What is boric acid?
Boric acid is derived from boron, a naturally occurring substance found in rocks, soil, and water. Boron is common in the environment.
Boric acid is generally a white solid, but it may be clear to murky. It is odorless and generally stable under normal conditions.
Boric acid naturally occurs in air, water (surface and ground water), soil, and plants, including food crops. It enters the environment through break down of rocks, loss from seawater, and volcanic eruptions.
What is boric acid used for?
Boric acid and salts of boric acid are active ingredients of pesticide products used against insects, spiders, mites, algae, molds, fungi, and weeds.
Boric acid pesticides exist in various forms including aerosols, liquids, granules, wettable powders, dusts, pellets/tablets, and impregnated materials (baits, stakes, etc.).
How does boric acid work?
Insects are killed by eating boric acid and its salts. The salts of boric acid are abrasive to the exterior of the insect.
Boron is an essential plant nutrient, and some boric acid products are used to aid plant growth.
Plants need small amounts of boron but high levels are toxic.
Boric acid kills weeds by disrupting normal plant functions and causing water loss.
Boric acid interferes with reproduction of moulds and fungi.
How toxic is boric acid?
Boric acid is very low to low in toxicity when eaten.
Boron compounds are low to very low in toxicity when inhaled.
Boric acid is low in toxicity when applied to the skin. It is poorly absorbed in rabbits across intact skin, but damaged skin experiences increased penetration.
Boric acid is classified as low to very low in toxicity for skin irritation.
Boric acid is generally low in toxicity for eye irritation. An exception is a specific boric acid salt, which is highly toxic to the eye.
In a 90-day study, investigators fed dogs boric acid. At the highest dose, they noted altered blood chemistry, a buildup of fat in select tissues, and toxicity to the testes.
Researchers fed dogs boric acid in the diet for 2 years and detected no adverse health effects.
Signs of toxicity in laboratory animals poisoned with boric acid include depression, impaired muscle movement, vomiting, purple-red skin color, and lowered body temperature.
What effect does boric acid have on wildlife?
Boric acid is practically nontoxic to fish and other water organisms. Boric acid has a low potential to buildup in organisms.
Boric acid is practically nontoxic to birds. Boric acid may adversely affect development of young birds. In studies with ducks, the highest tested doses in ducklings caused increased mortality, altered behaviour, and decreased growth and hatching success.
Boric acid is relatively nontoxic to bees.
Signs of toxicity in humans.
Investigators evaluated cases of people who ate boric acid. No patients experienced severe toxicity, and the majority did not have symptoms. In patients experiencing symptoms, the most common complaints were vomiting, stomach pain, and diarrhoea. Sluggishness, lightheadedness, and rashes were less common symptoms.
Two siblings, one 24 days old and the other 14 months, were inadvertently fed boric acid in their formula. Symptoms included irritability, diarrhoea, and redness in the groin area. Neither child developed severe toxicity nor had symptoms 1 month after the incident.