Li N, Duan Y, Hong M, Zheng L, Fei M, Zhao X, Wang J, Cui Y, Liu H, Cai J, Gong S, Wang H, Hong F. Spleen injury and apoptotic pathway in mice caused by titanium dioxide nanoparticules. Toxicol Lett. 2010 Jun 02;195(2-3):161–8. doi: 10.1016/j.toxlet.2010.03.1116. PMID: 20381595.