I think it is worth highlighting that the dosages mentioned by that study I. E. 0.1mg/ml - 0.6mg/ml refers to concentrations of borax in BLOOD not WATER. Given that borax is very poorly absorbed and we have approx 4200ml of blood in our bodies, it would need huge quantities of borax ingested to approach anywhere near the concentrations suggested by that experiment.
A quick Google check reveals that a teaspoon of borax is equivalent to 5 ml. At 1/4 tsp a day for men, that means ingestion of only 1.25 ml per day. For women, the recommended usage is half that amount.
This is in the order of 1% of the theoretical toxic dose - hardly threatening.
Colleen, if you are fact checking, then you should check all relevant facts.