The Canadian Pest Management Regulatory Agency (PMRA) is proposing that products containing 2,4-DB are acceptable for continued registration in Canada, provided that the proposed risk mitigation measures are implemented.
2,4-DB is a conventional herbicide used to control a wide spectrum of broadleaf weeds in major legume forage crops, widely sown forage grasses and pastures containing forage legumes. Products containing 2,4-DB can be applied once per year using ground or aerial application equipment. Use of 2,4-DB on cereals (wheat, barley, oats) and field corn was not supported by the manufacturers and were not considered in the re-evaluation; therefore, these uses will be removed from product labels.
Human Health
Label improvements to meet current standards
| • |  A minimum rotational crop plant-back interval of 30 days must be observed for all crops other than those listed on the label. |
| • |  The current label restrictions for grazing livestock on treated crops should be amended to include hay. |
Proposed risk mitigation
| • | To protect mixer/loader/applicators: |
| Â – Wear a minimum level of protective clothing: long-sleeved shirt, long pants, shoes and socks, and chemical-resistant gloves. | |
| Â – When mixing and loading large amounts of active ingredient (greater than 247 kg a.e./day), use a closed mixing/loading system. | |
| Â – For groundboom application involving amounts greater than 247 kg a.e./day, use a closed cab. | |
| • | To protect workers entering treated sites: |
| Â – A 12 hour restricted-entry interval (REI) for all activities. |
Environment
Proposed risk mitigation
| • | Addition of precautionary label statements regarding toxicity to non-target terrestrial plants and aquatic organisms. |
| • | Addition of statements to reduce the potential for runoff to adjacent aquatic areas. |
| • |
To reduce runoff from treated areas into aquatic habitats avoid application to areas with a moderate to steep slope, compacted soil, or clay. |
| Â – Avoid application when heavy rain is forecast. | |
| Â – Contamination of aquatic areas as a result of runoff may be reduced by including a vegetative filter strip between the treated area and the edge of the water body. | |
| • |
Addition of spray buffer zones for non-target terrestrial habitats: 1–2 meters for ground applications and 55–75 meters for aerial applications.
|
2,4-DB is currently acceptable for use in Organisation for Economic Co-operation and Development (OECD) member countries, including the United States, Australia and New Zealand. The approval of 2,4-DB was renewed in 2017 by the European Commission. 2,4-DB is currently under registration review by the United States Environmental Protection Agency. No decision by an OECD member country to prohibit all uses of 2,4-DB for health or environmental reasons has been identified.
This consultation is open for comment from 16 March 2018 to 14 June 2018 (90 calendar days).
Source: Health Canada