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Proposed Re-evaluation Decision PRVD2012-03, Boric Acid and its Salts (Boron)

Notice to the reader: The online consultation is now closed. Comments and suggestions received during the public consultation period are being considered in the finalization of this document. The final report will be made available as soon as possible.

Pest Management Regulatory Agency
October 16, 2012
ISSN: 1925-0967 (PDF version)
Catalogue number: H113-27/2012-3E-PDF (PDF version)

This page is a summary of the consultation document. If you would like to comment, please request the full consultation document.

To obtain a full copy of Proposed Re-evaluation Decision PRVD2012-03, Boric Acid and its Salts (Boron), please contact our publications office.

Should you require further information please contact the Pest Management Information Service.

Summary

Table of Contents

What is the proposed Re-evaluation Decision?

After a re-evaluation of the non-antisapstain uses of boric acid and its salts, Health Canada's Pest Management Regulatory Agency (PMRA), under the authority of the Next link will take you to another Web site Pest Control Products Act, is proposing continued registration of products containing boric acid and its salts in Canada. This re-evaluation includes the active ingredients boric acid, borax (pentahydrate), borax (disodium tetraborate decahydrate), disodium octaborate tetrahydrate and zinc borate, hereafter referred to as boron.

The antisapstain uses of boron were assessed separately. The results of the re-evaluation of the antisapstain uses of boron are presented in the Re-evaluation Decision Document RRD2004-08, Re-evaluation of Antisapstain Use for 2-(thiocyanomethylthio) Benzothiazole (TCMTB), Copper-8-quinolinolate, Borax and Disodium Octaborate Tetrahydrate. The wood joinery/millwork applications of boron will be assessed under a separate initiative by the PMRA.

An evaluation of available scientific information found that, under the proposed conditions of use:

  • Most product types containing boron do not present unacceptable risks to human health or the environment when used according to revised label directions. As a condition of the continued registration for these particular boron uses, new risk-reduction measures are proposed to be included on the labels of certain products. Additional data are being requested as a result of this re-evaluation.
  • Some uses of boron are being proposed for removal because the human health risks do not meet current standards. These uses are:
    • All dust/powder formulations for both commercial and domestic class products (including pressurized dust products).
    • All uses involving brush, trowel and/or putty knife application of the paste formulation for both commercial and domestic class products.
    • Uses involving brush application of the solution formulation for both commercial and domestic class products.
    • Uses of granular formulations involving application by pressure sprayer and seed spreader (commercial class products only).

This proposal affects all end-use products containing boron registered in Canada. Once the final re-evaluation decision is made, the registrants will be instructed on how to address any new requirements.

Proposed Re-evaluation Decision PRVD2012-03, Boric Acid and its Salts (Boron) is a consultation document that summarizes the science evaluation for boron and presents the reasons for the proposed re-evaluation decision. It also proposes additional risk-reduction measures to further protect human health.

The information in Proposed Re-evaluation Decision PRVD2012-03, Boric Acid and its Salts (Boron) is presented in two parts. The Overview describes the regulatory process and key points of the evaluation, while the Science Evaluation provides detailed technical information on the assessment of boron.

The PMRA will accept written comments on Proposed Re-evaluation Decision PRVD2012-03, Boric Acid and its Salts (Boron) up to 60 days from the date of publication of Proposed Re evaluation Decision PRVD2012-03, Boric Acid and its Salts (Boron). Please forward all comments to Publications.

What Does Health Canada Consider When Making a Re-evaluation Decision?

The PMRA's pesticide re-evaluation program considers potential risks, as well as value, of pesticide products to ensure they meet modern standards established to protect human health and the environment. Regulatory Directive DIR2001-03, Pest Management Regulatory Agency Re evaluation Program, presents the details of the re-evaluation activities and program structure. Re-evaluation draws on data from registrants, published scientific reports, information from other regulatory agencies and any other relevant information available.

To reach its decisions, the PMRA applies hazard and risk assessment methods as well as policies that are rigorous and modern. These methods consider the unique characteristics of sensitive subpopulations in both humans (for example, children) and organisms in the environment (for example, those most sensitive to environmental contaminants). These methods and policies also consider the nature of the effects observed and the uncertainties present when predicting the impact of pesticides. For more information, please refer to the following:

Given the outcome of the human health risk assessments and a review of the chemistry of Canadian products, the PMRA is proposing a re-evaluation decision and appropriate risk reduction measures for Canadian uses of boron. In this decision, the PMRA takes into account the Canadian use pattern and issues (for example, the federal Next link will take you to another Web site Toxic Substances Management Policy [TSMP]).

For more details on the information presented in this summary, please refer to the Science Evaluation of Proposed Re-evaluation Decision PRVD2012-03, Boric Acid and its Salts (Boron).

What is boron?

The non-antisapstain uses of boron registered in Canada include the control of a broad range of insects and fungi in structures, wood and wood products. Zinc borate is registered for use as a wood composite preservative and as a material preservative for the manufacturing of paints, coatings, plastics and rubber. Boron inhibits reproduction of fungi by acting on the general metabolism, and act as a stomach poison in insects. Boron products are formulated as soluble powders, dusts or powders, pastes, granular formulations, pressurized products, solutions or solid rods. Boron products can be applied by a wide variety of application systems (for example crack and crevice treatment, dusting, broadcast spreading, aerosol or foam injection in drilled holes or openings, brush or roller, low pressure spraying, drops and baits, rod insertion, dip-diffusion, dip or spray, double vacuum system, bundle dipping, spray box system, flood coating and pressure treatment). Boron products can be applied by professional applicators or by homeowners.

Health Considerations

Can Approved Uses of Boron Affect Human Health?

Boron is unlikely to affect health when used according to the revised label directions.

Potential exposure to boron may occur while handling and applying the product or by entering treated sites. When assessing health risks, two key factors are considered: the levels at which no health effects occur in animal testing and the levels to which people may be exposed. The dose levels used to assess risks are established to protect the most sensitive human population (for example children and nursing mothers). Only those uses where exposure is well below levels that cause no effects in animal testing are considered acceptable for continued registration.

Boron is a known developmental and reproductive toxicant. The most sensitive endpoint that could result from short and longer term exposures to boron is an effect on the testes (small testicles, tubular atrophy, arrest of spermatogenesis), which was observed in all mammalian species examined (mouse, rat, and dog).

Due to the nature of these endpoints and their potential implications for the health of the young, extra protective factors were applied during the risk assessment to further reduce the allowable level of exposure to boron.

Residues in Food

Boron is not likely to pose dietary risks from food.

There are currently no registered food uses; as such a risk assessment for this scenario was not required.

Risks in Residential and Other Non-Occupational Environments

Residential and other non-occupational risks are not of concern for handlers for most uses of boron.

Most risk estimates associated with mixing, loading, and applying activities for boron reached the target Margin of Exposure (MOE) with the exception of dust/powder formulations when applied by a shaker can/squeeze bottle and for paste and solution formulations applied using a brush or trowel.

Residential risks for postapplication scenarios are not of concern for most uses of boron.

Most uses of boron are in areas that would not be frequented by persons and thus residential postapplication exposure is expected to be minimal. Indoor uses where boron is not placed in enclosed bait stations (for example open bait placement), do not reach the target MOE and therefore postapplication risks are of concern for these uses.

Occupational Risks from Handling Boron

Occupational risks to handlers are of concern for certain uses of boron.

Target MOEs for mixing, loading, and applying boron were reached for the following uses: enclosed bait stations; solid formulation; paste and solution formulations for open baiting; solution formulation while rolling or spraying; and granular formulation using a bellows-type duster/snuffer. All other assessed uses of boron (paste formulation applied by brush, trowel or putty knife; solution formulation by brush; dust/powder formulations; soluble powder formulation; pressurized dust formulation; and granular formulation using a pressure sprayer and/or a seed spreader) did not meet the target MOE and are of concern.

Occupational risks for postapplication scenarios are not of concern for most uses of boron.

Occupational postapplication risk assessments consider exposures to workers entering treated sites. Based on the current use pattern for boron, re-entry into treated sites is expected to be minimal for professional pest control operators.

Environmental Considerations

What Happens When Boron is Introduced into the Environment?

An environmental risk assessment was not conducted on the boron use patterns described in this document as none of them result in significant environmental exposure. These uses include remedial treatment of wood utility poles and other wood structures. The exposure to the environment from these uses of boron is limited to a small area of soil in the immediate vicinity of the treated wood. Therefore, an environmental risk assessment is not required.

Proposed Measures to Minimize Risk

Registered pesticide product labels include specific instructions for use. Directions include risk reduction measures to protect human and environmental health. These directions must be followed by law.

Additional Key Risk-Reduction Measures:

Human Health

Risk-reduction measures are being proposed to address potential risks identified in this assessment. These measures, in addition to those already identified on existing boron product labels, are designed to further protect human health. The following additional key risk-reduction measures are being proposed.

  • The soluble powder formulation will be limited to use as a material preservative. Limitation on the amount handled per day as well as the use of additional personal protective equipment (PPE) or engineering controls will be required.
  • Indoor uses where a product may be accessible to toddlers, children and pets will require enclosed bait stations.

The PMRA has assessed the available information and identified health risks of concern for certain uses of boron. Therefore, the PMRA is proposing to remove the following specific boron uses in Canada:

  • All dust/powder formulations for both commercial and domestic class products (including pressurized dust products).
  • All uses involving brush, trowel and/or putty knife application (paste formulation) for both commercial and domestic class products.
  • Uses involving brush application of the solution formulation for both commercial and domestic class products.
  • Uses of granular formulation involving application by pressure sprayer and seed spreader (commercial class products only).

What Additional Scientific Information is Being Requested?

Data are required as a condition of continued registration under section 12 of the Pest Control Products Act. The registrants of this active ingredient must provide these data or an acceptable scientific rationale to the PMRA within the timeline specified in the decision letter. Appendix I of Proposed Re-evaluation Decision PRVD2012-03, Boric Acid and its Salts (Boron) lists all data requirements.

Next Steps

Before making a final re-evaluation decision on boron, the PMRA will consider all comments received from the public in response to Proposed Re-evaluation Decision PRVD2012-03, Boric Acid and its Salts (Boron). The PMRA will then publish a Re-evaluation Decision document that will include the decision, the reasons for it, a summary of comments received on the proposed decision and the PMRA's response to these comments.