environmentally-acceptable antifoulingbiocides,coatings and processes. The following series of recommendations were seen as ways of improving fouling control on vessels and therefore reducing the incidence and risk of translocation and introduction of exotic marine species to Australia in hull fouling communities.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw With respect to antifouling registration in Australia, it is recommended that:

• The registration process be reviewed with respect to allowing new, potentially safer and more effective commercial products to be granted interim approval, or use under permit, until the full registration process can be completed. Such approval or use would be subject to availability of certain data, most likely from overseas, that indicates the product is both safe and effective, or on the basis of overseas approval; and

• The need to register ‘‘active’’-free antifouling products be investigated to provide some warranty of efficacy With respect to the evaluation and validation of antifouling product performance, it is recommended that:

• The current antifouling patch trial project be reviewed to determine how future, similar programs can be introduced to ensure best available antifouling products are available and promoted for use by all ship and boat owners; and

• Aneducationprogramisestablishedtoensureboatandshipoperatorsarefullycognisantof the options, performance and efficacy of different antifouling products to ensure optimum fouling control.
In anticipation of increases use of fouling release coatings, it is recommended that attention be directed to the development of hull management practices including:

• Development of mechanised, non-abrasive cleaning technology for use in-water;

• Clearer understanding of performance with respect to optimum application techniques, vessel speeds, and surface degradation; and

• Development of cleaning regimes to ensure vessel hulls are maintained fouling-freeboth to optimise ship performance and to minimise the risk of organism translocation. With the limited options currently available for antifouling control, and continuing concerns on the environmental impact of antifouling biocide and the likelihood that more stringent restrictions are likely, it is also recommended that active support be provided to:

• Australian research on biofouling processes and new methods of fouling control; and

• Studies on the environmental fate and ecotoxicology of antifouling agents relevant to the Australian marine environment.
A recommendation of the Phase 1 Report (AMOG Consulting 2001) was the creation of a cooperative research program or centre, which would bring together universities, paint companies, shipping companies, boating organisations and other research organisations with a specific interest in hull fouling and its prevention. This would facilitate research with outcomes offering economicbenefitstothemaritimeindustry,while atthe sametimereducingtherisks of marine pest introductions and translocations in Australia. A number of the programs recommended in this Phase 3 report couldbe successfully undertaken or coordinated from such as program or centre.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw TABLE OF CONTENTS 1. PREVENTION OF FOULING ON VESSELS: A BRIEF HISTORY

. . . . . . . . . . . . . . . 1 2. ANTIFOULING COATING TYPES

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 BIOCIDAL ANTIFOULING COATINGS

. . . . . . . . . . . . . . . . . . . . . . . 5 2.1.1 Metal Sheathing

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1.2 Conventional Antifouling Paint Types

. . . . . . . . . . . . . . . . . . . . . . . . 6 2.1.2.1 Soluble Matrix

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.1.2.2 Contact Leaching

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1.3 Self-Polishing Copolymer (SPC)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.1.4 Controlled Depletion Polymer (CDP)

. . . . . . . . . . . . . . . . . . . . . . . . 10 2.1.5 ‘‘New Technology’’ Tin-Free Antifouling Paints

. . . . . . . . . . . . . . . . . . 10
2.2 FOULING-RELEASE COATINGS

. . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3 NON-TOXIC AND NON-LEACHING ACTIVE COATINGS

. . . . . . . . . . . 11 3. ANTIFOULING BIOCIDES & OTHER ACTIVE COMPONENTS

. . . . . . . . . . . . . 13
3.1 ORGANOTIN COMPOUNDS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 COPPER AND COPPER COMPOUNDS

. . . . . . . . . . . . . . . . . . . . . . 14 3.2.1 Cuprous Oxide

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.2.2 Metallic Copper

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.2.3 Copper Thiocyanate

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 3.2.4 Copper Pyrithione

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 3.2.5 Other Copper Compounds

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.3 OTHER METALS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.4 ORGANIC BIOCIDES

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.4.1 Diuron

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.4.2 Dithiocarbamates

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.4.3 Chlorothalonil

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 3.4.4 Irgarol 1051

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 3.4.5 Sea-Nine 211 (C-9211, Kathon 5287, RH-287)

. . . . . . . . . . . . . . . . . . . . 20 3.4.6 Zinc Pyrithione

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 3.4.7 Other Booster Biocides

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.5 NATURAL BIOCIDES

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.5.1 Natural Antifouling Defences

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.5.2 Natural Antifouling Products

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.6 PAINT ADDITIVES

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 4. FOULING RELEASE COATINGS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.1 FLUORINATED POLYMER COATINGS

. . . . . . . . . . . . . . . . . . . . . . 29
4.2 SILICONE COATINGS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 5. NOVEL COATINGS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.1 FIBRE COATINGS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.2 Electromagnetic Coatings

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 6. CURRENT AND PROSPECTIVE LEGISLATION ON ANTIFOULING PAINT USAGE

. 39
6.1 STATE CONTROLS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
6.2 NATIONAL REGULATIONS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 6.2.1 NRA Registration

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 6.2.2 ANZECC Code of Practice

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 6.2.3 Australian Government Policy

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 6.2.4 International Regulation

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 6.3 ANTIFOULING REGULATION & REGISTRATION IN OTHER COUNTRIES 42 6.3.1 United Kingdom

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 6.3.2 Europe

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 6.3.3 United States/Canada

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 6.3.4 Asia/ New Zealand/South Africa

. . . . . . . . . . . . . . . . . . . . . . . . . . 45Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 6.4 PROSPECTIVE RESTRICTIONS AND REGULATIONS ON ANTIFOULING COATINGS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 7. ALTERNATIVES TO TBT ANTIFOULING COATINGS

. . . . . . . . . . . . . . . . . . . 48
7.1 REQUIREMENTS OF THE BOATING & SHIPPING INDUSTRY

. . . . . . . . 48
7.2 TBT-FREE ANTIFOULING COATINGS

. . . . . . . . . . . . . . . . . . . . . . . 49 7.2.1 Conventional TBT-Free Antifouling Coatings

. . . . . . . . . . . . . . . . . . . . 51 7.2.2 ‘‘New Technology’’ Antifouling Coatings

. . . . . . . . . . . . . . . . . . . . . . 52
7.3 BIOCIDE-FREE ALTERNATIVES

. . . . . . . . . . . . . . . . . . . . . . . . . . 60 7.3.1 Fouling-Release Coatings

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
7.3.2 Fibre Coatings

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 7.3.3 Biocide-Free Self-Polishing Coatings

. . . . . . . . . . . . . . . . . . . . . . . . . 67 7.3.4 Scrubbable and Inert Coatings

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
7.4 METALLIC COATINGS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
7.5 PROSPECTS FOR OTHER ANTIFOULING TECHNOLOGIES

. . . . . . . . . . 69 7.5.1 New Biocides

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 7.5.2 Minimally Adhesive Surfaces and Surface Micro-topography

. . . . . . . . . . 70 7.5.3 Natural Antifoulants

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 7.5.4 Physical, Electronic & Chemical Deterrents

. . . . . . . . . . . . . . . . . . . . . 74 8. THE IMPACT OF THE BAN ON TBT COATINGS AND ITS IMPACT ON THE INTRODUCTION OF EXOTIC MARINE SPECIES

. . . . . . . . . . . . . . . . . . . . . 76 9. CONCLUSIONS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 10. RESEARCH GAPS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 11. RECOMMENDATIONS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 11.1 Registration and Approval of Antifouling Products

. . . . . . . . . . . . . . . . 85
11.2 Evaluation and Validation of Antifouling Product Performance

. . . . . . . . 85
11.3 Hull Maintenance Practices for Fouling Release Coatings

. . . . . . . . . . . . . 86
11.4 Research and Development of New Antifouling Technologies

. . . . . . . . . . 86
11.5 Cooperative Research on Fouling Prevention

. . . . . . . . . . . . . . . . . . . . 87 12. REFERENCES

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 13. PERSONAL CONTACTS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113

APPENDIX 1 114 Antifouling Products Registered by the National Registration Authority in Australia

. . . . .115 APPENDIX 2 117 List of ‘‘New Technology’’ Copper-based Antifouling Coatings

. . . . . . . . . . . . . . . . . .117 APPENDIX 3 1 List of Commercial, Biocide-Free, Fouling Release Coatings

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r2000.j33.02.0.aw LIST OF TABLES

Table 1 The registration status of antifouling biocides in Australia (L. Cahill, pers. comm.)

40 Table 2 List ofNRA approved antifouling actives andtheirusageinregistered antifouling

products.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Table 3 List of UK approved antifouling actives and their usage in registered antifouling

products. (* approval of products containing diuron has since been revoked)

. 50 Table 4 List of US approved antifouling actives and their usage in registered antifouling

products.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Table 5 List of ‘‘new technology’’ copper-based antifouling coatings.

. . . . . . . . . . . 53 Table 6 Percentage of all vessels with respective antifouling ratings.

. . . . . . . . . . . 56 Table 7 Percentage of vessels within scheme life with respective antifouling ratings.

. . 57 Table 8 Comparative costs per tanker of TBT-based paints and TBT-free alternatives

(Source: ORTEPA))

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 Table 9 Fouling release coatings available on the world market

. . . . . . . . . . . . . . 60 Table 10 Fouling release systems applied as test patches to USN ships

. . . . . . . . . . 62 Table 11 Pros and cons of different antifouling types (from Chapman, 1998)

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r2000.j33.02.0.aw LIST OF FIGURES Figure 1 Diagrammatic representation of soluble matrix copper antifouling paint (from

Callow, 1990)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Figure 2 Diagrammatic representation of contact leaching copper antifouling paint (from

Callow, 1990)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Figure 3 Diagrammatic representation of self-polishing copolymer (SPC) antifouling paint

(1-3 represent coats of paint) (from Callow, 1990)

. . . . . . . . . . . . . . . . . . 9 Figure 4 DWT and dry-dock interval for the 1980’s vs. 1990’s (from Anderson, 1998)

. . 48 Figure 5 Percentage of ships satisfactory vs. in-service period (from Anderson, 1998)

. . 51 Figure 6 Percentage of ships satisfactory for copper acrylate SPC vs. TBT SPC (from

Anderson, 1998).

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r2000.j33.02.0.aw ABBREVIATIONS & ACRONYMS

AHMV Automated hull maintenance vehicle AMOG AMOG Consulting ANZECC Australian and New Zealand Environment and Conservation

Council AQIS Australian Quarantine Inspection Service ASTM American Society for Testing and Materials BCL Benzalkonium chloride BP British Petroleum BPD Biocide Products Directive CAEP Copper Antifouling Environmental Program CDC Controlled depletion copper CDP Controlled depletion polymer CPT Copper pyrithione DBTDL Dibutyltin dilaurate DRA Defence Research Agency (UK) DSTO Defence Science and Technology Organisation (Australia) DWT Dead weight tonnage EPA Environmental Protection Agency (US) EQS Environmental quality standard EU European Union FIFRA Federal Insecticide, Fungicide and Rodenticide Act (US) FR Fouling release FRP Fibre reinforced plastics HEMA Hydroxyethyl methacrylate HSE Health and Safety Executive (UK) IMO International Maritime Organization ISO International Standards Organization LNG Liquid natural gas LPG Liquid petroleum gas MER Marine Engineers Review MFO Mixed function oxygenase NOEC No effect concentration NRA National Registration Authority for Agricultural & Veterinary

Chemicals NSWC Naval Surface Warfare Center (US) OECD Organisation for Economic Cooperation and Development ORTEPA Organotin Environmental Program Association PDMDPS Polydimethyldiphenylsilicone PDMS Polydimethylsiloxane PEC Predicted environmental concentration PHEMA Polyhydroxyethyl methacrylate PNEC Predicted no effect concentration PNIPAAM Poly(N-isopropylacrylamide) PSA Pyridine sulphonic acid PTFE Polytetrafluoroethylene PVC Polyvinyl chloride RAN Royal Australian Navy RTV Room temperature vulcanisationPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw SPC Self-polishing copolymer TBT Tributyltin TBTO Tributyltin oxide TCMC Pyridine Tetrachloromethylsulphonyl pyridine TMTB Thiocyanomethylthiobenzothiazole UNSW University of New South Wales VOC Volatile organic compound VOHAP Volatile organic hazardous air pollutants WWF World Wildlife Fund ZPT Zinc pyrithionePhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 1. PREVENTION OF FOULING ON VESSELS: A BRIEF HISTORY The history of practices to prevent the growth of fouling organisms on ship and boat hulls and the development of antifouling paints has been reviewed by a number of authors (Laidlow, 1952; Lunn, 1974; Callow, 1990, 1996, 1999; Bennett, 1996; Lewis, 1998). However, this will be briefly recounted here as background to the ban on antifouling systems containing tributyltin (TBT) and the availability of alternatives. Until the latter part of the eighteenth century, the only effective method of controlling fouling was to regularly beach vessels to allow manual removal of the fouling growth. The first authenticated protective treatment applied to a vessel was the experimental attachment of copper sheet to the frigate HMS Alarm in 1758. This experiment was a success and,by 1780, copper sheathing was in general use throughout the British Navy (Laidlow, 1952).However, copper sheathing couldnotbeused ontheiron-hulled ships constructed in the earlynineteenth centurybecause of the corrosive action of copper on iron. The weight of fouling on unprotected hulls made the ships unmanoeuvrable and unseaworthy and various alternatives to copper sheathing were tried, including sheathings of zinc, lead, nickel, galvanised iron and alloys of antimony, zinc and tin (Callow, 1996). Antifouling paints offered a solution and, by 1865, more than 300 patents for antifouling compositions had been issued in England alone, most of which were utterly useless (Hare, 1993). The first practical compositions to be widely used were hot soap compositions containing copper sulphate. Subsequently antifouling paints incorporating cuprous oxide, mercuric oxide or arsenic in shellac varnish or a resin matrix with turpentine, naphtha or benzene as solvents were developed (Callow, 1996). Although many non-chemical methods, including ultrasonics, electric currents, magnetic fields, and optical methods have been proposed as means of preventing fouling attachment (Fischer et al, 1984), toxic antifouling coatings are recognised as the most cost effective means of fouling control (Little & DePalma, 1988; Callow, 1996; Hare, 2000). Advantages include ease of manufacture, high speed and low cost application, durability, and applicability to a variety of structural forms and substrates. Despite continuous research seeking effective antifouling biocides, relatively few were found. In the early 1950s mercury and arsenic were considered alongside copper as primary antifouling biocides for use in coatings. However, these were subsequently banned on occupational health and safety grounds (Fischer et al., 1984). Then, in the mid-1950s, organotin compounds were found to have broad-spectrum biocidal properties and, by the early 1960s, their excellent antifouling properties were being commercialised (Evans, 1981; Gitlitz, 1981). When first introduced, organotin compounds were thought to be environmentally safe because they degraded rapidly to harmless inorganic forms of tin (Evans & Hill, 1983). In the sea, tributyltin isbroken downmicrobially, first to themuch less toxic dibutyltin, then to monobutyltin, and ultimately to inorganic tin. However, in the late 1970s, Pacific oysters grown commercially near small boat harbours and marinas in France were found to have a high incidence of shell malformation that affected their marketability and survival (Alzieu et al, 1980). The oysters were found to contain elevated tin levels and the malformations were subsequently confirmed to be due toPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw low levels of TBT in the water. As a result, in 1982, the French governmentbecame the first authority to legislate to restrict the use of organotin paints. Since that time, substantial research has been undertaken worldwide to document levels ofTBT in the marine environment, to evaluate its environmental effects, to assess its toxicity to abroad range ofmarine organisms, and to determine more closely its fate and theprocess of degradation (Champ & Seligman, 1996; de Mora, 1996). In summary, TBT contamination was found to occur almost universally in inshore regions with shipping or boating activity. Highest levels were commonly associated with high densities of recreational craft or near boat and ship repair facilities, particularly in semi-enclosed waters such as small boat harbours and marinas that had limited water exchange with more open waters. Malformed oysters were found to occur in a number of countries, and the growth and survival ofanumber of differenttypes ofshellfishwere also affected.Perhapsthemost sensitive indicator of TBT contamination is the incidence of a condition known as imposex in various species of gastropod molluscs, such as the European mud whelk (Gibbs & Bryan, 1996a, 1996b). Imposex is the development of male characteristics in female individuals and in its most severe form can lead to sterility in some species. It has been postulated that levels of TBT in seawater as low as 1 ng l-1 (1 part per trillion) can induce imposex in the European mud whelk. In Australia malformed Pacific oysters were found in Tasmania, similar abnormalities were found in Sydney rock oysters (Batley & Scammell, 1991) and imposex has been observed in shellfish in NSW, Victoria, South Australia, Western Australia and Queensland (Kohn & Almasi, 1993; Nias et al., 1993; Foale, 1993; Wilson et al., 1993: Reitsema & Spickett, 1999; Rees et al., 2001). Many other marine organisms were affected by TBT, but none was as sensitive as the shellfish. Differences in the toxicity of TBT between various animal and plant species have been attributed to the varying abilities of organisms to metabolise the compound. For instance, finfish and crabs are able to metabolise accumulated TBT relatively effectivelyviathemixedfunction oxygenase (MFO) system, andthis systemmayconfer some resistance to TBT toxicity. However, shellfish have very low MFO activity and this correlates well with their limited ability to metabolise TBT (Lee, 1996). Studies on the degradation of TBT in marine waters confirmed that it does sequentially debutylise to ultimately form inorganic tin. In San Diego Bay waters, the half-life for TBT was determined to be between 6 and 19 days with microbial metabolism implicated as the principal degradation pathway (Seligman et al., 1986). Degradation within sediments appears to be much slower, with a half-life of 162 days estimated for San Diego Bay (Stang & Seligman, 1986) and up to 1.85 years in New Zealand (de Mora et al., 1989). The above studies suggested that themarine environmenthas the capacity to copewith some TBT input, as long as input levels were not too high. However, it is apparent from many surveys and observations on shellfish malformations that the unrestricted use ofTBTpaints causedthis capacitytobe exceeded,particularlyininshore areaswith high concentrations of small craft and poor water exchange. As a consequence, management actions to restrict the input of TBT into the marine environment were widely introduced. Three approaches were taken:Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw • To restrict or prohibit the use of TBT paints on small craft;

• To prevent or control the release of TBT wastes from dockyards and slipway; and

• To impose a maximum permissible TBT release rate on antifouling paints applied to large vessels. Such restrictions includedbans on the use of TBT on vessels less than 25 m in length in Norway, Finland, South Africa and countries of the European Union, a 4 μg TBT cm-2 day-1 release rate limit in addition to a < 25 m ban in the United States, Canada and Sweden, a 5 μg TBT cm-2 day-1 release rate limit in addition to a <25 m ban in most States of Australia, and a total ban on all TBT use in Japan and New Zealand. These controls proved effective in many regions. For example, in France tin levels in areas of concern were 5 to 10 times lower in 1985 than in 1982, and there was a concomitant decrease in organotin levels within oyster tissues. Over the same period the percentage of oysterswith shell abnormalities dropped from 100% to less than40%, while the incidence of acute form abnormalities dropped from a peak of 91% to less than 5% (Alzieu, 1986). The incidence of imposex declined (Evans et al., 1996; Evans, 1999), and in Australia oyster growth returned tonormal,with TBTbarely detectable in their tissues (Batley, 1995).
Restrictions imposed on the use of TBT on small craft were clearly justifiable. Marinas and moorings for small craft were often close to shell fisheries or native marine communities sensitive to TBT effects. Furthermore, the high boat densities in shallow and sheltered waters with poor water exchange often led to elevated TBT levels in surrounding waters. Practices in shipyards and slipways also contributed significantly to environmental contamination. Paint wastes, from both blasting and painting processes, were invariably washed into the sea and, particularly where paint chips or flakes incorporated into sediments, contamination is likely to persist for many years.
For large shipping arguments for and against controls on antifoulings containing TBT were less clear-cut, from both an environmental and economic viewpoint (ORTEPA, 1990). TBT paints continued tobe used on large vessels as tin-free alternatives were not considered to provide equivalent performance in terms of effective life, polishing characteristics, or coating durability (Anderson, 1993). However the search for alternative, more environmentally acceptablebiocide and antifouling systems and other means of controlling fouling continued in earnest, and the research has appeared to be successful. While, asnoted above, thenegative impacts ofTBTwere observed to diminish in many inshore regions, impacts attributable to TBT became more widely reported in offshore regions and significant levels measured in animals high in the food chain such as seals and dolphins (Tanabe, 1999; Takahashi et al., 1998, 2000). In Canada, a recent review of the persistence, bioaccumulation and toxicity of TBT in aquatic environments concluded it met all criteria for designation as a Track 1 substance under Canada’s Toxic Substances Management Policy. This requirement required that measures be introduced to virtually eliminate it from the Canadian environment (Maguire, 2000). However, because of the long persistence of TBT in sediment, it was predicted that there could be a ‘‘legacy problem’’ in some locations in Canada for perhaps 30 to 40 years after a total ban on TBT use was introduced.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw In 1999, the Marine Environment Protection Committee of the International Maritime Organisation resolved to develop an instrument to reduce the use and impact of harmful antifouling coating systems. The first action was to be a global ban on the use of TBT antifouling coatings on shipping. In 1998, within its Oceans Policy, the Australian Government declared proactive support for the IMO action. Over the years from 1999 to 2001, the MEPC developed a Convention to facilitate controls on harmful antifouling systems and, in October of this year a Diplomatic Conference approved this convention. The Convention bans the application of TBT antifouling paints to shipping from 1 January 2003. With respect to the phase-out of TBT paints, authors have variously claimed that alternatives to TBT are available, but not proven and accepted on a global basis (Champ, 2000) or, more strongly, that ‘‘there are no substitutes currently available which are as effective as TBT’’ (Abel, 2000), and that a phase-out of TBT-containing antifouling paintswouldhaveseriouseconomicconsequencesfortheshippingindustry because no available tin-free antifouling paint could match the 5-year dry-docking interval enabled by TBT copolymer paints (Maguire, 2000). If future antifouling practices were asineffective as claimed,therisk oftranslocation ofexotic species ashull fouling species would increase and is a concern that warrants serious consideration. As a consequence, the alternatives to TBT as an antifouling biocide, to TBT-containing antifouling paints, their availability, performance, and potential for useby the shipping industry will be explored in the remainder of this report, and an assessment of how their use will impact on the risks of introduction and translocation of marine pests in Australian waters.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 2. ANTIFOULING COATING TYPES

2.1 BIOCIDAL ANTIFOULING COATINGS Biocidal antifouling coatings prevent or minimise fouling growth by the release of active agents from or through the surface of the coating. Until the advent of fouling-release coatings, all successful antifouling applications were based on delivery of toxins into the very thin (lamella) zone in the vicinity of the paint film (Hare, 2000). The thickness ofthetoxiclayerisreduced asthe speed ofthevesselincreases; at2knots it is about 500μm, at 20 knots, about 10μm. To be effective the agent must be released continuously, and at a rate sufficient to maintain toxic or inhibitory agent concentrations at the surface for all potential fouling organisms. The life of a biocidal antifouling coating is therefore limited by the content and mechanism for delivery of the biocide. An effective biocidal antifouling coating therefore depends on both having a broad-spectrum biocide or biocide package and a paint or coatingvehicle able to deliverbiocide continuously at the required rate over an extended period of time.
2.1.1 Metal Sheathing Sheathing of vessels with lead was practiced as far back as 700 BC, but lead only provided barrier protection against wood borers and had no antifouling effect. Of the metals, only copper and its alloys, and silver and zinc were found to resist fouling to a degree greater than that of other hard smooth surfaces. Extensive observations undertaken in the course of corrosion studies enabled the common metals and alloys to be grouped on the probability that they would foul when exposed to the sea (LaQue, 1948).Allthemetals and alloysclassified asleastlikelytofoulcontainedmorethan 64% copper. Zinc resisted fouling only temporarily and the protective action of galvanising was lost as the surface becomes coated with corrosion products (Redfield, 1952). Silver similarly had limited resistance to fouling.
Pure copper, and 70/30 and 90/10 copper-nickel alloys have been demonstrated to exhibit long-term antifouling activity (Efird & Anderson, 1975; Efird, 1976; Wildsmith, 1984). Copper-nickel alloys are less prone to impingement corrosion than pure copper and, as a result, have become widely used, particularly for seawater pipework and condenser tubing where low pitting attack and resistance to erosion corrosion are essential (Chamberlain & Garner, 1988). 90/10 copper-nickel has also become widely used because of its antifouling performance, for example as splash-zone sheathing on the legs of oil and gas platforms, and as expanded mesh for fish cages and intake screens at power stations (Moreton & Glover, 1980; Chamberlain & Garner, 1988). As cladding, composite plates are manufactured by hot rolling a thin layer of copper-nickel, 1.5-2 mm thick, with a steelbacking plate. Sheathing methods havebeen developed to provide a more economical method of hull protection and for retrofit situations. Techniques include welding panels of copper-nickel sheet to a steel hull and adhesive bonding of copper-nickel foil (Boultonet al., 2001).Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 2.1.2 Conventional Antifouling Paint Types Antifouling paints can be classified into a number of different types on the basis of the way the biocide is dispersed and subsequently released from the paint matrix (Callow, 1990; Bennett, 1996; Lewis, 1998; Hare, 2000). Conventional, or ‘‘free association’’ paints have biocide particles physically dispersed through the paint matrix or binder. When the painted surface is immersed, seawater penetrates the paint film and contacts the biocide, which dissolves and migrates to the coating surface by simple diffusion. Conventional coatings can be of two types: ‘‘soluble matrix’’ and ‘‘contact leaching’’. 2.1.2.1 Soluble Matrix In soluble matrix antifoulings, the binder is slightly soluble in alkaline seawater and fresh biocide is continually released as the binder dissolves. The primary film-forming component of conventional soluble matrix antifoulings is gum rosin, a natural product obtained from the tree Pinus elliottii (Callow, 1996). Rosin consists of a mixture of acids, primarily abietic acid. The acidic rosin slowly dissolves in seawater exposing the particles of cuprous oxide and other biocides, which are then released. The rate of binder dissolution is a critical aspect for effectiveness. Ifbinder dissolution is too slow, the coating will not provide sufficient biocide to be effective; if too fast, the biocide reservoir will be too rapidly exhausted, limiting the effective life of the coating (Hare, 2000). Soluble matrix systems based on natural rosin are often found to be too soluble at the pH of seawater (Hare, 2000). Limed rosin, in which rosin was reacted with lime at high temperature to neutralise some of its acidity and decrease solubility, or phenolic varnishes or chlorinated rubberhave thereforebeen used to crudely regulate the rate of binder dissolution. Unmodified rosin was also very soft, and films made from it were quite weak. Modern soluble matrix paints generally contain more rosin and plasticizer, and less insoluble polymer, than traditional soluble matrix paints. These deplete more consistently, and longer effective lives can be achieved. However, rosin is alsobrittle,has limited resistance to UV, and is unstable to oxidation. Rosin-based antifoulings can therefore physically degrade if they experience prolonged exposure to the atmosphere, such as during ship construction, dockings and along the wind and water line (boot top) of vessels. If dried out, the resin becomes hard and insoluble in seawater, allowing fouling attachment on re-immersion until solubility is regained (Foster, 1994).Forsimilarreasons,traditionalsolublematrix antifoulingsneed to be immersed within 24 hours of application. Insoluble co-film forming materials are often added to improve the film forming properties,but the presence of these materials also leadstotheformation ofalargeleachedlayer onthe surface ofthecoating afterthe release of the soluble components, resulting in an inefficient polishing action, problems in recoating and less controlled release.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Figure1 Diagrammatic representation of soluble matrix copper antifouling paint

(from Callow, 1990) Conventional, soluble matrix types of antifoulinghavebeen in use since the early 1930s but were rarely effective for more than 12-18 months. The relative short lifetime of such conventional antifouling coatings is a result of the low mechanical strength of the rosin and the ability to build up only relatively thin systems (Kjaer, 1992). The reliance on mechanical dissolution, rather than a chemically controlled process, meant that the rate of dissolution was not as well controlled and, even for the most modern systems, the effective life was considered to be a maximum of 3 years (Anderson, 1998). Also, the longer the systems were immersed, the thicker the leached layer that formed at the surface as a consequence of the surface erosion not matching the rate of copper dissolution from within the film. As the leached layer grew in thickness, the biocide release rate at the surface decreased, and effectiveness was compromised. 2.1.2.2 Contact Leaching Contact leaching antifoulings, also known as insoluble matrix or diffusion coatings, are based on insoluble resins, such as chlorinated rubber, acrylic and vinyl. Rosin can also be added if a degree of solubility is required (Hare, 2000). Thebiocide content needs to be high enough to ensure that biocide particles are in contact throughout the dry film. As biocides and other soluble ingredients are dissolved from the surface layers, underlying biocide particles are exposed. These polymer resins had higher mechanical strength than rosin, which enabled thicker systems tobe applied (Kjaer, 1992). Contact leaching antifoulings are hard, mechanically tough antifoulings that do not erode at all over time (Anderson, 1998). They have a maximum life of 2 years since, after this time, there is too little biocide reaching the surface to be effective.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Figure2 Diagrammatic representation of contact leaching copper antifouling paint

(from Callow, 1990) The principle drawbacks with contact leaching coatings were the initially excessive biocide release rate, diminishing exponentially with time, and the residual paint matrix remaining on the hull surface which contributed to progressive development of hull roughness and reduction in ship performance.
2.1.3 Self-Polishing Copolymer (SPC) A significant advance in antifouling technology took place in the mid-1970s with the development of organotin copolymer paints, commonly known as self-polishing copolymer (SPC) coatings. In the first organotinpaints, the organotinbiocidewas freely associated in thebinder of soluble matrix and contact leaching paint types (Hare, 2000) but the organotin copolymer provided both the biocide and the acrylic binder for the paint. In tributyltin (TBT) copolymer paints, tributyltin methacrylate was usually copolymerised with methyl methacrylate (Anderson, 1993; Hunter & Cain, 1996). When TBT SPC coatings are immersed, the reaction between seawater and TBT occurs rapidly butisconfinedtothetopfewnanometres ofthe surfacelayer.Thisisbecause of the hydrophobic nature of the paint film and the bulky nature ofboth the TBT and the copolymer. The TBT is released as result of the hydrolysis of the ester groups that link the TBTmoietytotheacrylicbackboneofthebinder (Hare,2000).Thereactionoccursin the presence of an alkaline pigment with slight seawater solubility. Zinc oxide is often used,but cuprous oxideis another option.Removal oftheTBT causes anincreaseinthe glass transition temperature of the copolymer, making it brittle, and a change from insoluble to soluble. Solubilisation then allows the entangled copolymer chain to be removed fromthe surface,providingboththe self-polishing effect andfurther exposure of biocide. Beneath the immediate surface of the film, the non-hydrolysed polymer remains quite hydrophobic until it is eventually exposed to the seawater by the dissolution of the hydrolysed material above it.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Figure3 Diagrammatic representation of self-polishing copolymer (SPC)

antifouling paint (1-3 represent coats of paint) (from Callow, 1990) The hydrolysis reaction of the TBTpolymerwith seawater is confined to a surface layer approximately 20 μm thick, which stays thin even with prolonged immersion (Anderson, 1998) This proffers an advantage at recoating and repair, as only a high pressure fresh water wash is needed to remove this ‘‘leached’’ layer as preparation for recoating. The acrylic nature of the coatings also provided strength and durability and the coatings could survive wet/dry cycling stresses on boot tops and during ship construction and maintenance. The polishing rate of TBT copolymers is directly proportional to vessels speed, so products with different polishing rates could be tailor-made for specific vessel types (Anderson, 1998): a slow polishing product could be used on high activity, high speed ships, whereas slow vessels, or vessels that remain stationary for long periods, could use a fast polishing product. The advantages of SPC coatings were:

• An effective life of 5 or more years, proportional to coating thickness;

• Controlled and constant biocide release rates, unlike the exponential decline of biocide release from conventional coatings;

• Recoat ability;

• Continuous replacement of active surface; and

• A self-smoothing or polishing action that results from peaks of roughness eroding faster than surrounding areas. On fuel savings alone, the economic benefits of organotin copolymer antifoulings were substantial and, when considered along with the extended docking intervals and lower maintenance costs, shipowners benefited significantly from this new technology. Compared with the traditional soluble matrix paints, SPC paints allowed an improvement of 300% in dry-docking intervals and an estimated saving to the marinePhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw industry in fuel, dry-docking and other costs of some $2500M per annum (Milne, 1991; Callow, 1996).
2.1.4 Controlled Depletion Polymer (CDP) Tin-free polishing/ablative type antifoulings commercialised in the later 1980s utilised a dissolution/erosion process for biocide delivery by combining a large proportion of seawater-soluble binder with high-performance polymeric ingredients to physically control the dissolution rate (Kjaer, 1992). When in contact with seawater the biocides, the solublebinder,andtheingredientscontrollingdissolution,dissolvetogetherandare washed away as micro-lumps. Theprocess of ablation is aphysicalprocess and as such CDP systems are a type of soluble matrix coating. However, the technology enabled application of high build systems, which provided an effective life of up to 36 months. However, polishing rates of these systems were found tobe inconsistent and the active surface layer was relatively thick, predisposing the coatings to premature failure by formation of insoluble surface precipitates (Lewis, 1998).
2.1.5 ‘‘New Technology’’ Tin-Free Antifouling Paints A range of ‘‘new technology’’ tin-free coatings offers the promise of effective life and polishing performance approaching or matching that ofTBT copolymer coatings. These coatings are claimed to provide controlled rates ofbiocide release, reduced thickness of active surfacelayers,andcoatingstability.Thesecoatingsarebasedonseveraldifferent polymer systems,includingcopperacrylate,zincacrylateandsilylpolymers.Theyhave in a common an acrylic backbone polymer, similar to that in TBT copolymer systems, with an ester linkage that undergoes hydrolysis in seawater (Anderson, 1998). Copper acrylate polymers act through a chemical hydrolysis mechanism similar to TBT copolymer systems (Hunter & Cain, 1996; Ohsugi et al., 1989). The copper acrylate polymers reactinseawatertoreleasethecopperion andproduce an outersolublelayer, which dissolves at a constant rate. The result is constant controlled release of the biocide. The copper released through hydrolysis of the polymer is, however, insufficient to control fouling on its own. All therefore also contain copper oxide as the main biocide, and usually an organic booster biocide such as Sea-Nine 211 or ZPT (see Sections 3.4.3, 3.4.5). Similarly, in zinc acrylate copolymers, zinc ions exchange with sodium ions and the resulting structure then dissolves in a controlled manner (Taki et al., 2001). The dissolution rate can be controlled by varying the concentration of the functional group and the hydrophilicity of the polymer. Rotor tests demonstrated that surface roughness was similar to organotin self-polishing coatings and smoother than other tin-free antifouling paints. The copper acrylate, zinc acrylate and silyl polymer systems are considered to be true self-polishing copolymer systems, in the sense of TBT SPC systems, in that:

• The leached layer remains thin after prolonged immersion;

• There is a characteristic polishing pattern on ships;

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r2000.j33.02.0.aw • They provide long-term performance on ships (Anderson, 1998).
An alternative approach is the use of hydrolysable zinc carboxylate salt binder technology with micro fibre reinforcement (Hempels in Anon., 1999b). Thepolishing is said tobe controlledby the reaction of thebinder with seawater through ion exchange. The zinc carboxylate polymer salt binder has a low hydrophilic level but, through exchange of the zinc ions for sodium ions from the seawater, a thin reactive surface layer becomes water soluble. When this hydrolysed surface layer is subsequently dissolved, the biocides are released. The polishing rate can be adjusted by modifications within the polymer chains. The micro fibres make the coating more flexible and impact resistant, addressing thepoormechanicalproperties often exhibited by conventional tin-free coatings that crack and peel.
Kuo et al

. (1999) report on the development and testing of surface-fragmenting, self-polishing tin-free antifouling coatings. In these coatings, instead of side chains of the copolymer hydrolysing, the hydrolysable group is built into the backbone of the cross linked copolymer. When the copolymer hydrolyses at the film/water interface, it fragments into small pieces to effect polishing.

2.2 FOULING-RELEASE COATINGS Considerable attention in recent decades has focused on the concept of a non-biocidal and non-toxic coating system which has surface properties that prevent the secure adhesion and attachment of fouling organisms; i.e. non-stick coatings. The objective for these ‘‘fouling release’’ or ‘‘minimally adhesive’’ surfaces was to create surface characteristics which reduce the adhesion strength of attaching organisms to the point where theorganismdetachesunderitsownweightasitgrows,orisdislodgedbywater movement as, for example, when a ship moves through the water. Significant developments have occurred in this field and, in 1997, there were about 40 patents registered (Watermann et al., 1997). A number of these products are now commercially available. The major class of candidate fouling release coatings is a group of synthetic polymers and copolymers generallycalledlowsurfaceenergy (Baier &Meyer, 1994).The surfaces of these are free of groups which, at oceanic ionic strengths, are charged either positively ornegatively. The initial focus in the development of fouling release coatings was on fluorinated coatings, but interest subsequently moved to silicone polymers (Bradyet al., 1987; Bultman & Griffith, 1994). Fouling release coatings are discussed in more detail in Section 4.

2.3 NON-TOXIC AND NON-LEACHING ACTIVE COATINGS Biocide-free self-polishing coatings have been developed which utilise similar chemistry and technology to the TBT and tin-free, copper-based self-polishing coatings (Watermann et al., 2001a, 2001b). In non-toxic SPCs, a non-toxic compound is substituted for the copolymer bound biocide (i.e. the TBT monomer in the TBT copolymer). The hydrolysis process is identical. Methacrylate and several specially designed epoxies have been used to create non-biocidal self-polishing coatings. ThePhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw objective of these is to create an active, polishing surface that wouldbe too unstable for fouling to remain attached. Biological and biochemical processes with potential for preventing fouling settlement have been proposed as an alternative to using toxic compounds. These include the dissolution of adhesive substances by enzymes, intervention in metabolic processes, adhesive synthesis or calcium transport, competitive inhibition of receptors, and negative chemotaxis (Abarzua & Jakubowski, 1995) The potential of non-leaching biocides has also been suggested (Clarkson & Evans, 1993). These are attached to a surface and exert a toxic effect on organisms that contact the surface, but without the biocide being released into the surrounding environment. If this approach proved effective, the total quantity used would be small, and the amount released into the environment greatly reduced compared to conventional antifoulants, thus creating a cost-effective, environmentally acceptable system. Non-leaching biocides (NLBs) are toxins held onto the surface to deter fouling organisms, and are not leached into the surrounding environment (Clarkson & Evans, 1993). The antifouling potential of quaternary ammonium salts as NLBs has been investigated (Mellouki et al.

. 1989). The salts were grafted on to a vinyl copolymer by means of a covalent non−hydrolysablebond, and did not diffuse into the environment. After fourmonths immersion onlybacteriawerepresent in themicrobial films; diatoms and cyanobacteria were absent. Clarkson & Evans (1993, 1995b) assessed DC5700 as a potential non-leaching biocide. However, the compound leached from the surfaces, whether bonded via a silane coupling agent or incorporated into a silicone elastomer. These authors concluded that, with the current state of knowledge, the concept of NLBs, although theoretically desirable, was found in practice impossible to achieve. The use of non-toxic organic repellents as antifoulants has been proposed. Sodium benzoate has been found to be effective in preventing barnacle settlement on soluble matrix paints (Vetere et al., 1999). The compound also retarded the growth of the green macroalga Enteromorpha, and diminished the settlement of tube building amphipods. The effect of barnacles was considered to be the larvae either being repelled and swimming away, or a narcotic effect of the benzoate causing the larvae to become sluggish. Some promising research has also been undertaken on neurotransmitter blockers to prevent the settlement and metamorphosis of barnacles and mussels (Yamamoto et al., 1998). Larval attachment and metamorphosis is influencedby a range of environmental factors and larval signal transduction and neurotransmission systems are integral to this process. Interference with neurotransmission is seen as a potential non-toxic antifouling mechanism.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 3. ANTIFOULING BIOCIDES & OTHER ACTIVE COMPONENTS Despite intensive research for more than a century, relatively few effective antifouling biocides have been found to have the necessary combination of physical, chemical and toxicological properties to make them effective antifoulants. Biocides must react with seawaterinsuch awaytoenableconsistent,controlledreleasefromthepaintfilm ofthe active component; they must also be toxic, or have a deterrent effect on the immense diversity ofpotential fouling organisms, yetnot cause toxic effects tonon-target species after release. The characteristics of an ideal antifouling agent were summarised by Jacobson (1998) as:

• Efficacy in the control of organisms on a ship’s submerged hull;

• Rapid degradation in the environment;

• Rapid partitioning in the environment resulting in limited bioavailability to non-target organisms;

• Minimal bioaccumulation of toxicologically significant compounds; and

• Minimal toxicity to non-target organisms at concentrations present in the environment.

3.1 ORGANOTIN COMPOUNDS As previously mentioned, organotin compounds were found to have broad-spectrum biocidal properties in the mid 1950s and, by the early 1960s, their excellent antifouling properties were being commercialised (Evans, 1981; Gitlitz, 1981). The first organotin antifoulings were free-association paints, containing tributyltin oxide, tributyltin fluoride or triphenyltin fluoride (Evans, 1987). Of the organotins, tributyltin compounds were considered to offer the widest separation between antifouling properties and mammalian toxicity. Tributyltin tin oxide is a liquid and was initially used mainly in coatings where relatively short-term protection wasrequired asitsleachingratewashigh.Tributyltinfluoride, awhite solid, was usedinlongerlifepaints.Triphenyltincompounds,includingthefluoride,chloride and hydroxide,were alsoused, asweretripropyltincompounds.Thelatter areexcellent fungicides andbroad-spectrumbacteriocides andwere used in combinationwith TBTO to broaden the spectrum of effectiveness (Evans & Hill, 1983). Both soluble matrix and contact leaching antifouling coatings were formulated using free-association trialkyltin compounds. However, these all had relatively high TBT release rates and were widely banned by the introduction of regulations restricting permissible release rates to 4 or 5μg cm-2day-1

. Long-term performance of organotin antifouling paints was achieved through the development of organometallic copolymer systems. The most successful of these was tributyltin methacrylate/methyl methacrylate and, in 1974, the first commercial organotin copolymer antifouling paint was based on this system (Evans & Hill, 1983). TBT copolymer systems frequently also contain copper compounds and an organicPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw booster as co-biocides to provide effective protection against the whole spectrum of fouling organisms, and under all operating conditions (Voulvouliset al., 1999). The environmental impact of TBT is now widely acknowledged (see Section 1) and has led to the imminent global ban on application and use of antifouling paints containing organotins as active biocides.
In response to the impending ban on tributyltin compounds as antifoulants, Abbott et al. (2000) discussedthe opportunitiesforusing alternativetributyltin compoundswhich may have had useful biological activity but less of the harmful side-effects. Examples quoted included tri-cyclohexyl tin, used as a miticide on apples, and triphenyl compounds used on potatoes against blight. The possibility of substituting organic moeties to formulate, for example, pentylbutyl octyl tin, in a process analogous to that used in the pharmaceutical industry to eliminate harmful side effects was also raised. However legislation, such asthatintheUK,was alreadyinplacetoproscribetheuse of all triorganotins as antifoulants, although hundreds of potential triorganotins have never been synthesized and less than half a dozen ever tested or used.

3.2 COPPER AND COPPER COMPOUNDS Copper, inthe form ofcopper salts,wasthe first antifoulingbiocidestobeincorporated into antifouling paints and continues to be used widely today, both as a co-biocide in TBT copolymer paints and as the primary alternative to TBT. Copper is an essential element, required for the growth of allplants and animals, and occurs commonly in the environment (Lewis & Cave, 1992). However, high concentrations canbe deleterious to marine organisms. The most bioavailable, and thus the most toxic form of ionic, unbound copper, is the free hydrated ion, Cu(H2O)62+ (Voulvoulis et al., 1999). The antifouling effect of the copper is achieved through dissolution and release of free cupric ions from the coating surface, which have a toxic effect on settling fouling organisms. After release organic ligands in seawater bind the cationic copper species to form anionic, hydrophilic and kinetically inert copper chelates, which reduces the toxicity. Speciation studies in coastal waters indicate that more than 99% of the total copper is strongly bound or chelated with organic ligands, leaving the concentration of free cationic copper at levels that are non-toxic to most organisms. There is also strong evidence that strong copper chelators are synthesized and excreted by microorganisms in response to gradual and potentially toxic increases in copper concentrations in the water column (Ahsanullah & Florence, 1984; Donat et al., 1994; Voulvoulis et al., 1999). However, when some booster biocides, including dithiocarbamates, are used with copper, synergistic effects can occur as a result of the formation of lipophilic organic copper complexes that can diffuse across plasma membranes (Bonnemain & Dive, 1990). The copper levels in oysters harvested near marinas and mooring areas in France increased between 1979 and 1991 and this was attributed to increasing use of copper-based antifouling paints following theban on TBT use on small craft (Claisse & Alzieu, 1993). Although copper is broad spectrum in action, it is particularly effective in controlling animal fouling (Callow, 1996). Copper leaching rates of 10 and 20 μg cm-2 day-1 are required to prevent settlement of barnacles and diatom slimes respectively (Banfield, 1980). Several significant algal foulers also show marked copper tolerance, includingPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw the green alga Enteromorpha, the brown alga Ectocarpus, and the diatom Achnanthes

. When release rates decline, animal foulers such as species of the encrusting bryozoan Watersipora and the serpulid tubeworm Hydroides are also able to colonise the paint surface. A booster biocide is therefore usually incorporated in copper-based antifoulings to broaden the spectrum of control. Some concern has been raised about the loading of copper in the marine environment from the use of copper-based antifouling paints on recreational and commercial vessels (Hall & Anderson, 1999). The contribution of copper from antifouling paints has been estimated as 2% of the total copper load in New York NewJersey Harbour, and 10% or less of anthropogenic input in the UK, whereas antifouling coatings from Navy, commercial, and pleasure craft are considered major sources of copper loading in San Diego Bay in the US.
A deterministic ecological risk assessment for copper in European saltwater environments demonstrated the probability of ecological risk from acute dissolved copper exposures to be generally low (Hall & Anderson, 1999). Available data from copper monitoring studies formed the basis of the assessment, and 31 studies encompassing 101 sites were used. In only two studies (marina/harbour sites in France and Greece) did the mean observed environmental concentration exceed the predicted no effect concentration. The chemistry of copper in natural saltwater was considered a key in assessing this risk. Generally over 99% of the toxic form of copper, Cu(II), is bound to naturally occurring organic ligands, such as humic substances, leaving only a very small fraction of Cu(II) bioavailable to biota in saltwater aquatic environments.
3.2.1 Cuprous Oxide Cuprous oxide (Cu2O), a red powder, is the most widely used antifouling biocide in tin-free coatings. Alternative copper compounds were often used only when compositions coloured other than red or red-brown were required, such as using cuprous thiocyanate (white), copper acetoarsenite (green) or metallic copper flake (copper bronze), or for application to aluminium substrates. The wide use of cuprous oxide is a consequence of its low-cost and broad spectrum activity against fouling organisms. However, antifouling formulations based on cuprous oxide often contain booster biocides to enhance performance (N. Blossom in 1999b). Some proprietary lines of cuprous oxide are claimed by the manufacturer Chemet to have lower initial release rates than competitive materials and a new line, called Controlled Depletion Copper (CDC), is claimed to further reduce initial, and yet maintain steady, release rates. Antifouling products based on this material were claimed to achieve significantly lower release rates when tested by the new ASTM copper release test method.
3.2.2 Metallic Copper Fouling prevention on copper and copper alloy sheet was initially considered tobe due to gross exfoliation (Redfield, 1952). Oxidation ofthe copper surfaceproduced a loosely attached or slightly soluble oxide layer, which caused attached fouling to be sloughed. However, exfoliation alone could not be considered responsible, as the corrosion rate was too low when compared to other metals such as iron and zinc. A toxic effect was therefore implicated, and this was attributed to dissolution of the copper, not to an inherent toxic quality of the copper surface (Redfield, 1952). The long-term antifoulingPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw performance of copper-nickel alloys is now considered to result from a combination of the release of toxic material together with sloughing of fouling attached to loosely adherent layers of corrosionproduct (Efird & Anderson, 1975; Efird, 1976; Chamberlain & Garner, 1988; Powell, 1994; Blunn, 1986). Coppernickel alloyshavebeen observedtohave aself-cleaningproperty, andvelocities of 3-8 knots have effectively removed fouling accumulations (Powell, 1994). Under static conditions accumulated fouling has been easily removed by wiping or light scraping (Blunn, 1986). Copper-nickel alloys, particularly 70/30 and 90/10 with small additions ofiron,canbemoresusceptibletofoulingbycoppertolerant organisms.This fouling may onlybe amicrobial slime ofcoppertolerant diatom species,whichmaynot significantly affect vessel performance, but in some regions fouling by copper tolerant macrofouling species, such as the brown alga Ectocarpus or the tubeworm Hydroides may cause significant problems (Lewis & Smith, 1991; Hall & Baker, 1986).
3.2.3 Copper Thiocyanate Copper thiocyanate is not as effective an antifoulant as cuprous oxide (J. Lewis, pers. obs.), but is less aggressive in its corrosive effect on aluminium. It is therefore widely used as the primary or co-biocide in antifouling paints for aluminium vessel hulls and other aluminium components such as stern drives. Use of cuprous thiocyanate also permits paint formulation in different colours, as it does not have the strong red pigmentation of cuprous oxide. Available TBT-free antifouling coatings for aluminium surfaceshave amuch shorter effectivelifethanthose containing cuprous oxide, often as short as twelve months. White cuprous thiocyanate is considered to have, in many ways, similar properties to those of cuprous oxide (Vetere et al., 1997). Both dissolve in seawater principally as CuCl21- and have the same solubility, although cuprous thiocyanate is less oxidisable. Barnacle larval bioassays found cuprous thiocyanate to be more toxic than cuprous oxide, with the toxic action demonstrated to be due to the free copper ion, and not the thiocyanate anion. Cuprous oxide based antifouling pigments contain 3.32 times more copper per unit volume than the cuprous thiocyanate based material. However, the higher toxicity of the latter means that pigment content did not need tobe increased to match the same copper per unit volume as cuprous oxide (Vetereet al., 1997).
3.2.4 Copper Pyrithione Copperpyrithione (Copper Omadine®) ismanufactured alongsidezincpyrithione (see Section 3.4.5)byArch Chemicals (formerly Olin Corporation) andwas introduced as an antifouling biocide in 1996. It is claimed to have similar activity against soft fouling organisms as zinc pyrithione, and to have similar rapid degradation and to neither bioaccumulate nor persist in the marine environment (Turley & Waldron, 1999; Turley etal.,2000).Copperpyrithione (CPT)isnotyetregisteredforusebytheU.S.EPA,but a registration application has been filed (R. Martin in Anon., 1999b). A similar situation exists in Australia, with use of copper pyrithione dependent on acceptance and registration by the NRA. The efficacy of CPT was tested in experimental paints immersed in Biscayne Bay, Florida (Turley & Waldron, 1999). Prototype paints containing combinations of cuprous oxide and CPT were tested alongside abiocide-freeblank, an antifouling paintPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw containing TBT and cuprous oxide, and a commercial copper-based antifouling paint. Key findings were:

• Combinations of CPT and cuprous oxide were more effective than either biocide alone;

• Relative low levels of CPT (~ 3%) were effective; and

• CPT/cuprous oxide paints preformed better than commercial controls.
3.2.5 Other Copper Compounds Copper napthenate, copper resinate, copper sulphate and cuprous sulphide are also used as active copper sourcesin some antifoulingpaints approvedforuseintheUnited Kingdom (Health & Safety Executive, 2001).

3.3 OTHER METALS In the early 1950s, mercury and arsenic were considered alongside copper as primary biocides in antifouling paints, but were subsequently banned on occupational health and safety and environmental grounds (Fischeret al., 1984).
Zinc oxide is commonly added to copper-based antifouling paints, primarily as a filler (Callow, 1996). The zinc not only enhances the performance of the antifouling paint (French etal., 1984),but is also economically advantageouswith respect to raw material costs; zinc oxide being less expensive than the cuprous oxide it replaces.

3.4 ORGANIC BIOCIDES As mentioned in Section3.2, although copper is effective against themajority offouling organism, several significant algal biofoulers show marked physiological tolerance to copper (Voulvoulis et al., 1999). A booster biocide is therefore usually incorporated in copper based antifoulings to control copper-resistant species. In the United Kingdom, for example, twelve booster biocides are used as active ingredients in approved antifouling products (Voulvoulis etal., 1999; Health and Safety Executive, 2001): Irgarol 1051, diuron, Kathon 5287 (Sea-Nine 211), maneb, zineb, thiram, ziram, chlorothalonil, dichlofluanid, TMTB, TCMS pyridine and zinc pyrithione. The activities of these booster biocides can be quite different; for example the fungicides thiram and nabam are active against diatom slimes (Hunter & Cain, 1996) and Irgarol 1051 against macroalgae (de Nys et al, 1996), whereas chlorothalonil and Sea-Nine 211 show more broad-spectrum activity (deNysetal., 1996).Biodegradability ofthesebiocidescan also vary considerably, ranging from readily biodegradable (Sea-Nine 211) to non-biodegradable (diuron and Irgarol 1051) (Callow & Willingham, 1996). The unforeseen impact of persistent antifouling biocides in the marine environment, particularly in relation to TBT but again highlighted by the recent detection of residual Irgarol in inshore waters (Readman, 1996), has seen a general strengthening of registration requirements for new antifouling biocides. In the United States, for example, informationmustbeprovidedto satisfytheEnvironmentalProtectionAgency (EPA) that the benefits of the new pesticide outweigh any risks (see Section 6.3.3). The review and approval process can typically take 3-5 years and requires submission of aPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw database and the absence of any evidence that the active ingredient will pose any significant risk to human health or the environment (Bingaman & Willingham, 1994).
3.4.1 Diuron

- dichlorophenyl dimethylurea
Diuron inhibits photosynthesis and is one of the major urea herbicides used in agriculture sincethe 1950sforweed control onno-crop areas (Voulvoulisetal., 1999).In 2001, 89 approved antifouling products in the UK contained diuron (Health & Safety Executive, 2001). In one survey, diuron was present in 73.4% of antifouling paints sold by chandlers in one region of the UK (Voulvoulis et al., 2000), and another survey estimated that 45-52% of recreational craft were painted with antifoulings containing diuron (Boxallet al., 2000).
In theUnited Kingdom, diuron is one ofthepesticides thatmost frequently exceeds the Environmental Quality Standard (EQS) of 1 mg l-1 in controlled waters. This is predominantly attributed to its use in agriculture, although some inputs have been related to its antifouling use (Voulvoulis et al., 1999). On the Mediterranean coast of Spain, diuron, together with Irgarol 1051, was the most ubiquitous antifouling biocide detected. Itwas found in everymarina andharbour sampled (Martinezetal., 2001). The highest concentration measured was 2.19 μg l-1

. Diuron has notbeen found tobe readily degraded in seawater (Callow & Willingham, 1996).
In one study in an estuary in Essex, UK, diuron was not traced in any of the samples collected although, from amarket survey, itwaspresent in 74% of all antifoulingpaints sold intheregion (Voulvoulisetal.,2000).However,in a second study,both diuron and Irgarol 1051 were found in water samples from areas of high yachting activity and diuron was measured at the highest concentrations (Thomas et al., 2001). In a survey of sediments, diuron was detected in samples at one site, a marina in Southampton Water (Thomas et al., 2000). Its presence was thought to be associated with paint chippings, emphasising the importance of environmental management of shore-side practices. Both amateur andprofessionaluse ofdiuronin antifoulingproductswasrevokedinthe UK in 2000 (Health & Safety Executive, 2000; Nash, 2001d). Concentrations of diuron measured in sediments on the Queensland coast are considered sufficientlyhigh to result in ecosystem impacts (Haynes etal., 2000a, 2000b). However, this contamination was attributed to the widespread use of diuron as a herbicide by the sugarcane industry rather than use in antifouling paints. In the marine environment, diuron can inhibit photosynthesis and growth in periphyton, phytoplankton and seagrasses (Molander etal., 1992; Mayer, 1987; Ralph, 2000; Haynes et al., 2000b).
3.4.2 Dithiocarbamates Thiram (bis(dimethylthiocarbamoyl)disulphide), ziram (zinc bis(dimethyl thio-carbamate), zineb (zinc ethylene bisdithiocarbamate), and maneb (manganese ethylene bisdithiocarbamate) have a wide range of action against a number of organisms (Voulvoulisetal., 1999).In agriculturethey areused asprotectivefungicides,Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw particularly for fruit and vegetable crops or, in the case of maneb, as a leaf and seed treatment. Zineb is the only dithiocarbamate still used as a cobiocide in the UK and is currently a component of ten approved tin-free and 33 TBT-based antifouling products (Health & Safety Executive, 2001). Zineb is highly effective in antifouling paints as it is strongly synergistic with copper and enablesthe amount ofcoppertobereducedwithoutloss of antifouling effect (Hunter &Evans, 1991a., 1991b).Afteritsreviewofboosterbiocidesin 2000, the UK Advisory Committee on Pesticides recommended that the approval of zineb in antifouling products for professional use by all application methods, and approval of amateur products by brush and roller, should continue (Advisory Committee on Pesticides, 2000).
3.4.3 Chlorothalonil

- 2,4,5,6-tetrachloroiso-phthalonitrile Chlorothalonil, also known as Nopcocide N-96 ® (Henkel), is used in agriculture as a fungicide and in paints and adhesives as a preservative. It is highly toxic to fish and aquatic invertebrates, but not phytotoxic (Ernst et al., 1991; Caux et al., 1996). Fifteen antifouling coatings approved for use in theUK contain chlorothalonil (Health & Safety Executive, 2001).
A study of the degradation of chlorothalonil in seawater found degradation to become apparent after four weeks and to proceed more rapidly in seawater supplemented with cultured marine bacteria (Callow & Willingham, 1996). High concentrations of chlorothalonil were measured in water and sediment in the Blackwater estuary in the UK, but the cause appeared more likely to be agricultural run-off than to its use in antifouling paints (Voulvouliset al., 2000).
In 2000, the UK Advisory Committee on Pesticides recommended that all amateur uses of antifouling products containing chlorothalonil should be revoked because information on humans indicated that the risk of skin sensitisation in humans was unacceptable (Advisory Committee on Pesticides, 2000).
3.4.4 Irgarol 1051

- 2-methylthio-4-t-butylamino-6-cyclopropylamino-s-triazine Irgarol 1051® (Ciba-Geigy) is an agricultural herbicide that is highly effective against freshwater and marine algae (Voulvoulis et al., 1999). It belongs to the s-triazine group of compounds that act as photosystem-II inhibitors, by inhibiting photosynthetic electron capture transport in chloroplasts (Dahl & Blanck, 1996; Voulvoulis et al., 1999; Hall et al., 1999). Irgarol is primarily used as a booster biocide to improve a coating’s resistance to slime and algae (J. Windus in 1999b). Irgarol 1051hasbeencommerciallyavailableandsoldformorethanadecadeinEurope and the Far East. In 2001, one hundred and three antifouling products containing Irgarol were approved for use in the UK (Health & Safety Executive, 2001) and, in one region of the UK, 20.3% of antifouling paints sold by chandlers contained Irgarol (Voulvoulis etal.,2000).TheUSEPAregisteredIrgarol as an antifoulingbiocidein 1994Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw (US Federal Register, November 2, 1994). Additional ecological effects data and environmental fate data were required to be submitted by end-use formulators of antifouling paint containing Irgarol, and in 2001 7 antifouling paints containing Irgarol were registered for use in the US (J. Bloom, pers. comm.). Readman (1996) expressed concerns, and raised the question as to whether coastal ecosystems were at risk from Irgarol. Irgarol has now been detected in marine and estuarine waterandsedimentsamplesfromareasassociatedwithboatingactivityinthe United Kingdom (Gough et al., 1994; Scarlett et al

. 1997; Voulvoulis et al., 2000; Thomas et al., 2000, 2001), France (Tolosa et al., 1996), Spain (Ferrer et al., 1997; Ferrer & Barcelo, 1999; Martinez et al., 2001), Germany (Biselli et al., 2000), Japan (Liu et al., 1999), Bermuda (Connelly et al., 2001) and Australia (Scarlett et al., 1999). The highest levels detected in Plymouth Sound, UK, (> 120 ng l-1) significantly inhibited the growth of Enteromorpha spores under laboratory conditions and the no effect concentration on photosynthetic activity in adult Enteromorpha fronds was 22 ng l-1 (Scarlett et al., 1997). Available data suggests that Irgarol is more toxic to algae than other trophic levels, and can inhibit algal growth at concentrations between 10 and 100 μg l-1 (Rogers et al., 1996; Voulvoulis et al., 1999). A probabilistic risk assessment of the use of Irgarol indicated low ecological risk in estuaries, coastal areas andvarious open-type marinas (Hall etal., 1999). However 10% ormore oftheplant species in enclosedmarinaswith low flushing rates were determined to be possibly exposed to levels that would reduce photosynthetic activity and growth over summer. Studies inJapan similarly found that both Irgarol 1051 and its degradation product (2-methylthio-4- tert-butylamino-6-amino-s--triazine) could influence the primary producer community in the aquatic environment. The NOEC (0.3 μg/l) of Irgarol to the brown macroalga Eisenia bicyclis was the same as the maximum concentration (0.296 μg/l) detected in Japanese coastal waters. Irgarol is not readily degraded in seawater (Callow & Willingham, 1996). White rot fungus, Phanerochaete chrysosporium, appears to biotransform Irgarol, but does not cleave the heterocyclic ring, suggesting that degradation products may accumulate in the environment (Liuet al., 1997; Voulvouliset al.,1999).
A number of countries have recently imposed restrictions on the use of Irgarol as an antifouling biocide because of its persistence in the marine environment (see Section 6.4). Irgarol has been considered, but not approved, by the NRA for use as an antifouling biocide in Australia (L. Cahill, pers. comm.).
3.4.5 Sea-Nine 211 (C-9211, Kathon 5287, RH-287)

- 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one Sea-Nine 211® (Rohm and Haas Company) is a highly effective, broad-spectrum antifouling biocide (Willingham & Jacobson, 1993). Its antifouling efficacy was recognised more than 20 years ago (Miller & Lovegrove, 1990), but it was only commercialised after concerns were raised on the environmental impact of organotins (Callow, 1996). The performance of copper paints is improved by the addition of Sea-Nine, which can be used in all types of paint matrices (Harrington & Willingham, 1993). The controlled release of Sea-Nine 211 from a monolithic, non-ablative coating based on vinyl chloride/vinyl acetate copolymer resin indicated many species were inhibited at release rates of5 μg cm-2 day-1,but that fluxes ofup to 20 μg cm-2 day-1 couldPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw be needed to completely prevent barnacle attachment and diatom slimes when the biocide was used alone (Vasishthaet al., 1995; Callow, 1996). Rohm and Haas obtained U.S. EPA registration for Sea-Nine 211 in 1994 and this was the first organicbiocide registered for use in antifoulingpaintswithin the United States (Bingaman & Willingham, 1994, 1995). On the basis of its lower persistence in the environment and its lower toxicity towards humans in comparison to TBT, Rohm & Haas won the United States Presidential Green Chemistry Ward in 1996, and was Chemical Engineering’s Environmental Champion in 1997. The major features of Sea-Nine 211 claimed to meet current and prospective criteria for antifouling biocides are (L. Graziano & J. Harrington in Anon., 1999b):

• It has a wide spectrum of activity against fouling organisms including slime, grasses, and barnacles;

• It has a short half-life in seawater and sediment and therefore does not accumulate in the environment; and

• It imposes minimal risk to non-target organisms due to its rapid degradation, the lack of accumulation in organism tissues, and because it is not a chronic or reproductive toxin. Studies onthe degradation ofSea-Nineinseawaterhaveestimatedhalf-lives of8.5 days in naturalcoastalseawater (Callow &Finlay, 1995;Callow &Willingham, 1996)andless than 1 hour in aerobic and anaerobic microcosms of marine sediment and seawater (Jacobson et al., 1993; Jacobson & Willingham, 2000). In seawater, Sea-Nine binds strongly and essentially irreversibly to sediment, and in both seawater and sediment it is rapidly degraded by microorganisms to ring opened structures with greatly reduced toxicity (Willingham & Jacobson, 1993). Jacobson (1998) reviewed the environmental chemistry and environmental toxicity of Sea-Nine 211 and zinc pyrithione (ZPT) in comparison to TBT. He concluded thatboth were environmentally preferable to TBT as they both degraded extremely rapidly under environmental conditions, bound tightly to sediment, thus limiting bioavailability, and did not bioconcentrate. Although Sea-Nine 211, ZPT and TBT were all acute toxicants, the former two are not chronic toxicants and metabolites of Sea-Nine and ZPT are 4-5 orders of magnitude less toxic than the parent. Predicted environmental concentrations for both Sea-Nine and ZPT were also 60-4000 times less toxic than the lowest chronic toxicity value. This contrasts to TBT where predicted environmental concentrations were 4 to more than 100 times greater than the chronic effect level. Outside of the United States, Sea-Nine 211 is licensed, as Kathon 5287, for use as an active component in antifouling products in the United Kingdom (Voulvoulis et al., 1999) and 27 tin-free products containing the biocide are currently approved for use in that country (HSE, 2001). In all of these it is used as a booster biocide to cuprous oxide or as a co-biocide with other active agents. Sea-Nine 211 has been fully assessed by EnvironmentAustraliaforuseasanantifoulingbiocide (L.Cahill,pers.comm.)andone product containing Sea-Nine (Jotun Seavictor 50) is registeredby the NRA. In Sweden, Sea-Nine is subject to some restrictions and the biocide has the same regulatory status as diuron (Ranke & Jastorff, 2000).Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Sea-Nine 211wasrecentlyreportedtobepresentatconcentrationsofupto3700ngl-1in marina waters in Spain (Martinez et al., 2001). This appears to be the first positive report ofthisbiocide inmarinewaters, andmay reflect its increasing use as a substitute for the more persistent biocides Irgarol 1051 and diuron. Sea-Nine 211 is a skin sensitiser and is predicted to also be a skin and eye irritant (Advisory Committee on Pesticides, 2000). Amateur use of products containing Sea-Nine biocide were revoked in the UK in 1999 for this reason and, in 2000, the AdvisoryCommittee onPesticidesrecommendedthat althoughprofessionaluse should be permitted to continue, this should be subject to the use of additional personal protective equipment and further data requirements.
3.4.6 Zinc Pyrithione

- zinc 2-pyridinethiol-1-oxide
Zinc pyrithione, sold as Zinc Omadine ® (Arch Chemicals, formerly Olin Corporation) is used in agriculture as a bacteriocide and fungicide, and in shampoos as an antidandruff treatment. It has been used for the latter during the past 35 years and no environmental effects havebeen noted in this time, suggesting that pyrithione does not persist in the environment (Turley et al., 2000). Zinc pyrithione (ZPT) has low solubility in water, which contributes to its effectiveness as an antifouling pigment. It acts especially well in combination with cuprous oxide and cuprous thiocyanate, and forms stable complexes with copper, mercury and silver (Ranke &Jastorff, 2000). The copper complex is considered to be of particular interest as it is formed during release from copper-containing antifouling coatings. Zinc and Copper Omadine ® are said to be dependable biocides for the control of soft fouling organisms and to complement the hard fouling control of cuprous oxide (R. Martin in Anon. 1999b).
Zinc pyrithionehasbeen used in antifouling formulations inJapan since 1991. ZPTwas registered by the US EPA for use as an antifoulingbiocide in 1997, and five antifouling coatings containing the biocide are now approved for use (J. Bloom, pers. comm.). ZPT has recently been approved by Environment Australia for use in antifouling paints (L. Cahill, pers. comm.), and the first product containing this biocide has recently been registered in Australia (NRA, 2001, 2002). Twenty-nine approved antifouling products in the UK contain ZPT (Health & Safety Executive, 2001). Thomas et al. (2000) summarised knowledge on the fate of ZPT in the marine environment. ZPThas a shorthalf-life innatural seawater (t1/2=<4h; Turleyetal.,2000) and low aqueous solubility (Fenn & Alexander, 1988). The most effective degradation pathway is photodegradation with a reported half-life of less than 20 minutes in the presence of UV light (Neihof et al., 1979). In waters were UV degradation is likely tobe poor or non-existent, it hasbeen hypothesized that the pyrithione would accumulate in the sediment as the stable Mn2+ - pyrithione complex (Galvin et al., 1998). However, other studieshave shown the Cu2+ complex tobe the most stable (Nakajima etal., 1990) and in areas such as marinas where copper concentrations are relatively high (Matthiessen etal., 1999), Thomas etal

. speculate that thepyrithione may accumulate as the copper pyrithione complex (CPT). In other work by these authors (Thomas, 1999; Thomas et al., 2001), ZPT and CPT were found to be below the level of detection (<20 ng/l) inmarinawater samples.Theywereunaware ofany studies onthe accumulation of ZPT on suspended particulate matter.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Turley et al. (2000) further discuss fate and degradation pathways for pyrithiones. They observe that pyrithione chelates many transition metal ions to complexes with different dissociation constants. Whether introduced into the marine environment as zinc or copper pyrithione, copper pyrithione, with the lowest dissociation constant, would become the predominant complex and follow the one fate pathway. Degradation rates were found to be rapid whether due to photolysis, biodegradation or redox, and in aerobic and anaerobic water and sediments. Aspyrithionehasyettobe detectedinthemarine environment,modelshavebeenused to predictenvironmentalconcentrationsundervariousconditions (Turleyetal.,2000).A preliminary predicted environmental concentration (PEC) in the water column was estimated to be < 0.04 μg l-1, which compares to acute toxicity values for aquatic organisms of2.6 to400 μg l-1

. The chronicno effect toxicity concentration (NOEC) is 1.5 μg l-1

. Applying a safety factor of 10 based on OECD guideline, Turley et al

. (2000) calculated the predicted no effect level (PNEC) tobe 0.15 μg l-1, and the worst case risk quotient (PEC/PNEC) to be <1. The major stable degradation product of zinc and copper pyrithione, 2-pyridine sulfonic acid (PSA) was considered to be at least four orders of magnitude less toxic than the parent compound.
A comparison of the environmental chemistry and aquatic toxicology of ZPT and Sea-Nine 211 with TBT is discussed above (Section 3.4.3). The review concluded that both ZPT and Sea-Nine 211 were environmentally preferable alternatives to TBT (Jacobson, 1998).
In 2000, the UK Advisory Committee on Pesticides recommended continued approval of zinc pyrithione in antifouling products for professional use by all application methods, and amateur use by brush and roller (Advisory Committee on Pesticides, 2000).
3.4.7 Other Booster Biocides Other booster biocides used in antifouling applications include dichlofluanid (N -dimethyl-N

-phenylsulphamide), TCMTB (2-(thiocyanomethylthio)benzothiazole), and TCMS pyridine (2,3,5,6-tetrachloro-4-(methylsulphonyl)pyridine) (Voulvoulis et al., 1999). Dichlofluanid is used as an agricultural fungicide and TCMTB as an agricultural fungicide, as a wood preservative, and in the leather industry. TCMS pyridine has no other applications.
In the UK, 38 approved antifouling products contain dichlofluanid, five TCMTB, and nine TCMS pyridine (Health & Safety Ecxecutive, 2001). Dichlofluanid was present in only 0.6% of antifouling paint sold by chandlers surveyed in a UK study, but was nevertheless detected in relatively high concentrations at several localities in the region after a boating season (Voulvoulis et al., 2000). Dichlofluanid has also been detected in marina waters in Spain (Martinez et al., 2001). The presence of dichlofluanid was not assessed inthestudyofantifoulingbiocidecontaminationofsedimentsinSouthampton Water (Thomas et al., 2000). Dichlofluanid is much less soluble in water than both Irgarol 1051 and diuron, which may allow it to become associated with particulate matter and thushave thepotential tobioaccumulate. Thomas etal. (2000) also comment that although dichlofluanid has been used extensively on various crops, very little is known about its environmental fate and effects.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw In 2000, the UK Advisory Committee on Pesticides recommended that approvals for dichlofluanid in professional products (all application methods) and in amateur products (for application by brush, roller and spreader) continue. However, it also recommended that approvals for amateur use by airless/conventional spraying and aerosol applicationbe revoked (Advisory Committee on Pesticides, 2000). Amateur use of TCMTB was revoked in 1999 due to concerns on skin irritation and sensitisation potential. In 2000, the ACP recommended that approval forprofessional use ofTCMCT in antifouling products could continue subject to additional requirements for use of personal protective equipment.

3.5 NATURAL BIOCIDES
3.5.1 Natural Antifouling Defences The search for new methods of fouling control have extended to looking at the marine organisms themselves. The surface of any organism in the sea, like any artificially immersed surface, is the potential attachment site for fouling species. Whales and turtles, for example, often carry ahealthypopulation ofbarnacle species. However, the majority of marine species do not readily foul, and understanding the way that they do this is seen to potentially provide novel solutions for the prevention of fouling.
Marine organisms have evolved three major classes of adaptation to fouling pressure: tolerance, avoidance and defence (Wahl, 1989). These are not necessarily exclusive, and a given organism may use several adaptations or adopt different strategies at different life stages. Tolerance can be seen in organisms, such as some bivalves, tubeworms, ascidians and barnacles, which secrete an outer shell or tube that is able to foul almost completely leaving only the essential orifices clean. Avoidance can include accelerated growth rates to produce new tissues at a rate higher than the local fouling rate, avoidance in timeby investing energy in reproduction rather than antifouling defences, or retreat into less vulnerable habitats. Defence mechanisms can be divided into three types: mechanical, physical and chemical (Wahl, 1989). Mechanical defence can include the development of special surface structures such as spicules which hinder attachment, intense production of mucous to impede adhesion, periodic sloughing of outer shells, cuticles or epidermis, friction againstsediment,andactiveremovalofattachedlarvaebyscrapingandpicking with specialised appendages. Wahl (1989)speculatedthat organismsmayutiliseminimally adhesive outersurfaces as a physical defence against fouling, but evidence was virtually non-existent. A subsequent study found two gorgonian corals to have surfaces with surface energies in the range previously correlated with minimal bioadhesiveness (Vrolijk et al., 1990). Surface qualities and chemistries were considered to be important evolutionary strategies for antifouling defence as they were not as metabolically demanding as constant production ofsecondarymetabolites ormucus, and antifouling compounds do not always elicit an inhibitory or toxic response across the full spectrum of potential colonists. However, with biofouling such a complex phenomenon, it is considered improbable that a single strategy could inhibit the full range of potential fouling organisms, nor are mechanisms likely to be mutually exclusive (Vrolijk et al., 1990; McKenzie & Grigolava, 1996). Several antifouling strategies may operate synergistically, withminimally adhesivesurfacesbased onlowenergy outermostlayersPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw a primary, passive, antifouling defence, at least in gorgonian corals. In echinoderms, antifouling capabilities have alsobeen attributed to a physical primary defence system, consisting of steric repulsion and low adherence (McKenzie & Grigolava, 1996). Microorganisms that breach this defence and do attach are possibly attacked by chemical mechanisms integral to the cuticular surface and/or shed by localised sloughing. Becker (1995) investigated the natural antifouling mechanisms of the green mussel Perna viridis, which appeared to be less densely colonised by epibionts than other artificial and natural hard substrata. The filtration activity of aggregated mussels was found to be a major factor in reducing fouling settlement. Grazing gastropods also reduced numbers ofprotozoa andmacroorganisms.Shellextracts showedsometoxicity to bacteria and fungi, but the effect was not strong.

3.5.2 Natural Antifouling Products More than 2000 natural products have been described from marine organisms (Faulkner, 1991; Pawlik, 1992). Many algae and soft-bodied invertebrates are conspicuously free of foulers, and chemical defence, through the creation of unfavourable or toxic conditions at or above an organism’s surfaceby surfacebound or exuded secondary metabolites, is often suggested as a widespread antifouling adaptation (Bakus et al., 1986; Davis et al., 1989). Natural antifouling products have therefore received considerable attention in the search for novel antifouling biocides (Wahl, 1989; Clare, 1995, 1996; Abarzua & Jakubowski, 1995; Abarzuaet al.,1999). The prime candidates for screening ofnatural antifoulant activity havebeen plants and animals able to maintain fouling free surfaces. Using this approach, natural antifouling products have been isolated from sponges (Targett et al., 1983; Rittschoff et al., 1985; Porter &Targett, 1988;Searsetal., 1990;Sarmaetal., 1991;Gotoetal., 1992;Willemsen & Ferrari, 1993;Bakusetal., 1994; Tsukamotoetal., 1997;Henrikson &Pawlik, 1998;Geraci et al., 2001), octocorals (Keifer et al., 1986; Rittschoff et al.,, 1986; Gerhart et al., 1988; Avelin Maryetal., 1991;AvelinMaryetal., 1994),bryozoa (Kon-yaetal., 1994),ascidians (Stoecker, 1978;Young & Chia, 1981; Davis &Wright, 1990;Wahl & Lafargue, 1990; Teo & Ryland, 1995; Davis & Bremner, 1999), algae (Bakus & Kawaguchi, 1984; Katsuoka et al., 1990; de Nys et al., 1995; Lau & Qian, 2000; Geraci et al., 2001; Hellio et al., 2001) and seagrasses (Todd et al., 1993; Callow & Callow, 1998). Active antifouling products have also been extracted from terrestrial plants (Sawant et al., 1992; 1994). Identification of antifouling activity has generally been by solvent extraction of the organisms’ tissues then use of a bioassay to assess the antifouling potential of the extract. Of the large number of studies have been undertaken to identify natural antifoulants, few have involved the isolation and chemical characterisation of the active agent. Where they have been identified, a range of structures has been elucidated. For example, homarine (Targett et al., 1983), furanogermacrene (Izac et al.,, 1982), muricins (Bandurruga & Fenical, 1985) and the diterpenes, renillafoulin (Rittschoff et al.,, 1986), pukalide and epoxypukalide (Gerhart et al., 1988), have been identified from different octocorals. The antifouling substances can also have varying and quite specific effects. Renillafoulins and pukalides inhibit barnacle settlement but have no effect on the settlement of larvae of the bryozoan Bugula neritina (Rittschoff et al., 1988). A different fraction inhibited bryozoan settlement, but had no effect on barnacle larvae. Isolated substances with the most potent antifouling activity are fatty acids, terpenes,Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw terpenoids, lipoproteins, glycolipids, phenols, lactons, peptides and steroids (Abarzua & Jakubowski, 1995). A number of furan analogs of octocoral metabolites have been found to reduce diatom numbers in bioassays more effectively than copper (Targett & Stochaj, 1994).
A U.S. Navy sponsored research program has focussed on the terpenoids renillafoulin, pukalide and juncellin, and zosteric acid in an attempt to further understand and possibly exploit such natural agents and their analogs (Sundberg et al., 1997). Synthetic pathways for producing these compounds and/or their derivative was considered an important part of the program because their isolation from organisms would represent prohibitive production costs and unacceptable impacts on natural populations.
Zosteric acid, a sulphated phenolic acid isolated from the marine angiosperm Zostera marina, appears to prevent fouling attachment by non-toxic means (Sundberg et al., 1997). The specific mechanism is thought to involve changes in cell surface hydrophobicity thatprevent cells such asbacteria from interactingwith filmed surfaces that may themselves possess cues for settlement, interaction with specific receptor molecules onthe surfaces ofbacteria and algal sporesthatpreventbindingtomolecules present on the target surfaces, or blocking the polymerisation or curing of proteinaceous adhesives secreted by invertebrates. Compounds without acute toxicity are frequently considered to be non-toxic, but most compounds that prevent settlement or metamorphosis increase the probability of death of the target organism (Rittschof, 2000). Non-toxic mechanisms include disruption of attachment and metamorphosis, reversible anaesthesia and repulsion. Complex natural products often display multiple activities. Compounds withantifoulingactivityhavealsobeenisolatedfrommicroorganismsand, in thecaseofbryozoansandsponges,someoftheantifoulingactivityexhibitedbythese animals may originate from epiphytic or symbiotic microorganisms (Clare, 1996). Several bacteria have been isolated from surfaces in marine waters that inhibit or are toxic to fouling bacteria or settling larvae (Avelin Mary et al., 1993; Holmström et al., 1992; Holmström & Kjelleberg, 1994; Armstrong et al., 2000; Peppiatt et al., 2000). One isolate, from an adult tunicate, secreted substances that inhibited both settlement of barnacles andarangeofmarinebacterialspecies.Inreviewingbacterialeffectsonlarval settlement, Holmström & Kjelleberg (1994) found that inhibitory strains were quite common in marine waters. In one study, twelve of 16 isolates frombiofilms associated with thebarnacle Balanusamphitritewere found tobe inhibitory to larvae ofthat species (Avelin Mary et al., 1993), and in a second study seven of 18 isolated strains inhibited barnacle settlement (Maki et al., 1988). Bacterial films have alsobeen found to affect the attachment of both diatoms and algal spores (Holmström et al., 1996). Bacterial strains isolated from living surfaces such as marine plants and animals seem tobe more active in preventing the settlement of fouling organisms when compared to bacterial strains from inanimate surfaces (Holmström et al., 1996). This habitat-specific mechanism may be due to the bacteria requiring specific exudate metabolites from the host organism. The use ofbacteria as a source ofnaturally-produced antifoulants clearly has a number of advantages in that bacteria are easy to culture and maintain and it is easy to collect large amounts of the inhibitory component (Holmström & Kjelleberg, 1994).Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Methods for immobilising antifouling bacteria in gels have been investigated (Holmström et al., 2000). The life span of ‘‘biological active’’ gels was extended to more than 2 months, which was considered a period of time consistent with the needs of some antifouling and antibacterial applications. After reviewing the available literature on chemical inhibition of settlement, Pawlik (1992) concluded that, although many natural extracts couldbe demonstrated to have a toxic effect on competent larvae, there was little evidence that these putative fouling inhibitors are released at concentrations that would influence settling larvae. Clare (1996) concludedthatresearch aimed at discoveringnaturalproduct antifoulantswasin its infancywithfewchemicalstructureselucidatedandlittletestinginthefield.Aswith synthetic biocides, the challenge remains to find natural products that werebothbroad spectrum and environmentally benign. Procurement or synthesis of commercial quantities of product would also be necessary, as would investigation of chemical and toxicological properties to ensure compliance with the requirements of regulatory authorities. Clare did however take an optimistic view that the potential for discovering marine natural product antifoulants is great. To fully determine this potential, he calledforfundamentalresearch onthe ecologicalrole ofthese compounds, their relation to other natural antifouling defences and their mechanism of action, coupled to applied research on coatings compatibility, controlled delivery, minimum effective release rates and field testing.
In a subsequent paper, Clare (1996) commented that although general statements about the mechanism of action of ‘‘natural product antifoulings’’ could be made, in no instance hadprecise mechanismsbeen established. In this context,he considered that a paucity of information on the molecular basis of chemical cue perception by fouling larvae during settlement was apparent, and an understanding of this offered potential in identify ways of interfering with the process. Calcium had been identified as important in settlement of several invertebrate larvae, including the barnacle Balanus amphitrite, and also to adhesion and motility in the fouling diatomAmphora coffeaeformis (Wigglesworth-Cooksey & Cooksey, 1992; Cooksey & Wigglesworth-Cooksey, 1995; Holmström et al., 1996). Clare considers this to be encouraging from the viewpoint of antifouling development, since it offered the prospect of broad-spectrum activity. Further studies on how natural products inhibit larval settlement might enable components of theprocesses tobe identified,which could thenbe used in screening for candidate antifoulings (Clare, 1996; Morse, 1994). Natural antifouling products are easily degraded chemically, photochemically and biologically and, when incorporated in paint formulations, antifouling effectiveness of the surface diminishes within a short period of time. Marine organisms are able to continually synthesise new compound to maintain the antifouling effect, but such an option is not available to the paint formulator. One novel approach to overcome this deficiency was microencapsulation and controlled release (Price et al., 1992, 1994). Microcylinders of copper or iron metal formed on a substrate of phospholipid have been utilised to deliver tetracycline, isothiazolone antifouling agents and crude extracts of the sea pansy Renilla

. The latter study found microencapsulation to enhance the activity of the natural antifoulants, with metallic tubules providing heat and solvent stability and a barrier to light.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Lanolin and ti-tree oilhavebothbeen claimed tohave antifouling activity andproducts containing these substances have been promoted in Australia. Long-term efficacy of these products has not been substantiated. Capsaicin, a chilli extract, has also been claimed to be effective as an antifouling agent. In the U.S., the Center for Biotechnological Research in Pennsylvania has produced a product called Hot Bottom Paint (Kettlewell, 1999). The product contains 33% copper and a ‘‘secret formula based on capsaicin’’.

3.6 PAINT ADDITIVES An antifouling paint additive marketed in the U.S. under the name Compound-X is claimed to increase the effectiveness of antifouling paints by stopping barnacles, slime, and grassy growth when added to other bottom paints and to ‘‘double the life of most antifouling paints’’ (Kettlewell, 1999). Starbrite Compound-X ® is an antibiotic compound, with the active ingredient is listed as oxytetracycline hydrochloride. The additive is reported to be non-toxic, EPA approved, and not to affect paint adhesion, workability or appearance. A 10 gram bottle treats one gallon of antifouling paint (www.boatingreview.com). University of Florida tests are claimed to show reductions in fouling during two-year tests.
Peterson etal. (1993) investigated the impact of tetracycline following thepublication of an article in a yachting magazine advocating the addition of tetracycline capsules to cheap copper-based antifouling paints to boost their effectiveness (Palley, 1988). Preparation of antifouling paints using tetracycline powder was found to produce an unstable product that leached rapidly into seawater. Concentrations toxic to bacterial and algal fouling were considered unlikely to be reached at the paint surface, and on release into seawater the tetracycline wouldbe rapidly inactivated through complexing with calcium and magnesium. The authors concluded that tetracycline would not pose an environmental threat to marine ecosystems, nor would it be likely to produce an effective antifoulant. Verbal accounts have been given of small boat owners adding herbicides, such as Round-Up ®, to antifouling paints in southern Australia. Users claim that the herbicide improves the antifouling effectiveness and life of the paint. The addition of any substance to an antifouling paint is illegal in Australia (L. Cahill, pers. comm.).Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 4. FOULING RELEASE COATINGS

4.1 FLUORINATED POLYMER COATINGS Poly(tetrafluorethylene) (PTFE) was initially considered to offer promise as a fouling release or non-stick coating because of its low surface energy. However PTFE is not easily processed because it is not dissolved, softened or wetted by commercial solvent. In their liquid state, conventional epoxy and polyurethane resins, which produce the toughest marine coatings, also do not wet PTFE (Bradyet al., 1987). Fluorinated epoxy and polyol resins were subsequently synthesized with low surface energies similar to PTFE and these enabled powdered PTFE to be used as commercial paint pigment. However, the usefulness of PTFE coatings was still found to be limited. PTFE surfaces rapidly accumulated foulingbecause irregularities in the surface enabled adhesives to invade and cure in microcavities and create a secure mechanical interlock (Brady, 1994, 1997; Davis, 1996). The ability of barnacles to adhere securely to fluorinated surfaces, despite their low critical surface tensions, was considered to possibly relate to a highly localised polarity to the carbon-fluoridebond which allowed very polar groups in barnacle cement to develop a close association over time (Griffith & Bultman, 1997).
An alternative approach was to polymerise perfluorooctyl acrylate or perfluorooctyl methacrylate esters with monomers containing ionising functional groups to create a fluorinated polymeric surfactant (Brady, 1994; Schmidt et al., 1994). The polymer was reacted with a water-reactive cross-linking polymer to form a sturdy cross-linked film when appliedto a surface and cured.The coatinghas a surface energy of 111-16mJm-2, synthetic adhesive did not stick to the film, and it was not wetted or attacked by common solvents.Theperformanceofthissurfaceasafoulingreleasecoatinghasyetto be assessed. Adsorbed monolayers of perfluorinated surfactants are considered to have the lowest known surface free energies (Lindner, 1992, 1994). Monolayers were simulated by mixing compounds into an epoxy coating and by synthesizing acrylate, methacrylate and siloxane polymers with long perfluorinated sidechains. These polymers showed much lower surface free energies than Teflon-type perfluorinated polymers with no side chains, and showed excellent antifouling properties. Fluorinated diols have also been considered to have potential for creating minimally adhesive surfaces (Ho & Wynne, 1992).
To achieveeffectivefoulingreleasefrom afluorinatedcoating,initialbonding ofmarine organisms must be discouraged (Brady, 2000a-c). The requires construction of a well-organised surface ofclosely-packed fluorinated groups, to achieve as low a surface energy aspossible,andcross-linkingorotherwisestabilisingthesurfacesothatitresists rearrangement and penetration of marine adhesives. To minimise fouling, fluorinated coatings must meet five conditions:

• The surface must be very smooth;

• The surface must be composed exclusively of fluorinated groups;Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw • There mustbe sufficient fluorine in thebulk ofthe coating to ensure thepresence of a sufficient amount of fluorine at the surface;

• Fluorinated groups must be large enough to cover polar groups and dipoles; and

• The surface must be cross-linked in order to hold fluorine in place, resist rearrangement and infiltration of marine adhesives, and maintain stability in the marine environment. A fluorinated coating considered to have achieved these goals contains an array of closely packed, oriented CF3-terminated perfluoroalkyl groups on the surface (Brady, 2000b). In arecent study,the coatingwasfoundtoresistthe attachment offoulingmore effectively than any other fluorinated coating (Bradyet al., 1999; Brady, 2000a-c). Reduced settlement of bacteria, algal spores and barnacle larvae has been observed on fluoropolymer films (Graham et al., 2000). Bacteria attached more weakly to the films than tocontrolsurfaces, algalzoosporestendedtosettle atsurfacefaults andcracks and showed some sensitivity to fluorine content, and barnacle cyprids could find only occasional sites for attachment on the films. The overall conclusion from this study was that, due to their low surface energies, smooth films of perfluoropolymers showed considerable promise as fouling resistant coatings. However, further work was seen as necessary to achieve adequatesmoothness overlarge areas offilm,freedomfromcracks and surface blemishes, and strong attachment to underlying substrates.

4.2 SILICONE COATINGS The most successful fouling release coatings to date have been formulated using silicone polymers, confirming the hypothesis proposedby Baier (1973) and Meyer et al

. (1988) that, from physico-chemical surface analyses, silicone based coatings should behave as fouling release coatings (Callow & Fletcher, 1994). Silicone polymers are based on a backbone of repeating (- Si - O -) units with the non-backbone valencies of the silicone attachedtosaturated organicradicals (Milne &Callow, 1984).Thepotential of silicone rubbers as materials for fouling control on underwater surfaces was essentially happened upon by accident (Milne & Callow, 1984). Rubber sheeting containing organotin compounds hadbeen found to potentially have an effective life of five ormoreyearsbutthe applicationmethodwas consideredinconvenient,requiring a wallpapering or tiling process. Efforts were therefore directed toward reproducing the systems but for application in liquid form. The possibilities were limited to a small number of ambient-temperature-curing liquid elastomers including urethane elastomers and room-temperature vulcanised (RTV) silicone rubbers. In initial trials it was found that the biocide-free controls showed better antifouling characteristics than the experimental antifouling materials containing biocides, and even biofilms were remarkably non-adherent. Initially this effect was suspected to be due to the release of a toxin, such as the diorganotin compounds used as curing agents, but bioassays using Enteromorpha spores discounted this possibility. The inhibitory effect was therefore attributed to surface effects and studies were initiated in 1970 to find the optimal silicone fouling release elastomer.
A problem faced in the development of silicone coatings was that the coatings were non-stick on both sides, and were therefore difficult to apply to surfaces (Griffith & Bultman, 1997;Brady,2000a).Itwasnecessaryto develop acoating systemthatcoupledPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw the soft elastomeric silicone coating to the hard metal substrate, which became known as the ‘‘duplex’’ approach.

. This has been achieved by using a three coat system: an epoxy-polyamide anticorrosive primer, a tiecoat consisting, for example, of an interpenetrating polymer network of butyl acrylate styrene and silicone polymers, and the polydimethylsiloxane top coat. The styrene butyl acrylate copolymer is not a good anti-adhesive topcoat,butis anearperfecttransitionlayerbecause ofthe strength ofthe bonding that can be developed with epoxy substrates and with silicone topcoats. This tie coat also imparts ‘‘pseudo toughness’’ to the entire system because only the topcoat is susceptible to damage. Griffith & Bultman (1997) listed other difficulties in converting silicone moulding compounds to practical marine paints such as flow and drip control, spray ability, gel and cure times, VOC restrictions, and repair and recoat. The cost of silicones was also an issue as silicones were among the most expensive synthetic materials on the general market for caulks, sealants, adhesives etc.
In 1973, Baier proposed that the application of controlled surface energy coatings could be used to combat biological fouling (Baier, 1973). Subsequent studies demonstrated that the optimum range for the free energy of a surface designed to shed biofouling is recommended to be between 20 and 30 mJ m-2 (Baier & Meyer, 1992). Efforts to reduce the surface energy below this range are considered to be counterproductive. The effectiveness of fouling release coatings appears tobebased, not only on a combination of surface energy, surface structure and surface roughness (Watermann etal., 1997),but also on the low glass transition temperatures and low modulus of elasticity (Swain, 1999). These properties minimise mechanical locking of biological glues, thereby increasing slippage and fouling release. Brady (1999b) examined the influence of bulk and surface properties apart from critical surface tension and, from this, developed requirements forpolymerswhichrefuse orresist strongbondingto othermaterials.The influence ofproperties apartfrom surface energyis supportedby studies onthe fouling of glassrodssilanizedwith differentreagentstoproducecoatingswith different surface energy (Holm et al., 1997). The effect of surface energy on the development of fouling communities in the long term appeared indirect at best, and was complicated by temporal variation. Although the surface energies of silicones lie within the optimum range for good fouling release of 20-30 mN m-1 (Meyer et al., 1988), not all work effectively (Nevell et al., 1996). Surface energies of various silicone elastomers have also been observed to increase with increasing immersion time in seawater and, although this takes years for some materials, ultimately the material became susceptible to fouling. The changes are considered tobe duetorearrangement ofpolymer chains closetothe surface, drivenby the formation of hydrogen bonds between the solvent and oxygen atoms in the backbone (Nevellet al., 1996). Silicone elastomers used in commercial fouling release coatings are mainly based on polydimethylsiloxane (PDMS),which consists ofsiloxane subunitsinthe form ofchains and rings (Watermann et al., 1997). Silicone coatings used for antifouling purposes are rubbers and elastomers (Watermann et al., 2001). Curing (vulcanisation) converts the silicone compounds into silicone rubbers or elastomers but, as unfilled silicone rubbers have lowmechanicalstrength,reinforcingfillerssuchashighsurfaceareasilicas,quartz powders, chalk, talcs and calcium silicates are incorporated. Condensation-curing compounds are used, which cure (vulcanise) at room temperature (RTV), and metalPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw catalysts including dibutyltin or titanium compounds are added to achieve complete curing. Yonehara and Momiyama (1993) compared the fouling release performance of a number of silixane-based formulations. They concluded that surface energy was not important inimprovingantifoulingperformanceofthesiliconpolymers,butthesurface structure played a significant role. Microphase separation was found to improve antifouling performance, with the minimum amount of adsorbed proteins occurring on the most clearly phase-separated surface.
Mera et al. (1997) compared properties and performance of alkoxysilane and platinum-cured PDMS. The former was found to be unstable when immersed in water for three months, with mass lost and the contact angle hysteresis changing substantially. This was attributed to the presence of CaCO3, filler and cross-linking chemistry. In contrast, the surface of Pt-cured PDMS was found tobe chemically stable in water, and this was reflected in better fouling release performance. Fouling release from an unfilled hydrosilation cured PDMS network was compared to an RTV, filled ethoxysiloxane cured PDMS elastomer (RTV11) (Wynne et al., 2000). Barnacle adhesion strengthwas significantly less on the former, and thiswas attributed to differences in bulk and surface properties. Preliminary results suggested that bulk modulus may be the most important parameter in determining barnacle adhesion strength. Thickness of coatings was also important, with thin coatings favouring adhesion. The performance of fouling release coatings is determined by three properties (Brady, 2000c; Brady & Singer, 2000). The first is surface energy, which governs the ability of a surface to bond to another surface. Low surface energy will minimise the strength of adhesion of the fouling. The second, the elastic modulus of the coating, influences the mechanism by which the joint between the surface and the fouling organism will fail. Minimum adhesion has been found to correlate with the lowest value of elastic modulus tested, although this did not correspond to the lowest surface energy tested (Kohl & Singer, 1999). Thirdly, the thickness of the coating can influence whether the separation of an organism from the surface will be a peel fracture or a shear fracture. Elastomeric coatings, such as silicone fouling release coatings, deform readily and fouling is released by a peeling mechanism, unlike fluoropolymers which release fouling by shear. A peeling mechanism requires less energy than a shearing mechanism. Studies on the release of mechanism of barnacles from silicone elastomers have confirmed the separation to be a peeling process and that release forces decrease with increasing coating thickness (Singeret al., 2000). The most effective route to fouling-free performance of silicone coatings is to promote quick and easy peeling at the adhesivejoint of the fouling and the surface byjudicious control of thickness and elastic modulus (Brady, 1999; 2000c). This is best enabled by:

• The silicone resin having a linear, highly flexible silicone-oxygen backbone that bears a sufficient number of groups to diminish surface energy while preserving backbone mobility;

• The silicone resin being stable in the marine environment and resistant to hydrolysis, which causes loss of mass and development of surface roughness;Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw • The coating being applied at a thickness that favours release by peeling rather than sheer; and

• The coating being very smooth.
Various materials have been added to silicone coatings in order to enhance the foul releaseproperties ortoimpart an antifoulingcapabilitytothefoulreleaselayer (Griffith & Bultman, 1997). The addition of oil that slowly exudes to the surface provides a thin, liquid layer to enhance foul release properties. Some silicone coatings are designed as microcellular sponges filled with hydrophobic fluids to exude from the surface. For example, the addition of polydimethyldiphenylsilicone (PDMDPS) oil to a PDMS coating decreased the addition of barnacles and certain species of oyster (Truby et al., 2000). Fluids incorporated have included mineral oils, polyolefines, silicone fluids and paraffin. These additivesmaycreateweaksurfacelayers andmacromosaicsurfacesthat further promote fouling release (Swain, 1999). The addition of silicone oil that migrates from the bulk of the coating to the surface can initially improve fouling release, due to the fouling attachment to the oil being very weak and failing readily (Brady, 2000b). One ofthefirstreportedexperimentalapplicationsofanon-toxicfoulingreleasecoating was on offshore platforms (Miller et al., 1984). These systems were manufactured from silicone-rubber-based materials to which an exuding fluid was added. 200 μm thick coatings applied to test panels on a raft remained free of fouling for over four years, and applications on pipe sections on offshore rigs showed similar success. The performance ofthese coatings was improved by the addition of hydrophobic fluids and the life expectancy of the coatings was expected to be a function of the reservoir of fluid within the coating. However, despite promising performance from commercial coatings containing free silicone oil, depletion of the oil within several years causes the coating to loss physical integrity, become brittle and crack. Fouling can then attach tenaciously. The coatings also release silicone oilintothe environmentwhich, althoughnot consideredtoxic, does not readily degrade.
In some studies, the addition of silicone fluids to elastomers has appeared to enhance long-term antifouling performance (Milne & Callow, 1984),but in others it appeared to have no influence (Callow et al., 1986). Studies sponsored by the UK Defence Research Agency (DRA) found that the addition of a silicone oil to a silicone elastomer was only beneficial ifadissimilaroilandpolymerwereusedandthatadditionofsmallquantities of oil could reduce performance in contrast to the enhancement from greater quantities (Davis, 1996).
In barnacles, experiments to determine the force required to remove cyprids from a variety of surfaces show that, in general, low surface energy surfaces promote a weak bond between the attachment disc and the surface (Callow & Fletcher, 1994; Yule & Walker, 1987). On effective silicone coatings, the basic adhesion mechanism of adult barnacles seems tobe fundamentally disrupted (Watermann etal., 1997). Those that did not fall off immediately after metamorphosis produced an excess amount of cement, probably to compensate for reduced adhesion. Adhesion can also involve deformation of thebasal plates to enable sucker-like attachment. Watermann et al. (1997) observed a discrepancy inthatthemore effective coatings didnotinhibitbarnacle settlementinthe laboratory but did soto ahigh extentinthe field.Thiswas attributed, atleastinpart,to different hydrodynamic forces under field conditions.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw The failure mechanism of barnacle bioadhesive bonding to PDMS coatings was determined to be a cohesive failure (Berglin & Gatenholm, 1999). Good fouling release from these surfaces was considered to result from a combination of low surface free energy, resulting in few chemical interactions, low glass transition temperature, and possibly the amount of uncross-linked molecular chains present on the surface. These polymer chains are removed when a barnacle is dislodged as a result of the low intramolecular forces between the PDMS chains. On low surface energy surfaces, the byssal pad of mussels has been found to cover a greater surface area and force of adhesion is a function of the surface energy of the surface (Crisp et al., 1985; Walker, 1987). The break load for the byssus pad was 50 times less from PTFE than from slate (Young & Crisp, 1981). Blue mussels have been found to be unable to attach their byssal pads to effective silicone coatings (Callow & Fletcher, 1994), and attachment of the freshwater mussel Limnoperna fortunei was considerably reducedonsubstrateswithlowsurfaceenergy (Ohkawaetal., 1999).Inthe latter study, only 1 of 50 mussels tested (2%) attached to silicone, compared to 4/50 (8%) to Teflon and 22/40 (55%) to slate. The adhesive of fouling organisms varies between organism types and influences the release mechanism from a coating. Bryozoans secrete a hydrophilic collagen-containing adhesive, whereas barnacle adhesive is a hydrophobic protein (Brady, 1997). The adaptability of proteins is evident when their adhesion to polymers is tested; barnacles prefer surface energies in the range from 30 to 35 mJ m-2, but bryozoans adhere best to surfaces with energies of between 10 and 30 mJ m-2, which encompasses the critical value of 22 mJ m-2 at which adhesion is considered to be minimised. In field studies, dominant fouling organisms showed three common patterns in response to surface energy (Rittschof et al., 1998). Bryozoans settled on surfaces with low energy, barnacles settled on surfaces with high energy, and hydroids settled in equal proportion on surfaces of all energies. Successful fouling release coatings would therefore not be produced by determining surface energy alone (Brady, 1997). A detailed consideration of the fracture mechanics at the interface of the fouling and the coating suggests that thick coatings having low elastic modulus and low surface energies should provide the least resistance to removal of fouling and therefore be the best fouling release surfaces (Brady & Singer, 2000).
Test programs have shown that silicone based coatings performed better than other surfaces due to a slower rate of fouling accumulation, a tendency to slough, and ease of cleaning (Mussalli, 1989; Meyer & Baier, 1992; Fletcher & Callow, 1992; Watermann et al., 1997). It was initially considered that the poor abrasion resistance and tear strength of the silicone elastomers would inhibit their general use as marine antifoulings, but that they had potential for use in coastal power stations, offshore and in aquaculture (Milne & Callow, 1984). However, silicone paints have since shown potential in ship trials (Brady etal., 1987; Matsushita & Ogawi, 1993), as well as in controlling fouling on salmon-cage netting (Hodson & Burke, 1994) and for resisting the invasive zebra mussel in power station cooling water conduits in the Great Lakes (Leitch & Puzzuoli, 1992). The Electric Power Research Institute (EPRI) in the U.S. evaluated 30 non-toxic fouling release coatings for control of fouling on steel and concrete surfaces and found silicone coatings performed best with predicted field lives of two to four years. (Mussalli, 1989, cited in Baier & Meyer, 1994).Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Conventional procedures for assessing the performance of antifouling paints on test panels, in which the composition and abundance of fouling attachment was quantified, are not suitable for foul release coatings because these frequently foul under static conditions. The effectiveness of the coating is indicated by the strength of adhesion of this fouling. Two test methods have been developed to quantify fouling adhesion strength on fouling release coatings (Swain et al., 1994; Swain & Schultz, 1996; Swain, 1997): a barnacle shear test, and a water jet test. The barnacle adhesion test was approved as an American Society for Testing and Materials (ASTM) standard in 1994 (ASTM, 1994). A brush abrasion test to sequentially evaluate fouling release coatings after increasing numbers of wet brushing cycles has also been developed because standard abrasion tests were not applicable to elastomeric coatings (Baieret al., 1997). Two-year exposure tests were undertaken in Italy on sets of panels coated with silicone-based coatings, with and without additives, and results compared both to sets of panels coated with ablative copper and non-toxic epoxy paints (Terlizzi et al., 2000). The best performing coatings were silicone foul release coatings without additives, and these substantially influenced community composition, shifting it to the earliest stages of colonisation and proving to be unsuitable for colonisation typical of mature communities due to their low surface energy. The study led to the conclusion that silicone coating technology represented an alternative to the use ofbiocidal antifouling paints. However, the need for improvements in aspects such as delamination and abrasion were noted. Reduced macrofouling abundance on silicone fouling release coatings may be due, at least in part, to biotic factors. Caging experiments have demonstrated that fouling development on caged panels was much higher than on uncaged and partially caged panels, suggesting that grazing and predation influences community development (Swain et al., 1998). The implications of these findings were that silicone coatings exposed in environments with high biotic disturbance would perform well but, in environments where predators were absent, heavy fouling may occur. The commercial availability of silicone-based fouling release coatings has been increasing but, within the shipping sector, applications of silicone coatings were initially largely restricted to naval vessels, fast patrolboats, high speed catamarans and fast ferries (Hunter & Cain, 1996). Widespread research has continued, however, in attempts to improve both the durability and the fouling release properties of fouling release coatings (Clarkson &Evans, 1995a;Adkinsetal., 1996).Thefoulingreleaselifeof silicone elastomers varies according to the formulation from a few, to up to 12 years (Callow, 1996). Research on the adhesion of organisms to fouling release coatings undertaken at the Florida Institute of Technology led to the development of a model to predict the ship speed required for self-cleaning of individual barnacles (Schultz et al., 1999; Swain, 1999). This predicted that, assuming free stream velocity and no boundary layer, the best-performing silicones would self-clean at about 10 knots. However, Swain considered that there was insufficient information available at present to predict the water velocities required to remove other fouling types and communities. Thiswas due to differences in the adhesion strengths and the drag and lift coefficients for different fouling types as well as the variable hydrodynamic characteristics of boundary layer thickness and flow characteristics along a ship hull. Data suggested that hydrodynamicPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw lift and drag forces would be insufficient to remove all the fouling on the best present-day formulations. Heavy slime films and macroalgal attachmenthasbeen observed on silicone elastomers cured with dibutyltin dilaurate (DBTDL) (Callow et al., 1987). Laboratory studies confirmedthatEnteromorpha zoospore settlementwas enhanced on silicone elastomers cured by DBTDL (Callow & Callow, 1998). Residual DBTDL in the coating would hydrolyse to dibutyltin hydroxide and lauric acid, or calcium laurate in seawater, and experiments with fatty acids suggested that itwas the lauric acid component of DBTDL that was responsible for enhanced zoospore adhesion. However, early colonisation by algae was considered unlikely to adversely affect the long-term performance of commercial silicone coatings with this curing agent, since the combined effects of minimal adhesion and grazing were likely to ensure the surfaces remain relatively free of algal fouling (Callow & Callow, 1998). Organic booster biocides can be used effectively in silicones to provide a temporary antifouling capability that is backed by the fouling release properties (Griffith & Bultman, 1997). Griffith & Bultman report favourable results from U.S. Naval Research Laboratory (NRL) trials of a broad spectrum, rapidly degrading biocide used in this way. Test panels immersed in Chesapeake Bay for a year were effectively antifouling while retaining a strong fouling release nature as the active ingredients became depleted. Vincent & Bausch (1997) suggested that to improve performance of silicone foul release coatings in the short term, it might be necessary to utilise coatings with a non-toxic fluid additive, or low release rates of biodegradable antifouling agents. Additional development was considered necessary to identify commercially viable means of combing the antifouling agents and PDMS based coatings. Experiments have been conducted in which non-leaching biocides have been added to silicone elastomer polymers (Clarkson & Evans, 1995b). The addition of (3-(trimethoxysilyl) propyloctadecyldimethyl ammonium chloride (DC5700) caused a reduction of fouling in the short term (23 d), but in the longer term (13 wk) both controls and experimentalmaterialswere fouledby a similarbiomass of slime,barnacle and hydroids. Anderson (1998) summarised the key features and benefits of fouling release coatings for shipping as:

• Non-biocidal

o No release of biocides into the sea

o No toxic waste in dry-dock

o Not affected by biocide legislation

• Smooth, glossy surface

o Maximum speed

o Minimal fuel consumptionPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw • Extended fouling control

o Long-in-service periods (5 years)

o Reduced maintenance costs

• Chemically durable

o Surface stays smooth

o Only touch-up to damage needed at maintenance docking

• Copper-free

o Lower weight than standard antifoulings

o Safe to use on aluminium

• High solids

o Low solvent content

o 2 coat system (for 5 years)

Disadvantages of silicone systems were that they are expensive and more difficult to apply than biocidal antifouling paints (Anon., 1999b). An additional problem is that these systems cannotbe applied on single componentproducts and therefore cannotbe used ontopofexistingantifoulingsystems.Griffith &Bultman (1997)warnthat,ifthere is a defect in a silicone coating that can allow an immature barnacle to achieve a solid attachment, the coating will be undermined at that spot. Silicones used in fouling release coatings arepersistent, and their degradability is likely tobe zero (Watermann et al., 1998). Several silicone coatings extrude oils that act on the surface to enhance effectiveness and, if the oils are silicone-based, such a mechanism is of concern because of environmental contamination. However, not all silicone fouling release coatings exude oil in this manner.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 5. NOVEL COATINGS
5.1 FIBRE COATINGS Flocking is a process for making smooth surface into fibrous ones using an adhesive and electrostatically-charged fibres (Phillippi et al., 2001). The fibres are attached vertically andcreateathree-dimensionalsurface.Forsberg (1994)reportedthatlarvaeof mussels did not grow on fibre-flocked surfaces and barnacles appeared to be deterred from settling. Gyllenhammer (1997) found that flocked surfaceshad a lower abundance of barnacles and green algae than untreated surfaces. Fibre characteristicswere alsofoundtobeimportantin determiningthe effectiveness of flocking. Gyllenhammer (1997) found that fibres longer than 1 mm were more effective at controlling hydroid and barnacle fouling, while shorter fibres were more effective against mussels, tunicates, and brown and red algae. Flocking can be done to most surfaces and with a variety of adhesives (Müller, 1995; Phillippi et al., 2001). PVC and nylon nets have been flocked for study and antifouling paint has been used as an adhesive for the flock fibres (Phillippi, 1999).

5.2 ELECTROMAGNETIC COATINGS A different approach to fouling control has been achieved through the use of an electrically conductive paint that is insulated from the substrate by non-conductive coatings (Hare, 2000). Minor differences inpotential are electrically introducedbetween the hull and the coating. This leads to the electrolytical generation of either chlorine or hypochlorousions.Theconductivepaint alternates aseitherthecathode orthe anode of a cell on the hull, depending on the polarity of the current. Marine growth is inhibited when the hypochlorous ion concentration in the lamella zone next to the coating is above 0.1 ppm (Nishiet al., 1992).Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 6. CURRENT AND PROSPECTIVE LEGISLATION ON ANTIFOULING PAINT USAGE

6.1 STATE CONTROLS In Australia, the authority to control antifouling products initially rested with the States, and controls on the use of TBT antifoulings were introduced through State legislation and regulation. The general approach to TBT regulationby the Stateswas to ban their application to vessels less than 25 m in length. For larger vessels, only paints with a TBT release rate of less than 5 μg cm-2 day-1 (as measured by the U.S. EPA Method) could be applied, and only under permit in some States. A number of States also imposed regulations on vessel repair facilities to ensure TBT contaminated hull wash-down water and grit-blasting waste was contained for disposal on land as toxic waste and not released into the adjacent waterway. Authority for the registration of antifouling products passed to the Commonwealth in 1994, when the National Registration Authority, an organisation established to approve agricultural and veterinary chemicals, was assigned this role. Regulation of waste discharges and practices within vessel repair facilities remains with the States.

6.2 NATIONAL REGULATIONS 6.2.1 NRA Registration The National Registration Authority for Agricultural and Veterinary Chemicals (NRA) was established by the Commonwealth in 1993 as the responsible authority for the registration of agricultural and veterinary chemicals up to the point of retail sale (NRA, 1999). Following an application to register a product, the NRA undertakes a detailed, independent assessment of all data on the chemical to ensure that high standards of quality, safety and efficacy are met, and that the product will have no unacceptable adverse impact on public health, occupational health and safety, trade or the environment. For specialist advice during the assessment process, the NRA receives input from three Commonwealth agencies:

• The Chemicals and Non-prescription Drugs Branch of the Department of Health and Aged Care, which undertakes detailed assessment of toxicology and human health data;

• The Risk Assessment and Policy Section of Environment Australia, which assesses the product’s environmental implications; and

• The National Occupational Health and Safety Commission, which assesses the data relating to occupational health and safety to ensure that risk to chemical users is avoided. Registration may take up to 15 months (or more if there are major deficiencies in applications) to complete in the case of new products with new active constituents (NRA, 2000).Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Antifouling substances are defined as agricultural chemicals by the relevant Commonwealth legislation as they are ‘‘designed to destroy, stupefy, repel, inhibit the feeding of, or prevent pests on plants or other things’’ (C. Byrnes, NRA Antifouling Seminar/Workshop, Melbourne, September 2000). Antifouling paints which fit the definition are interpreted to be those which contain biocides, including products produced from ‘‘natural’’ antifouling agents. Operationally, the NRA has determined that the following antifouling products do not require registration:

• Paints that do not involve any biocidal action, such as:

• Silicone coatings

• Fibrelock coatings

• Products which are ‘‘foulant release’, i.e. modify surface tension

• Construction materials such as copper cladding. Under the NRA process, 10 chemicals are presently registered for use as active constituents in antifouling products (Table 1). Only two of these, Sea-Nine 211 and zinc pyrithione have been fully assessed, with the remainder either ‘‘grandfathered’’ into the present system or registered for agricultural use. Actives that have not been fully assessed are likely to be at some time in the future. Irgarol 1052 was not grandfathered into the system,was submitted for approval anumber ofyearsback,but has not been registered. The antifouling biocides dichlofluanid, TCMTB and TCMS pyridine, which are approved for use in the UK, have never been considered by the NRA for use in Australia (L. Cahill, pers. comm.).

Table 1 The registration status of antifouling biocides in Australia(L. Cahill, pers.

comm.) Active Registration Status Metallic copper Registered for agricultural use Cuprous oxide Registered for antifouling

−not yet fully assessed Cuprous thiocyanate Registered for antifouling

−not yet fully assessed Chlorothalonil Registered for antifouling

−not yet fully assessed Diuron Grandfathered: registered for agricultural use Seanine 211 Registered for antifouling

−properly assessed Thiram Registered for antifouling Zinc oxide Registered for antifouling

−not yet fully assessed Zinc pyrithione Registered as antifouling - properly assessed Zineb Grandfathered: registered for agricultural usePhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Applications for registration of antifouling products must also provide evidence of efficacy of the product. Applicants are expected to be able to show that when their antifouling coating is used according to label directions, it is effective for the purpose claimed. In most cases, this requires applicants to submit the results of properly designed and conducted laboratory, simulated field trial and field trials that prove the efficacy of the product. Data produced under Australian conditions are required in most cases, but relevant data from overseas is also considered.
6.2.2 ANZECC Code of Practice The Australian and New Zealand Environment and Conservation Council (ANZECC) released a Code of Practice that sets out best practice in the application, use, removal and disposal of antifouling paints to minimise adverse environmental effects (ANZECC, 1997; Australian Marine Conservation Society, 1998). Major issues addressed by the code include:

• Human occupational health and safety considerations;

• The need to limit application, maintenance and removal of antifouling coatings to approved, licensed facilities;

• The need for uniform licensing of such facilities;

• The need for more restrictions on the use of tributyltin based antifoulants on craft >25m in length, where these operate in confined waters;

• The need to ensure that new facilities be designed to enable eventual safe disposal of treated waste waters; and

• The need to ensure that existing facilities plan for upgrading to safe disposal of waste waters and to sewer if waste water plants will accept these wastes. The pamphlet promoting the ANZECC Code of Practice (Australian Marine Conservation Society, 1998) promotes a number of alternatives to TBT paints: foulant-release coatings, ceramic-epoxy coatings, epoxy-copper flake paints, electrical current systems, andbiological compounds.Alternativebiocidal systems are essentially dismissed with the statement: ‘‘Toxic alternatives to TBT, such as copper oxide paints and triazine herbicides, accumulate in marine systems and damage marine biota.’’
An ANZECC Code of Practice for In-water Hull Cleaning and Maintenance was also established in consultation with the Australian Quarantine Inspection Service (AQIS) and published along with the Code of Practice on Antifouling (ANZECC, 1997).
6.2.3 Australian Government Policy The Australian Government’s current policy on TBT was set in late 1998 with the release of ‘‘Australia’sOceansPolicy’’ (Anon., 1998).ThepolicyisthattheGovernment will:Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw • Ban the use of tributyltin (TBT) antifoulingpaintby 2006 onvesselsbeing repainted in Australian docks, unless the International Maritime Organisation sets an earlier date for suchban,inwhich caseAustraliawill ensurethatit complieswith any such arrangements noting Defence’s operational requirements; and

• Continue to promote the introduction of a global ban on TBT through the International Maritime Organization. With the IMO adopting the International Convention on the Control of Harmful Anti-Fouling Systems onShips,2001,AustraliaiscommittedundertheOceansPolicyto a ban on the application of TBT paints in Australian docks from 1 January 2003. The process has now commenced to enable Australia to formally ratify the International Convention (E. Kleverlaan, pers. comm.).
To support its position on banning TBT, the Australian Government allocated $650,000 over 1999-2002 to an Antifouling Program to support the development of suitable alternatives to TBT, and to facilitate the implementation of the Government’s proposed ban. One major project initiated through this process is the Antifouling Patch Trial Project which aims to test the effectiveness of a range of ‘‘new technology’’ antifouling paints (see Section 7.3.2).
6.2.4 International Regulation At its Diplomatic Conference in October 2001, the International Maritime Organisation adopted the ‘‘International Convention on the Control of Harmful Anti-Fouling Systems on Ships, 2001’’ (International Maritime Organization, 2001). The purpose of this conventionwastoprovideforthereduction or elimination ofadverse effects onthe marine environment and human health caused by anti-fouling systems. The prime intent was toban the use of organotin antifoulingbiocides and, to fulfil this,Annex 1 to the Convention specifies that, for organotin compounds which act as biocides in antifouling systems, ships shall not apply or re-apply such compounds from 1 January 2003. Further, from 1 January 2008, ships either: (1) shall not bear such compounds on their hulls or externalparts or surfaces; or (2) shallbear a coating that forms abarrier to such compounds leaching from the underlying non-compliant anti-fouling system. The Convention was framed, not only to eliminate the use of organotins, but to also enable action on other antifoulingbiocides perceived to cause harm at some time in the future. Under Article 6 of the Convention, any Party may propose and amendment to Annex 1. If considered warranted, the Committee can then proceed with an in-depth review which may lead to the introduction of international controls on the biocide of concern by means of an amendment to Annex 1.
6.3 ANTIFOULING REGULATION & REGISTRATION IN OTHER COUNTRIES 6.3.1 United Kingdom In the UK antifouling products are regulated as pesticides under ‘‘The Control of Pesticides Regulations 1986’’ and ‘‘The Plant Protection Products Regulations 1995’’. A list of approved products is published annually by the Pesticides Safety Directorate in conjunction with the Health and Safety Executive (e.g., Health & Safety Executive, 2001). Products are listed by product name and marketing company under the activePhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw biocide(s), and approved use (amateur and/or professional) designated. Details of listed biocides and products for 2001 are discussed in Section 7.2.
In 1997, following reviews of the triorganotin and copper compounds in antifouling products, UK’s independent Advisory Committee on Pesticides (ACP) agreed that reviews of all booster biocides should be considered in the year 2000 to allow a concerted environmental risk assessment (Advisory Committee on Pesticides, 2000). The ACP considered all available physico-chemical, toxicological, environmental fate andbehaviour, ecotoxicological and efficacy data relating to the use ofthe eightbooster biocides approved at that time for use in antifouling products: Kathon 5287, Irgarol 1051, chlorothalonil, dichlofluanid, diuron, TCMTB, zinc pyrithione and zineb. The recommendations of the ACP were subsequently accepted by government and, as a consequence, in addition to specifying maximum permissible w/w concentrations for all biocides, the following actions were taken:

• Amateur use of Kathon 5287, chlorothalonil and TCMTB was revoked, due to concerns over the skin sensitisation potential of the compound;

• Amateur use of Irgarol 1051 was revoked, and its professional use restricted to vessels over 25 m in length, in view of adverse environmental monitoring data collected in 1998; and

• Amateur and professional use of diuron was revoked, in view of both adverse monitoring data collected in 1998 and human health concerns.
At least one paint company has already acted to reformulate a number of major antifouling products on sale in the UK by replacing Irgarol 1052 and diuron with more environmentally preferred booster biocides (Nash, 2001b).
6.3.2 Europe In the European Union, Council Directive 98/8/EC concerning biocidal products obligates the member states to implement national laws installing an approval procedure for biocides in antifouling coatings based on extensive data requirements (Ranke &Jastorff,2000).TheBiocideProductsDirective (BPD)enteredintoforceinMay 2000. The Directive had little immediate impact on the supply of existing active substances and their biocidal products, but this was expected to change over the subsequent three years (Watermann etal., 2001). The intent of the directive is to remove barriers to trade in biocides across the EU by harmonising controls for their marketing and use while ensuring high levels of health and environmental protection (Chapman, 1998). Antifoulings are exempt from certain criteria in the directive during a 10-year transition period. The BPD process is described by Watermann et al. (2001). A first review regulation establishes the processes and the timetable that the companies must follow if the active substances currently supplied or included in products are to be included in the review programme. It requires that companies identify existing active substances and notify those they wish to have evaluated. A subsequent review regulation will list all identified and notified active substances. This will also give the deadline for final withdrawal from the EU market of all active substances, for use in biocidal products that are not on the list.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Under the directive, biocides approved for use anywhere in the EU before 2000 can be approved for use in national states until 2010 under existing directive national rules (Denn, 2000). However, all new biocides proposed for market authorization cannot be approved unlessthe activeingredientislistedinthe directive as onethatis safeforuse. Companies developing novel active ingredients have to compile a dossier proving they are eligible for inclusion. Products authorized by one member state and approved by a member state committee of experts can thenbe marketed freely in the rest of the EU. If a new compound is developed, which is not based on an existing active substance, the company must provide human and environmental toxicity data to get the new active substance on the list of active substances. Watermann et al

. (2001) considered that the BPD process would reduce the number of biocides on the EUmarket. In addition, they saw the BPD increasing themanufacturing costs , thus cutting thenumber ofmanufacturers andbiocidalproducts. Some estimates put the costs at more than EUR 5 million for each biocide. Small and medium sized companies would not have the money to generate the data required by the BPD. Many European countries presently have domestic regulation of antifouling products. All antifouling coatings sold and applied in Belgium, the Netherlands, Ireland and Sweden within the EU, and Austria, Malta, and Switzerland outside of the EU, require registration, while other States have no restrictions.
In 2000, Denmark prohibited the import, sale and use of antifouling paints containing diuron and Irgarol for ships less than 25m in length. They also banned the use of antifouling paints on pleasure craft used predominantly in freshwater, and on boats of less than 200 kg.
6.3.3 United States/Canada In the United States, antifouling biocides and formulations containing these biocides must be approved by the Environmental Protection Agency (Anon., 1999b). Registration of a new active ingredient requires the development of an expensive technical data package. The EPA, as mandated under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), must determine that the benefits of the new pesticide outweigh the risks prior to granting approval for the new product (Bingaman & Willingham, 1995). This review and approval process can typically take at least 3-5 years, given submission of a complete database and no evidence that the active ingredient will pose a significant risk to human health or to the environment. US EPA registration isnot onlyimportantfortheUS,butis alsoviewed globally as ameasure of environmental acceptability. Alternative biocides are subject to a comprehensive risk assessment of data submitted by the manufacturer (Wood-Thomas, 1998, 1999). Requirements include data on product chemistry, residue chemistry, toxicology, ecological effects, environmental fate, and human exposure. The system is a two-tiered system: Tier 1 tests and data are required in all applications (although specific test may be exempted if specified conditions are met); Tier 2 tests and data may be required depending on the results obtained through Tier 1 testing.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw With respect to toxicology data requirements, Tier 1 requirements are (Wood-Thomas, 1998): acute and 90-day oral, dermal and inhalation toxicity, acute and 90-day neurotoxicity, primary eye and dermal irritation, dermal sensitisation, developmental toxicity, reverse mutation and mammalian cell assays, in vivo cytogenetics and immunotoxicity. Tier 2 requirements are: developmental toxicity, dermal penetration, chronic feeding, carcinogenicity and reproduction. For ecological effects, Tier 1 requirements are: avian oral LD50, freshwater fish LD50, acute EC50 freshwater invertebrates, acute LC50/EC50 estuarine and marine organisms, fish early life stage aquatic invertebrate life cycle, fish life cycle, whole sediment acute invertebrates freshwater and marine, seedling emergence and aquatic plant growth. Tier 2 requirements are: aquatic organismbioavailability/biomagnification, simulated or field testing aquatic organisms, and whole sediment acute invertebrates freshwater and marine. Environmental fate testing requirements are: Tier 1, hydrolysis and leaching studies; Tier 2, photodegradation in water, aerobic and anaerobic aquatic metabolism, adsorption/desorption, bioaccumulation studies in aquatic non-target organisms, and monitoring ofselectedU.S.waters.Datarequired onhumanexposureincludesproduct use information, dermal and inhalation exposure outdoor during application and biological monitoring. Similarly, post application data on dermal and inhalation exposure andbiological monitoring is required to evaluate human exposure during the removal of antifouling coatings from boat hulls.
To then get approval of coatings containing approved biocides, formulators must accumulate data studies on the performance of their formulations, generally over a 60 month period. Formulations for application in U.S. shipyards must also meet Volatile Organic Compound (VOC) emission standards and products available for use in Japan and Europe may not be permissable (Wood-Thomas, 1998). To comply with air quality legislation amaximum of400g ofVolatileOrganicHazardousAirPollutants (VOHAPs) per litre of wet paint is allowed. All antifouling products applied in Canada must be Government registered, and registered antifoulings containing copper must have a release rate of less than 40 μg cm-2 day-1

. Registration isnot required fornon-biocidal systems such as silicone fouling release coatings.
6.3.4 Asia/ New Zealand/South Africa In Singapore, Malaysia, Korea, Taiwan and China there areno restrictions on the use of antifouling products. InJapan and Hong Kong China, all antifouling products mustbe registered. Registration isnot required fornon-biocidal systems such as silicone fouling release coatings. All antifouling products for application in New Zealand, except non-biocidal fouling release systems, must be registered and registration of antifouling paints is also required in South Africa.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 6.4 PROSPECTIVE RESTRICTIONS AND REGULATIONS ON ANTIFOULING COATINGS As Ranke & Jastorff (2000) comment, despite the environmentally motivated wish to generally dispense with the use of biocides in fouling protection, in the short term this seems unrealistic. There is therefore aneed forbetter understanding of advantages and risks of using alternative biocides to ensure that those used cause no environmental harm.
A number of antifouling biocides apart from TBT have now come under scrutiny. As discussed above (Section 6.3.1) approval of diuron as an antifouling biocide has been revoked in the UK, the use of Irgarol 1051 restricted to vessels longer than 25 m, and amateur use of Kathon 5287 (Sea-Nine 211), chlorothalonil and TCMTB revoked. Both Irgarol and diuron have also been banned on pleasure boats in Scandinavian countries (Watermannet al., 2001). Although Irgarol has neverbeen approved for use in antifouling products in Australia, diuron is a predominant booster biocide and is present in nearly half of the antifouling products registered by the NRA in Australia. With respect to copper, a traditional view of antifouling paints for small boat owners was ‘‘the heavier the can, the better the antifouling properties and the higher the cost’’ (Kettlewell, 2000). This was a consequence of the copper content, with paint effectiveness considered proportional to copper content, and copper content proportional to cost. Kettlewell commented that consumer publications frequently told consumers to weigh paint cans to find best value. Paints with lower copper content, boosted with organic biocides are now being promoted as a more effective and environmentally preferable approach. Watermann et al., (2001) observed that the use of copper as an antifouling biocide is becoming increasingly restricted. Sweden has a ban on copper-containing antifoulings on recreational craft operating on its east coast, and a ban on the west coast will take effect in 2002. Scandinavian countries have banned the use of copper in freshwater areas and, from the beginning of 2001, the Netherlands will no longer approve copper-based antifouling paints for pleasure boats. Recent investigations in San Diego Bay, California, have found dissolved copper levels in the yacht basin to exceed the federal and state standard of 3.1 mg l-1

. This may lead to the Regional Water Quality Control Board in San Diego requiring that copper levels be reduced, possibly by introducing non-toxic antifouling strategies. More widespread US restrictions on the use of copper antifouling paints within 5 years have also been predicted (Kettlewell, 2000).
A number of countries have indicated a desire to reduce the input of copper from antifouling paints by imposing limits on the permissible copper release rate. However, the standard test method developed for measuring TBT release rates from antifouling coatings was unsuitable for copper (Lewis & Baran, 1993). Research was undertaken to develop such a method and, in 2000, both an ISO Method (ISO, 2000a, 2000b) and an ASTM method (ASTM, 2000) were released. Canada appears to be the first country to restrict copper-based antifouling paints by imposing a release rate restriction.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw The threat of aban on copper as an antifouling has prompted five European and North American biocide manufacturers to form a pressure group to fight any such move (Nash,2001c).The group,theCopperAntifoulingEnvironmentalProgram (CAEP)was established to undertake research in an effort to ensure legislating authorities have the full scientificfactsattheirdisposalbeforemakingdecisionsthatareconsideredpossibly to have wide-ranging, long-lasting and highly expensive consequences. CAEP is concerned that the bans in Sweden and the Netherlands will be used by radical environmentalists to persuade other governments to institute a ban on copper.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 7. ALTERNATIVES TO TBT ANTIFOULING COATINGS

7.1 REQUIREMENTS OF THE BOATING & SHIPPING INDUSTRY Boat and ship ownerswould, ideally,prefernever tohave to dock or slip theirboats for underwaterhullmaintenance.However,foulingaside,mechanicaldamageanddamage to anticorrosive coating systems necessitates dockings to avoid hull structural damage due to corrosion. Maritime safety regulations mandate ship owners to dock their vessels at a maximum interval of 5 years, and for older vessels the mandatory docking cycle canbe shorter.TBT copolymer antifouling systemswerethe firsttoprovide5year fouling protection for ship hulls, and this facilitated the implementation of 5 year docking cycles. Five years has therefore been the target longevity for premium TBT alternatives. However, despite the efficiency ofTBT,not all ships owners extended docking cycles to the permissible 5 years. Anderson (1998) analysed data on dry dock intervals ofvessels greater than4,000 dwtrecordedintheInternationalPaints database and compared data from the 1980s with data from the 1990s. The two most frequent dry-dock intervals for ships were at 24 and 30 months (Figure 4). Overall there were more ships dry-docking at these intervals in the 1990s than in the 1980s, which Anderson attributed to the increased use of TBT antifoulings in the 1990s. However, a greater percentage of ships dry-docked at less than40months interval in the 1990s compared to the 1980s; i.e. there was a trend to shorter, not longer, dry-dock intervals. Overall, the number of ships that docked at 60 month (5 year) intervals was small, representing less than 10% of the total.

Figure4 DWT and dry-dock interval for the 1980’s vs. 1990’s (from Anderson,

1998) Damodaranetal. (1999)surveyedshipownersfordrydockinginformation.Theirsurvey found that nine of eleven shipping companies that used TBT paints operated on a five-year dry-docking interval, whereas eight of eight that used tin-free paints dry-docked on a 30-month cycle. The TBT painted ships operating on less than a five-year dry-docking interval generally did so because other maintenance needs necessitated more frequent dry-docking. U.S. ships, for example, are requiredby law to dry-dock every 30 months. Watermann et al. (2001) made a similar observation on docking intervals. They comment that although TBT SPCs could provide performance of 60 months, onlyPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 15-20% of the world fleet need actual docking intervals of 60 months. However, this percentage was mostly composed of container ships, which are of increasing importance in world trade. Shipowners operating in the Baltic and North Sea also commented that the average vessel goes three years between drydocking and only about 10% need a five year system (MER, 1998a). Liberia, in a submission to IMO (MEPC 46/5/10, 16February2001),estimatedthat20%ofships,representingamajority of tankers, bulkers and container ships, operate on a dry-dock schedule of 60 months.

7.2 TBT-FREE ANTIFOULING COATINGS There are presently 43 tributyltin-free antifouling products registered by the NRA for use in Australia (Appendix 1). These contain 10 different active ingredients (Table 2). The registration of these actives was discussed in Section 6.2.1. Almost all contain copper as the primary biocide, with 74% containing cuprous oxide. Those without cuprous oxide, including those containing cuprous thiocyanate, are marketed primarily for application to aluminium hulls, stern drives and other submerged aluminium components, although yacht owners desiring white or other light coloured paint systems would alsoneed to use cuprous oxide freeproducts. The most commonly used booster biocide is the herbicide diuron.

Table 2 List of NRA approved antifouling actives and their usage in registered

antifouling products. Active No of Products % of Products Metallic copper 1 2.0 Cuprous oxide 38 77.6 Cuprous thiocyanate 8 16.3 Chlorothalonil 1 2.0 Diuron 23 46.9 SeaNine 211 1 2.0 Thiram 2 4.1 Zinc oxide 11 22.4 Zinc pyrithione 0 0 Zineb 4 8.2 Total 49

For comparison, in the UK there are 355 approved TBT-free antifouling products containing 17 different actives (Table 2). A comparison of the actives shows a similar proportion of copper-based products to Australia. Major differences are in the use of booster biocides. Diuron is used less widely, seemingly substituted by the use of the actives Irgarol and dichlofluanid which are not permitted in Australia. However, in 1998, diruon was estimated to be present in ~50%, Irgarol 1051 ~30%, ZPT ~3% and dichlofluanid ~2% of the paints used in the UK (Thomas et al., 2001). The incorporation and registration in the UK of the ‘‘newer’’ biocides, Kathon 5287 (=Sea-Nine 211) and zinc pyrithione is also significant, these now found in 8.7% and 7.9% of products respectively. Zinc oxide is not considered an active constituent in the UK.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Table 3 List of UK approved antifouling actives and their usage in registered

antifouling products. (* approval of products containing diuron has since been revoked) Active No of Products % of Products Metallic copper 15 4.2 Cuprous oxide 269 75.8 Cuprous thiocyanate 56 15.8 Copper napthenate 1 0.3 Copper resinate 3 0.8 Cuprous sulphide 1 0.3 Copper sulphate 1 0.3 Chlorothalonil 11 3.1 Dichlofluanid 26 7.3 Diuron* 90 25.4 Irgarol 99 27.9 Kathon 5287 31 8.7 TCMS Pyridine 8 2.3 TCMTB 5 1.4 Zinc napthenate 3 0.8 Zinc pyrithione 28 7.9 Zineb 8 2.3 Total 355

203 antifouling products (TBT-containing and tin-free) are registered for use in the US but, in contrast to the UK, fewer antifouling actives are approved for use (Table 3) (J. Bloom, pers. comm.). Apart from copper compounds, only three booster biocides (Irgarol, Sea-Nine 211 & zinc pyrithione) are approved and all are relatively new products. Significant exclusions are diuron and the dithiocarbamates such aszineb. The lower usage of cuprous thiocyanate is considered to be due to US legislation allowing the continued use ofTBTpaints on aluminiumhulls and other underwater components on small craft.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Table 4 List of US approved antifouling actives and their usage in registered

antifouling products. Active No of Products % of Products Metallic copper 13 6.4 Copper hydroxide 4 2.0 Cuprous oxide 176 86.7 Cupric oxide 2 1.0 Cuprous thiocyanate 6 3.0 Irgarol 7 3.4 Seanine 211 3 1.5 TBT methacrylate 15 7.4 Zinc oxide 1 0.5 Zinc pyrithione 5 2.5 Total 203

The majority of the products registered for use in Australia, the UK and the US are mostly conventional coatings directed at the recreational and small boat markets and the expected effective antifouling life of these would range between 12 and 36 months.
7.2.1 Conventional TBT-Free Antifouling Coatings Anderson (1998) compared the performance of TBT and TBT-Free antifouling paints using data extracted from the International Paints database known as Dataplan (see AMOG Consulting, 2001). For this comparison, a fouling rating of less than 10, which represents only microfouling (slime) presence, was deemed as satisfactory. The graphical representation of results (Fig 5) show that of 966 ships painted with TBT, more than 80% were deemed satisfactory after 37-42 months. In contrast, of 399 ships painted with soluble matrix paints and 299 ships painted with contact leaching paints, less than 75% were deemed satisfactory after only 13-18 months and, at 37-42 months, around 60% of those with soluble matrix paints and under 45% of those with contact leaching paints remained satisfactory.

Figure 5 Percentage of ships satisfactory vs. in-service period (from Anderson,

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r2000.j33.02.0.aw This performance is reflected by Bennett (1996) in describing the experience of shipowners who evaluated ‘‘new’ formulations introduced in response to TBT regulations in the late 1980s and early 1990s. Paints performed well for the first two or three years, but then problems including poor structural integrity, premature fouling, and the need for more frequent dry-docking were reported. British Petroleum (BP), which switched to tin-free systems in the early 1990s, found their performance was not equal to TBT systems (MER, 1999). Conventional solublematrix and contact leaching systems, as discussed in Section2.1.2, have limited effectiveness due to the rapid leach layer build up, deposition of basic cupric carbonate, and consequent exponential decay in biocide release rates, ultimately restricting effectiveness to 12-18 months. Though considered obsolete technology, with little technical advance over the last 30 years, these remain and are likely to continue to remain at the ‘‘cheap and cheerful’’ end of the market (Royston, 1999). Ablative/eroding systems, such as CDP types, are essentially better formulated versions of conventional systems, which erode by a combination of dissolution and mechanical removal, and can have effective life of up to 36 months. Damodaran etal. (1999)conducted acomparative analysis ofthecosts ofusingTBTSPC antifouling coatings and their alternatives to determine the nature and sources of economic impactontheoperatorsofdeep-seavessels.Theanalysisincludedthecostsof antifouling paint, dry-dockingrates,cleanhullfuelconsumption, andfuelconsumption penalties as a result of hull fouling. An assumption of this analysis was that tin-free products could not match the five-year dry-docking interval of TBT painted ships, and that a 30-month dry-docking interval would be required. Copper ablatives were estimated tobe one-and-a-halfto four timesmore expensive than TBT SPCs, due to fuel penalties, higher dry-dockingcosts,revenuelost, andpaintcosts.Based oninformation supplied by three paint companies, paints costs for copper ablative paints were quoted as varying from 68% to 290% of the cost of TBT SPCs.
7.2.2 ‘‘New Technology’’ Antifouling Coatings As discussed in Section 2.1.5, ‘‘new technology’’ tin-free antifouling coatings are based on newresinsystems,whichareclaimedtopolishconsistentlyinserviceandtoprovide antifouling performance comparable to TBT copolymer systems, i.e. 5 or more years. Products considered to be ‘‘new technology’’ products are listed in Table 4 and Appendix 2.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Table 5 List of ‘‘new technology’’ copper-based antifouling coatings. Manufacturer Product Series Name Resin System Actives Akzo Nobel Intermooth Ecoloflex Copper acrylate Cuprous oxide ZPT Chugoku Sea Grandprix 1000, 2000 Silyl polymer Cuprous oxide ? Sea Grandprix 500, 700 Metallic acrylate Cuprous oxide ? Hempels Globic SP-ECO Zinc carboxylate Cuprous oxide SeaNine 211 Jotun Sea Quantum Silyl polymer Cuprous oxide CPT Kansai Exion Zinc acrylate Cuprous oxide ZPT Sigma Alphagen ? Cuprous oxide SeaNine 211

A common characteristic of these systems is the use of one of three of the ‘‘new’’ biocides as booster biocides, Sea-Nine 211, zinc pyrithione and copper pyrithione, to complement the performance of the copper. Some manufacturers’ claims for these products are as follows: Jotun Seaquantum: ‘‘These new products will be the most effective non-tin self-polishing products to date. The technology will be equal to the performance of the previous tin-containing formulations and willbe capable of providing dry dock intervals of five years or more. Jotun’s products havebeen applied to more than 194 test vessels since 1995’’ (C. Rosler in Anon., 1999b). SeaQuantum was developed by Jotun in conjunction with Nippon Oils and Fats (NOF Corporation) in Japan. The base is a silyl polymer which is claimed to hydrolyse in a similar mannertoTBTcopolymers andsmoothinservice (MER,2001).Jotunhavecited a 15%reductioninthefuelconsumption ofaSeaQuantum-coatedVLCCwhichequated to overNOK2.5M in the first twoyears alone.Jotun also claim that theperformance of the producthasbeenproven oversevenyears oftesting.Theproductis quoted asbeing three or four times the cost per litre of tin-based products (MER, 2001). Three SeaQuantum products have been formulated to suit different antifouling needs (Anon., 2000a):

• SeaQuantum Plus, for vessels with speeds above18 knots;

• SeaQuantum Classic for speeds of 12

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r2000.j33.02.0.aw • SeaQuantum FB for use on flat bottoms. The benefits of SeaQuantum are stated to be (Anon., 2000a):

• Constant linear polilshing rate giving total protection for up to 60 months;

• Environmentally acceptable while giving TBT-containing performance;

• Hard paint film making it suitable for high speed vessels;

• High dry film thickness allowing long-term system design;

• Good recoatability, giving virtually no limit to overcoating; and

• Well suited to newbuildings.

International Intersmooth Ecoloflex: ‘‘Developed in conjunction with International’s technology partner in Japan, Nippon Paint Marine Coatings, the patented, self-polishing copolymer technology of Intersmooth Ecoloflex SPC ensures continual biocide release and inherent self smoothing for extending in-service periods....... Intersmooth 460 Ecoloflex SPC has a number of major features andbenefits in deepsea, as well. The medium polishing rate with controlled biocide release allows tailored specification design with optimum dry-film thickness. Its self-smoothing controls average hull roughness for maximum fuel efficiency. Just like its deepsea counterpart, Intersmooth 360 Ecoloflex SPC assists operating efficiency with freedom from current or future restrictions on the use of tin and associated waste disposal costs........’’ (J. Kelly in Anon., 1999b). The Intersmooth Ecoloflex SPC system is claimed to be have been proven through experience inmorethan5000 ship applications over9years (Anon.,2000c).Intersmooth 460 and 465 Ecoloflex are for use on deepsea ships, while Intersmooth 360 and 365 Ecoloflex areforcoastalvessels,withbothproviding anequivalentperformancelevelto premium-grade TBT SPC antifoulings. They are considered suitable for in-service periods of up to 60 months, and to offer controlled biocide release, even at slow vessel speed, and self-smoothing characteristics that reduce hull roughness and therefore generate fuel savings.

Hempel: Globic SP-ECO ‘‘Globic SP-ECO is Hempel’s new generation of tin-free antifouling. The hydrolysable zinc carboxylate polymer salt binder technology makes use of a composite reinforcement with micro fibres (patent pending) for improved polishing and mechanical properties, compared to conventional tin-free antifoulings.......Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw In Globic SP-ECO there is a controlledbuildup of the leaching layer, thus the release of bio-active material is constant through the system’s lifetime. Its controlled polishing rate results in a better self-smoothing effect, with fuel-saving benefits’’ (Hempel in Anon., 1999b). Globic SP-ECO is marketed as a fast and slow polishing type and targeted towards coastal operating and world-wide deepsea vessels respectively. The fibres incorporated in the paint are claimed to yield exceptional mechanical strength and optimal polishing control, virtually eliminating cracking,peeling and impact damage (MER,2001).Ahigh solids content minimises the use of solvents and VOC emissions, and the controlled leach layer enables recoating at dockings with only a high pressure freshwater washdown.

Chugoku Sea Grandprix Chugoku Marine Paints claims a holding of around 50% market share in Japan, and 15% worldwide, in the supply of paints and coatings to the shipping and shipbuilding markets (Anon., 2000b). With respect to tin-free coatings, they claim full-ship applications oftheirSeaGrandprixtomorethan 1000largedeepseavessels.Threetypes of tin-free technology are utilisedby Chugoku, silyl resin, acrylate resin, and hydration resin, with the silyl based systems claimed to provide 5 year protection. To quote from a recent report (Anon., 2001a): ‘‘Chugoku offers four different mainstream systems, the newest of which is Sea Grandprix 1000 for ships with a high fouling risk such as LNG tankers and VLCCs trading to the Arabian Gulf, also cruise liners, short-sea and coastal ships sailing in the Mediterranean and Caribbean regions. An associated version

− Sea Grandprix 2000

− is particularly formulated for vessels generally sailing on coastal voyages. Both these systems are based on organo-silyl acrylate resins and offer owners up to five-year periods between drydockings. An equivalent performance to paints containing high-strength tributyl-tin (TBT) is claimed. The company’ssecond-generationconcept (SeaGrandprix500,orSeaGrandprix 700for coastal ships) is based on metallic acrylate resin and is suitable for most deep-sea and coastal vessels. Drydocking intervals between three and five years are possible, and perfomance is saidtobe equivalentto amedium-strengthTBT system.It canbe applied over other antifoulings. Typical uses are on bulk carriers and tankers, ferries and ro-ro ships, and car carriers.......’’ .

Sigma AlphaGen The AlphaGen series of coatings released by Sigma Coatings are based on ‘‘newlypatented European technology and [are]believed tobe the first to utilise apure organic molecular system to control the polishing action’’ (Anon., 2000d). The AlphaGen series comprises Sigma AlphaGen 20, for general deepsea tankers and bulker service, Sigma AlphGen 50, for ships with lower and more intermittent operational rates, and Sigma AlphaGen 10 for the flatbottom areas of all ship types. The AlphaGen series is claimedPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw to use co-biocides with superior resistance to UV degradation, to have low VOC levels, and to enable specifications for 24, 36 or 60 month performance.
A comparison of the performance of the International paints copper acrylate system, using data extracted from the International Paints Dataplan, showed 90% of 302 ships painted with this system to have satisfactory performance after 37-42 months; better than the 80% performance from 966 ships painted with TBT SPC (Fig. 7.2.2) (Anderson, 1998).

Figure 6 Percentage of ships satisfactory for copper acrylate SPC vs. TBT SPC

(from Anderson, 1998). A comparison oftheperformance ofnewtechnologyproducts (Ecoloflex) against aTBT copolymer antifouling (Intersmooth 210) and a conventional types of tin-free antifouling (Interspeed 642), extracted from the International Paints Dataplan database (Tables 5, 6), shows better performance overall of the new technology product with respect to weed fouling. The Dataplan ‘‘Satisfactory Performance Ratings’’ for these products were: Intersmooth 210

− Weed: 75%; Interspeed 642

− Weed: 79%, Animal: 95%; Ecoloflex SPC 200

− Weed: 85%, Animal: 99%; Ecoloflex SPC 600

− Weed: 87%, Animal: 100% (J. Millett, pers. comm.).

Table 6 Percentage of all vessels with respective antifouling ratings. Fouling Rating Interspeed 642

(256 vessels) Intersmooth 210

(555 vessels) Ecoloflex SPC 200

(363 vessels) Ecoloflex SPC 600

(66 vessels) Weed Animal Weed Animal Weed Animal Weed Animal 0- <1 44.1 74.6 43.1 n/a 66.7 87.3 66.7 89.4 01-04 14.8 12.5 18.4 n/a 11.6 8.8 9.1 7.6 05-09 12.5 4.3 10.5 n/a 5.0 2.2 4.5 3.0 10-19 11.3 3.5 10.3 n/a 6.3 0.8 6.1

- 20-29 5.1 0.8 5.9 n/a 3.6 0.6 3.0

- 30-49 3.1 2.0 4.3 n/a 1.7 0.3 6.1

- 50-74 5.1 1.6 4.0 n/a 2.5

- 3.0

- 75-100 3.9 0.8 3.6 n/a 2.8

- 1.5

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r2000.j33.02.0.aw Table 7 Percentage of vessels within scheme life with respective antifouling

ratings. Fouling Rating Interspeed 642

(129 vessels) Intersmooth 210

(296 vessels) Ecoloflex SPC 200

(141 vessels) Ecoloflex SPC 600

(39 vessels) Weed Animal Weed Animal Weed Animal Weed Animal 0- <1 51.2 79.1 47.8 n/a 67.4 93.6 76.9 92.3 01-04 12.4 14.0 19.7 n/a 12.8 4.3 5.1 5.1 05-09 15.5 2.3 8.1 n/a 5.0 1.4 5.1 2.6 10-19 8.5 2.3 8.8 n/a 4.3 0.7

- - 20-29 3.9 1.6 6.1 n/a 1.4

- - - 30-49 2.3 0.8 2.7 n/a 2.8

- 7.7

- 50-74 1.6

- 4.4 n/a 5.7

- 2.6

- 75-100 4.7

- 2.4 n/a 0.7

- 2.6

-

Five year Intersmooth Ecoloflex SPC systems have now been applied to entire underwater hulls, and International Paints recently reported on its performance on one ship after 61 months in service (www.international-marine.com). To quote: ‘‘The M/V Ramiah, a 300,361 DWT Double Hull Tanker was built in Japan, and delivered to the owners, National Shipping Company of Saudi Arabia, inJanuary 1996. The antifouling system applied at Newbuilding was Intersmooth Ecoloflex SPC. Mideast Ship Management Co Ltd, who manage the M/VMariah for the owners, drydocked the vessel in Dubai during February 2001. The Intersmooth Ecoloflex SPC antifouling on a total underwater are of 20,050 sq metres was found to be in excellent condition, with slime only after 61 months in-service. The attending Superintendents were very impressed with the performance of the antifouling systemandcommentedthattheyhadneverseenavesselinsuchgood condition after such a long in-service period.
A sister vesselM/V Safaniyah also dry-docked in Dubai during April 2001 and the antifouling system was again in excellent condition after 51 months in-service.’’ Patch trials of tin-free antifouling systems were undertaken by DSTO and the RAN on operational vessels based in Cairns, Sydney and Western Australia over the period 1993-1999 (Lewis 2001). In these trials, six different tin-free antifouling coatings were applied to each side of each vessel in strips extending from above the waterline to the keel. International Ecoloflex was the only ‘‘new technology’’ tin-free system available when the trials were initiated; the other five coatings were soluble matrix/CDP technology systems. International Ecoloflex was clearly the best-performing tin-free product onallthreevessels,andremainedmacrofoulingfreeandphysicallysoundafter 4 yearsontheCairns-basedvesselandforover5yearsontheSydneybasedvessel.Full hull applications have since been applied to two RAN ships: the patrol boat HMAS Geraldton, and the ANZAC frigate HMAS Warramunga

. To date, the coating hasPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw demonstrated excellent antifouling performance and physical durability on these ships, and dynamic flow experiments by DSTO have demonstrated polishing performance similar to TBT SPC (Lewis, 2001). Lewis (2001) saw the immediate future without tributyltin as a return to copper-based products for most shipowners. However, use of the newtechnologyproductswould come at aprice, astheseweremore expensivethan TBT systems. International Ecoloflexhas recentlybeen registeredby the NRA (NRA,2001,2002) and is now the first and only ‘‘new technology’’ tin-free coating available for application in Australia. Under the Coasts and Clean Seas program, Environment Australia are currently funding anantifoulingpatchtrialprojecttoevaluate ‘‘newtechnology’’tin-freecoatings on Australian commercial shipping. The Australian Shipowners Association is managing the project, and the Technical Committee also includes representatives from the National Registration Authority, The Australian Paint Manufacturers Federation, and the Defence Science and Technology Organisation. Seven paint companies are represented, Ameron, Chogoku, Hempels, International,Jotun, Kansai, and Sigma, and patches willbe applied on up to 24 vessels. To date patches havebeen applied to three vessels, BHP’sIron MonarchandIron Chieftain, and theAltrans

. Some concerns have been raised about the performance of Ecoloflex on Liquid Natural Gas (LNG) and Liquid Petroleum Gas (LPG) ships operatingbetween Australia’s north west shelf region and Japan. A company analysis of International Dataplan data indicated that fouling levels were much higher on LNG/LPG ships painted with both Ecoloflex and TBT coatings than on other ship types with the same systems. Approximately 50% of LNG/LPG tank ships had fouling ratings greater than 10, irrespective of which system they were painted with, whereas for bulk carriers, only 17% paintedwithTBT and 6%paintedwithEcoloflexhasfoulingratings greaterthan 10. The foulinglevelsareattributedtotheLNG/LPGshipsoperatinginoneofthetoughest fouling environments on a global basis (Akzo Nobel, 1999). One of the LNG ship operators, ALSOC, now uses the new technology systems Jotun Sea Quantum, Chugoku Sea Grandprix, and International Intersmooth Ecoloflex on their fleet (D. Amble, pers. comm.). Vessels are on a 24-month docking cycle and the operators are finding little reduction in ship performance over this time. Minimal maintenance is required at the scheduled dockings of these vessels. These vessels,built in Japan, were compelled to use TBT-free paints under Japanese regulations.
In Sweden, where the use of TBT was subject to greater restriction than the rest of Europe, a survey found that the majority of shipyards and shipowners who used the latest non-TBT paints have observed insignificant problems

− economic or otherwise (MER, 1998a).
A cost analysis of TBT SPC coatings and tin-free alternatives for deep-sea vessels (Damodaran et al., 1999), compared costs of both copper ablatives and tin-free SPCs. Tin-free SPCs were estimated to be one to one-and-a-half times more expensive than TBT SPCs due to higher dry-docking costs, revenues lost, and paint costs. It was assumed in this analysis that use of tin-free SPCs would necessitate increasing the frequency of dockings because the authors ‘‘found no data indicating that tin-free paints can, at present, match the 60-month dry-docking interval TBT SPC paints can offer shipowners and operators’’. The overall cost analysis therefore factored in thePhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw costs of additional dockings for vessels using tin-free SPCs. Based on information supplied by three paint companies, paints costs for copper SPC paints were quoted as varying from 160% to 295% of the cost of TBT SPCs. ORTEPA, the association of organotinproducers, circulated a similar analysisby e-mail ahead of the IMO Diplomatic Conference in October 2001. The data was extracted from a report prepared by Princeton Economic Research and claims that the cost of using TBT-free paints on tankers, bulkers and containers is between two and two-and-a-half times more expensive. The set of figures presented for tankers is given in Table 7.

Table 8 Comparative costs per tanker of TBT-based paints and TBT-free

alternatives (Source: ORTEPA)) TBT (60 mos.) Copper Ablative (60 mos.) Copper SPC (60 mos.) Dry Dock Rate $196,000 $392,000 $392,000 Paint Cost 24,884 (est.) 45,786 (est.) 70,670 (est.) Lost Revenue 322,000 644,000 644,000 Diversion Cost 138,000 276,000 276,000 Total ($) US $ 680,884 US $ 1,357,786 US $1,382,670

The underlying assumption in this analysis, which seems to be based on the Damodaran et al

. (1999) study, is that ships using TBT-free coatings will need to dock for repaintingtwice as often aswhenpaintedwithTBTcoatings.Whilethismaybetrue for copper ablative systems, results now suggest that TBT-free SPCs are able to provide 60-month performance. If this is so, all costs in Table 7, apart from the paint cost would be equivalent for the TBT SPC and the Copper SPC. The paint cost for Copper SPC would also be halved, as only one application would be required for the 60-month period, so the comparative paint cost would be $24,884 for TBT SPC, and $35,355 for Copper SPC. This represents an increase of less than one half in paint costs, and an increase in costs of less than one tenth overall.
Evans et al. (2000) reported on a survey of ship operators on their experiences using non-TBT paints conducted by the International Chamber of Shipping. Satisfaction with performance was expressed by many of the 37 respondents (from eight countries), although 10 respondents claimed that fouling rates of alternatives were higher than those of TBT paints. No indication was given as to the type of tin-free paints used by these operators: ‘‘new’’ or conventional technology. Trials of experimental surface-fragmenting, self-polishing, tin-free antifouling coatings showed promising results (Kuo et al., 1999). As expected, polishing rates were faster than in other self-polishing tin-free paints and varied with the resin used in the formulation. Paints containing cupric oxide and chlorothalonil were determined in raft tests tobe 80-90% as effective as the conventional tin-containing antifouling paints and, in tests on two fishing vessels, were free of macrofouling after 26 months.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 7.3 BIOCIDE-FREE ALTERNATIVES 7.3.1 Fouling-Release Coatings Many of the major international marine paint companies market silicone-type fouling release coatings and these include the systems listed in Table 9 and Appendix 3. Watermann et al. (1997) reported that since the 1970s there had been roughly forty patents for silicones as fouling release coatings on ships and underwater constructions. These included pure poly(dimethylsiloxane) (PDMS) elastomers (e.g. Intersleek, Everclean) and silicone coatings containing hydrophobic liquids (e.g. Biox, Bioclean). A fluorinated coating has also been marketed, but this is based on early fluoropolymer coating technology (R. Brady, pers. comm.).

Table 9 Fouling release coatings available on the world market

Manufacturer Product Name Chugoku Marine Paints Bioclean / Eco-Speed Hempels Hempasil SP-EED International Intersleek / Veridian Kansai Biox Sigma Sigmaglide NOF Corporation Everclean

Silicone-based fouling release coatings have been considered ideal for high speed, high activity craft, particularly ‘‘Fast Ferries’’ which operate at speeds in excess of 30 knots (Anderson, 1998). Ferry operators to have applied the International Paints system Intersleek in 1998 included Buquebus (Argentina), Stena (UK), Ceres (Greece), CTS-Parkview (Hong Kong), Condor (UK), CMNN (France), ACTV (Italy), FBSF (Norway), Fuller Cruises (New Zealand), Trasmediterranea (Spain), Deniz Otobusleri (Turkey), Crew Boats Inc (USA), and Mashantucket Pequot (USA). Fuel consumption on one vessel was measured to dropbybetween 20,000 and over 30,000 l mo-1 when it switched from a conventional antifouling coating to Intersleek. Observations on the performance of silicone FR coatings on fast ferries have noted that slime fouling can remain adhered to the coatings, even at speeds greater than 30 knots (Anderson, 1998). This was attributed to the slime-forming organisms having a low profile, which enabled them to exist within the laminar layer next to the hull. This protected them from turbulent flow, irrespective of vessel speed. The price of silicone-based FR coatings is much higher than that of other types of antifouling paints (Anderson, 1998).Itwastherefore onlyconsideredbyAndersontobe economically tenable as a replacement for TBT SPC systems on vessels able to fully exploit its particular characteristics (see Section 4.2). However, Anderson commented further that the original TBT SPC systems were considerably more expensive (x3) than the products they replaced, and that as the technologymatured, and economies of scale were realised, the price dropped significantly. He predicted that the same wouldPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw happen with fouling release coatings and that the technology would become increasingly important for control of fouling in the 21st century. Clarkson (1999)reviewedthe status and antifoulingpotential ofsiliconeelastomers.She concluded that non-toxic silicone elastomers seemed to be a successful alternative to toxic systems and, with continued research and development, could fulfil their foul release potential. They were considered a high cost alternative to conventional paints, but lower overall costs were anticipated from the potential effects of increased sales on production and raw material costs, simplification of the composition and ease of application, and improvement and extension of coating life. The accumulation of fouling on three silicone fouling release coatings, GE RTV11, Dow Corning RTV 3140 and International Intersleek, was examined on test panels immersed in Pearl Harbor, Hawaii, and compared to an epoxy anticorrosive paint as the control (Holm et al., 2000). The control coating failed rapidly (180-220 d); fouling of the GE coating and Dow Corning coatings was slower, but eventually reached a similar community structure and coverage as the control (~300 d); the Intersleek coating remained lightly fouled throughout the experiment (743 d). Changes in the surface properties of GE silicone elastomers on prolonged immersion in water were investigated (Estarlich etal., 2000). Considerable increases in hydrophilicity and surface rugosity were measured, which were attributed mainly to surface structural rearrangements accompanying adsorption of water. Although fouling settlement was least on GE RTV11 and greatest on fluorosilicones, the range of variation was small compared to the long term fouling resistance of the materials. The RoyalAustralianNavy andtheDefence Science andTechnologyOrganisationhave undertaken panel trials of a range of fouling release coatings and vessel trials of the International Intersleek system (Lewis, 2001). The first Defence vessel application of Intersleek was to an aluminium-hulled workboat based in Western Port in 1993. This boat has a maximum speed of 8 knots and low activity. Fouling has been easily removed by waterjetting at pressures of about 1500 psi. No recoating or repainting has been undertaken since the coating was first applied. The bow section of a patrol boat based in Cairns was coated with Intersleek in 1995. The system performed effectively, with no significant macrofouling, through a4 year docking cycle. However, significant fouling growth did establish on submarines painted with the Intersleek system. This was attributed to their shape, operating profile and speed. Fouling could be easily removes by waterjetting when the boats were out of the water, but improved cleaning methods were seen as necessary for in-water hull husbandry. The U.S. Navy have also undertaken patch trials of Intersleek and other fouling release coating systems. The U.S. Organotin Anti-fouling Paint Control Act of1998 required that the Environmental Protection Agency (EPA) and the Navy conduct research on chemical and non-chemical alternatives to organotin paints (Pilgrim et al., 1995). Concerns were also held that increasing regulatory pressure on cuprous oxide antifouling paints could leave the Navy with no compliant alternatives. Accordingly, the Naval Sea Systems Command (NAVSEA) established a Non-polluting/Biodegradable Antifouling Coatings program. Under this program test patches were applied to theU.S.S. Spruance andU.S.S. PaulF.Foster in 1995

. Six fouling release coatings were applied as patches to the U.S.S. Spruance, and six fouling release and five cobiocide systems to the U.S.S. Paul F. Foster (Pilgrim et al., 1995). The fouling release coating systems applied are listed in Table 10.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Table 10 Fouling release systems applied as test patches to USN

ships
U.S.S. Spruance U.S.S. Paul F. Foster International Intersleek International Intersleek Dow Corning/Hempel 8730 Dow Corning/Hempel 8730 Dow Corning/Hempel 8740 Dow Corning/Hempel 8740 Chugoku Marine Bioclean Chugoku Bioclean DX General Electric Exsil 2200 General Electric Exsil 2200 Naval Research Laboratory Duplex system Devoe Devclear

The test systems were to be inspected by divers at three-month intervals, but reports from these inspections or other reports on system performance have not been seen.
In a subsequent trial under the NAVSEAprogram, International Intersleekwas applied to the entire underwater hull of the U.S.S. Scott in 1996 (Di Giovanni et al., 1996). This was the first full ship application of an easy-release coating system on a U.S. Naval surface combatant. As with the patch tests on the U.S.S. Spruance and U.S.S. Paul F. Foster, no subsequent reports on the trial have been seen.
A cooperative project between Defence research laboratories in Australia, Canada and the United States compared the performance of fluorinated urethane and silicone fouling release coatings on elastomeric surfaces (Lewis et al., 1997). The silicone elastomer coating (=Intersleek)wasfoundtobebothflexible and durable ontheflexible substrates and to retain effective fouling release properties through long-term immersion.
In early 1998, LimnoMar in Germany undertook a trial of biocide free coatings on two ferries operating in the Wadden Sea (Watermann et al., 1998). Four coatings were silicone fouling release coatings, a fifth a biocide-free self-polishing coating. Test patches 1or2mwidewereappliedtotheships’sidesbetweenthewaterlineandchine. Patches were inspected at two-month intervals by allowing the vessels to ground and dry on low tides. The siliconecoatingsperformedreasonablywell.Thepatchesfouledto acertain degree, but the adhesion ofthe organismswas reduced. On onevessel,macrofouling coverwas estimated to be 10, 35 and 10% at the three inspection times. The composition was predominantly macroalgal, with some barnacles. At the third inspection, biocide-containing control coatings were 20% fouled by macroalgae. On the second vessel, barnacle abundance dropped between the second and third inspections, indicating that fouling hadbeen sloughed during vessel operation. All fouling couldbe easily cleaned from the silicone coatings by light brushing or sponging, and/or water pressure of 1 bar. The majority of fouling was removed during the exposure time prior to inspection, and fouling removal was positively related to the speed of the vessel.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Later in 1998, WWF Germany extended the ferry trials by initiating a collaborative project to test environmentally sound biocide-free alternatives on vessels >25m in length in coastal and brackish waters (Cameron, 2000). The project involved a wide range of interest groups, including three Ministries, eight shipping companies (both federal and private), eleven paint manufacturers, the German Paint Manufacture Association, LimnoMar, and WWF Germany. Four types of coating were tested: non-toxic, non-stick coatings (smooth silicone, Teflon or hydrostatic coatings), self-polishing, biocide-free coatings, fibre-flock coatings, and hard, non-abrasive coatings in combination with special cleaning procedures (e.g. hydro-jetting, rotating brushes). In total 23 biocide-free formulations were tested and compared with paints based on TBT, copper and organic biocides. Test conditions encompassed ships which did and did not contact the sea bottom, high to low fouling pressures, and a range of ship speeds from slow (5 knots) to fast (19 knots). Tests ran for 1 or 2 years. All silicone-based coatings were ‘‘fairly’’ effective (Cameron, 2000). Although some fouling developed, most of the organisms did not adhere securely. On all silicone coatings theadhesionforceofbarnacleswassubstantiallylessincomparisontosurfaces such as epoxy resins, and algal growthwas also reduced. The silicone coatings couldbe easily cleaned with a water pressure of 1-10 bars. On fast moving vessels the coatings were more effective than on slowmovingvessels and thosewith longerperiods inport. All silicone coatings remained intact through the trials and still performed well in the second year. The hydroviscosic and Teflon-based coatings did not perform well in marine waters, but could be cleaned on ships operating in brackish water. However, higher water pressures were required to clean these coatings than the silicone coatings. The hard, non-abrasive coating did not perform well and cleaning was ineffective.
A more detailed report on this project is provided by Watermann et al. (2001), and an overview oftheproject also appearsinthecoatingsjournalJPCL (PCE-JPCLStaff,2001). Nineteen vessels were selected for the trials: two container ships, two bulkers, one chemical tanker, one frigate, two cruisers, two passenger ferries, five research vessels, three patrol boats and one fishery vessel. The two cruisers and the frigate travel world wide, the two container ships operate in the South and North Atlantic, the bulkers and the chemical tanker operate in the Baltic Sea, North Sea, N-E Atlantic and the Mediterranean Sea, and the remaining vessels are coastal traders. Three of the vessels had test patches applied in 1998, one in 1999, and the remainder in 2000. Thirteen ‘‘non-stick’’ fouling release coatings, mainly based on silicone, are included in the evaluation, andthese are applied aspatches,hullsections, orfullhull applications.Two fibre coatings,ninebiocide-free self-polishing coatings, and three anticorrosive coatings are also being evaluated in this program. The trials are intended to continue for 60 months. Until the end of 2000, six ships had been inspected. Of the test patches applied in 1998 and inspected after 28-31 months, only silicone fouling release coatings remained in fairly good condition. Four of the silicone coatings were considered to be highly effective over this period of time, while the effectiveness of two others decreased with time. On vessels with low activity levels and a low average speed only one silicone-based coatingshowedgoodperformanceover6-11months.Onthecoastguard patrol boat,whichhadlow activitylevel (20%)buthigh average speed (18knots),three silicone coatings showed consistent performance over three years with fouling cover of about 20%. The performance of a fourth silicone coating on this vessel diminished afterPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw one year, with fouling coverage increasing to 80%. Similar results were seen on a more active (50%), but slower (11 knots) passenger ferry. Over three years two silicone coatings maintained fouling levels at around 20% while, on a third, fouling levels increased to 70% in the second and third year of the trial. On the fishing vessel, which operated in coastal waters subject to high fouling pressures, three silicone-based non-stick coatings maintained fouling levels at 20-30% on one side, and 10% on the other over a 28 month period. Scammell (2000) reports on trials of a silicone fouling release coating, Aquoxsil, he has developed in Australia. The coating was applied to six small craft in three marinas in the Sydney region and performance monitored over subsequent months. Results were indicative ofresults seenwith other silicone fouling coatings: the coating deterred some fouling, boat speed increasedwhen thehullwas clean, and any established foulingwas easily removed. The coating was estimated to cost 20% more than traditional antifouling paints, but concurrent savings were expected in pollution control practices during application and maintenance. Swain (1999) concluded, from full-scale ship and boat trials, that under optimum operating conditions the present generation of silicone fouling release coatings were able to provide satisfactory biofouling control. The major advantage of these systems was considered to be that they were non-toxic and, in addition, that they provide a smoother surface,reducing skin friction drag andthereforeimprovedperformance.The disadvantages were that they were expensive, could exhibit poor adhesion to the substrate, were easily damaged, and required some form of hull cleaning. These drawbacks was thought possibly overcome by improved coating application and dock yard practice, improved fendering and hull care, and new technology for in-water cleaning.
A decision to use a non-toxic coating is also seen as a decision to accept responsibility for routine hull maintenance by Brady (2000b). The interval between cleanings would depend on the waters in which the ship was operating and the length of time the ship spends at berth. Brady quoted 22 knots as the effective water velocity for removal of attached fouling and considered that high-performance, high-activity craft may never need cleaning. For those that did, Brady saw a need for a new generation of hull cleaning equipment to remove marine fouling from complex hull shapes without excessive damage to the coating. For non-toxic coatings, the new equipment should be designed to take advantage of the unique ways in which fouling is released from these coatings. Hard, tough fluoropolymers that release fouling by shear fracture at the coating-fouling joint shouldbe cleanedby devices that apply shear force parallel to the coating surface at high speed. In contrast, softer, lower modulus silicone coatings are much more susceptible to cuts, tears and other mechanical damage and release fouling by letting itpeel from the surface. Theseneed tobe cleanedby a machine that applies a weak force to the fouling at low frequency and maintains the force on the fouling until the joint with the coating peels apart. Brady (2000b) also commented that although the cost of the silicone coating materials is high, application and removal costs are less than other systems. This was because no toxic materialswerepresent, and costs for containment, environmentalmonitoring, and waste disposal would therefore be less than for other coatings. Silicone coatings were more susceptible to tearing and puncturing than other coatings, but were readily repaired by removing the damaged coating completely down to bare steel andPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw rebuilding the primer, tie coat, and topcoat, giving close attention to the adhesion between the old coating and the patch.
Lewis (2001) concluded that non-toxic, fouling release coatings do show promise for some sectors of the shipping industry. The systems were found to foul on low activity vessels, and the ideal platform was therefore considered to be a fast vessel with rapid port turnaround times. Attached fouling could be easily removed, but development of more efficient methods for cleaning surfaces in-water without causing damage to the coatings was seen as necessary. Towingtankexperimentshaveshownthat siliconefoulingreleasecoating systemshave less drag than a typical SPC antifouling when initially applied, and the reduction in drag couldbe correlated with the surface roughness (Candries et al., 2001). In a second series of tests, although the roughness of the foul release system was higher than the SPC due to poor surface conditions at the time of application, the foul release system still exhibited lower drag. Data from full ship applications of foul release coatings in service have shown that the ubiquitous presence of slime fouling appears to offset the initial reduced drag. However, even with the slime present, foul release coatings give speed and fuel performance equivalent to that of TBT SPC antifoulings. Recent applications of foul release systems to propellers of LNG tankers have resulted in reports ofreducedvibration and anincreaseinship speed ofupto 1knot (C.Anderson, pers. comm.). International Marine Coatings have now extended applications of Intersleek beyond fast ferries (MER, 2001). Test patches of Intersleek applied to theAgawam, a 35,000 dwt tanker with a maximum speed of 15 knots, and the Tampa, a 44,000 dwt Ro-Ro vessel, were found to be in excellent condition and to have only a light to moderate slime covering after 69 an 59 months in service respectively (www.international-marine .com). Intersleek 700 is now marketed for deepsea, high activity vessels with speeds between 15 and 30 knots. ‘‘Outstanding’ potential durability and longevity are promised, with no deterioration seen in long-term tests. A single application is recommended to provide up to 5 years service. International Marine Coatings recently applied Intersmooth Ecoloflex to the sides, and Intersleek 700 to the underwater flats of the P&O cruise ship Oriana

. Sea Grandprix Eco-Speed, the copper and biocide-free fouling release coating system offered by Chugoku Marine Paints, is considered primarily of interest to high-profile operators, such as navies and environmental agencies (Anon., 2001b). However, container and cruise ship companies can also benefit from potential fuel savings over five-year drydocking cycles. Thebase coating, Sea Grandprix Eco-Speed, is suitable for deepsea and fast coastal vessels, while a second-generation version, Sea Grandprix Eco-Speed C, is designed for slow coastal and low activity vessels.

7.3.2 Fibre Coatings Fibre-flock coatings (see Section 5.1) have been developed into a commercial product. Forsberg (1994) reported that a company in Sweden, Seal-Flock AB, was established to develop a Swedish patent for a fibre-flock coating. The coating is now available under the name SealCoat AF and marketed by the company Sealcoat Scancoat, based in GreecePhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw but operating in 20 countries around the world (www.sealscoat.com). The product is claimed to be a poison free method of preventing the build up of hard fouling growth. Alm & Gyllenhammer (1999) report that the Sealcoat fibre-flock surface gives good protection against hard fouling organisms like barnacles, mussels and tubeworms. There was slight attachment of soft fouling organisms, such as hydroids, tunicates and seaweed, on static vessels, but this growth was claimed to be loosely attached and would be washed off a vessel underway. Gyllenhammer (1997) found that although flocked surfaces reduced the recruitment of barnacles and green algae, red and brown algae were more abundant on the flocked surfaces. Larsson (1997) similarly found that barnacle recruitment was reduced on flocked surfaces,but recruitment ofmussels, green algae and the solitary ascidian Ciona were increased. Phillippi et al. (2001) reported the results of a further investigation into the effects of flocking on the recruitment of fouling organisms. They found that flocking surfaces resulted in lower recruitment of green (Enteromorpha spp.) and brown (Feldmannia sp., Petroderma sp.) algae, but had no effect on red algae (Polysiphonia spp.). For invertebrates, flocking was effective at inhibiting the recruitment of encrusting animals (encrusting bryozoans, encrusting ascidians, spirobid tubeworms), had no effect on stoloniferous animals (hydroids, stoloniferous bryozoa), and increased the abundance of tube-building polychaetes (Polydora ligni) and solitary ascidians. An exception was the encrusting sponge, Halichondria sp., which recruited equally to flocked and unflocked surfaces. The settlement processes of the various organism groups were examined in an attempt to explain the variable settlement. For example, the motile spores of green andbrown algae were considered more likely to respond to the stimuli of the fibres than those of red algae, which settle passively. Alternatively, flocked surfaceswereconsideredtopossiblyprovideafavourablehabitatforsmallgrazerssuch as copepods, amphipods and nudibranchs, which could graze on settled spores. Phillippi et al. (2001) concluded that flocking could be a cost-effective strategy for aquaculturists if the organisms causing problems were those inhibited by flocking, i.e. green and brown algae or encrusting invertebrates including barnacles. The major disadvantage of flocking was considered to be wet weight gain in areas where solitary ascidians were abundant because of their high water content and affinity for flocked surfaces. Flocked surfaces also gained mass from the detritus and sediment they trapped. The fibre-flockcoatingtestedintheWWF-Germanycoastalvesseltrialsperformedwell, with selective effectiveness againstbarnacles even on slow vessels with long periods in harbour (Cameron, 2000). Algal growth was also negligible. However, the system was only tested over one year.
Two fibre coatings are being evaluated as part of the German trial of biocide-free antifouling paints on deep-sea vessels (Watermann et al., 2001; see Section 7.3.1). The two coatings differed in the length of the fibres: one had fibres 1.1 mm long, the other 1.3 mm long. To date four vessels painted with these coatings have been inspected. On one vessel, a research vessel with an average speed of 8 knots, fouling levels were around or less than 20% after 12 months, but increased to 50-70% after two years with most of this animal fouling. In general, after 12 months, the fibre coatings showed ‘‘fairly good’’ performance in preventing barnacle settlement, but poor performance inPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw preventing macroalgal growth. The coating with longer fibres seemed marginally more effective than that with the shorter coatings.
In 2001,Sealcoatpatches350 and200m2in areawere appliedtotheVLCCLibraStarin Dubai (K. Alm, pers. comm.). The vessel travels between North America and the Arabian Gulf. At a recent inspection the patches were largely free of macrofouling and physically sound apart form pigment loss near the water line. A full hull application to a ULCC is planned for April/June 2002 .
7.3.3 Biocide-Free Self-Polishing Coatings The biocide-free self-polishing coating included in the patch trials on German ferries showed variable performance (Watermann et al., 1998). On one vessel the coating was completely fouledby macroalgae after4 months, and on the second fouling levels were higher thanthe silicone coatings. Somefoulinglossbetweeninspectionswasnoted, and this correlated with ship speed.
In the two-year German trials ofbiocide-free antifouling systems on coastalvessels, one of the two self-polishing coatings performed well, especially on fast moving vessels (Cameron, 2000). Adhesion of barnacles and total length of algae were reduced and, when green weed developed, it was easily removed.
Nine biocide-free self-coatings were included in the German trial of biocide-free coatings on deep-sea vessels (Watermann et al., 2001). From observations to date, best performance was seen on a slow-moving (11 knots) research vessel where, after 12 months, animal fouling was limited to less than 20% coverage, which was better than for the silicone coatings on the same vessel. On a second vessel, with average speed of only 8 knots, animal fouling coverage was between 20 and 60%, but this was still less than on the silicone coatings.
A Swedish company Lotréc AB was reported early in 2001 to be releasing what it claimed to by the world’s only biocide and metal-free, non-toxic antifouling coating under the LeFANT brand name (Nash, 2001a). Testing over more on more than 5000 yachts in Holland, Germany, Austria and Sweden over the 2000 season is claimed to have yielded outstanding results. Some scepticism has however been expressed on the likely performance of the product under high fouling conditions.
7.3.4 Scrubbable and Inert Coatings Watermann (1999) discusses the option, proposed by David Jones (UMC International, UK), of not applying an antifouling coating at all, but instead applying a hard, smooth anticorrosive systemandtomaintainitinthisconditionbyregularunderwatercleaning for several years. Watermann and his colleagues determined that special coatings were needed to extend cleaning intervals up to several months. For such a system to be economic, Watermann (1999) considered that sophisticated, possibly robotic, cleaning systems were necessary to support this approach. A network of hull cleaning stations on allimportanttraderouteswould alsoberequired, andcleaningshouldbe automatic, either by means of a car wash system or remotely operated vehicle. Even then, awkward areas such asbilge keels, rudders and stern archeswould still requiremanual cleaning.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw This approachextendsthein-watercleaningpracticescommonlyusedinrecentyearsto extend the time between an antifouling losing effectiveness and dry-docking. Diver operated machines with rotating brushes were utilised for this purpose, and vessels cleaned while loading or unloading in port. Such practices have become increasingly restricted because of concerns about thepulse release of antifoulingbiocides during the scrubbing of the paint. In Australia, ANZECC have recommended that in-water cleaningbebannedbyportsbecause of aperceived risk that thepractice could facilitate spread of marine pests (ANZECC, 1997; Parliament of Victoria, 1997). The U.S. Naval Surface Warfare Center (NSWC) is developing an Automated Hull Maintenance Vehicle (AHMV) capable of cleaning hulls and of removing the debris the process creates (Anon., 1999a). Hull cleaning has been widely used by the USN to extend the dry-docking intervals and maintain propulsive efficiency of major vessels, but the methods used release fouling and copper into the environment. The AHMV is designed to contain both chemical and biological debris and remove it to the quayside. A prototype has been constructed and tested successfully on a model hull. Swain (1999) observedthatmany,particularlylarger,marine creaturesfrequently adopt behavioural activities which prevent biofouling. These can include spending extended periods of time out of the water (seals, sea lions, sea otters etc.), migrating into fresh water or, asis seen on coralreefs, attending cleaning stationswherefish or shrimppick off attached fouling organisms. Such practices are mirrored by boat owners using dry boat storage, freshwater soaks, and hull cleaning.

7.4 METALLIC COATINGS Between 1970 and 1994, 17 vessels are known to have been constructed with solid copper-nickel or with copper-nickel clad steel hulls (Powell, 1994). Copper-nickel sheathing has alsobeen used on oil and gas platforms, and in the form of mesh for fish cages and power station intake screens. Copper and copper alloy sheet and mesh have proven tobe highly effective in preventing foulingby zebra mussels in the Great Lakes (Dorman et al., 1996). The cost of initial application of copper-nickel cladding or sheathing may seem prohibitive in comparison to the costs of an antifouling coating. However, it has been estimated that the cost can be recouped in 4-7 years through decreased hull roughness, fuel savings, and reduced docking costs (Powell, 1994). A detailed economic analysis of copper-nickel sheathing in comparison to a conventional and SPC antifouling paint similarly concluded that copper-nickel sheathing had economic potential (Czimmek & Sandor, 1985). Swain (1999) notes that a 1 millimetre thick copper foil, corroding uniformly at a rate of 20 μg cm-2 day-1, would theoretically last about 120 years. The yacht Pretty Penny was designed and built with the aim of creating a maintenance free sailing yacht and the frame, hull and structural topside were fabricated in 90-10 copper nickel (Powell, 1995). Launched in 1979, the vessel was docked and inspected in detail for the first time in 1995. During this time the yacht hadbeen afloat continuously and moored for the greater part of the time in the River Swale off the Thames estuary. The owner reported that thevesselhad remained free of fouling for the first three years but, after that, the vessel needed to be scrubbed at least once a year to remove fouling. The fouling consistedmostly ofweed andbarnacleswithin about 12 inches ofthewater line. These were quite easily removed. The degree of fouling was attributed to the low activity of the vessel, and sailing speeds insufficient to remove fouling once it hadPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw occurred. When the hull was inspected in 1995 the hull plating was considered tobe in ‘‘almost new condition’’. Copper nickel sheathing has also been evaluated on two commercial passenger ferries operating in Auckland Harbour, New Zealand (Boulton et al., 2001). One ferry was a monohull, slow ferry (10 knots) which is kept mostly in reserve, the other a fast catamaran ferry (22 knots) which has been in service for about 30,000 nm since construction. Both had fibreglass reinforced polymer (FRP) hulls, with the former retrofitted with adhesive-backed 90-10 copper-nickel foil in 1993, the latter sheathed with the same foil during construction in 1994. The sheathing was found to have good resistance to macrofouling, but green algal slimes did form during service. When macrofouling did colonise, it was loosely attached and could be easily removed. An annual low-pressure water blast easily removed fouling, but this docking was not considered necessary with periodic hull cleaning using brushing. Swain (1999) thought it somewhat surprising that cupro-nickel sheathing had not been more widely used. He cited higher capital costs compared to antifouling paints, the possibility of galvanic interactionwith other metal components and cathodicprotection systems, and unpredictable performance in polluted waters as possible reasons. Metallic copper can also be applied in a metallising process where molten metal is sprayed on to the surface (MER, 1998b). The U.S. based company International Metalising Corporation promotes such a product called Copperclad 888, which is claimed suitable for application to steel, aluminium, wood, plastic and fibreglass structures. The product is promoted as a permanent antifouling for various marine structures including ships. Though not truly metallic sheathing, copper containing epoxy coatings are considered to be a similar approach to fouling control, with the epoxy serving as a binder for the copper metal. A number of these products have been available over the past twenty years, but none have seemingly achieved market penetration.

7.5 PROSPECTS FOR OTHER ANTIFOULING TECHNOLOGIES 7.5.1 New Biocides Bingaman and Willingham (1995) highlight the rigour and expense required to obtain the environmental and toxicological data necessary to gain approval ofnew antifouling biocides. Registration in the U.S. already takes at least 3-5 years, and the cost to obtain required data estimated at US$10 million. Registration requirements are also likely to become more rigorous as regulators increase the scope of their data needs. We now see that onebiocide,Irgarol 1051, approvedin comparativelyrecenttimebytheU.S.EPAis now being restricted or banned elsewhere because of concerns about its environmental fate and effects. The prospects for the discovery ofnew antifoulingbiocides do not seem high. Not only have few effective products been found in over 150 years of antifouling research, but the added necessity of environmental safety makes the task even more daunting. Added to this, the costs of assembling regulatory data sets puts development and commercialisation beyond the reach of all by the major pesticide companies.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw However, research does continue in efforts to identify new, environmentally acceptable antifouling biocides (e.g. Finlay & Callow, 1996, 1997).
7.5.2 Minimally Adhesive Surfaces and Surface Micro-topography Griffith & Bultman (1997) commented that very few classes of synthetic polymers hold any promise for being sufficiently anti-adhesive minimise adhesion of all marine organisms. They observed that barnacles bond securely to epoxies, polyurethanes, alkyds, polyesters,polysulphides, andpractically all other common coating types. They saw only fluoropolymers and silicones as offering possibilities for practical coatings. Polymeric hydrocarbons, such as polyethylene and polypropylene, were considered to have some promise, but to lack the necessary ‘‘convenience-of-use’’ to be seriously considered. Considerable research is continuing to more generally understand the critical features of fouling release coatings, including silicones, in an effort to improve their performance (Bonafede et al., 1999; Brady, 1999b; Brady & Singer, 2000). Approaches suggested include, for alkoxysilane cured PDMS, modification of the crosslinking chemistry and improved reinforcement materials for improved stability (Mera et al., 1997). Similarly, for platinum-cured silicone coatings, more robust catalysts for hydrosilation and investigation of novel reinforcement methods to improve toughness are seen as necessary. Advances in fluoropolymer technology may also lead to new commercial products superior to those already commercialised (see Section 4.1). Silicone coatings are considered to presently have the edge over fluoropolymer coatings, but in the longer term both are likely to find sustained use in hull coatings (Brady, 2000a, b). As well as silicones and fluoropolymers, other chemistries are being investigated to minimise the strength of attachment of fouling organisms. ADSIL, a U.S. company is undertaking research on silicate coatings as potential antifouling products (Kettlewell, 1999). The company describe the products as utilizing ‘‘SiO or SiO2 structures chemically grown without firing’’. These inorganic, advanced silicates chemically bond to the surface atroomtemperaturetoform athin, durablepre-ceramiclayer.Thecoated surface has similar characteristics to a sheet of glass, and fouling organisms are claimed to have difficulty adhering to the surface. The potential of ‘smart polymers’ as biofouling-release agents has been investigated by initial experimentsusingthin films ofpoly(N -isopropylacrylamide) (PNIPAAM) (Ista & Lopez, 1998). Results demonstrated the potential of this and similar polymers for antifouling applications, and suggested that tethered PNIPAAM might be useful as regenerable fouling-release surfaces.
In Sweden, MASTEC, an interdisciplinary program at Göteborg University and Chalmers University of Technology, aims to increase the understanding of interfacial phenomena at thepolymeric surface (Gatenholm etal., 2000). The long-term goal of this research program is to develop a non-toxic coating that will control biofouling by synergism between directed biological response and low bioadhesion. Studies have been undertaken on the effect of microtexture on biofouling resistance of low surface energy RTV silicones. Microtextured surfaces were found tobe less fouledbybarnacles than smooth control surfaces (Andersson et al., 1999). Surface texture with profile heights within a topographic range of 30-45 μm reduced settlement and recruitment by 92% asPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw compared to smooth surfaces (Berntsson et al., 2000a). This reduction in settlement is attributed to a behavioural response by the settling larvae which show a preference for smooth over microtextured surfaces. Further investigations have determined that optimum reduction of barnacle settlement was achieved with riblets in the range of 50 to 100 μm with low angle of inclination, and that such surface geometry also reduced drag (Gatenholm et al., 2000). The orientation of the microstructures was found to be important, with minimum friction when the grooves were parallel to the flow (Berntsson etal., 2000b). For one surface, the skin frictionwas ~ 10% lower compared to a hydraulically smooth surface. Various techniques are now being investigated for preparing surfaces with tailor-made architecture. Microtextured silicone surfaces are considered to have potential use in Scandinavian countries where barnacles are serious fouling organisms and where the use of toxic antifouling coatings on pleasure boats is becoming increasingly restricted (Berntsson et al., 2000a). However, it is recognised that surface textures that reduce barnacle settlement maybe preferredby other fouling organisms such as mussels and hydroids. The success of including one or several scales of surface texture is considered a difficult optimisation problem, which would differ among applications and for different geographical areas (Berntssonet al., 2000b). Hydrophobic surfaces have been found to favour the formation of biofilms, and hydrophilic surfaces have therefore been investigated for their antifouling potential. Hydrogels are aspecialclass ofhydrophilicmaterialthat absorblarge amounts ofwater into their structure (see Cowling et al., 2000). They are used in biomedical applications and generally show minimal protein interaction. On this basis, the antifouling behaviour of PHEMA hydrogels, based on 2-hydroxyethyl methacrylate (HEMA), with and without the incorporation of active substances was investigated (Cowling et al., 2000). The research was primarily directed at finding a method of keeping oceanographic sensors free of fouling and PHEMA hydrogel containing benzalkonium chloride (BCL) was successful in keeping surfaces visually clean for a period of twelve weeks, longer than the requirement for the sensors. One sample remained free of fouling for five months. As a potential antifouling agent, toxicity studies assessed BCL as being, at worst, two orders of magnitude less toxic to oysters than TBT and one order of magnitude less toxic than copper (Cowling et al., 2000). At laboratory scale production, the costs of the PHEMA/BCL combination was of the order of three times the cost per square metre of premium quality proprietary copper-based antifouling paints, purchased in volumes typically required for family-sized boats. However, this cost differential was considered likely to be eliminated if the hydrogel was produced in a commercial production process. The creation on hydrophilic non-stick coatings by the ‘‘tethering’’ of drag-reducing molecules such as polyox (polyoxyethylene) to surface was proposed by Gucinski et al. (1984). This has not been developed further in the marine area. However, hydrophilic polymers and zwitterionic polymers are used in the biomedical area to prevent or reduce theadhesionofmicrobialcells,someofwhichmayhaveantifoulingapplications (Milne, 1991). The surface characteristics and hydrodynamics of the skin of cetaceans, teleosts and elasmobranchs have attracted interest in relation to fouling performance (Swain, 1999). The no-foul condition of porpoise and killer whale skin has been attributed to thePhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw outermost surface being composed of a glycoproteinaceous material with low surface energy (Gucinski & Baier, 1983).
In Germany, researchers at the Hanover School of Veterinary Medicine found that the surface of pilot whale skin is made up of tiny pores, 0.1 micron across, surrounded by raised ‘‘nanobridges’’ (Randerson, 2001). A rubber-like gel, containing enzymes that denature proteins and carbohydrates, is found between the ridges, and this gel is replenished asthewhale shedsits skin.The foulingbacteria and diatoms arethoughtto be unable to attach to the ridges, and to be attacked by enzymes in the gel. Macrofouling settlement is in turn inhibited by the absence of a biofilm. The German researchers are proposing to create a similar surface using a hard polymer matrix with silica crystals embedded in the surface to provide the nanoridges.
7.5.3 Natural Antifoulants Wahl (2000) summarised the outcomes of studies (e.g. Wahl et al., 1998) on how marine species maintain fouling-freebody surfaces over periods equivalent to those sought for antifouling protection of artificial structures. Studies of many species indicated that defences could fall into four categories: mechanical (microtopography, mucous secretion, sloughing, grooming, burrowing), physical (‘‘biocompatible’’ surface tension), chemical (extreme pH values, repellents) and associational (commensal grazing, cumulative filtration, defended epibionts or neighbours). Several case studies were presented to show that, typically, natural antifouling defence relies on a multiple system where several mechanisms act together and where each potential coloniser is inhibited by more than one mechanism. The selective advantage of such a system is that thedefenderdoesnotrelyononehighlytoxicbroad-spectrumpoison,withtherisk of autotoxicity, and that the multiple defence barrier blocks co-evolution of epibionts. Research by Davis (1998) led to a similar conclusion, that the suite of sessile invertebrates examined utilised a suite of antifouling defences, and did not depend on chemical defences alone. Wahl also presented a case study to illustrate the sometime doubtful ecological relevance of antifouling bioactivity as determined by classical toxicity screening. Although many species of colonial tunicates exhibited antibacterial activity when screened, their defence levels did not correlate with the degree of epibioses. In contrast, non-toxic repellent activities did. Further investigation suggested that the defensive activity varied with time, and stochastic alternation of different repellents at the body surface would effectively reduce fouling while maintaining chemical crypsis. Despite this generalpessimism in regard tonatural antifouling solutions, somepositive results have been achieved using substances derived from natural product chemistry. Furanones from the red alga Delisea pulchra, appear to be non-toxic inhibitors of colonisation, inhibiting bacterial colonisation by interfering with genetic regulatory processes (Steinberg et al., 1998). UNSW trials in Norway comparing the performance of various furanone/coating combinations against Sea-Nine 211 have given some positive results (R.DeNys,pers. comm.).Thisresearchisprimarily directedtowardthe aquaculture industry, where an effective life of six months would be a successful achievement, but the technology could also be developed for the boating and yachting market. Long life coatings, suitable for shipping, would require development of coatings able to provide controlled release of the furanones over the required life of the coating.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Elsewhere paints containing other natural antifouling products are under trial. Japan’s Marine Biotechnology Institute is evaluating paints containing synthetic compounds similar in characteristics to tribrogramine (TBG), a compound produced by the bryozoan Zoobotryonpellucidum (Hadfield, 1998). TBG is claimed tobe a repellent rather than atoxin, asit actsbyinterferingwiththeneurotransmitter serotonininthelarvae of barnacles and mussels by blocking its receptors. This prevents the larvae from settling. A mixtureoftheenzymehexoseoxidase,anextractoftheredalga Chondruscrispus,and paint hasbeenpatentedby Danisco of Copenhagan as anon-polluting antifoulant (Fox, 2001). The patent claims that, in the presence of oxygen, the enzyme breaks down any glucose and maltose nutrients nearby, which stops marine growth. Rittschof (1999) reviewed the prospects for natural products as antifoulants. He considered that the concept of non-toxic antifouling, using natural products or their analogues, isatheoreticalimpossibility.Thiswasdespitemorethan20yearsofresearch into non-toxic antifouling compounds, and increasing popularity of the concept. Rittschof’s pessimism was summarised in four points:

• Fouling is a result of a largenumber of differentmechanisms, and a surface can only be protected if the entire spectrum of mechanisms is inhibited;

• An effective approach would require the delivery at the correct concentrations to an impractical number of molecules that interfered with specific kinds of fouling, and delivery oflargenumbers ofmoleculesin asinglecoatingwithcorrectphysical and mechanical properties is unlikely;

• Organic molecules contain energy and those energy-containing molecules serve as food for some kinds of fouling organisms. Organisms that colonize the surface and consume the available food source would neutralise the antifouling activity; and

• Many fouling mechanisms are physical chemical interactions that cannot be chemically inhibited. Rittschof did consider the possibility of application of non-toxic natural antifouling products in situations with reduced numbers of foulers, or against pernicious fouling groups such as barnacles or tubeworms. However, he observed that these approaches had had limited experimental success. Although non-toxic antifouling action was considered near impossible, Rittschof thought reduced toxicity antifouling approaches using degradable organic compounds possible. However, this possibility was tempered by the view that, non-toxic antifoulants are vulnerable to consumption by non-target species, natural products are often not compatible with existing coatings and require new technology for compatibility and delivery, and toxic natural products must meet all the standards required of other registered biocides and have similar technical issues as the non-toxic alternatives. Some biological compounds are among the most toxic known; bufalin, for example, is over 100 times more toxic than TBT and over 6000-fold more potent with respect to anti-settlement activity (Rittschof, 2000). Rittschof (1999) considered that the development ofnaturalproductswas influencedby political reality that economics are more important than the environment, and a political balance would exist between economically viable alternatives and environmental degradation. Until there was a political incentive to develop nonPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw metal-based technology,the actualpossibilitieswouldnotbeexplored.Politicalclimate notwithstanding, the timing and economics associated with registering, licensing, and developing thenecessarytechnologywasveryunfavourable.Hequoted,asanexample, the U.S. EPA registration of the Rohm & Haas biocide Sea-Nine 211, which was reported to have taken 11 years and cost approximately US$11,000,000. Combining this time and expenditure with an equally sluggish testing approach for new antifouling coatings led to a time interval for commercialisation of an already developed coating to approximately 15 years in the United States. This commitment was considered prohibitive for most businesses. Rittschof (2000) considered that the practical challenge to be met for successful introduction of antifouling solutions with reduced environmental impact was to find ways to promote industry/academic interactions, accelerate testing and reduce the expense ofessentialenvironmentalfateandeffectsassessment.Unlesstheseissueswere resolved, hefelttherewouldbeno substantialprogresswithnovel approaches. Such an approach was not presently achieved because academia has often frowned on industry collaboration and industry does research in-house.Also,because ofthe cost ofpotential failures, the antifouling coatings industry and consumers were very conservative.
7.5.4 Physical, Electronic & Chemical Deterrents Electrochemical systemshavebeen investigated for the control offouling on submersed panels, in pipe systems, and on ship hulls (Smith & Kretschmer, 1984; Fears & Mackie, 1997; Ryan, 1998; Smythe et al., 1998; cited in Leya et al., 2001). In recent studies, electrochemical prevention of bacteria and diatom fouling was demonstrated in laboratory experiments (Nakayama et al., 2001; Okochi et al., 2001). The effect here was attributed to direct electrochemical oxidation of intracellular substances rather than electrochemically generated toxic substances. High frequency alternating current has also been investigated as a potential means for keeping immersed sensor surfaces free of fouling for periods of at least 30 days (Leya et al., 2001). The control mechanism was attributed to interference with the fouling organisms’ cell membrane potential. In Italy, continuous anodicpolarizationhasbeenproposed as a method toprevent fouling of an offshore buoy system (Salvago et al., 2001). In small-scale field experiments, no macrofouling developed on a small buoy over a period in excess of two years. The electro-conductive coating developed by Mitsubishi and discussed in Section 5.2 was tested onthehull ofa small shipwith anunderwater area ofapproximately 100m2 (Nishi et al., 1992). No fouling growth was present after 3 months. However,before the system could be considered for application to larger vessels, it was considered necessary to improve the performance of the coating with respect to durability and electro-conductivity, optimise the relationship between current supply and seawater properties, establish effective application systems, verify long-term antifouling performance and durability, and confirm practicality and reliability on actual ships. More recent reports on the performance of this system, named the Marine Growth Prevention Systemby Electrolysis Technology (MAGPET), indicate effective antifouling activity over several months on a tug and similar success in trials on ferries and cargo vessels (Watermann, 1999). An advantage of this system is that the systems can be switched on and off as required, as for example when the vessel is in harbour or travelling at low speed. One concern has been raised, the potential generation of halogenated by-products.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Another electroconductive system is the Alternating Current Anti Fouling (ACAF), which is claimed, to prevent barnacle attachment by ‘‘capacitance technology’’ (Watermann, 1999). The system consists of a conductive coating sandwiched between two non-conductive coatings. Abare electrode exposed to the seawater forms the other side of the capacitor. Swain (1999) commentedthatneither systemsthat functionby creating anodic (chlorine evolution) nor cathodic (high pH) conditions at the paint surface have been made to work for extended periods of time due to voltage drop across the surface, cathodic chalk formation, and possible corrosion of the underlying steel. Chapman (1998) considered that widespread use of these technologies was limited by cost, lack of industry experience, and application difficulties. Barnacle settlement can be inhibited by low frequency (30 Hz) sound waves (Branscomb & Rittschof, 1984) with less than 1% of very young cyprids settling in the presence of the sound. Frequencywas considered tobe critical,with 30 Hz found tobe significantly more effective than either 15 or 45 Hz. In the laboratory, per cent settlement did increase in older larvae as theybecame less discriminating,but this may not be as critical a factor in the field if alternative settlement sites are available. The low frequency sound caused no harm to the barnacle larvae, unlike ultrasonic frequencies, which are known tobe lethal tobarnacles and mussels. The method was considered to have potential for fouling control in situations where other methods are ineffective, such as inside pipes and cooling systems.
More recent studies have added additional information on the response of fouling larvae to sound (Rittschofet al., 1998). Particular findings were that:

• The vibration from ocean waves on a sandbeach deterredbarnacle settlement; this vibration contained 27 Hz harmonics;

• The vibration pattern generated by point source sound transducers on a rigid surface was complex, and structure such as ribs greatly altered the vibration signature;

• There was a clear relationbetween inhibition ofbarnacle settlement, the amplitude of the vibration, and the surface energy of the settlement substrate; and

• Sound did not deter the settlement of the bryozoanBugula neritina

. Several sound generation units claimed to prevent fouling have been marketed. These include the Barnakil ® vibration anti-fouling system (Sciencetech Inc.), and the Clean Machine sonic anti-fouling system (Rodadd Ltd, UK). Magnetic fields have also recently been reported to reduce seaweed fouling (Ainsworth, 2001). Although not preventing fouling completely, the research at the Glasgow Marine Technology Centre and the University of Newcastle in the UK suggested that incorporating magnets in steel structures would be beneficial.
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r2000.j33.02.0.aw 8. THE IMPACT OF THE BAN ON TBT COATINGS AND ITS IMPACT ON THE INTRODUCTION OF EXOTIC MARINE SPECIES The risk of transfer of exotic marine species as hull fouling relates directly to the effectiveness of the antifouling coating system. Up until the introduction of TBT self-polishing copolymer antifouling paints in the 1970s, the effective performance of antifouling paints rarely extended beyond two years, and invariably ships were significantly fouled within this time. TBT copolymer paints enabled ships to maintain fouling-free hulls for periods in excess of 5 years. Banning TBT paints has created fears of a return to the pre-TBT days, with a consequent increase in the translocation of fouling species and of exotic and potentially invasive marine pests. As recently as last year, concerns were still being expressed that efficient and cost-effective alternatives to TBTwerenot available for largevessels. Strandenes (2000), for example, considered that the ban on TBT would not only have first order effects on ship operators by reducing ship speed and fuel consumption as a consequence of increased foulinglevels,butwouldalsohavesecondordereffects,suchasshiftingtrade from seaborne to other transport modes as a consequence of increased shipping costs, and adding to global environmental problems such as global warming and acid rain as a consequence of increased fuel consumption. Abel (2000) claimed that not only was there no effective substitute for TBT currently available,but there were disincentives to the paint manufacturers to developing one. Manufacturers were considered likely to benefit from the shipping industry reverting to less effective substitutes as more paint would be sold. If such a situation did exist and continue, the risks of increased transport of exotic species as fouling would similarly be expected to increase.
However the competitiveness of the major companies in marketing new alternatives to TBT paints appearstobelie such claims.Inthepast fiveyears,most ofthemajormarine paint companies have releases ‘‘new technology’’ coatings that are claimed to provide performance comparable with TBT SPC copolymer coatings. Many of these developments originatedinJapan,whichwasthefirstcountrytointroduce aban onthe use of TBT paints on all shipping built or maintained in that country. Increasing evidence from trials and commercial applications of these coatings supports the optimism that they will provide efficacy and longevity comparable to TBT systems. Concerted argumentshavealsobeenputforwardthatthebanonTBTwillleadtoother, possibly greater environmental impacts from alternative biocides (e.g. Evans et al., 2000). Increasing concernsregardingthepersistence ofIrgarol 1052were commonlyput forward to support this argument, but various countries have already acted to ban or restrict this biocide, and it was never approved for use in Australia. New antifouling booster biocides, Sea-Nine 211, ZPT and CPT, have had to progress through a much more rigorous toxicological and environmental risk assessment to gain approval for use in countries such as the U.S. and Australia, and evidence suggests they are much safer products thanthosetheyarereplacingandfurthermore,whenincorporatedinacoating as a booster biocide to copper, indications are that they provide antifouling effectiveness equivalent to organotins.
Two major constraints are faced by the shipping industry in adopting the ‘‘new technology’’ products. The first is registration status, the second the higher costs of the coating. In light of the consequences of the introduction of TBT antifoulings, there is justifiable caution applied to the acceptance and approval of new antifouling products in theU.S.,Australiaandanumberofothercountries.Asaconsequence,registrationofPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw a new product can take many years, particularly if the product contains an active that has not previously been assessed. However, with most international deepsea vessels constructed, maintained and repaired outside of Australia, the benefits of new technology systems are likely to be seen in Australian ports and inshore waters long before products are registered for use in Australian ship repair facilities. Increasedproduct costs are also, at least inpart, attributable to the increased scrutiny of new products. The cost to biocide manufacturers of acquiring data required for toxicological and environmental assessment by regulatory authorities has been estimated at US$10 million or EUR5.5 million (Denn, 2000), and this cost is subsequently reflected in material supply costs. Similarly the cost of developments in resin technology would add to coating costs. However, it is anticipated that costs will come down as the technologies mature and volume sales increase. Another predicted consequence of the reduced number of approved biocides is that antifouling formulas will become more universal and standardised among manufacturers, eliminatingmarketingdifferencesbetweencompanies (Denn,2000).The increasing costs of development and long development cycles will make it more difficult for small companies to compete against thebig companies. If amanufacturer is not prepared to invest the money, time and resources to obtain antifouling product, whether in the EU, Australia, or the U.S., they will not be able to sell their products. Three major alternatives are commercially available as alternatives to TBT copolymer paints for largevessels: conventional tin-free, copper-based coatings, ‘‘new technology’’ tin-free, copper based coatings, and non-toxic silicone fouling release coatings. Failure and consequent fouling of an antifouling system is a result of either ineffective biocides or inadequate release of the biocides at the coating surface. In conventional coatings, in theory, failure would occur when the biocide reservoir within the coating was completely exhausted. However this rarely occurred. More often the failure was a result of impervious layers of spent paint, insoluble copper precipitates, or biofilms or detritus developing on the surface and preventing further biocide release. In effective self-polishing copolymer coatings, failure would not occur until the coating had completely polished away. However, premature failure can occur if the surface of the coating is chemically transformed to obstruct the polishing action, or if the polishing rate is not matched to the operating speed and activity of the vessel. Thechallengetopaintresearchers andformulatorshasbeento developtin-freecoatings with performance and polishing actions comparable to that achievable with tributyltin acrylate coatings, and to find environmentally benign biocide packages to match the broad spectrum performance achieved in TBT copolymer paints. The development of copper and zinc acrylate and silyl polymer resin systems, combined with new biocides such as Sea-Nine 211, zinc pyrithione and copper pyrithione to boost the performance of cuprous oxide, appears to have achieved this aim. Further refinement of these systems would also be expected as more experience is gained in ship applications. However, an additional constraint on the development of effective antifouling systems is the rarity of biocides which meet the stringent requirements of broad spectrum effectiveness, rapid degradation, solubility, stability, and limited ecotoxicity needed for formulating safe yet effective antifouling systems.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Conventional coatings do not provide the long-term performance achieved with TBT. Even themost advanced ofthe solublematrixpaints, the Controlled Depletion Polymer systems, can only offer effective performance for up to 3 years, and polishing is not as consistent as in TBT copolymer systems. Many of the biocides used to boost the antifouling performance of these systems, such as diuron and Irgarol, are also now under scrutiny andhavebeenbanned oruse restricted in some countries. However, the ‘‘new technology’’ copper-based systems offer both consistent polishing rates, effective performance for up to 5 years, and more environmentally acceptable booster biocides.
In considering current alternatives to TBT copolymer paints, Chapman (1998) tabulated the pros and cons of the various systems. This comparison is reproduced in Table 11 and highlights the general availability of products for the shipping industry and the cost and performance considerations inherent in product choice. Chapman recommended that ship operators should consider the following in choosing an antifouling:

• The risk of fouling is higher when an antifouling that does not meet a vessel’s performance criteria is selected;

• The costs of fouling

− both in terms of trading time lost due to reduced speed as well as extra fuel consumption

− should be weighed against the costs of a product that meets a vessel’s antifouling needs in terms of film thickness and biocide strength;

• By looking at a vessel’s typical trading pattern and speed, a ship owner can select an antifouling that balances cost with performance. In some ways, paying for higher performance is similar to buying insurance. The cost of the premium reduces the risk of failure; and

• Any environmental restrictions on the product selected should be considered. The above considerations also relate directly to product choice to minimise risk of carriage of marine pests. They highlight the fact that adopting best products to minimise marine pest translocation also confers economic and operational benefits to the ship operator, a corollary which should be exploited in promoting best practice.

Table 11 Pros and cons of different antifouling types (from Chapman, 1998)

PROs CONs Tin-Based Self-Polishing Antifouling ■ Relatively low cost/m2; economical through life costs ■ Polishes with time, reducing coating build-up ■ Polishing leads to smoothing, which reduces fuel consumption ■ High performance and reliability ■ No problems recoating at next dry docking ■ Can withstand constant immersion and drying ■ Long life (5+ years) ■ Environmental effects/restriction ■ Large range of performance levels available, leading to possibility of selecting an inappropriate product for the needs of the shipPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Table 11 Pros and cons of different antifouling types (from Chapman, 1998)

PROs CONs Tin-Free Self-Polishing (‘‘New Technology’’) Antifouling ■ High antifouling performance ■ No problems recoating at next dry-docking ■ Long life (predicted 5 years) ■ Polishes with time, reducing coating build-up ■ Polishing leads to smoothing, which reduces fuel consumption ■ Relatively high cost/m2 ■ New in market, so not yet fully proven

Tin-Free Erodible Antifouling ■ Relatively low cost/m2 ■ Dry-docking intervals of up to 3 years ■ Polishes over time, reducing coating thickness ■ Provides only moderate antifouling performance ■ Problems recoating at next dry-docking due to skeletal film left at surface ■ Deterioration of film properties over time, leading to reduced performance on boottops ■ Slow drying Tin-Free Conventional Antifouling ■ Low cost/m2 ■ Life of up to 12-24 months only ■ Hard, non-polishing, which leads to coating build-up ■ Increased hull roughness leads to higher fuel consumption ■ Performance only suitable for low fouling areas Non-Biocidal Antifouling ■ Environmentally friendly ■ High performance in specialist applications ■ Can last 5 years or more ■ High cost/m2 ■ Limited to specific applications, not yet a mainstream product ■ Application technique is critical for successful results

The performance of ‘‘new technology’’ tin-free products is considered comparable to that ofTBTpaints. This risk of transport of exotic species on ships using theseproducts as replacements to TBT is therefore not expected to significantly increase. However, vessels painted with conventional tin-free coatings would not be expected to achieve 5 year docking intervals without some fouling. As hull fouling also equates to loss of performance, an increase in fuel costs, and economic losses to due prolonged voyage time, a judicious ship owner would elect to apply the more expensive ‘‘new technology’’ systems on vessels with five year docking cycles. Aluminium hulled vessels are a special case as most tin-free coatings cannotbe applied to these hulls due to corrosion problems. The only long-life option for these vessels are silicone fouling release coatings. While these systems can remain fouling free on high speed, active vessels, slower and less active vessels will foul. In-water cleaningPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw procedures must be carried out on these hulls to both prevent the translocation of hull fouling species and to maintain operational efficiency. As discussed in the Phase 1 report (AMOG Consulting, 2001), hull fouling has continued to pose a risk on recreational craft. ‘‘New technology’’ coatings have the potential, not onlytoprovide an effective alternativetoTBTpaints forlargevessels,but to alsobetterprotect small craft if the technology canbe transferred to this sector of the industry. Similarly, the possibility of greater reliability over shorter time frames could provide positive benefits if new technology products are used on ships with docking cycles of 36 months or less. The regulation and registration process for antifouling paints impacts significantly on the availability of products. While essential to ensure the safety of products used, the time needed to approve new products can be seen to be counterproductive if the introduction of new and safer products is delayed. The inertia of the system proved beneficial in the case of Irgarol, which proved to be environmentally hazardous during the period it was under review, but similar delays in the registration of ‘‘new technology’’ coatings could increase the risks of pest transfer if not approved by the time of the TBT phase-out. A case could be put that, for products showing superior performance in overseas applications, and where other countries with comprehensive regulatory controls have considered the actives as safe, then either fast-tracking of registration or the issuing of interim approvals could be justified. This option may be environmentally more responsible than allowing the continued use of actives such as diuron, now banned in some overseas countries, and not yet fully assessed as it was grandfathered into the present system. The possibility exists of more environmentally acceptable and better performing products only being applied in countries with no, or limited regulation on antifouling use.
From the viewpoint of marine pest transfers, the structure of the present Australian regulatory controls has another limitation in that it only requires registration of products with an ‘‘active’’ constituent. While manufacturers have to demonstrate efficacy, aswell as environmental safety, for coatingswith actives, for a coatingwithno defined active, such as a fouling release coating, to be sold no guarantee of efficacy is required. Thisposesariskthatsuchcoatingscouldbeineffective,foul,andthereforeact as vectors for invasive pest species. Although trials of new technology tin-free products to date are very positive, the reliability of long term (i.e. 5 year) effectiveness is yet to be proven. However, the first vessels painted with these systems are now approaching five-year dockings. Independent trials, such as the Environment Australiapatch trialproject, and theWWF Germany project, will be invaluable in the evaluation of these systems. However, it should benotedthatthesetrialswillnotbe completeduntilwell aftertheban onTBTis introduced. The approval of zinc pyrithione and registration of the first new technology coatings in Australia benefited substantially from the DSTO/RAN trials in which this new product was included on the basis of promising results in Japan, and ahead of it being commercialised for the global market. The down side of the new technology products is their higher cost relative to TBT SPC systems. Althougheconomies ofscale andcompetitivenessmaybringprices downwith time, it has been noted that new biocides are always likely to cost more to compensate for the costs incurred in obtaining all the necessary data now requires for regulatory approval. There is an expectation in the coatings industry that many shipowners willPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw shorten docking cycles rather than pay additional costs for high performance coatings (J. Millett, pers. comm.). However, the benefits to shipowners of new products over cheaper, less reliable products, in terms of both ship performance and reduced maintenance and dockings should substantiate their use, or at least warrant a detailed cost benefit analysis. Such benefits, if promoted through the industry, would secondarily minimise the risks of hull fouling and consequent pest translocation.
A second deficiency of the new technology systems is that, because they contain cuprous oxide as the primary biocide, they cannot be used safely on aluminium hulled vessels or other underwater aluminium fittings. The major maritime sector likely to be impacted by this is the high speed catamaran, fast ferry industry. For long-term effectiveness, silicone fouling release coatings may be the most effective option. This leads to another difficulty with current regulations relating to hull maintenance in Australia; the ban on in-water cleaning. Vessels painted with even the most effective fouling releasecoatingswillfoulifinactiveforextendedperiods oftime.Whilethebulk of this growth may be subsequently dislodged when the vessel leaves port, it is likely that some growth, particularly low profile growth, will persist. To manage this, and ensure that organisms are not translocated, in-water cleaning would be the most effective way ofensuring thatwhat grows in theport stays in theport.Avessel leaving port with a clean hull will also benefit from the smooth hull and perform more efficiently due to reduced skin friction. Looking to the future, in the short to medium term, it is unlikely that any new material able to provide the long-term antifouling effectiveness needed on large shipping will become available. Despite optimism expressed with respect to natural antifouling products, none are yet commercially available or proven effective in coatings, even for less demanding applications, and no registration applications are known to have been submitted for natural compounds. Other novel approaches, such as the use of fibre flock coatings, or physical or electrochemical have not yet shown the broad-spectrum effect necessary for effective antifouling control.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 9. CONCLUSIONS The withdrawal ofTBT antifoulingproductswill leave shipownerswith a limited set of options for antifouling control:

• Conventional copper-based (copper metal, cuprous oxide or cuprous thiocyanate) antifouling paints, often containing a secondary biocide such as diuron, chlorothalonil, thiram or zineb;

• ‘‘New technology’’ self-polishing copper-based antifouling paints, likely to contain a ‘‘new’’ secondary biocide such as ZPT, CPT or Sea-Nine 211;

• Silicone-based, ‘‘non-toxic’’ fouling-release coatings;

• Novel coatings based on new ‘‘natural’’ biocides, or having fibrous surfaces; or

• Physical, electronic and chemical deterrents. Of these, only the first three are considered tobe commercial options for ship owners at this time. While numerous ‘‘natural’’ antifouling biocides have been identified and some formulated into experimental coatings, no commercial coatings based on this technology are seen to become available in the foreseeable future. Other technologies are yet to be proven as viable antifouling solutions for shipping. Conventional copper-based coatings have not been found to match the performance of TBT-based antifouling paints, and expected effective life rarely exceeds 36 months. However, ‘‘new technology’’ copper-based paints have been demonstrated to remain effective for 5 or more years. Silicone-based fouling-release coatings show the necessary durability and can remain macrofouling free on faster, active vessels, but do require hull cleaning on slower, less active vessels. The conclusion to be drawn from this review is that the impending ban on TBT is unlikely to greatly compound the problem of transfer of marine pest species as new products are available which approach, if not match, the performance of TBT-based antifouling systems. Application of these products on vessels currently using conventional TBT-free systems may actually offer benefits by reducing the risk of fouling. In particular, the transfer of new technology systems and biocides to the recreational andsmallboatmarkerwouldimproveoverallantifoulingcontrolandactto minimise the risk of transfer of hull fouling organisms. The Phase 1 report (AMOG Consulting, 2001) listed the following vessels as posing the greatest risk in relation to fouling and pest translocation:

• Platforms, barges, pontoons, and derelict and laid-up vessels which have been moored for extended periods of time;

• Recreational and small craft which spend significant periods at moorings or in marinas, and which also do not, or could not use high performance antifouling coatings;

• Poorly maintained merchant vessels;Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw • Vessels nearing the end of their docking cycles; and

• Vessels with long docking cycles which do not undertake in-water cleaning of unprotected or poorly protected areas, such as propellers, and around rudders and seawater intake grates between dockings. The TBT ban is likely to impact significantly only on one of these categories, vessels nearing the end of their docking cycles, if less effective coatings are used. Admittedly this could be highly significant if a system failed well short to the scheduled docking. Promotion of the use of high performance, new technology coatings is therefore important to minimise these risks. The bottom line is to promote best practice in hull maintenance and use of ‘‘best available’’ antifouling technology. One limitationinthe adoption of ‘‘newtechnology’’copper-basedisthat only one, of 17 or more such products commercially available elsewhere in the world, is registered by the NRA for application to vessels docking in Australian shipyards. While this impacts on only a small proportion of the ships visiting Australia, as most international shipping docks for maintenance in overseas ports, there are several potential negative effects for those ship operators who generally choose to have maintenance undertaken in Australia:

• One paint company has a clear advantage over its competitors in provided an effective alternative to TBT;

• Shipowners notelectingtousethispaintcompanywillbeforcedtoeitheruse aless effective product, with consequent hull fouling risks, or take their maintenance work offshore; and

• Australia’s strong political stance in promoting the global TBT ban could be compromised by Australia not facilitating use of the full range of best performing alternatives. Lookingtothefuture,thereareindicationsthattheuseofcopperinantifoulingcoatings may also come under scrutiny. In terms of marine pollution, fouling release coatings offer the most environmentally benign approach to fouling control. These coatings are of immediate relevance for aluminium-hulled craft, such as high-speed catamarans, which cannot use cuprous oxide based systems due to their potential corrosive effect. However, close attentionneeds tobe directed to developinghull managementpractices for fouling release coatings for this to be a safe option with respect to marine species translocation.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 10. RESEARCH GAPS In researching for this review, the most significant deficiency in information relates to the limited number of independent, comparative studies of antifouling coating performance on any scale. The exceptions are the international program of panel trials of extensive ship patch trials of non-toxic coatings in the WWF-LimnoMar program in Germany (Watermann et al., 1998, 2001), and the Environment Australia funded antifouling patch trial project and DSTO/RAN projects in Australia. Most other information on performance and efficacy of products comes from trials conducted by the paint manufacturers themselves and, understandably, only positive outcomes are publicised. Also, despite the considerable number of research programs underway worldwide directed at finding new methods of fouling prevention and control, the limited number of commercially-available alternatives to TBT products highlights the continuing need for research in this area. Few active agents or processes identified in research programs have been transitioned through to commercial products and research to facilitate this process is warranted. Such research would include both the development of technologies into usable products, and determination of environmental and ecotoxicological characteristics necessary for the approval and registration of any new bioactive substance or process. Ways of facilitating technology transfer and linkages between research organisations and paint manufacturers also warrant investigation.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 11. RECOMMENDATIONS

11.1 REGISTRATION AND APPROVAL OF ANTIFOULING PRODUCTS The NRA process for registration of antifouling products in Australia is essential to ensure the environmental and occupational safety of theseproducts. However, the data needs, costs and time currently required to process a new antifouling product are all high which means that registration of a new products, particularly if it contains a previously unregistered active, can take a number of years. While designed to protect the environment, the process could be interpreted as counter productive if the introduction of new, more effective and more environmentally sound products is prolonged. The use of less effective products can heighten the risks of translocation of marine organisms as hull fouling.
A second aspect of the current registration process of relevance to hull fouling is the requirement that only antifouling products containing an ‘‘active’’ agent must be registered and therefore have demonstrated efficacy. Any ‘‘non-toxic’’ product can be commercially distributed regardless of its effectiveness. With respect to registration, the following recommendations are made to further minimise the incidence of hull fouling on shipping:

• That the registrationprocessbe reviewedwith respect to allowingnew commercial products to be granted interim approval, or use under permit, until the full registration process can be completed. Such approval or use would be subject to availability of certain data, most likely from overseas, that indicates the product is both safe and effective, or on the basis of approval overseas; and

• The need to register ‘‘active’’-free antifouling products be investigated to provide some warranty of efficacy

11.2 EVALUATION AND VALIDATION OF ANTIFOULING PRODUCT PERFORMANCE The benefits of effective antifouling technology in regard to reduced risk of marine organism translocation equates to benefits to the shipowner in improved vessel performance andreduced operating andmaintenance costs.The dearth ofindependent, comparative studies of antifouling effectiveness leaves most ship andboat owners with only personal experience, or in the hands of the paint supplier, in the decision on what antifouling system to use. The few independent comparative studies of antifouling performance have demonstrated the variability inboth antifouling efficacy and coating durability that can occur betweenproducts claimed tobe equally effective. Independent studies are also of considerable value in meeting NRA registration requirements for data on efficacy in Australian conditions, as seen in the value of DSTO/RAN trials in providing data for recent registration processes. The Environment Australia funded antifouling patch trial project, in which patches of ‘‘new technology’’ antifouling products from a number of paint manufacturers have been applied to commercial vessels, was established in recognition of the need for this type of study. However, such a project is not without difficulties, largely because ofPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw competitive, commercial issues from within the paint companies. To be successful, considerable cooperation between ship and/or boat owners, government agencies, research organisations, paint companies and other involved parties is essential. An alternative to the conduct of such trials on commercial vessels may be to utilise Government owned vessels, such as research, customs and defence vessels, for such trial programs Education is a major component in improving fouling control measures, and a wider understanding of antifouling product performance in all maritime sectors, to hopefully lead to more effective antifouling practices would not only minimise marine organism transfer risks but also generate operational and economic benefits to ship and boat owners. It is therefore recommended that:

• The current antifouling patch trial project be reviewed to determine how future, similar programs can be introduced to ensure best available antifouling products are available and promoted for use by all ship and boat owners; and

• An educationprogrambe establishedto ensureboat and ship owners are cognisant of the options, performance and efficacy of different antifouling products to ensure optimum fouling control.

11.3 HULL MAINTENANCE PRACTICES FOR FOULING RELEASE COATINGS The current and future prospects for use of non-toxic fouling release coatings require the development of hull fouling management and maintenance practices to ensure vessels do carry fouling between ports. It is therefore recommended that research be undertaken to enable:

• Development of mechanised, non-abrasive cleaning technology for in-water hull cleaning;

• A clearer understanding of performance with respect to vessel speeds, surface degradation; and

• Development of cleaning regimes to ensure vessels hulls are maintained fouling free- both to optimise ship performance and to prevent pest transfer

11.4 RESEARCH AND DEVELOPMENT OF NEW ANTIFOULING TECHNOLOGIES The limited number of environmentally-acceptable options presently available as alternatives to the TBT coatings highlights the continuing need for research into new methods of fouling control. The apparent wealth and diversity of research programs underway world-wide, into both the biofouling process and means of its control, should not be seen to negate the need for continued and increased support of research within Australia. The significance and economic importance of marine pest issues in Australia, the recognition that hull fouling is a significant vector for the introduction of marine organisms to Australia, and the international position taken by Australia inPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw advocating a globalban on TBT antifouling paints, all support the need for Australia to foster research in the area of biofouling control. Also, recognising the need to ensure the environmental safety of any new products in the Australian environment, support for related research on the environmental fate and ecotoxicology of antifouling agents is also warranted. Such information would support the NRA in assessing the safety of new antifouling products. It is therefore recommended that active support be provided to:

• Australian research on biofouling processes and new methods of fouling control; and

• Studies on the environmental fate and ecotoxicology of antifouling agents relevant to the Australian marine environment.

11.5 COOPERATIVE RESEARCH ON FOULING PREVENTION A recommendation of the Phase 1 Report (AMOG Consulting 2001) was the concept of a cooperative research program or centre, which would bring together universities, paint companies, shipping companies, boating organisations and other research organisations with a specific interest in hull fouling and its prevention, should be considered. This would facilitate research with outcomes offering economic benefits to the maritime industry, while at the same time reducing the risks of marine pest introductions and translocations in Australia. A number of the programs recommended above could be facilitated within such a facility.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Price, R.R., Patchan, M., Clare, A.S., Rittschof, D. and Bonaventura, J. (1992) Performance enhancement ofnatural antifouling compounds and their analogs through microencapsulation and controlled release.Biofouling6, 207-216. Price, R.R., Patchan, M., Clare, A.S., Rittschof, D. and Bonaventura, J. (1994) Performance enhancement ofnatural antifouling compounds and their analogs through microencapsulation and controlled release. In, Thompson, M.-F., Nagabhushanam, R., Sarojini, R., and Fingerman M. (eds.), Recent Developments in Biofouling Control

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r2000.j33.02.0.aw Wahl, M. (2000) Natural defense against fouling: "soft" multiple systems. In, TBT: A threat to the oceans shown in three ecoregions - environmentally sound ship-paints as alternatives

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r2000.j33.02.0.aw Wood-Thomas, B.C. (1999) Marine antifoulants: Current requirements and experience in the United States / Challenges in negotiating the global treaty. In, 10th International Congress on Marine Corrosion and Fouling, University ofMelbourne 1999: Book ofAbstracts. p. 68. Wynne, K.J., Swain, G.W. , Fox, R.B., Bullock, S. and Uilk, J. (2000) Two silicone nontoxic fouling release coatings: hydrosilation cured PDMS and CaCO3 filled, ethoxysiloxane cured RTV11.Biofouling16, 277-288. Yamamoto, H., Satuito, C.G., Yamazaki, M., Natoyama, K., Tachibana, A. and Fusetani, N. (1998) Neurotransmitter blockers as antifoulants against planktonic larvae of the barnacleBalanus amphitriteand the musselMytilus galloprovincialis

.Biofouling13, 69-82. Yonehara, Y. and Momiyama, I. (1993) Introduction of new technology for foulant-releae coatings. In, Third Asia-Pacific Conference ofthe Paint Research Association: Proceedings. International Centre for Coatings Technology. Paper 15 (11 pp.). Young, C.M. and Chia, F.S. (1981) Laboratory evidence for delay of larval settlement in responmse to a dominant competitor.Int. J. Invert. Reprod. Devel.3, 221-226. Young, G.A. and Crisp, D.J. (1988) Marine organisms and adhesion. In, Allen, K.W. (ed.),Adhesion. Applied Science Publishers, London. pp. 19-39 Yule, A.B. and Walker, G. (1987) Adhesion in barnacles. In, Southward, A.J. (ed.), Barnacle Biology. A.A. Balkema, Rotterdam. pp. 389-403.Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw 13. PERSONAL CONTACTS Alm, K., SealCoat Corp., Greece Amble, D., Australian LNG Ship Operating Co Pty Ltd, Perth Bloom, J., U.S. EPA, Washington DC Burghaty, E., Wattyl Paints, Brisbane Byrnes, C., National Registration Authority, Canberra Cahill, L., National Registration Authority, Canberra de Witt, E., The Netherlands Elliott, D., Hempels Marine Paints, Melbourne Kleverlaan, E., Environment Australia, Canberra McCullough, K., Canada Millett, J., Akzo Nobel, Sydney Otto, S., WWF, Germany Riding, E., Jotun Paints, Melbourne Vyse, J., Chugoku Marine Paints, Perth Watermann, B., LimnoMar, GermanyPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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# APPENDICESPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw APPENDIX 1 Antifouling Products Registered by the National Registration Authority in Australia
Source: PUBCRIS Database on NRA Website (www.nra.gov.au)

Company Product NameCopper MetalCuprous OxideCuprous ThiocyanateChlorothalonilDiuronSea-Nine 211ThiramZinc OxideZinc PyrithioneZineb

NRA Code Resene Paints (Aust) Ltd ABC-3 X X X 42420 Hempel’s Olympic 76600 (7154) X X 42603 Nautic 7190 X X 46920 Mille Dynamic 71700 X X 46919 Mille Dynamic ALU 71600 X X 46918 Seatech X X 49687 Pacific 7609 X 46921 International (Akzo Nobel) Intersmooth 360 Ecoloflex X X 51971 Interspeed Super Topcoat X X 47588 Interviron Super Basecoat X X 47587 (Epiglass) VC Offshore Extra X X 49609 (Epiglass) Longlife High Strength X X 49606 (Epiglass) Interspeed 2000 X X 49607 (Epiglass) Cruiser Superior X X 49608 (Epiglass) Bottomkote X 49610 (Epiglass) Micron CSC X X 49611 (Epiglass) Coppercoat X X 49612 (Epiglass) Coppercoat Extra Trade X X 49992

Biolux Micron Extra X X 53398 Jotun Sea Guardian X 40163 Supertropic X 40164 Seasafe X X X 46487 SeaVictor 50 X X 46488 SeaVictor 40 X X X 46489 Kansai1 Rabamarine AF100 X 48675 Norglass Topflight X 54048 Wattyl Marine Coatings Ecol IV Black X 52864 Ecol IV Red/Brown X 52961 Newport 77 X X 52243 Newport 88 Hard Racing X 52241 Newport 99 X 52240 Seapro X 40185 Sigmaplane Ecol X X 40186 Sigmaplane Ecol HA 120 X X 52242 Trawler X X 54009Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

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r2000.j33.02.0.aw Company Product NameCopper MetalCuprous OxideCuprous ThiocyanateChlorothalonilDiuronSea-Nine 211ThiramZinc OxideZinc PyrithioneZineb

NRA Code Tasmanian Paints Coppertox Longlife X X 42439 Membrane CR95 X X 42708 Fishermans X X 42709 CR97 CTC X X X 42710 Atlantic Controlled Solubility X X X 48843 Asian Paints (Qld)) Transocean Cleanship 2.95 X X 48969 Transocean Longlife 2.77 X 48970 Rextel Pty Ltd, for U.S. Paint Corporation AWLSTAR Gold Label X 49377Phase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

Pests in Australia 117

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r2000.j33.02.0.aw APPENDIX 2 List of ‘‘New Technology’’ Copper-based Antifouling Coatings

Company Product Name Matrix Biocides Life Vessel type Akzo Nobel (International) (Nippon Paint) Intersmooth Ecoloflex 460/465 Copper acrylate Cuprous oxide Zinc pyrithione 5 yrs Deepsea
(Nippon Paint) Intersmooth Ecoloflex

360/365 Copper acrylate Cuprous oxide Zinc pyrithione 5 yrs Coastal Chugoku Sea Grandprix 1000 Organo-silyl acrylate polymer Cuprous oxide 5+ yrs Deepsea Sea Grandprix 2000 Organo-silyl acrylate polymer Cuprous oxide 5+ yrs Coastal Sea Grandprix 500 Zinc acrylate 3 yrs Deepsea Sea Grandprix 700 Zinc acrylate 3 yrs Coastal Hempel’s Globic SP-ECO 81900 Zinc carboxylate polymer/ inorganic fibre Cuprous oxide

Sea-Nine 211 Coastal

Globic SP-ECO 81950 Zinc carboxylate polymer/ inorganic fibre Cuprous oxide

Sea-Nine 211 Deepsea

Globic SP-ECO 81920 Zinc carboxylate polymer/ inorganic fibre Cuprous oxide

Sea-Nine 211 Deepsea

Jotun (Henry Clark) (NOF) SeaQuantum Plus Organosilyl polymer Cuprous oxide

Copper pyrithione <5 yrs >18 knots (NOF) SeaQuantum Classic Organosilyl polymer Cuprous oxide

Copper pyrithione <5 yrs 12-20 knots (NOF) SeaQuantum FB Organosilyl polymer Cuprous oxide

Copper pyrithione <5 yrs Flat bottoms SeaQuantum Ultra Organosilyl polymer Cuprous oxide

Copper pyrithione Extended port time, laid up, stationary vessels/ structures Kansai1 Exion Zinc acrylate polymer 3+ yrs Deepsea Captain Exion Zinc acrylate polymer 3+ yrs Coastal
Colour Exion Zinc acrylate polymer Fishing vessels, pleasure craftPhase 3 - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of Marine

Pests in Australia 118

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r2000.j33.02.0.aw Company Product Name Matrix Biocides Life Vessel type Sigma Coatings Pty Ltd (Wattyl) Alphagen 50 Cuprous oxide 5 yrs Coastal Alphagen 20 Cuprous oxide 5 yrs Deepsea Alphagen 10 Cuprous oxide 5 yrs Flat bottoms Notes: 1 Kansai products distributed in Australia by Corrosion Control Management, MelbournePhase 3 Study - The Significance of the Prospective Ban on Tributyltin Antifouling Paints on the Introduction & Translocation of

Marine Pests in Australia 1

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r2000.j33.02.0.aw APPENDIX 3 List of Commercial, Biocide-Free, Fouling Release Coatings

Company Product Name Matrix Type Life Vessel type Advanced Silicone Products (US) Sea Thru PDMS Aegus Seapoxy Polysiloxane Single pack Slow- or fast-moving Chugoku Seajet 2000 Silicone Fast ferries, Navy
Bioclean DX Silicone Eco-Speed Silicone 5 yrs Deepsea & fast coastal Eco-Speed C Silicone 5 yrs Slow coastal & low-activity Hempel’s Hempasil SP-EED 77100 Silicone Moisture cure Medium- high speed
International Intersleek 425 Silicone Three pack 5+ yrs >30 knots
Intersleek 700 Silicone Three pack 5+ yrs 15-30 knots Kansai1 Captain Biox Silicone Coastal, low speed Lehmann Pacific Industries (Aus) Teqmar Single pack Leigh’s Biogard = Captain Biox Sealcoat Sealcoat Epoxy Fibre-flock 3-5 yrs Sigma Sigmaglide Silicone Sound Speciality Coatings (US) Aquaply M
Transocean Ultima Silicone
Futureline 95.60 Surface

repellents