The use of a particular 'Iodine tablet' used in portable water purification has also been determined as somewhat effective at reducing radioiodine uptake. In a small study on human subjects, who for each of their 90-day trial, ingested four 20 milligram tetraglycine hydroperiodide (TGHP) water tablets, with each tablet releasing 8 milligrams (ppm) of free titratable iodine; it was found that the biological uptake of radioactive iodine in these human subjects dropped to, and remained at, a value of less than 2% the radioiodine uptake rate of that observed in control subjects who went fully exposed to radioiodine without treatment.