Borate wood preservatives are composed of naturally occurring minerals that protect wood from fungi, termites, and other wood-decomposing organisms. Borate wood preservatives are comprised of disodium oc- toborate tetrahydrate.
Disodium octoborate tetrahydrate is an alkaline salt, that can be produced in two forms: as a clear, liquid concentrate or packaged as a white, odorless, powdered chemical substance that is not flammable, combustible, or explosive and has low acute oral and dermal toxicity. In the liquid form, it is commonly diluted and sprayed on wood surfaces to kill termites, powder post beetles, carpenter ants, fungi, and algae. It is also available as pellets for embedding in structural wood.
This compound is often confused with boric acid or the laundry detergent additive used for stains.
Moreover, on 22 February 2018, the Swedish Chemicals Agency (KEMI) submitted a proposal to the European Chemicals Agency (ECHA) to list disodium borate as a Substance of Very High Concern (SVHC) under the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) Regulation.
Today, it is stated as a Substance of very high concern (SVHC) and included in the candidate list for authorisation.
Why are borate preservatives a hazardous substance?
Borate preservatives, composed of the substance disodium octoborate tetrahydrate pose potentially hazardous effects for both, human health and the environment.
Absorption of borates can take place via the oral route or respiratory route. To date, there is insufficient data to determine conclusively the effects of acute toxicity and the exposure limit values at which it would occur. However, acute effects may include nausea, vomiting, gastric discomfort, skin flushing, excitation, convulsions, depression and vascular collapse. Multiple exposures (high levels > 1g) result in various symptoms which may appear singly or together and include dermatitis, alopecia, loss of appetite, nausea, vomiting, diarrhoea, and focal or generalised central nervous system irritation or convulsions.
In terms of recurrent exposures, it is considered that this substance may damage fertility and may damage the unborn child.
Moreover, concerning the environment, once borates are released into it they can end up in soils, oceans and groundwater, contaminating them and being a potential hazard for the animals that live in the surroundings.
Where can borate be found?
Borate wood preservative treatments used primarily on indoor wood that is protected from weather, therefore, being present, amongst others, in the following elements:
- Joists
- Sheathing
- Sill plates
Moreover, beyond wood treatments, borates also have other uses in consumer products, such as fillers, putties, plasters or modelling clay.
Links:
This article can be found in the 2022 edition of the document. Find the full publication here:
Help us grow!
If you have any suggestions about these contents, find any error or would like to make us aware of anything, please fill out the form below.