Nanomaterials are complex, as are their interactions with biological organisms and the environment. While microscopically sized, they come in all sizes, shapes and compositions. To confound the situation further, the methods of production are still immature for most materials, often resulting in batch-to-batch variability in composition and purity, according to researchers. Impurities are hard to detect, difficult to extract and may obscure the real effects of nanomaterials.