Actual toxicity levels are..

Glad there is someone asking that question!

"•Borax is acutely toxic in the same manner that salt is (in rats, it’s 4500-5000 mg/kg of body weight, which is A LOT). Ingested in moderate quantities, it causes gastrointestinal upset and nausea. Bottom line: While it may be listed as “poison” on the box, it’s only toxic at very, very high levels. (Like salt, baking soda, and even water is.)" - http://www.crunchybetty.com/getting-to-the-bottom-of-borax-is-it-safe-or-not


And

Toxicity info:
"Borax toxicity

We only need very small quantities of boron for good health and to prevent diseases such as arthritis. In large quantities it has adverse effects, the same as any other compound.

Borax has very low toxicity. Borax's LD50 (median lethal dose) score is 2.66 g/kg in rats. (11) This is the same toxicity as boric acid. table salt is more toxic, with an LD50 of 3.75 g/kg in rats according to the Merck Index!

It is likely that toxicity symptoms will develop only after taking several grams (thousand mg) per day for several months. Signs of boron toxicity are diarrhoea, lethargy, nausea and vomiting. Eventually, also dermatitis. Excess boron can worsen or trigger conditions like ADHD, allergies, asthma, autism, cystic fibrosis, dyslexia, liver and oesophageal cancer. Boron tends to increase the levels of calcium and oestrogen, and lower blood glucose, and levels of vitamin B6 and zinc. Boron's antidote is vitamin B2.
"
http://www.growyouthful.com/remedy/borax.php
(Note, toxicity symptoms listed are indeed related to dieoff, and like all supplements and materials, are best taken in small doses or in higher grouping with it's helpers. It's rich in apples, grapes, apricots, some nuts, etc..)

I've taken the chelated boron capsules myself, and felt really good at 3-9 mg. I have had hormone issues (needed more estrogen) so what can I say, everything in balance. One of boron's big helpers is vitamin k2, which directs calcium directly to the right organs and strengthens bones and teeth.

Boron is part of the D3 helpers.
It looks like this in the best D3 supplement to date:
Vitamin D3 2,000 iu
Vitamin A 400 iu
Vitamin K2
Magnesium 100 mg
zinc
boron

Boron helps protect the kidneys from spilling magnesium and zinc, and it has powerful anti-fungal properties. Apple trees recover from trunk-rot problems when borax is sprinkled near the roots on the ground, and grow strong, health apples with it as a combination. Ants die off when borax is sprinkled in their vicinity (they are fungus farmers, it's their food, they know it's not good for them to use!), etc.

Warm wishes,
-illysmanx Tweet