4.1
This chapter first outlines the processes for registration and use of pesticides in Australia, including risk assessment by the Australian Pesticides and Veterinary Medicines Authority. It then discusses approaches to mosquito control and the role played by chemical insecticides.
4.2
The chapter details all mosquito-control products used on the Bellarine Peninsula since the 1980s and their current and historical methods of application.
Pesticide regulation in Australia
4.3
Between 1945 and 1993, the approval or registration of agricultural and veterinary (agvet) chemical products in Australia was covered by state and territory legislation. In 1993, the national Australian Pesticides and Veterinary Medicines Authority (APVMA) became responsible for regulating pesticides and veterinary medicines up to the point of retail sale, and state and territory governments became responsible for controlling their use.
APVMA role
Registration and safety
4.4
Before a product can be registered, the APVMA conducts a product evaluation, including a scientific assessment of whether the product meets statutory criteria for safety and a review of the applicant's proposed safety and use directions for the product label, according to the Agricultural Labelling Code. The APVMA told the committee:
The APVMA will not approve a product unless it is safe when used according to label directions. The Australian public can be assured that their use of registered agvet chemicals in accordance with the label instructions will not result in exposure considered likely to have an effect that is harmful to human beings.
Risk assessment
4.5
The APVMA does not assess the cancer hazard of any given pesticide product or its individual ingredients; rather, the APVMA assesses the cancer risk. Dr Jason Lutze, Executive Director at the APVMA, explained how the APVMA evaluates products compared with the International Agency for Research on Cancer (IARC):
When we consider risk, we consider both hazard and exposure. The IARC considerations consider the hazard part but not the exposure part of the risk calculations.
4.6
The Campaign for Accuracy in Public Health Research (CAPHR) explains that the IARC’s work is focused exclusively on assessing the cancer hazard of a substance or action, and that the IARC does not evaluate or determine cancer risk. The CAPHR also explains, however, that evaluating cancer risk is key:
Unlike a simple hazard analysis, a risk assessment takes into account factors such as dose/concentration, exposure pathways, and probability of exposure to determine the likelihood that any given hazard will actually cause harm. Therefore, evaluations of cancer risks are far more relevant to policymakers and the public than IARC-reviewed cancer hazards.
4.7
Dr Sheila Logan, Deputy Executive Director, Risk Assessment Team, and a toxicologist, explained to the committee the margins of safety that the APVMA applies to pesticide risk assessments:
When we are looking at agvet chemicals, if we were to find one that was carcinogenic, we would look at an exposure which is associated with the one-in-a million risk, as that is determined to be indistinguishable from background.
4.8
Dr Logan further advised the committee that the APVMA also adds margins of safety to its risk calculations:
Part of the assessment we do here in imposing safety limits is to look at a level which does not cause any problems, which is what we would call a threshold level, and impose safety margins on that.
Chemical review process
4.9
The APVMA process of chemical review involves the formal reconsideration of a prior product assessment. The APVMA told the committee that there were a number of potential pathways to a reconsideration: a notification under its Adverse Experience Reporting Program; a scientifically valid submission made by a member of the public; the APVMA’s own monitoring of scientific literature; or a compulsory notification from a product registrant. The outcome of a formal reconsideration may be to affirm, vary, suspend or cancel a product approval or registration.
Role of state and territory governments
4.10
Since 1993, state and territory governments have been responsible for regulating the use of pesticides beyond the point of retail sale. Any approved pesticide product is approved by the APVMA ‘for the purposes and uses stated on the product’s label’ and it is a condition of use that label instructions be followed by all users.
4.11
Regulation of pesticide use occurs through legislation, codes of practice and/or standard operating procedures. For example, the use of pesticides in Victoria is now governed by legislation and Australian Standards, state guidelines, and local council operating procedures. This is similar to the regulatory framework in place for pesticide use in other Australian jurisdictions.
Pesticides used for mosquito control
4.12
Pesticides used for mosquito control are classified as insecticides and may be chemical or biological in origin. Chemical insecticides include organophosphates, such as temephos, and synthetic pyrethroids, such as biomesrethrin. Biological insecticides (sometimes called ‘biocides’) include plant-based pyrethrum, bacteria such as Bacillus thuringiensis israelensis (Bti), and s-methoprene.
4.13
An insecticide may be either a larvicide (targeting mosquito larvae) or an adulticide (targeting adult mosquitoes). Larvicides are used to reduce numbers of mosquito larvae in bodies of water. These are applied directly to water at mosquito breeding sites where larvae are likely to be present, either in solid form, usually as pellets or powder, or in liquid form by spraying. An example of a chemical larvicide historically used on the Bellarine Peninsula is temephos.
4.14
Adulticides are used as a second line of attack and are therefore less commonly used than larvicides. Adulticides reduce numbers of flying adult mosquitoes and are applied by spraying and/or fogging methods. The technique known as ultra-low volume (ULV) fogging (also known as ‘cold’ fogging) uses air pressure to create a fine spray of the product, while ‘thermal’ fogging uses heat to convert the liquid product into a fog. Adulticides can also be sprayed onto a hard surface such as a wall or a fence as a residual barrier treatment.
4.15
Best practice for mosquito control is known as integrated mosquito management (IMM) and incorporates a number of techniques including surveillance of mosquito populations; the use of insecticides; health and environmental considerations; record keeping; and community education and involvement. The aim of IMM is to reduce reliance on chemical approaches.
Framework for mosquito management in Victoria
4.16
While the Victorian Government has adopted IMM approaches to mosquito control since 1974, the 2004 Framework for mosquito management in Victoria (framework document) established a state-wide IMM approach to mosquito control. It provides information and policy guidance ‘to assist councils and State government agencies to implement local mosquito management programs in an effective and environmentally appropriate manner’.
4.17
Under the framework document, responsibility for mosquito management is shared between state and local governments and communities, with councils acting as agents of the Victorian Department of Health (department). The framework document also outlines requirements for monitoring and record keeping, including at municipal level.
4.18
The framework document describes the usual approach to mosquito control in Victoria as follows:
Most mosquito management programs focus on treating mosquito larvae, although for emergency situations a quick knockdown of adult mosquitoes may be needed to restrict the spread of disease.
4.19
The framework document identifies the main types of mosquito larvicides used in Victoria as temephos, Bti and s-methoprene (insecticides). Written in 2004, the framework document clarifies that temephos use was declining at that time:
Temphos [sic] is increasingly being replaced by Bti and smethoprene [sic] which have been shown to be more targeted to mosquito larvae with little impact on some indicator species of crustaceans, birds or frogs.
4.20
The framework document specifies that the environmental sensitivity of a site should determine which materials and methods are appropriate for mosquito management. For example, it specifies that Bti and s-methoprene are the only suitable pesticides for use in areas of high or very high environmental sensitivity.
4.21
Similarly in South Australia, by 2006 the use of temephos for mosquito control had largely been replaced by the use of biological insecticides such as Bti and s-methoprene. While temephos was still registered for use as a mosquito larvicide at that time, concerns existed over its toxicity to non-target species.
4.22
The 2004 Victorian framework document states that the chemical adulticides malathion and pyrethroids were registered for use in Victoria at that time but that their use is ‘not common’.
Mosquito control on the Bellarine Peninsula
4.23
Local councils first implemented a mosquito-control program on the Bellarine Peninsula in the 1980s. Since its establishment in 1993, the City of Greater Geelong (City) has been the responsible authority for delivering the mosquito-control program. In 2004 the City had the largest annual mosquito-control program budget in Victoria, totalling $120,000.
4.24
The Barwon Heads area includes six wetland areas of different types, two of which are Wetlands of International Importance under the Ramsar Convention (known as Ramsar Sites) and therefore subject to additional environmental protections. These wetland areas and nearby lakes, such as Lake Connewarre and Murtnaghurt Lagoon, are recognised as prime mosquito-breeding territory. Mr Gareth Smith explained to the committee that permits are needed for the City’s mosquito-control activities within the Ramsar Sites:
Keep in mind we're also working on public land managed by Parks Victoria for the state government, and they're Ramsar sites as well … So we actually have permits to undertake the programs we have.
4.25
As well as its permanent urban population, the region has a large influx of holidaymakers during the summer season, who stay in holiday homes and caravan parks. Mosquito management is thus considered an essential local service for health and liveability, for residents and visitors alike. The City responds to more than 100 enquiries each year from members of the public concerned about high numbers of mosquitoes and mosquito management.
4.26
Mr Gareth Smith, Director City Planning and Economy, City of Greater Geelong, told the committee:
The city's program operates to reduce mosquito levels in the community. This minimises health risks associated with mosquito-borne diseases and reduces the impact of biting insects on community health and wellbeing and an ability to enjoy the environment.
4.27
The City commented that it needed a holistic approach, given that their purview includes 400 hectares of mosquito-breeding territory in the form of the nearby wetlands. Mr Lyndon Ray provided the committee with an example of the City’s IMM based approach to larvicide application:
… when we apply the product, we've got triggers for the larvae level. If there are small numbers of larvae in the wetland, we wouldn't apply it. We wait till we get significant numbers.
4.28
The City also reported that its activities include community education about mosquito-control measures.
4.29
The City advised the committee that it has always used approved products:
All products used in the mosquito treatment program, both historically and currently, have been approved by the Australian Pesticides and Veterinary Medicines Authority as suitable products for such uses.
Historical mosquito-control programs
4.30
Due to the amalgamation of six smaller council areas in 1993, the City submitted that council records prior to 1993 are limited. The City has nonetheless investigated mosquito-management programs prior to that date. It submitted:
Limited information is available regarding mosquito treatment activities undertaken prior to amalgamation, however City officers have carefully examined all recorded products and procedures used in wetland locations throughout the municipality.
4.31
At a hearing in Barwon Heads, the City gave evidence to the committee about past practices of mosquito control. Mr Gareth Smith advised that the City’s primary approach to mosquito control has always been source reduction—that is, the use of larvicides to kill mosquito larvae, which in turn reduces the numbers of adults hatching.
4.32
Mr Smith told the committee that fogging with adulticides was not part of the City’s core program and was only conducted in response to community concerns about high numbers of adult mosquitoes.
Insecticides used
4.33
The City stated that, in response to community concerns about which chemical insecticides had been used for mosquito control on the Bellarine Peninsula, it had reviewed all available records relating to historical mosquito-control programs.
4.34
Throughout 2019 and 2020, the City has also published information on its website about its use of mosquito-control chemicals and responded to individual queries.
4.35
The City also provided the committee with a historical timeline consolidating all available information for mosquito-control products used by the City and by former councils. The City explained the methodology for this review as follows:
The City has no records of detailed program schedules from the 1980s to 2004 but does have detailed records from 2005 to the present time. The City has reviewed all financial and written records relating to the mosquito program in Barwon Heads and has developed a summary table … of documents relevant to the mosquito control program since 1984.
4.36
This review found there has been little use of chemical insecticides on the Bellarine Peninsula compared with the use of biological pesticides.
4.37
The department also provided the committee with a list of all mosquito-control products used on the Bellarine Peninsula between 1984 and the present. This list includes both chemical and biological products and also shows more use of biological than chemical insecticides.
4.38
An overview of the evidence to the committee from the department and the City about mosquito-control products used on the Bellarine Peninsula is provided in Table 1.1.
4.39
This documentation provided by the City and the department identifies that the following chemical insecticides have been used on the Bellarine Peninsula:
Abate (temephos), a chemical larvicide used in powder or pellet form for direct application to mosquito-breeding sites such as stagnant water and drains; and
Reslin (biomesrethrin) and Twilight (phenothrin), both pyrethroid-based chemical adulticides used in liquid form for misting or ‘fogging’ of adult mosquitoes.
4.40
Mr Steve Sodomaco, the City’s Manager, Health and Local Laws, told the committee that there was increasing use by the then Bellarine Shire Council of biological larvicides towards the end of the 1980s. He stated that the council’s shift from chemical insecticides to biological insecticides, including Bti, at this time coincided with increasing use of Bti elsewhere in Australia, including in Queensland.
4.41
Mr Lyndon Ray, the City’s current Coordinator Environmental Health, confirmed that pyrethrum was the active ingredient in the adulticides historically used for fogging adult mosquitoes in the 1980s and 1990s.
Dates and methods of application
Current methods
4.42
At the hearing in Barwon Heads, the City described the two main methods of application currently used for mosquito insecticides, both using larvicides. The first method is manual treatment by council employees:
The program involves ground treatment, where our crew can treat an area manually, such as drains, pits, constructed wetlands …
4.43
The second method is aerial treatment, which is conducted under a permit during the mosquito-breeding season. The City explained:
Approval from the Commonwealth government permits aerial treatment for mosquito larvae in wetlands on the Bellarine Peninsula between 15 August and 15 March each year. … Aerial treatment only takes place over wetlands and never occurs over townships. Products used in our aerial treatments are in solid form, not liquid spraying, and are dropped from a helicopter flying at a low height.
4.44
Mr Ray explained that it is the City’s standard procedure for applying any chemical product to follow the instructions on the product label.
4.45
Mr Ray also commented that the reduction over time in the use of fogging techniques for adult mosquitoes was likely due to the more effective aerial treatments used in wetland areas to reduce mosquito numbers before the larvae develop into adults. The City’s website advises that the practice of fogging stopped completely in 2010.
Historical methods
4.46
Historical records sourced by the department and the City do not fully document the methods used by local councils to apply mosquito insecticides in the 1980s and 1990s. However, the City explained that additional details had been provided by long-term staff who had conducted mosquito-control activities on the Bellarine Peninsula under the previous council’s operations. Mr Smith told the committee:
We haven't been able to find that written record of those activities. We are working on the knowledge of staff who have been in [the mosquito] programs for a long period of time.
4.47
The City provided the committee with copies of historical public information campaigns and community advice about its mosquito-spraying activities. For example, a 1998 media release advises:
The chemical used in the operation is Bacillus thuringiensis which targets the mosquito larvae prior to hatching and is not harmful to humans or other aquatic species.
If this treatment process doesn’t prove entirely effective, a follow up program of ‘fogging’ is carried out. This involves misting the coastal marshlands with Pyrethrum.
4.48
The City further detailed its historical methods of larvicide application in evidence:
The focus of the program was the application of Bti (Bacillus thuringiensis) in pellet form in outlying wetland areas which were largely inaccessible to the community. Small boats and punts were used by the City to access these various sites that were inaccessible by other means. In evidence given before the Committee, Abate was a secondary product and not routinely used since 1987 given the existence of other and better products that were more effective against mosquito larvae control.
4.49
Mr Sodomaco, a long-term staff member, confirmed to the committee that the City’s mosquito program in the early 1990s focused on the treatment of stagnant water bodies outside the townships, which were breeding areas for mosquito larvae. He explained that this treatment was done by individuals, either on foot or using all-terrain vehicles, but that, in the late 1990s, the council began investigating the use of aerial application methods, including a trial of helicopter use in 1998.
4.50
Adulticides were applied by ‘fogging’ to kill live flying insects post larval stage. Adulticide treatments were conducted in areas where there were high numbers of adult mosquitoes. For example, the City’s records show that in 2005 each of four caravan parks was sprayed for 30 minutes with Py Fog, a pyrethrum-based product.
4.51
Mr Sodomaco also confirmed this evidence, stating that in the 1980s and 1990s the council sometimes fumigated using pyrethrum-based products around the perimeter of town, either in bushland or for stormwater, but that this spraying was ‘minimally effective’ compared with the application of larvicides to breeding areas.
4.52
The Victorian Chief Health Officer (CHO) explained that these fogging practices were consistent with best practice and were similar to the use of flyspray.
4.53
Mr Ray told the committee that a helicopter access permit was finally granted in 2005, and that this increased the impact of the biological insecticides used in extensive wetland areas, which in turn reduced the need for the use of adulticides including via fogging. This evidence was confirmed by the CHO, who stated that this evolution in mosquito-control methods occurred across Australia.
4.54
Chapter 5 discusses the concerns raised during the inquiry about the use of mosquito-control insecticides on the Bellarine Peninsula. The two major issues are the question of possible environmental exposure to chemical mosquito insecticides, and the question of whether such exposures could have caused cancer or autoimmune disease in the local community. Chapter 5 then considers the feasibility and scientific value of any further investigations.