Particulates of 1 to 100 nanometers size are being increasingly used for a variety of clinical and commercial purposes due to their large surface-to-volume ratio and unique physico-chemical, mechanical and electronic properties. While utilizing them for their beneficial functions, it has become vital to heed recent alerts on their toxic biological effects in order that benign systems might be developed. In this paper we review emerging mechanisms of nanotoxicity and possible means for remediation. Challenges in monitoring, characterizing and remediation of nanoparticles are also presented.