4.3 Magnesium hydroxide

4 Interim decisions on proposed amendments referred to the Advisory Committee on Medicines and Chemicals Scheduling in joint session (Joint ACMS-ACCS #26, November 2020)

4.3 Interim decision in relation to magnesium hydroxide

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 magnesium hydroxide as follows:

INDEX - New Entry

MAGNESIUM HYDROXIDE

Appendix B, Part 3

Materials considered

In making this interim decision, the Delegate considered the following material:

• The application to amend the current Poisons Standard with respect to magnesium hydroxide;
• The 123 public submissions - external site, including one written submission, received in response to the pre-meeting consultation under regulation 42ZCZK of the Regulations;
• The advice received from the Advisory Committee on Medicines and Chemicals Scheduling in joint session (Joint ACMS-ACCS #26);
• Subsection 52E(1) 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 (f) any other matters considered necessary to protect public health;
• The Australian Health Ministers' Advisory Council's Scheduling Policy Framework (SPF 2018); and
• The Scheduling handbook: Guidance for amending the Poisons Standard.

Summary of Joint ACMS-ACCS advice to the Delegate

The Committee recommended the down-scheduling of magnesium hydroxide to Appendix B in the current Poisons Standard.

The Committee also recommended an implementation date of 1 June 2021.

Members agreed that the relevant matters under Section 52E(1) of the Therapeutic Goods Act 1989 included: (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; (f) any other matters considered necessary to protect public health.

The reasons for the advice included:

1. the risks and benefits of the use of a substance:
   • Benefits
     • Insecticide to control whiteflies, mites, thrips and aphids in vegetable crops.
     • Is an active and excipient ingredient in biologicals, export only, listed medicines, over the counter, prescription medicines and as an excipient in devices.
     • Magnesium hydroxide is also a constituent of fire retardants.
2. the purposes for which a substance is to be used and the extent of use of a substance:
   • Insecticide to control whiteflies, mites, thrips and aphids in vegetable crops.
   • The intended use is up to 1200 L (1680 kg) of product per day, sufficient to treat 600 ha.
   • The proponent states that the product is intended for 'professional use', however, as this will be an unscheduled item there is no regulatory framework to enforce this.
3. the toxicity of a substance:
   • Not acutely toxic, is not an eye irritant, skin irritant or a skin sensitiser.
   • Powder in the eye could be a moderate eye irritant.
   • There is little evidence of carcinogenicity, genotoxicity, reproductive or developmental toxicity.
   • There are a number of cases of magnesium-salt overdoses, some resulting in death. The main clinical symptoms related to hypermagnesaemia include muscle weakness, hypertonia and cardiovascular responses. The observed effects are mostly due to an electrolyte imbalance manifested by an increased Mg²⁺/Ca²⁺ blood level ratio.
4. any other matters considered necessary to protect public health:
   • Inclusion in Appendix B provides clarity for agvet chemical producers that the substance has been through the scheduling process.

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

I have made an interim decision to exclude magnesium hydroxide from scheduling via inclusion in Appendix B of the Poisons Standard. The reasons for my decision are set out below.

Magnesium hydroxide is present in a number of products, ranging from agricultural pesticides to medicines and cosmetics, and poses low risk in all product categories. Studies investigating chronic exposure to magnesium hydroxide do not identify any adverse effects or health problems. Products containing magnesium hydroxide for agricultural use are not acutely toxic, not eye or skin irritants or skin sensitisers. There is little evidence of carcinogenicity, genotoxicity, reproductive or developmental toxicity. I find this substance does not meet the factors for inclusion in the Schedules of the Poisons Standard.

I am making the new entry in Appendix B for magnesium hydroxide to provide clarity for AgVet chemical producers that the substance has been through the scheduling process.

I note the one written public submission which was in support of the proposal.

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 (f) any other matters that the Secretary considers necessary to protect public health.

Proposed implementation date

1 June 2021