Dimethoate chemical review

In November 1994 the APVMA (then the NRA) invited the public to nominate active constituents, chemical products or labels for consideration for review. Community groups, individual citizens and government agencies nominated dimethoate for review, on the basis concerns relating to toxicology and residues. Of the 600 chemical nominations, 79 were prioritised for review, one of which was dimethoate.

All nominated chemicals were scored according to agreed selection criteria (public health, occupational health and safety, environment and agricultural concerns) by the APVMA and its partner agencies.

Dimethoate was included in the Priority Candidate Review List as published in the National Registration Authority Gazette Number 5, 2 May 1995.

The scope of the dimethoate review was developed in consultation with agencies, states and territories. The scope of the review included the related compound, omethoate and covered:

• toxicology and public health,
• residues and dietary exposure, residues impact on trade
• Occupational Health and Safety.

The APVMA sent Notices of reconsideration of dimethoate and omethoate in March 2004 and published the dimethoate and omethoate review scope document, which outlined the information needed to conduct a comprehensive scientific assessment of dimethoate and included a call for public submissions. The period for public comments and submission of additional information closed on 2 July 2004.

The review of omethoate is being conducted separately.

The toxicology assessment for dimethoate was published in January 2011 and the residues and dietary risk assessment report was published in August 2011.

The August 2011 residues and dietary risk assessment report determined that the use of dimethoate on many crops could result in dietary exposures that exceeded the Australian health standard (the acute reference dose). The APVMA announced that it proposed to suspend dimethoate products to issue new instructions for their use that mitigated the identified dietary risks and invited public submissions regarding this proposal.

On 6 October 2011 the APVMA finished its assessment of the public submissions and suspended all products containing dimethoate and issued new instructions that no longer allowed the use of dimethoate on a number of food crops due to unacceptable dietary risks. The suspension prohibited:

• use of dimethoate on certain horticultural crops with changes to withholding periods and conditions of use for other crops
• use on all food-producing plants in the home garden
• supply and possession of dimethoate products unless they carry the new instructions for use.

The following restrictions were applied to all dimethoate products as part of the suspension:

Home garden products: DO NOT use on food producing plants in the home garden.

Agricultural products: DO NOT USE as a foliar, post harvest or quarantine treatment on:

• tropical or subtropical edible peel fruit [babacos, carambolas (Five Corner), figs and edible peel varieties of guavas, kiwifruit and persimmons]
• pome fruit [apples, loquats, pears, quinces]
• stone fruit after petal fall [apricots, cherries, nectarines, peaches, plums, apricot]
• grapes after commencement of flowering
• berry fruit (other than blackberries, raspberries, bilberries, blueberries and other vaccinium berries)
• strawberries (except strawberry runners—vegetative planting material only)
• cucurbits (other than melons, watermelons and zucchini)
• vegetables other than those listed below.

Dimethoate may be used on artichoke (globe), asparagus, beans, beetroot, broccoli, cabbage (drumhead varieties only),capsicums, carrot, cauliflower, celery, chilli, peas, potatoes and sweet potatoes, onion, parsnips, radish, rhubarb, sweetcorn, tomatoes for processing, tomatoes (large field grown for fresh consumption, prior to commencement of flowering), turnip and zucchini,

Certain dimethoate products had the suspension of their registrations revoked to allow the approval of new labels that had instructions consistent with the suspension instructions.

On 7 March 2013, the occupational health and safety assessment component of the human health risk assessment of dimethoate was completed and published. This assessment was prepared by the Office of Chemical Safety.

In June 2016 the APVMA published the updated dimethoate residues and dietary risk assessment report. This second residues report incorporates consideration of additional data and consideration of requests for alternative use patterns that were submitted to the APVMA in response to the August 2011 report.

The APVMA published the Dimethoate: Proposed Regulatory Decisions report in October 2016 and sought comments and information that could used to refine the toxicology, occupational health and safety and residues assessments prior to finalising the review. 

On 26 October 2016 the Dimethoate proposed regulatory decision report: Volume 1 and Submissions and technical reports: Volume 2 were published for a consultation period of three months. Submissions close COB Tuesday 27 January 2017.

The public, industry and interested parties were invited to provide written submissions on the proposed decisions for the reconsideration. The APVMA will consider those comments when making the final decisions for the dimethoate review—which is due for completion in 1 March 2017.

Additionally the APVMA is proposing to amend the standard for the active constituent dimethoate to include maximum impurity levels for omethoate and isodimethoate. The consultation period for this ended on 27 January 2017.

The report takes into consideration the recommendations in the technical assessment reports:

• toxicology report
• occupational health and safety report
• re-entry interval calculations updated September 2016
• dimethoate residues and dietary risk assessment report: updated June 2016.

The APVMA has assessed the available information and concluded that the use of dimethoate according to its current instructions for use does not meet the safety criteria listed in sections 5A of the Agvet Codes for continued registration and approval.

The APVMA proposed to:

• maintain the approvals of dimethoate active constituents
• vary the label approvals of the most recent label approval for 400 g/L dimethoate products
• maintain the registrations of those products and the varied labels
• cancel the registrations of home garden products containing more than 100 g/L dimethoate and
• limit pack sizes of the agricultural 400 g/L dimethoate products to volumes of greater than 1 litre.

As a separate process the APVMA also proposed to amend the standard for the active constituent dimethoate to include maximum impurity levels for omethoate and isodimethoate. The consultation period for this ended on 27 January 2017.

As a result of information received from registrants and farmer representatives a number of uses on crops that were proposed for deletion in the 2011 residues report are now supported and can be maintained on labels. This additional information received:

• supports the use of dimethoate on avocadoes, beans, beetroot, black berries, blueberries, cereals, cotton, melons, peanuts, peas (not sugar or snap peas), pulses (grain legumes) and raspberries with minimal changes to use instructions and withholding periods
• supports the use of dimethoate on strawberries for runner production only, tomatoes for processing with a 21 day withholding period and large field grown tomatoes prior to commencement of flowering only.

The label variations that were proposed in the 2011 residues report and confirmed in this latest report include:

• deletion of pre-harvest use on:
  • abius, bananas, casimiroas, custard apples grapes, passionfruit, paw paw, santols, sapodillas, stonefruit (all remaining uses prior to petal fall), wax jambus, artichoke (globe), broccoli, cabbage, carrots, cauliflower, celery, chilli, parsnips, radish, sweetcorn, and leucaena,
• deletion of post-harvest use on chilli and eggplants
• deletion of seed dressing uses
• restriction of pastures, fodder and oilseed uses to early crop emergence stages only.

Further label variations arising from the 2013 OHS report include:

• amendments to safety directions
• addition of re-entry intervals.

In October 2016 the Dimethoate proposed regulatory decision report: Volume 1 and Submissions and technical reports: Volume 2 were published for a consultation period of three months. Submissions closed COB Tuesday 27 January 2017.

A total of five submissions were received. The information in those submissions has been assessed by the APVMA and considered as part of the final decisions for the reconsideration of dimethoate.

On 6 March 2017 the APVMA completed the reconsideration of approvals and registrations related to Dimethoate. On 20 March 2017 the APVMA published the Dimethoate regulatory decision report.

The APVMA has:

• affirmed all existing dimethoate active constituents approvals
• cancelled the registrations of existing home garden products
• varied the label approvals of the agricultural dimethoate products
• removed pack sizes of 1 litre or less from those agricultural products
• revoked the previous suspensions of four agricultural products as their labels have been varied to mitigate the concerns that lead to the suspension and
• affirmed the registrations of the agricultural dimethoate products and the approvals of the new, varied labels

This final decision has taken into account submissions received during the consultation period for the Dimethoate proposed regulatory decision report.

The cancelled home garden products may be used for a period of 12 months. They may no longer be sold.

The agricultural dimethoate products bearing previously approved versions of the label may be supplied and used for a maximum 24 month period ending 6 March 2019. After this period all product supplied should bear a currently approved label.