Uses of Borates in Insecticides and Pesticides
The first use of inorganic borates documented as an insecticide was in 1918. However as a commercial product boric acid was documented as an insecticide in 1922 when P.F. Harris invented the Roach Tablet.
The commercial use of borates in insecticides developed during the 1940's due to the need to protect foodstuffs in wartime conditions, and because of their effectiveness in protecting timber against insect attack (See ABC’s Wood treatment Bulletin). These uses of borates subsequently declined because of the increasing use of organic insecticides. Toxic compounds that are the basis for these organic insecticides include organophosphates, carbamate, chlorinated hydrocarbons, synthetic pyrethroids, and still others flourished and continue to this day.
However, there is mounting concern at the mammalian toxicity and persistence of certain organic insecticides and their impact on the environment. This has led to a revival of interest in the borates and other inorganic compounds which have low acute toxicity to mammals and appear to have no observable adverse effect on the environment when used in a responsible manner as stated in Material Safety Data Sheets (now called SDS, Safety Data Sheets).
In 1971 the use of borax in a bait to control ants in the domestic house was described. Boric acid was shown to be active against Pharaoh's ants in 1987.
Today borates are used in many products including ant baits, and other insecticidal compounds that target such organisms as fleas, mites, roaches, silverfish and spiders plus selectively targeting the larval forms of some insects. Based on EPA records, as of 1993, there were 189 registered pesticides containing borates.
Borate’s Value and Use in Insecticides and Pesticides – Mode of Insecticidal Action
Boric acid is generally known to act as a stomach poison in insects and it has been suggested that it also has an effect on their nervous system.
The Mohs hardness of boric acid is 3.0 on a scale of 1 – 10 with 10 classified as a diamond. Thus boric acid and some hydrated sodium borates are also abrasive to the insect’s exoskeleton which results in another way of insecticidal mortality. However if these dry refined borates (particularly powders) come in contact with water, their effectiveness as an abrasive can be reduced due to caking of the finished product since borates are water soluble.
In the case of the cockroach, lack of repellency of boric acid plus its electrostatic tendency to stick to the insect's body outweighs its relatively low toxicity by comparison with certain organic insecticides. In certain other insect species, the borate acts against the larval stage.
Application for Insecticides and Pesticides
Borates can be used in various consumer and commercial formulations. They are marketed in several different forms including liquids, soluble and emulsifiable concentrates, granular, powders, dusts, pellets, tablets, solids, paste, baits, plus crystalline rods and bi-component baits that use sugars and other cellulosic-based materials as attractants to insects as a food source.
The range of loadings in consumer and industrials products can be from 1.0% to 100% by weight in the final formulation and depending on the value borates are intended to bring to the final product.
Borates, being soluble in water, can be used only in protected situations where they will not be leached by rain or by ground water. They are suitable for application in structural and insulation materials, animal bedding, and areas of crack and crevice. Borates should not be applied directly on feedstuffs or foods.
In the US, proprietary borates are registered with the EPA for the control of larvae of the common house fly and latrine fly, and in manure, including use in poultry houses and in garbage and municipal dumps. EPA registration has been obtained for use against Darkling beetles andHide beetlesin poultry houses. Formulators have a responsibility to confirm such registrations are still efficacious and legal. To prevent misuse, boric acid or other borates must be kept out of the reach of children. It is important to confirm that a supplier of borate compounds has the appropriate registration and labeling of their products for use as an insecticide.
Regarding registrations, in 1948 Boric acid and other borate salts were registered for this use and later reregistered by the Environmental Protection Agency (EPA) in 1993.
However, for specific insecticidal use, registration with a national authority is a requirement in most countries and more specifically in the US and Canada. Formulators are responsible for ensuring that their product meets local, state and federal regulations.
Various new uses are under development. The reader should ascertain if his proposed use, method of use or formulation is captured in an existing or pending patent, or is subject to proprietary labelling. Boric acid and sodium borate compositions are not subject to patent protection, and many end-uses are not covered by patented claims.
Discussions described in this bulletin are given without warranty as to any patent, which may vary between countries.
American Borate Company Products:
- 10 Mol
- Etibor 48 (Borax 5 Mol)
- Anhydrous borax
- Anhydrous boric acid
- Etidot 67 (di-sodium octaborate tetrahydrate)
- Boric acid
It is further advised to check with American Borate Company’s (ABC) representative to determine if there is an opportunity to sub-register under ABC’s data. This has the potential of speeding up the process of sub-registering private label products when product is purchased from ABC.
Note: ABC does offer an EPA registered product specific to boric acid. Ask about registration and labeling availability for other ABC borate compounds.