Single and repeated oral dose toxicity study of hydrogen-rich water in mice

Abstract

Objective: As a part of general toxicity studies of hydrogen-rich water (HRW) prepared using Doctor Hydrogen Water® (DHW), a plastic shelled product that includes metallic magnesium
(99.9% pure) and natural stones in polypropylene containers (Doctor SUISOSUI®＝DHW, manufactured by FDR Friendear Inc., Tokyo, Japan) in mice, this study examined the toxicity of
HRW in single and repeated administrations following the previous report in order to apply this product in preventive medicine.
Methods: The safety of oral ingestion of HRW prepared using the DHW stick was examined in 6-week-old male and female ICR mice with single and 28-day repeated administration by gavage of the maximum acceptable dose of HRW and additional ad libitum ingestion of HRW prepared inside water feed bottles during the administration periods. The study was conducted using distilled water as a control following the methods for general toxicity studies described in the “Guidelines for Nonclinical Studies of Pharmaceutical Products 2002”. Using distilled water as a control, 1) observation of general conditions, 2) measurement of body weight, 3) determination of food consumption, 4) determination of water consumption, 5) blood test and urinalysis and 6) pathological examination were performed for the administration of HRW. Mice received HRW for 4 weeks and outcomes were compared with those of the control group that received distilled water. Animals were weighed once a week and average body weight was calculated for each group to determine the dose. Blood cell count was performed by collecting blood samples from tail veins at the beginning and end of the study. For urinalysis, samples were collected by forced urination at the end of the study. General symptoms were observed at least once a day. For pathological examination, necropsy was conducted by abdominal section on the last day of the study, followed by measurement of organ weight and gross observation to check for abnormalities.
Results: The results of the above examinations revealed no significant differences between control and HRW groups for both males and females. Thus, no notable toxicity was confirmed with single and repeated oral administrations of HRW.
Discussion: Safety of HRW was examined in 6-week-old male and female ICR mice by single and 4-week repeated oral administration of HRW and distilled water as a control. In both HRW and control groups, water was orally administered in two divided doses in the morning and evening (2 g/kg body weight/day) as well as given ad libitum during the day. Oral administration at the above dose did not result in abnormal symptoms or death during the observation period. No abnormalities in blood cell count or organ weights were seen. Without any evidence of toxicity to cells and organs, HRW is speculated to not adversely affect living organisms. The 50% lethal dose of HRW with oral administration in mice is estimated to be greater than 2 g/kg body weight/day (in two administrations by gavage) for both male and female mice.