Proposed Re-evaluation Decision PRVD2017-10, Sodium Bromide

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The online consultation is now closed.

Pest Management Regulatory Agency
31 July 2017
ISSN: 1925-0967 (PDF version)
Catalogue number: H113-27/2017-10E-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 PRVD2017-10,Sodium Bromide please contact our publications office.

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

Table of Contents

Executive Summary

Health Canada's Pest Management Regulatory Agency (PMRA)

Health Canada's primary objective in regulating pesticides is to protect Canadians' health and their environment. Pesticides must be registered by Health Canada's Pest Management Regulatory Agency (PMRA) before they can be imported, sold, or used in Canada. Before being approved for registration, pesticides must go through rigorous science-based human health, environmental and value assessments.

Under the Pest Control Products Act, all registered pesticides must be re-evaluated by the PMRA on a cyclical basis to make sure they continue to meet modern health and environment safety standards and continue to have value. The PMRA can however decide to initiate a re-evaluation sooner, when necessary. Re-evaluations may result in:

  • changes to how products are used;
  • changes to product labels to meet current health and environmental standards; or,
  • removing products from the market to prevent future harm to health or the environment.

The re-evaluation considers all available information, including data from pesticide manufacturers, published scientific reports, information from other regulatory agencies and other available, relevant information. To reach its decisions, the PMRA applies internationally accepted hazard and risk assessment methods and modern risk management approaches and policies. For more information on how the PMRA regulates pesticides, as well as the assessment process, please visit the Pesticides and Pest Management portion of Canada.ca website.

Re-evaluation of Sodium Bromide

Sodium bromide is a slimicide used in industrial settings. It is also used to keep pool and spa water clean from algae and bacteria.

For the re-evaluation of sodium bromide, risks to human health and the environment were assessed. The human health assessment considered the exposure to workers and bystanders from industrial uses as well as the exposure to Canadians from swimming pool and spa water treated with sodium bromide. The environmental risk assessment focused on the exposure to aquatic organisms when industrial fluids are discharged into natural waters.

Key Findings

In most cases, the risks to human health or the environment can be mitigated through label directions. However, the risk to human health cannot be mitigated for some pool and spa products, for example, uses related to electrolysis devices. It is therefore proposed that pool and spa uses for which the risk cannot be mitigated be removed from the market.

Next Steps

The proposed re-evaluation decision is now open for public consultation for 90 days from the date of the publication of Proposed Re-evaluation Decision PRVD2017-10, Sodium Bromide. Once the PMRA considers the comments and any information received during the public consultation period, it will publish a final decision.

Overview

What Is the Proposed Re-evaluation Decision?

An evaluation of available scientific information found that most uses of sodium bromide products do not pose unacceptable risks to human health or the environment when used according to the proposed revised label directions as described in this document. However, the PMRA is proposing to remove the following pool and spa uses as the potential risks of concern to human health cannot be mitigated:

  • Bromine generators and related sodium bromide products
  • Sodium bromide products used in chlorine generators
  • Scheduled spa sanitizers

Before making a final re-evaluation decision on sodium bromide, the PMRA will accept and consider written comments on Proposed Re-evaluation Decision PRVD2017-10, Sodium Bromide received up to 90 days from the date of PRVD2017-10. Please forward all comments to Publications. The PMRA will consider any additional data/information submitted during the public comment period in the final decision.

What Is Sodium Bromide?

Sodium bromide is registered in Canada to control slime-forming bacteria and other microorganisms that form problematic biofilms on the surfaces of equipment in contact with process waters in pulp and paper mills, cooling towers, and air washers.

Sodium bromide is also used as a sanitizer in pool and spa waters. Many products containing sodium bromide are registered for use in pools and spas. In addition, certain spa products currently on the market were exempt from registration since they meet the criteria outlined in Schedule II of the Pest Control Product Regulations. This re-evaluation included both currently registered and scheduled pool and spa products.

In all cases, sodium bromide must be activated to be effective, for example using an electrolysis device or another compound such as chlorine. Once activated, sodium bromide is transformed into hypobromous acid (generally referred to as bromine), which is the actual biocide.

Can Approved Uses of Sodium Bromide Affect Human Health?

Sodium bromide products which are proposed for continued registration are unlikely to affect human health when used according to the proposed revised label directions.

Potential exposure to sodium bromide may occur when handling and applying the product in industrial settings. There may also be exposure to sodium bromide when swimming in water treated with sodium bromide products. In assessing human health risks of sodium bromide via pool/spa uses, bromate was also assessed as one of its disinfection by-products.

Toxicological studies in laboratory animals describe potential health effects from varying levels of exposure to a chemical and identify the dose where no effects are observed. The human health hazard identification for sodium bromide was based on toxicological data for sodium bromide and the related chemicals, potassium bromide and ammonium bromide, all of which dissociate to bromide in the body. The human health hazard identification for bromate was based on the studies conducted with potassium or sodium bromate.

The available data in laboratory animals indicate that technical grade sodium bromide is of low acute toxicity via the oral and dermal routes, and of moderate acute toxicity via the inhalation route. Sodium bromide is determined to be a minimal to mild eye irritant, but not to be an irritant to the skin nor to cause an allergic skin reaction. The findings of the acute inhalation toxicity testing trigger the requirement for the hazard signal words "WARNING POISON" to appear on the label for technical grade sodium bromide.

Data provided by the pesticide manufacturers, as well as information from the published literature, were assessed for the potential of sodium bromide and bromate to cause various toxicity effects including neurotoxicity, chronic toxicity, cancer, reproductive and developmental toxicity. Although limited, the available information did not provide evidence that sodium bromide causes cancer while an increased incidence in several tumor types was observed following long-term dosing with bromate. Effects on the thyroid gland represented the most sensitive endpoint for the sodium bromide risk assessment, however, inconsistencies were noted with the dose level that caused these effects. The most sensitive endpoints used for the bromate risk assessment included effects on the kidney and the male reproductive system.

While the sensitivity to young age groups compared to the adults for either sodium bromide or bromate could not be fully determined due to limited available information, the risk assessment is conducted to be protective of all age groups from the potential toxicity effects with the proposed risk-mitigation measures. As such, sex and gender are taken into account in the risk assessment.

Risk from Handling and Applying Products Containing Sodium Bromide

Occupational risks to handlers are unlikely to affect human health when used according to the proposed revised label directions.

Workers can be exposed to sodium bromide through mixing, loading, or applying the pesticide in industrial settings. Exposure estimates for industrial processes were considered against the most sensitive indicator of toxicity, namely effects on the thyroid gland.

Health risks of concern were identified when mixing and loading industrial products containing sodium bromide with an open system. However, exposure is expected to be very low when using modern enclosed systems. The use of a closed transfer and loading via metered pump systems is therefore proposed for all industrial uses of sodium bromide. Increased personal protective equipment (PPE) is also proposed (protective eyewear, chemical-resistant coveralls over long-sleeved shirt, long pants, and chemical-resistant gloves).

Postapplication risks are expected to be low and are not of concern.

Postapplication exposure to bromide may occur from handling treated process fluids or materials. No data are currently available to characterize potential for postapplication worker exposure to sodium bromide from its use in industrial settings. However, exposure is expected to be minimal when proposed revised label directions are followed.

Risk in Residential and Other Non-Occupational Environments

Non-occupational risks from bystander exposure in industrial settings are not of concern.

The potential for bystander exposure to sodium bromide is considered to be low during use in industrial process fluids (for example, pulp and paper mills or cooling towers) as these uses are limited to industrial settings. Similarly, no postapplication exposure to bystanders is expected.

Residential health risks from postapplication exposures related to the use of swimming pool or spa electrolysis devices and the scheduled spa sanitizers are of concern, therefore phase-out of these uses is proposed.

Residential postapplication exposure to bromide and bromate occurs while swimming in the treated pool or spa water. For exposures related to swimming pool or spa electrolysis devices, cancer risks associated with bromate and non-cancer risks associated with bromide are of concern for all subpopulations. Therefore, the phase-out of these uses is proposed.

For the scheduled spa sanitizers, health risks of concern were identified since the bromide exposure estimates were close to the levels associated with thyroid effects. Furthermore, the contribution of bromide exposure from the scheduled spa uses is significant when taking into consideration background exposure levels due to bromide naturally present in foods. Therefore, the phased-out of scheduled spa sanitizers is proposed.

Residential health risks from postapplication exposures related to the use of other pool and spa products are not of concern when used according to the proposed revised label directions.

Residential postapplication exposure to bromide and bromate occurs while swimming in pool or spa water treated with sodium bromide. For swimming pool and spa uses which do not include the use of electrolysis devices, label statements are proposed to prohibit the use of these products in combination with electrolysis devices, ozonation, or ultraviolet (UV) disinfection in order to mitigate the potential cancer risk as a result of bromate formation.

Aggregate risks are not of concern when the proposed mitigation is considered.

Aggregate exposure is the total exposure to a single pesticide that may occur from food, drinking water, residential and other non-occupational sources, and from all known or plausible exposure routes (oral, dermal and inhalation). With the proposed mitigation, the contribution of sodium bromide to the aggregate risk from bromine or bromate is low and not of concern.

Can Sodium Bromide Affect the Environment?

Sodium bromide is not expected to pose risks of concern to the environment when used according to the proposed revised label directions.

Environmental exposure and risk is expected to be limited for sodium bromide used in pools and spas. Sodium bromide that is used in industrial processing waters is mixed with sodium hypochlorite or chlorine, to produce hypobromous acid, which works to control bacteria, fungi and slimes. Although levels of hypobromous acid are expected to be very low, it may cause toxic effects in aquatic organisms if it is allowed to enter natural waters. Label statements requiring that industrial water containing hypobromous acid be cleaned before being released to natural waters are therefore proposed for all industrial products.

What Value Does Sodium Bromide Provide to Canadians?

Sodium bromide has been registered and widely used in Canada as a slimicide and as a pool and spa sanitizer for over 40 years. As one of a handful of registered slimicide active ingredients, sodium bromide provides an important alternative for paper mills and cooling towers where the slime control program often involves rotating different biocide treatments to address biofilm resistance issues.

As a pool and spa sanitizer, sodium bromide reacts with an oxidizer to provide a source of bromine. The only alternative to bromine for spa and pool sanitization is chlorine. Even though they can both be formed from a number of different registered active ingredients, bromine and chlorine are the only two spa and sanitizer chemicals registered in Canada. Bromine has some practical advantages over chlorine by being less susceptible to degradation by the sun and a more effective sanitizer over a broader pH range.

Are Additional Measures Required to Further Minimize Risks?

Labels of registered pesticide products include specific instructions for use. Directions include risk-reduction measures to protect human health and the environment. These directions must be followed by law.

As a result of the re-evaluation of sodium bromide, the PMRA is proposing further risk-reduction measures in addition to those already identified on the sodium bromide and related device product labels. Additional risk reduction measures are discussed below.

Human Health

To mitigate residential exposures, the following requirements are proposed:

  • All bromine swimming pool or spa electrolysis devices and sodium bromide products intended to be used with swimming pool or spa electrolysis devices are proposed to be phased-out.
  • All chlorine swimming pool or spa electrolysis device products are to indicate that they are not to be used to produce bromide.
  • Scheduled spa products are proposed to be phased-out.
  • All other sodium bromide pool and spa products are to indicate that they are not to be used in combination with electrolysis, ozonation or UV disinfection.

To mitigate occupational (industrial) exposures, the following requirements are proposed:

  • Commercial industrial sodium bromide product labels are to require the use of protective eyewear, chemical-resistant coveralls over long-sleeved shirt, long pants, and chemical-resistant gloves and footwear when handling the concentrate and contacting treated process fluids.
  • Commercial industrial sodium bromide product labels are to indicate that they are for use with closed loading and transfer systems only.

Environment

  • For industrial products, label statements requiring the detoxification of effluent prior to discharge are required due to the toxicity of hypobromous acid to aquatic organisms.

What Additional Scientific Information is Being Requested?

  • No additional scientific information is requested.

Next Steps

The PMRA is inviting the public to submit comments on the proposed re-evaluation of sodium bromide, including proposals that may refine the risk assessment and risk management. Before making a final re-evaluation decision on sodium bromide, the PMRA will consider the comments and information received from the public in response to Proposed Re-evaluation Decision PRVD2017-10, Sodium Bromide. The PMRA will then publish a Re-evaluation Decision, which 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. Based on the final outcome of the re-evaluation, manufacturers will be expected to revise product labels to include new risk-reduction measures and/or phase-out uses according to the implementation schedule to be established by the PMRA.

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