Since 1948, people have used boric acid, a boron-based acid, as a pesticide and general germicide. Boric acid has the potential to be toxic to humans, but such instances are rare.
In humans, ingestion of boric acid becomes lethal at doses of 2 to 3 grams in toddlers, 5 to 6 grams in adolescents and 15 to 20 grams in fully grown adults, according to People for Clean Beds.
Boric acid may cause infertility and reduce testicular size in men, nausea, vomiting and other flu-like symptoms. Long-term exposure to boric acid may damage the liver and kidney and result in neurological problems.
Most humans, especially infants, are not in danger of boric acid poisoning because nurseries no longer use it as a fungicidal, nor is it used in most medicines to kill germs. Those most at risk for boric acid poisoning are people who work around it and those who accidentally ingest it. Accidental ingestion is rare because of the high dose needed to kill a human.
Call the National Poison Control hotline at 1-800-222-1222 if you suspect boric acid has been ingested. Be ready to provide the weight of the individual and how much boric acid is believed was ingested.
Overall, despite its potential to damage the organs and the possibility for neurological problems, boric acid is probably much better than using more dangerous pesticides, according to Beyond Pesticides.