Safety Evaluation of Nanocalcium Based on Physicochemical Characteristics

Abstract

This study was performed to assess the potential toxicity of nanocalcium in terms of physico-chemical characteristics. After the blind test of seven samples of calcium provided from Korea Food and Drug Administration using energy-filtering transmission electron microscopy (EF-TEM), componential analysis using X-ray diffractometry (XRD), and energy dispersive spectrometry, two samples of nano and micro sized calcium were selected for further study. The characteristics of nano and microcalcium were evaluated by EF-TEM, field-emission scanning electron microscopy, XRD, dynamic light scattering, and electron spin resonance. Both samples were agglomerated and did not produce any measurable reactive oxygen species. The specific surface area of nano- and microcalcium measured by the N2 Brunauere Emmette Teller (BET) method was 12.90 ± 0.27 m2/g, and 1.12 ± 0.19 m2/g, respectively. Inductively coupled plasma optical emission spectrometry (ICP-OES) analysis revealed the release of 2–3 times more calcium ion from nanocalcium compared to microcalcium at pH 5 and 7. Genotoxicity and single-dose and repeated-dose 14-days oral toxicity testing in Sprague-Dawley rats were performed to evaluate the safety of nanocalcium. The results of BET and ICP-OES analysis showed that nanocalcium has a large specific surface area and a greater potential for ionization. Neither genotoxicity nor in vivo toxicity was observed in our experimental conditions. However, we suggest long-term monitoring is need for nanocalcium due to their differential of ionization derived from their different specific surface area.

Keywords: nanocalcium, genotoxicity, physico-chemical characteristics, specific surface area