An improved neurosurgical sponge contains less than 0.45 EU/cm3 of bacterial endotoxins. A neurosurgical kit includes a plurality of sponges in a container, wherein the plurality of sponges contains less than 2.15 EU. Methods of producing the surgical sponge and using the surgical sponge in a surgical method are described. Rayon containing less than 0.45 EU of bacterial endotoxins per cm3 of rayon is also described.