Factory quotations vary based on purity levels, particle size distribution, and the end-use industry Factory quotations vary based on purity levels, particle size distribution, and the end-use industrybarium sulfate quotation factories. For instance, the medical sector requires high-purity barium sulfate for contrast agents, while the oil drilling industry may opt for less pure grades. Scientists analyzed research that examined how titanium dioxide nanoparticles interact with the brain for a 2015 review published in Nanoscale Research Letters. The researchers wrote: “Once the TiO2 NPs are translocated into the central nervous system through [certain] pathways, they may accumulate in the brain regions. For their slow elimination rates, those NPs could remain in the brain zones for a long period, and the Ti contents would gradually increase with repeated exposure.” After reviewing dozens of studies, the scientists concluded: “Long-term or chronic exposure to TiO2 nanoparticles could potentially lead to the gradually increased Ti contents in the brain, which may eventually induce impairments on the neurons and glial cells and lead to CNS dysfunction as a consequence.”