Is Borax added to a swimming pool safe for people?

The safety profile and permissible human levels of borates, including borax, are well established. As a micronutrient, boron and borates are essential to human health.

While skin reactions due to occupational exposures to borax dust have been reported, acute boric acid poisoning typically occurs due to accidental ingestion in children, with symptoms of nausea, vomiting, diarrhea, and skin rashes. The estimated lethal dose of boric acid for humans is about 15-20g (or about 4 tablespoons) for adults and about 3-6g for infants and children.

The typical levels of Boric Acid recommended to control algae and microorganisms in residential pools range from 50-100ppm (mg/L). Considering that the average home pool contains 20,000 gallons (about 75,700 liters) of water, the boric acid added would amount to about 3.5-7 kg, which is significantly lower than the lethal dose.

Additionally, the skin exposure to borates in swimming pools is minimal, as the skin primarily absorbs water rather than dissolved chemicals. Moreover, Boric Acid tends to react and bind with other ions, reducing its direct concentration and reactivity.

Overall, while caution should be exercised in handling concentrated forms of borax, the regulated use of borates for swimming pool maintenance, within recommended guidelines, is considered safe and does not pose a significant health risk to swimmers.