2.2 Interim decision in relation to momfluorothrin

2. Interim decisions on proposed amendments referred to the Advisory Committee on Chemicals Scheduling (ACCS #26, November 2019)

2.2. Interim decision in relation to momfluorothrin

Interim decision

Pursuant to regulation 42ZCZN of the Regulations, a Delegate of the Secretary has, in relation to the proposed amendment, made an interim decision to amend the current Poisons Standard in relation to momfluorothrin as follows:

Proposed date of effect of the proposed amendment

1 June 2020

Reasons for the interim decision (including findings on material questions of fact)

In this section: Applicant's scheduling proposal and reasons for the proposal | Current scheduling status | Scheduling history | Australian regulations | International regulations | Summary of pre-meeting public submissions | Summary of ACCS advice/recommendations to the Delegate | Delegate's considerations | Reasons for the interim decision

Applicant's scheduling proposal and reasons for the proposal

An application to amend the current Poisons Standard with respect to momfluorothrin was considered. The application proposed to include a cut-off for momfluorothrin in Schedule 6 for preparations containing 0.2 per cent or less.

The Applicant's proposed amendments to the Poisons Standard were:

The Applicant's main points provided in support of the proposed amendment were as follows:

• The proposal is to amend the Schedule 6 entry for momfluorothrin to include a cut-off for preparations containing 0.2 per cent or less of momfluorothrin is consistent with the original consideration for scheduling, when momfluorothrin was included in Schedule 6 without a cut-off. The scheduling delegate's final decision^[165] on momfluorothrin, published on the TGA web site on 19 November 2015, noted that it may be possible to consider a lower schedule for products with a low percentage content of momfluorothrin at a later time.
• The data provided with this application supports a lower schedule for products containing momfluorothrin at 0.2 per cent or less, through the evaluation of acute toxicity tests conducted using 0.17% momfluorothrin and 0.33% d-phenothrin. The acute oral toxicity tests on the product were conducted using modern protocols which tested up to 2000 mg/kg bw, with no adverse clinical signs.
• In acute toxicity studies in rats, momfluorothrin was of low acute oral toxicity, low acute dermal toxicity and low acute inhalation toxicity. Momfluorothrin was a slight eye irritant in rabbits, but was not a skin irritant in rabbits or a skin sensitiser in guinea pigs (maximisation test).
• The cut off of 0.2 per cent or less is considered to be supported by the data evaluated by the APVMA, based on the testing results from formulations containing 0.17 per cent momfluorothrin in either a hydrocarbon or water based formulation.

Current scheduling status

Momfluorothrin is currently listed in Schedules 6 of the Poisons Standard as follows:

Scheduling history

In July 2015, the Advisory Committee on Chemicals Scheduling considered a request from the OCS to create a new entry for momfluorothrin in Schedule 6 of the Poisons Standard, based on an application made to the APVMA to register a new active constituent.

The Committee recommended a new Schedule 6 entry be created for momfluorothrin based on it meeting the acute oral toxicity criteria for inclusion in Schedule 6.

The Delegate's interim decision,^[166] published on 1 October 2015, was to include momfluorothrin in Schedule 6. While much of the toxicity profile of momfluorothrin was consistent with the SPF criteria for listing in Schedule 5, the Delegate agreed that the LD₅₀ in female rats was within the Schedule 6 range. In making the interim decision to include momfluorothrin in Schedule 6, the Delegate noted that it may be possible to consider a lower schedule for products with a low percentage content of momfluorothrin at a later time.

The Delegate made a final decision^[167] on 19 November 2015, confirming the interim decision as no evidence had been received to alter the interim decision.

Australian regulations

• Momfluorothrin is not listed on the TGA Ingredient Database.
• There are no medicines currently active on the Australian Register of Therapeutic Goods (ARTG)^[168] that contain momfluorothrin as an active ingredient.
• Momfluorothrin is not permitted to be included in listed medicines as it is not included in the current Therapeutic Goods (Permissible Ingredients) Determination No.4 of 2019.^[169]
• The Database of Adverse Event Notifications (DAEN)^[170] contains no reports of adverse events for products containing momfluorothrin as an active ingredient.
• There is only one active constituent approval (XXXXX) for momfluorothrin listed on the APVMA Public Chemical Registration Information System Search (PUBCRIS).^[171]

International regulations

• As of 25 July 2019, there are two insecticide products containing momfluorothrin as the sole active ingredient and twelve insecticide products containing momfluorothrin in combination with a second active constituent registered with Health Canada.^[172]
• Momfluorothrin was approved by the US EPA in March 2015^[173] for use as an insecticide in indoor and outdoor residential and commercial settings.
• Momfluorothrin was approved for use as a biocide in the European Union^[174] in December 2016 in the European Economic Area (EEA). The European Chemicals Agency (ECHA)^[175] hazard classification and labelling for momfluorothrin identifies it as '...very toxic to aquatic life, very toxic to aquatic life with long last lasting effects, is harmful if swallowed and may cause damage to organs.'
• Momfluorothrin is not included in the New Zealand (NZ) Environmental Protection Authority's (EPA) Inventory of chemicals (NZIoC).^[176] The NZ EPA released document 'Application Form: HS8 Application for whether there are Grounds for a Reassessment of a Hazardous Substance (pdf,937kb)' on 21 September 2019 noting that momfluorothrin is a synthetic pyrethroid not included in the application to establish grounds for reassessment.

Summary of pre-meeting public submissions

No public submissions were received in response to the notice published under regulation 42ZCZK advising of the proposed amendment.

Summary of ACCS advice/recommendations to the Delegate

The Committee recommended that the current Schedule 6 entry for momfluorothrin be amended in the Poisons Standard as follows:

The Committee also recommended an implementation date of 1 June 2020.

Members agreed that the relevant matters under Section 52E(1) of the Therapeutic Goods Act 1989 included: (a) risks and benefits of the use of a substance; (b) the purpose for which a substance is to be used and the and extent of use; (c) the toxicity of a substance; and (d) the dosage, formulation, labelling, packaging and presentation of a substance.

The reasons for the advice included:

52E(1) Considerations	Reasons
a - the risks and benefits of the use of a substance	Momfluorothrin and the formulation of the products have some risks, but these are mitigated by the recommendations in the APVMA report, especially labelling. Public exposure modelling conducted by APVMA suggests that the risks for momfluorothrin are lower than for the accompanying active constituent of d-phenothrin and the risk was not assessed by APVMA for momfluorothrin for that reason. The US EPA has noted that the MOEs for momfluorothrin for all scenarios modelled, ranging from 8,300 to 240,000, are not of concern (EPA's level of concern (LOC) is an MOE of less than 300).
b - the purposes for which a substance is to be used and the extent of use of a substance	Products containing 1 g/kg (0.1%) momfluorothrin as one of the active constituents in an aerosol formulation is intended for use as an insecticide (flying and crawling insects) in the home garden environment. Application can be by surface or space spray. The pattern of exposure is expected to be short (application) to intermediate (post application) term duration. The presentation as a spray limits the magnitude of exposure.
c - the toxicity of a substance	Low toxicity at 0.2 %. Low acute toxicity. Systemic toxicity is generally observed at higher dose levels, with rats being the most susceptible species. No observed genotoxicity or mutagenicity. Carcinogenic in rats at dose rates approaching or exceeding the maximum tolerated dose. Not carcinogenic in mice. No reproductive or developmental toxicity, however, there may be a neurotoxic effect in dams. Mild neurotoxic effect in rats, consistent with other pyrethroids. No adverse effects reported for humans from the data available.
d - the dosage, formulation, labelling, packaging and presentation of a substance	The product will be packed in 200-500 g tin plated aerosol cans, packaged in cardboard boxes. Use of the product according to instructions has been determined to not pose a risk based on the momfluorothrin content.
e - the potential for abuse of a substance	Nil.
f - any other matters that the Secretary considers necessary to protect public health	Nil for momfluorothrin. XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX.

Delegate's considerations

In making this interim decision, I have considered the following material:

• The application to amend the current Poisons Standard with respect to momfluorothrin;
• Advisory Committee on Chemicals Scheduling's advice;
• Section 52E of the Therapeutic Goods Act 1989, in particular (a) the risks and benefits of the use of a substance; (b) the purposes for which a substance is to be used and the extent of use of a substance; (c) the toxicity of a substance; and (d) the dosage, formulation, labelling, packaging and presentation of a substance.
• The Australian Health Ministers' Advisory Council's Scheduling Policy Framework (SPF 2018); and
• Scheduling Handbook (V 1.1, July 2019).

Reasons for the interim decision

I agree with the Committee's finding that the relevant provisions of section 52E of the Therapeutic Goods Act 1989 are: (a) the risks and benefits of the use of a substance; (b) the purpose for which a substance is to be used and the and extent of use of a substance; (c) the toxicity of a substance; and (d) the dosage, formulation, labelling, packaging and presentation of a substance.

In my view, the relevant parts of the SPF 2018 are the Scheduling Factors for Schedules 5 and 6.

I have made a decision to exclude momfluorothrin in concentrations of up to 0.2 per cent from scheduling. In making my decision, I have considered the requirements the Scheduling Factors for Schedule 5 and Schedule 6.

Momfluorothrin is a broad spectrum synthetic pyrethroid currently listed under Schedule 6 of the Poisons Standard. Its mode of action is neurotoxic in insects, interrupting the sodium channels of the insect's nervous system, leading to paralysis and death. The original scheduling application for momfluorothrin in 2015 proposed a Schedule 5 entry. While much of the of the toxicity profile of momfluorothrin is consistent with the SPF criteria for listing in Schedule 5, at that time the Delegate agreed that the acute oral toxicity in female rats was consistent with the Scheduling Factors for Schedule 6 and this was the critical factor driving the scheduling decision. However, in making the decision to include momfluorothrin in Schedule 6, the Delegate noted that it may be possible to consider a lower schedule for products with a low percentage content of momfluorothrin at a later time.

I note that products containing 1 g/kg (0.1%) momfluorothrin as one of the active constituents in an aerosol formulation are intended for use as an insecticide (flying and crawling insects) in the home garden environment with application via surface or space spray. Having deliberated on whether to implement a cut off of 0.2% to unscheduled or a cut off of 0.2% to Schedule 5, I have determined that the weight of evidence supports the less restrictive cut-off of unscheduled.

Momfluorothrin is not potent in terms of mammalian neurotoxicity and acute toxicity tests conducted using 0.17% momfluorothrin (liquid hydrocarbon-based) and 0.12 % momfluorothrin (water-based) formulations revealed no adverse clinical signs in laboratory animals. The data also supports that momfluorothrin at up to 0.17% is not a skin irritant nor a skin sensitiser. While the data showed that both product formulations were slightly irritating to the eyes, I am satisfied that it was the formulation excipients that were responsible for the irritancy rather than momfluorothrin in this case. Momfluorothrin is only a slight eye irritant and I am in agreement with the Committee that its dilution within the formulations is sufficient to preclude it from causing irritancy.

While undiluted momfluorothrin has a moderate potential for causing harm (based on the acute oral toxicity in female rats), I am satisfied that the APVMA recommended labelling, which is intended to inform users about the safety measures to apply during handling and use (including safety directions), are also adequate to mitigate the possibility of eye irritancy. Further, the use of products containing up to 0.2% momfluorothrin in accordance with proposed APVMA labelling will not pose a significant risk to users.

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