Hindawi Publishing Corporation ISRN Nanomaterials Volume 2013, Article ID 207239, 7 pages http://dx.doi.org/10.1155/2013/207239 Research Article Harmful Impact of ZnS Nanoparticles on Daphnia sp. in the Western Part (Districts of Bankura and Purulia) of West Bengal, India Baibaswata Bhattacharjee, 1 Nilanjana Chatterjee, 2 and Chung-Hsin Lu 3 1 Department of Physics, Ramananda College, Bishnupur, Bankura, West Bengal 722 122, India 2 Department of Zoology, Ramananda College, Bishnupur, Bankura, West Bengal 722 122, India 3 Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan Correspondence should be addressed to Baibaswata Bhattacharjee; baib23@gmail.com Received 24 June 2013; Accepted 7 August 2013 Academic Editors: S. Misra, X. Tian, and Z. Xu Copyright © 2013 Baibaswata Bhattacharjee et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ZnS nanoparticles of diferent sizes are synthesized employing a simple wet chemical method. Tese nanoparticles are used to study their impact on the Daphnia sp. through traditional toxicity tests. Te percentage of mortality is found to increase initially with increasing nanoparticle concentration or exposure time and is fnally found to saturate for higher concentrations or exposure times. Mortality is found to be higher for smaller particles. Hopping frequency and heart rate are also found to increase with increasing nanoparticle exposure time for a fxed nanoparticle concentration. Tese observations can be attributed to the enhanced surface photooxidation property of the ZnS nanoparticles. Tus the present study will help people to understand the hitherto unknown harmful impact of ZnS nanoparticles on aquatic organisms in the western part of West Bengal (Bankura and Purulia districts), India. 1. Introduction Nanoparticles (1–100 nm) comprise the latest technologi- cal advances designed for various applications [1]. Many nanoparticle compounds occur naturally and are used in many vital life processes [1]. Because of their very small size, they have chemical properties that difer from those of their bulk counterparts [2]. As the size of the particle decreases, the percentage of atoms exposed on the surface increases. Because of their increased reactivity, the interaction of the particle with its environment also changes. Te change in reactivity increases the potential of nanoparticles for use in industry and pharmaceuticals [2], but this also is the reason for environmental concern. Recently, nanoparticles have come under scrutiny for their potential to cause environmental damage [3, 4]. Because of their increased reactivity, nanoparticles can be detri- mental to the environment. Terefore, it is very important to understand the potential impacts of nanoparticles upon environments. Te increased production of nanoparticles is making it more likely that such materials will end up in water- courses, either as medical or industrial waste, or when used as ecological tools, with unknown consequences for aquatic life. Terefore, it is gradually becoming very important to identify the most appropriate route of nanotechnology that will preserve the aquatic environment while also advancing industrial technology. Recent studies [5–9] have revealed some of the detrimen- tal efects of diferent nanoparticles on animals. Inorganic nanoparticles such as TiO 2 , SiO 2 , and ZnO had a toxic efect on bacteria, and the presence of light was a signifcant factor increasing the toxicity [5]. Titanium dioxide can have undesirable efects when inhaled and has a damaging impact on rodents [6]. At the one-year mark, rats continued to exhibit adverse efects even with an initial exposure of only 13 weeks [6]. Warheit et al. [7] found that exposure to carbon