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Is Borax Toxic?

Is Borax Toxic?

Many people are concerned about whether borax is a safe chemical. There are many sites on the internet claiming it is toxic. I disagree with these sites and believe that borax is as safe as table salt or washing soda—in other words, the dose makes the poison. Here’s why…

History of Borax

Borax-150039Humans have mined and used borax (also known as sodium tetraborate) since its discovery in Persia more than 4,000 years ago. Borax is a naturally occurring mineral found in concentration in dried salt lake beds, and consists of water, sodium, boron and oxygen. That’s it. The main areas where borax is mined today are in Turkey and California.

Boron is an essential trace mineral nutrient required for many functions in the body, like rebuilding bone and teeth, hormone regulation, absorption and metabolism of calcium, magnesium and phosphorus, and maintaining communication between your cells.

In fact, boron is as essential for the parathyroid gland as iodine is for the thyroid.

Boron is ubiquitous in soil and water, and is required for plant growth. Diets with a fair amount of fruit and vegetables provide about 2 to 5 mg of boron per day, but this also depends on the region where the food was grown and how it was grown.

The Evidence on Borax

All of the studies that showed evidence of possible hormone disruption in animals either used ridiculously high doses of borax (many grams delivered intravenously), or they conflated borax with boric acid, which is NOT the same stuff.

Borax (sodium tetraborate) is used in the process of making boric acid, but there is a tremendous chemical difference between the two. Many of the studies used to demonstrate the alleged danger of borax often used boric acid instead, or were ambiguous about which was used.

Boric acid is toxic at far lower doses than borax, so any study that isn’t clear about which of the two is used for the data should not be considered credible. (This includes the EWG data.)

Borax can be toxic at the very high doses used in animal studies. It has this effect at high doses is because it is essentially an overdose of the element boron, which is a nutrient required for hormone regulation in small quantities. Iron, zinc and calcium are required by the body too, but an overdose of any of these will also send you to the hospital!

However, adults could never possibly ingest anything even close to the amount of borax required to do harm—unless they worked unprotected for years in a borax mine or packaging factory. (However, you will want to keep your small children out of the borax, just as you would keep them away from the chewable vitamins.)

Borax is officially classified as non-carcinogenic and a mild skin irritant. The high alkalinity of borax (pH 9.5) is what causes skin irritation, which is the same reason that washing soda and even baking soda cause skin irritation, too. The alkaline pH of borax, washing soda and baking soda is what softens the water, and makes it possible for them to clean your clothes.

There are also several studies in the ToxNet database that show borax is only a very mild lung irritant and causes no lasting damage. If ingested, it is quickly excreted in the urine. In addition, it does not really penetrate the skin well, and is not bio-accumulative.

Finally, the Material Safety Data Sheet lists borax as a health hazard of 1—the same as baking soda and salt. In other words, borax is toxic in the same way that salt is toxic (Actually ounce for ounce, salt is more toxic): A small amount can do great things; a huge amount will kill you and other living things.

You wouldn’t want to ingest large amounts of salt or baking soda, inhale them, or rub them in your eyes. Borax is no different.

Uses for Borax

Borax is used in laundry detergents, hair potions and skin lotions. Like diatomaceous earth, it also can help kill fleas and dust mites in your carpet by dehydrating them. It is also used as a safer ant and cockroach killer.

Borax is also naturally anti-fungal and anti-viral (but not anti-bacterial), and—here’s the neat part—through a chemical reaction with water, borax produces hydrogen peroxide (the main ingredient in OxyClean) to brighten and sanitize your clothes.

Because borax is made of just sodium, oxygen, hydrogen and boron, many people even ingest small amounts of borax mixed in water to self-treat various health conditions that supplemental boron can really help, like arthritis, fluoride detoxification, osteoporosis, prostate cancer, menopausal symptoms, psoriasis, and candida.

People should use the same precautions (gloves, dust mask or bandana) with borax that they would use around any dusty substance, like washing soda, bentonite clay, diatomaceous earth, or powdered soap. (Heck, even flour or powdered sugar would be irritating if inhaled!)

So, Is Borax Toxic?

In sum, borax is wholly natural and has no inherently toxic ingredients. It doesn’t cause cancer, accumulate in the body or in nature, or absorb through the skin.

Because the dose makes the poison, borax is not harmful to the body or the environment with normal usage any more than salt or baking soda is. In fact, the largest borax (borate) mine in the world—found in Boron, California—is considered to be one of the most ecologically sound and environmentally sustainable mines in the United States.

I consider borax a safe, effective cleaner, and I will continue to use it in my household green cleaning and safer pest control.

About the author

Dawn Gifford

Dawn is the creator of Small Footprint Family, and the author of the critically acclaimed Sustainability Starts at Home - How to Save Money While Saving the Planet. After a 20-year career in green building and environmental sustainability, chronic illness forced her to shift her expertise and passion from the public sphere to home and hearth. Get the whole story behind SFF here.


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  • I just saw an article on a friends fb page stating that we should Beware of Homemade Slime which is made by using borax along with shaving cream, glue, soap, water and food coloring or paint. My daughter and her friends love making slime and up until today I had not heard any concerns with it. What are your thoughts on this concern? After reading your article above and some other articles I have found – I am not sure there is really anything to be concerned about – but would welcome your thoughts. Thanks.

  • Thanks for the post! Just cruious, if borax + acid = boric acid, is there a risk that you can inadvertently ‘make’ boric acid by using borax with another ingredient, such as apple cider vinegar which has hydrochloric acid?

    • You need a very strong acid to make boric acid from borax. Apple cider vinegar contains acetic acid at a very low concentration, not hydrochloric acid. You won’t need to worry about accidentally making it with vinegar, or orange juice, or any other food grade acid.

    • This is a classic example of the bait and switch I see in article after article. You’d think people would do more fact checking. The beginning of the article talks about borax, and then it goes on to warn about the dangers of exposure to boric acid.

      Borax and boric acid ARE NOT THE SAME THING. Boric acid can only be made by reacting borax (sodium tetraborate decahydrate) with a strong mineral acid, such as hydrochloric acid, which simply doesn’t happen in a household cleaning or crafting setting. Boric acid is much more of a concern than household borax, and conflating the two only confuses people and leads to unnecessary precaution.

      Ounce for ounce, borax is as dangerous as table salt, and less toxic than caffeine.

  • Thank you for such an informative article! I’ve been using borax, vinegar, etc, instead of store-bought cleaners for awhile, & had just read some questionable articles regarding the “toxicity” of borax, which I’d never heard before, so I looked further & found this article. I feel better now!

    • Me too! Just made several batches of cleaning products with it, and then started reading that it may be toxic. Thank you so much for this very informative article. Makes perfect sense, and I feel much better now that I have the facts. Thank you!!

  • Great write up. I agree with you on the “toxicity” of borax. It’s simple science, really. If borax is as natural as methane gas (also non-carcinogenic), then it’s perfectly safe to wash clothes with borax as it is to be in the same room with someone who is prone to flatulence.

    Odd, I know, but the truth can’t be denied.

  • Thank you, at last someone offering a rational informative answer to the question on many early years practitioners lips right now ( following current trend of slime recipes). Every other site I have looked at, while researching this, offered only fear inducing warnings or irrational objections; yet offered me no real advice or evidence that i could use as a basis for opinion. Of course I understand the need for caution when creating an environment safe for children to explore but I firmly beleive it is possible to do so in such a way that avoids blindly erradicating everything not guaranteed 100% chilld friendly. It harks back to the shaving foam panic we endured a few years ago, did we not then conclude that although there may be an element of concern in using it to enhance provision, the dangers are minimal and therein lies the exact reason we impliment thorough risk assessments. My manager calls it the double a, vital in early years, “awareness = avoidance”. This view, in my mind, is synonimous with lazy thinking,; not only does it markedly diminish a childs potential to develop critical thinking in a practical context, we are underestimating their innate capacity to manage danger for themselves as they seek out new and challenging experiences. Thanks again, I shall be sharing your advive with friends and colleagues so they too are able to make informed decisions re balancing safety with stimulation thus creating a future generatoon of innovative free thinking individuals (as opposed to worryworts who stick to what they know, or worse have been told by others!)

    • The author’s emphasis in writing this article is the safety of borax for household use, although she hints at being read up on borax as a supplement and cure for some ailments. Here is an interesting article by an Australian naturopathic kind of physician where he makes some astounding claims for the curative uses of borax: That man tells us that the European Union totally and completely banned the sale of borax (and boron too, I think) a few years ago so as not to threaten the profits of the drug companies.

      • The article blatantly conflates boric acid (which is not sodium borate and is toxic in low doses) with borax (which is sodium tetraborate and is not toxic at low doses) to make its case, which is totally dishonest.

        I also think, however, that any borax in vaccines is probably of relatively less concern compared to the many other significantly toxic ingredients in vaccines.

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