purple colored items of the formal style useage

Arguments inspire you to know more reasons than those you had. I and my friend argued about why urine is not used as a source of DNA extraction. Here below are the acceptable reasons so far investigated. purple colored items of the formal style useage

The use of biological samples and bodily fluids as sources of DNA for identification has been thoroughly
investigated and documented. Urine, however, has not been heavily studied as a potential source of
DNA for forensic identification purposes. This study attempts to evaluate the usefulness of extracting
nuclear and mitochondrial DNA from both female and male contributors.
Urine is not considered an ideal source of DNA due to the low concentration of nucleated cells present in
human urine. The nucleated cells found in urine are typically white blood cells and epithelial cells.