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Antifouling Efficacy Data Guidelines

Agricultural Requirement Series
Guidelines for Submitting Antifouling Efficacy Data

Contents

1. Introduction

These instructions describe the general requirements and the format to be used for submitting efficacy data in support of the registration of a new antifouling chemical product. The APVMA invites applicants and other interested parties to suggest improvements to the document. Any comments should be sent to the Manager, Agricultural and Veterinary Chemicals Evaluation Section, and will be considered when the document is next updated.

Applicants are expected to be able to show that when their product is used according to label directions, it is effective for the purposes claimed. In most cases, applicants will need to submit the results of properly designed and conducted laboratory and field studies that prove the efficacy of the product. Data produced under Australian conditions are required in most cases, but relevant data from overseas may also be provided.

Applicants should note that if the data submitted does not adequately support registration, it will not be granted. If data does not support registration, additional data may be requested. This data may be categorised as a supplementary application as defined in the APVMA policy on subsequent submissions (APVMA Gazette: Commonwealth of Australia Agricultural and Veterinary Chemicals Gazette, APVMA 9, 3 September 1996), or as a new application depending on the extent of further data required.

These requirements for reporting efficacy studies refer only to Part 8 (Efficacy) and should be incorporated into the overall application. Detailed information on the full data requirements for registering a new antifouling product, addressing issues of chemistry and manufacture, toxicology, metabolism, residues, occupational health and safety, environment, etc. are set out in the APVMA's Ag Manual and Ag Requirement Series.

The full submission should adequately demonstrate, using data or argument, that the new product is safe to use for humans and the environment, that it will be stable throughout storage and that it performs as the label claims.

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2. General Instructions

2.1 Products that require registration

2.1.1 Chemical products

Antifouling coatings or paints are film-forming products that contain controlled-release biocides that are released as a thin layer on the paint surface, preventing the settlement of fouling organisms (algae, crustaceans, molluscs etc.). The international definition of antifouling coatings [1] includes the following four generic types:

  1. Soluble matrix. An acidic film that slowly dissolves when immersed in sea water. As this type of product is relatively inexpensive and requires little surface preparation it can be used on all vessel types, but it has a short lifetime. It is particularly suitable for small coastal vessels. The primary biocidal agent is usually copper oxide.
  2. Insoluble matrix/contact leaching/long life. The film-forming component of this type of product is insoluble and does not polish or erode when immersed. When immersed in water, the biocide dissolves from the paint film and is released, leaving an insoluble, leached layer behind. The primary biocidal agent is usually copper oxide.
  3. TBT-free self-polishing. The film-forming component of this type of product contains polymers selected from hydrolysable, soluble and insoluble resins. No part of this product contains organotin compounds. These products slowly polish and ablate the paint surface, releasing the biocide at a consistent rate. The durability is directly proportional to the coating thickness, and extended periods of service can be achieved. Antifouling performance continues until the paint polishes or erodes away.
  4. TBT self-polishing copolymer. Tributyltin oxide (TBT) is the main biocide in these products and is bound to a film-forming acrylic copolymer. Copper oxide and other secondary biocides may also be added. When immersed, the biocides are released as a result of TBT copolymer hydrolysis in seawater. This process also results in polishing and smoothing of the paint surface. Highly predictable antifouling performance is achieved with these products, and periods of service can extend for up to five years.

All of these chemical products require registration with the APVMA.

2.1.2 Biological products

Biologically-derived biocides also require registration. Products described as 'natural antifouling agents', such as mucous secretions from starfish or neurotransmitter antagonists based on marine organism excretions, require registration. The following product groups are regarded as biological products, and should be registered as such.

  • Biological chemicals (including pheromones, hormones and biorationals). 
  • Extracts of plants, marine molluscs or other organisms. 
  • Microbial products. 

Biological control agents (excluding macroscopic parasites and predators, but including disease agents, viruses, fungi etc.).

For further details see the APVMA's Guidelines for Registration of Biological Agricultural Products (available from the APVMA).

The import of biological control agents and the field release/conduct of studies is subject to approval by the Australian Quarantine and Inspection Service (AQIS). For more details contact AQIS.

2.2 Products that do not require registration

Products developed as physical deterrents to fouling DO NOT require registration. This includes products, such as silicon coatings, fibrelock surfaces, products developed so that the surface tension creates a non-stick surface etc. Products used as 'in can' preservatives do not require registration,

If you are unsure of whether your product requires registration and you require advice, please send a full description of the product, by fax, to the APVMA's Agricultural and Veterinary Chemical Evaluation Section on: 02 6210 4818.

2.3  General Instructions

2.3.1 Minimum data standards

It is recognised that antifouling coatings include all of the product types described and it is difficult to prescribe rules to cover all these different products. However, when trying to establish the efficacy of an antifouling coating, applicants should follow the general rules described in this document.

It is the responsibility of the applicant to present adequate data to support any claims made in application for registration or label changes for chemical antifouling products. Claims for efficacy against fouling organisms, in terms of broad spectrum activity, durability and efficacy under static and/or dynamic conditions in marine and/or freshwater environments must be supported by valid, relevant data that is both appropriate to the product and to the aquatic environment. Some concession may be considered for products that target only minor pests on a case-by-case basis.

Comprehensive data should be submitted showing results of laboratory, simulated field-scale and field-scale trials which prove that the new antifouling product, when used according to the label directions, is effective for the purposes claimed. Such studies should be conducted by, or under the guidance of, people with appropriate qualifications.

Data supporting the application may come from sources such as evaluation of the product in unpublished/commissioned trials, published papers and books. It is the responsibility of the applicant to collect and present the data to adequately support the claims being made for the product and provide the APVMA with copies of any reference publications. The APVMA cannot be expected to locate these. Anecdotal evidence, including a lack of complaints about the product, is unacceptable in support of applications. Testimonials from government organisations provide useful support but they do not stand alone.

Efficacy and durability should be demonstrated for the level of antifouling activity claimed on the label. Efficacy studies should include:

  • calculated data on leaching or release rates of the active chemical from the coating; and
  • information to indicate the period of protection expected.

Data on non-target animal and environmental safety are also required but should be presented separately as Part 7 (Environment) as specified in the APVMA's Ag Requirement Series. However some data or information may be relevant to more the one part of the submission.  For example data on leaching or release rates of the active chemical , from the coating, is information that is essential to both Part 8 (Efficacy) and Part 7(Environment).  In this situation the data should be supplied in both efficacy and environmental submissions.

The submission should give a comprehensive summary of the work undertaken, including what the applicant considers to be the most relevant conclusions, which should be incorporated on the product label. Applicants are advised to provide as much detail as possible. A list of all studies submitted in support of the application must be included. The aim is to enable the reviewer to evaluate an application for approval without the need to refer back to the applicant for further information or clarification.

2.3.2 Overseas data

Data from overseas countries may be used to support an application. However, in most cases, data produced under Australian conditions are required.

The relevance of overseas data to Australian conditions must be established by the applicant, including a consideration of factors such as salinity, water temperature and type of fouling organisms present, relative to Australian climatic zones, marine conditions and species.

2.3.3 Products similar to registered products

When a product is similar to a registered product, the APVMA may accept bridging data that compares the action of the new product at label rates with that of a registered product (known as the reference product).  This type of data is often referred to as 'bioequivalence data'. It is the responsibility of the applicant to provide sufficient data in conjunction with sound argument demonstrating that the two products are equivalent.

2.3.4  Justification for label claims

Applicants should use the results of studies to give an argument supporting the use of their product. The following points are of particular importance throughout.

  • All of the text proposed for the label must be justified. 
  • A clear and concise explanation and justification for the text of the label for which approval is sought must be included. This should be in the form of a combination of study data and an explanation of how the studies support all the proposed uses and recommendations. In particular, it is important that the all label text proposed is justified.
All recommendations and claims not supported by data must be explained. This may involve extrapolation of data from one vessel/situation to another (e.g. control of fouling from a vessel to mariculture equipment). Any extrapolation should also consider the potential impact on non-target organisms and the aquatic environment, however, full details of these considerations should be presented in Part 7 (Environment).

Alternatively, in the case of warnings and restrictions (e.g. climatic zones/conditions), that are not supported by data, extrapolation may be appropriate from already approved products containing the same or similar active constituents. In these instances, it should be stated clearly that no specific study data exist and that extrapolation has been used. Where appropriate, approved labels of these products may be included as an appendix and explanation made as to how they support the proposed label statements. Similarly, justification must be given for all instructions that are not supported by data but which are considered to constitute accepted best practice.

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3. Outline of Data Requirements and Application Layout

3.1  Data checklist

A checklist of efficacy data requirements for an application for chemical antifouling products, and the way in which they should be set out, as shown in Table 1.

Table 1: Data requirements for the efficacy section of applications for chemical antifouling products

Part 8  Efficacy

Table of contents

Overall summary

Introduction and justification for use

Efficacy studies

Summary

Methodology (site, study design, treatments)

Results (assessment, analysis of study data, study validation, statistical analysis)

Conclusions

Any other relevant issues

The format suggested is only for guidance. It is not a protocol that must be followed slavishly nor is it intended to limit the means of the applicant to effectively present the submission as a whole. The wide diversity of product uses, study methods and registration history, requires flexibility in the structure, layout and presentation of results.

3.2 Overall summary

Each application should include an overall summary of the efficacy data relating to the product. The summary should describe each aspect of efficacy studied. Normally, the summary will not extend beyond a few pages in length. Tables are favoured as a means of condensing data. Studies reported in the summary should be cross-referenced to the reports in the main application.

In the summary, an explanation must be given of how the data are relevant to the application and how they support the proposed label claims (or why certain reservations should be discounted). A suggested approach to the presentation and interpretation of results is to explain and justify the label claims in the order that they appear on the label. Each section of the label could be reproduced exactly as it is on the draft label, followed by tables of study results and an explanation of how the study results, references or extrapolations support the label text. It may be useful to annotate the draft label to indicate where to find the sections in the overall summary to support the individual label claims.

3.3  Introduction and justification for use

The introduction is a vital part of the application because it introduces the efficacy reviewer to the product, the background to its development and its projected role in the prevention of surface fouling.

Information about the value of the product and where it 'fits' in the field or practical situation should be provided, including the following information.

  • Identification of the product - if company codes are used to describe a product under test, they should be clearly referenced back to the product name or formulation to avoid confusion. As far as possible, product names should be used rather than company codes.
  • Type of antifouling coating and the mode of action of the biocide.
  • The nature and economics of the pest, fouling or other related problems in Australia and, if applicable, a description of the pest situation overseas.
  • Current management tools - status, benefits and problems.
  • Benefits of the product to particular industries or other usage situations.
  • Performance of the product according to prescribed label conditions and claims.
  • The contribution of the product to risk reduction and sustainable fouling protection in the specific industry or application.
  • Background information on the product - any previous relevant use of the product or its active constituents, or its use in other products; or any overseas registration of the product or active constituents.

These factors will be taken into account in regulatory decision-making. Potential unique or long-term benefits of a product to fouling management or risk reduction may be balanced against its possible drawbacks or disadvantages.

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4.  Efficacy Studies

4.1  General

All efficacy studies must be fully scientifically documented. Fouling organisms should be identified by type (ie macroscopic algae, barnacles, tubeworms etc.) and abundance, described in terms of frequency, individual density counts, percentage surface cover or biomass. Latin binomial names for any organisms should be provided if known. Common names, though useful, are too imprecise and variable to be used exclusively.

Sufficient detail must be provided for the reviewer to understand exactly how the trials have been carried out. For example, target species, surface composition and preparation, number of coats, method of application and wet or dry film thickness should be described. If trials are based on a particular Australian Standard, the name and number of the standard should be listed and any deviation from the standard should be described. Details of the research establishment, study coordinator, personnel, location and study reference number must be recorded. Author, title, date, location and whether results are published must be detailed for each study. The design of the efficacy studies must include the following considerations.
  • The antifouling characteristics of antifouling products are biocide (active constituent) release rates, erosion (polishing) rates, physical durability and biological activity. These characteristics should be assessed.
  • Representative study sites should be used. For example, vessel exposures should be carried out on vessels following their normal trading pattern or on standard shipping routes known to result in high levels of fouling; and net treatments should be carried out in areas where the nets are to be used. Accelerated laboratory-scale tests should closely model typical exposures and extremes (i.e. in pH, salinity, fluid shear, etc.).
  • Current application technology/best practice should be used. Studies should demonstrate the optimum application rate (number of coats and recommended dry or wet film thickness per coat) and should reflect the proposed use (i.e. ship hulls, aquaculture nets, etc.).
  • Studies should be carried out over at least one year. However, longer trials may be necessary to demonstrate performance under varying or atypical weather conditions. Long trials may also be required to provide evidence of product efficacy and durability of the product over the time period claimed on the label.
  • Valid study designs should be used, with appropriate statistical analyses, including sufficient replicates to allow reliable analysis of data.
  • Studies should include controls.
  • When data are conflicting, additional experiments should be carried out until a weight of evidence allows satisfactory conclusions to be made.

If any of the above points are not considered by the applicant to be appropriate, relevant scientific arguments against the need for the information should be provided. Extrapolation from other information may be acceptable in some situations, but this needs to be supported by sound technical argument

4.2  Summary

A comprehensive summary of each efficacy study should be included, with an outline of the methods used and a description and interpretation of the results. (Individual summaries should also be provided with each study.)

4.3  Methods

Study methodology must be described in full detail so that it is immediately clear how the results were obtained and how results from different studies can be compared. Where different types of studies or tests were carried out in similar ways (e.g. efficacy and environmental tolerance studies), the common technique should first be described for these studies, followed by any variations in techniques under appropriate headings. An explanation should be included of why recommended application rates, methods of application and  why any extra information provided on the label appears (e.g. durability claims).

4.3.1  Sites

Location details, including climatological data, should be provided for both local and overseas studies. Details of vessel routes, marine or freshwater conditions and climatic zones should be provided for both local and overseas studies. For example, information on temperature, tides, currents, fresh or salt water, salinity, pH, light intensity, tropical or temperate zone etc. These details should be presented in tabular format for each study as an appendix.

4.3.2  Test product details

A summary should be given of the test products and of any standards or reference products included in the studies. Details such as product name/experimental code, active constituent name, active constituent content, dose/leaching rates, release rates and method and period of immersion are all relevant.

If more than one formulation has been used in development studies, full formulation details and, where relevant, details of 'bridging' studies must be presented. Where earlier formulations of the product or other products containing the same active constituents are cited in supporting evidence, the relevance of this evidence to the current formulation must be justified.

4.3.3    Experimental design

Efficacy tests must be designed to allow valid and appropriate analyses of the data. Treatment group sizes and number of replicates should be determined before starting the studies. A minimum of three replicates should be carried out. If there is any doubt about the number of replicates or treatment group sizes required, biometric advice should be sought. The product should be tested at various locations. Methods of estimating levels of fouling must be described.

Assessment of the efficacy of an antifouling system should consider the biocidal activity (release rates), erosion (polishing) rates, physical durability and biological activity of the product.  Each of these characteristics should be considered in relation to each component of the product to be registered; the biocide, the end-use product formulation and the antifoul control system.

Biocides are the active constituents or the chemical incorporated into the coating that inhibits the fouling organisms. The end-use product formulation is the formulated coating or paint plus the biocide. The antifoul control system is the overall surface preparation, antifouling coating plus any additional protective coats.

  • Biocide release rates and coating erosion can be determined in laboratory tests, raft/panel studies (simulated field tests) or patch/strip tests (field studies).
  • End-use product formulation can be tested by panel studies on stationary rafts, rotor tests and patch/strip tests performed on vessels in use (field studies). This tests the efficacy, erosion and durability characteristics of the antifouling product. The end-use formulation needs to provide an effective mechanism for continuous and controlled release of the active constituent.
  • Antifoul control systems can be tested by panel studies performed on stationary rafts and patch/strip tests performed on vessels in use (field studies). The antifoul control system for a net treatment can be tested in the same manner. A test of the antifoul control system tests the overall efficacy, durability and erosion characteristics of an antifouling product under similar operating conditions and stresses as would be encountered when in use.

Details of appropriate methods and study designs are outlined in the following international and Australian standards.

Laboratory tests

ISO/FDIS 15181-1:2000 - Paints and varnishes - determination of release rate of biocides from antifouling paints, Part 1: General method for extraction of biocides.

ISO/FDIS 15181-2:2000 - Paints and varnishes - Determination of release rate of biocides from antifouling paints, Part 2: The determination of copper ion concentration in the extract and calculation of the release rate.

Simulated field tests

AS 1580.481.5 - 1993 - Paints and related materials - methods of test. Method 481.5: Coatings - durability and resistance to fouling - marine underwater paint systems. Standards Australia.

ASTM D 3623 - 78a Standard test method for testing antifouling panels in shallow submergence. American Society for Testing and Materials, Philadelphia, PA.

ASTM D 4939 - 89 Standard test method for subjecting marine antifouling coating to biofouling and fluid shear forces in natural seawater. American Society for Testing and Materials, Philadelphia, PA.

ASTM D 6442 - 99 Standard Test Method for Copper Release Rates of Antifouling Coating Systems in Seawater. American Society for Testing and Materials, Philadelphia, PA.

These standards describe various methods of assessing the efficacy of antifouling products. All methods described are acceptable to the APVMA. The details that must be provided are: date/interval after application/interval assessment; efficacy assessment method (refer to standards rating scale); sample size and type (e.g. strips per vessel); test method (e.g. rotor test, fixed strip); estimate/weight of fouling matter (e.g. k/m2 at 85% dry matter); and an explanation of any abbreviations used.

In order for laboratory, simulated field tests or field studies to result in meaningful data and to be relevant, the following conditions must be met.

  • The study conditions must reflect the label recommendations and application technology should address current industry practices. This should be reflected on the product label. For example, the label should specify surface preparation, number of coats required, the rate of application (weight coating/surface area). The instructions listed on the label must be based on the efficacy trials. 
  • Test objectives should be clearly defined and should include only treatments aimed at those objectives, plus adequate controls. 
  • The test antifouling substance should be identical to (or within tolerance limits of) the formulated product for which registration is sought. When data relating to a different formulation are to be used, this must be stated clearly and the relationship between the two formulations must be explained. 
  • Adequate pest pressure must be present. Fouling settlement may be artificially induced or natural. If artificial inoculation is used, these methods must be described. 
  • Data showing the effect of treatment on preventing fouling are essential in most instances. Fouling data under antifoulant-free or standard antifoulant conditions are also desirable.  
  • For a test to be scientifically valid, antifouling treatments must be compared with one or more control treatments. These include an untreated (negative) control and/or standard antifouling treatments currently in use.

The use of control treatments is essential as they provide a reference point for the results of the trial. It is acknowledged that, in field trials (commercial vessels in use), this may not be achievable and positive controls (ie comparison to appropriate existing coatings) may be more realistic.

The following application details should also be presented: type of application equipment (ie spray/brush); application equipment details (pressure of spray, droplet size on nozzle etc.); date of application; surface composition (ie wood, steel, aluminium, acrylic etc); surface condition/preparation at application; and coating application specifics (ie, primer used, coating application rates). These details may be presented in an appendix.

4.3.4 Statistical analysis

A full description of the methods of statistical analysis used must be provided. Explanations should be given for the choice of methods used and for any reasons for not carrying out statistical analysis. An example of a description of statistical analysis is: 'All data were subjected to analyses of variance and treatment means were separated at the 95% probability level (P < 0.05) using Duncan's multiple range test. Treatment means in the same columns/rows followed by the same letter are not statistically different'.

4.4  Results

It is essential that all relevant data, including photographs, diagrams, models, etc. are provided. Relevant data must be presented, showing the weight/extent of any fouling, the types of fouling organisms and the expected life of the product from all experiments or trials. Photographic evidence alone is not acceptable to demonstrate efficacy/fouling - it must be supported by quantitative data. Where negative or aberrant results have been recorded, these should be included together with discussion as to how or why the anomalies occurred.

Results can be presented in many different ways depending on the methodology used to assess efficacy. Care should be taken to include all information that is important to the interpretation of results. Explanations must be given when individual control values differ appreciably from the majority. In such cases, comparison to a reference product can be particularly useful.

Actual measurement values should be presented. Wherever possible, standard units (for example area and/or weight of foulant infestation per square metre) should be presented. Alternatively, results can be given as a percentage relative to the standard treatment and untreated controls. In this case, it is essential to give the actual level of fouling on the standard treatment and untreated controls and any other reference treatments. Each result must carry a reference to the report from which it was obtained.

Relevant results of statistical analyses should also be presented. These may include: standard errors, degrees of freedom, least significant differences, probability levels of significance and letter suffixes to denote significant differences between treatment means. Where graphs or statistics are used to illustrate a result, reference to the raw data from which it originated must be provided.

4.5 Conclusions

Each study must be fully evaluated and analysed, with conclusions drawn, before it can be used for comparison with other studies. Conclusions made should be based on the results of the data analysis and any claims concerning product performance should be based on these conclusions. Conclusions should be stated for each experiment and comparisons should be made with data from other experiments. Comparisons between Australian and overseas data may be useful. Relevant scientific literature may be used in support of conclusions.

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Glossary

Active constituent The substance or substances in a formulated product, which is/are primarily responsible for the biological or other effects that make the product an agricultural chemical product. In antifouling products the active constituent is also referred to as a biocide.

Antifouling product A surface coating that inhibits the colonisation by aquatic organisms of a surface submerged in water or intermittently in contact with water (splash zone).

Biocide See active constituent.

Efficacy The ability of a product to perform according to label claims.

End-use product/formulated product See product.

Formulated product See product.

Phytotoxicity The property of causing a deleterious effect to plant tissues; of being toxic to plants.

Product A formulation containing one or more active constituent(s), and possibly non-active constituents(s), which is intended for application, with or without dilution before use, and which is labeled with directions for use.

Reference product A currently registered product and its label.

Registration The process whereby the APVMA approves the sale and use of a formulated product in Australia, after the evaluation and assessment of appropriate scientific data demonstrating that the product is effective and not unduly hazardous to human health or to the environment, and that it will not adversely affect trade.

Relevant scientific argument

relevant means:

  • related to the active constituent and/or product; and 
  • related to the claims and use patterns.

scientific argument includes arguments based on:

  • accepted scientific principles;
  • data published in peer reviewed journals;
  •  relevant texts;
  • relevant laboratory studies; and/or
  • relevant field studies.

Resistance The inherited ability of a fouling population to tolerate the label rate of application of an antifoulant product.

Study protocol A document describing a trial design used to generate data to support applications for approval and registration or a permit (also called a trial protocol).

Use pattern The combination of all factors involved in the use of a formulated product. These include the concentration of any active constituent in the preparation being applied; the rate of application; the method of application; the frequency and duration of treatments; the ablation (erosion) rate of antifouling coating; the additives recommended; and other directions which determine the total quantity applied.

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References

Note: Details are provided for the current edition at the time of publication in each case. Applicants should always ensure that they obtain the most up-to-date version of any publication. These publications can be obtained from AusInfo shops (formerly Australian Government Publishing Service, AGPS) in capital cities or from the APVMA at PO Box 6182  KINGSTON  ACT  2604.

National Registration Authority for Agricultural and Veterinary Chemicals 1996. Ag Manual: The Requirements Manual for Agricultural Chemicals, APVMA, Canberra. ISBN 0 642 25922 4.*

National Registration Authority for Agricultural and Veterinary Chemicals 1996. Vet Manual: The Requirements Manual for Veterinary Chemicals, APVMA, Canberra. ISBN 0 642 25882 1.*

National Registration Authority for Agricultural and Veterinary Chemicals 1997. Ag Requirements Series: Guidelines for Registering Agricultural Chemicals, APVMA, Canberra. ISBN 0 642 26492 9.*

National Registration Authority for Agricultural and Veterinary Chemicals 1997. Vet Requirements Series: Guidelines for Registering Veterinary Chemicals, APVMA, Canberra. ISBN 0 642 26491 0.*

National Registration Authority for Agricultural and Veterinary Chemicals 2000. Guidelines for the Registration of Biological Products, APVMA, Canberra.

Organisation for Economic Co-operation and Development (OECD) report on utilisation of more 'environmentally friendly' antifouling products. Document BSG (0900)7. Fourth Meeting of the OECD Biocides Steering Group, September 2000.