By Dennis Walsh, Andra Renzi and Sherri Aruda
Can gender and age be determined through urinalysis? The following research by Dennis Walsh, an Associate Professor of Forensics at MassBay Community College, and Andra Renzi and Sherri Aruda, sought to answer this question.
The purpose of this research was to identify a person's gender and age through urinalysis. Experimentation was done using urine on rug and newspaper surfaces. Our study examines the relationship of gender and age to changes in the function of the body to produce certain chemicals that may help in identifying a member of the human species.
There were seven human participants of both genders, ages 5-68 years, and a male cat. Reagents applied to urine samples on small test surfaces revealed that there were strong differences in the indicators of gender and age. The taking of medications (i.e., birth control pills) had a great affect on the results of the reagents. The research was limited by a small test group, and the majority of the urine samples tested were from female subjects. All subjects were in good health without any known kidney diseases such as urinary tract infection.
Rug remnants 6 to 12 cm2 in size with various thicknesses and texture were collected. Once organized within the individual groupings, each remnant was dampened with the individual urine sample assigned to it. Each remnant was swatched. The samples were allowed to completely dry on a clothes line under the exhaust hood and sprayed with ninhydrin. Ninhydrin was used because it reacts with the amino acids contained in the urine(1). The swatches were observed for color change due to the reaction of the urine with ninhydrin on the particular swatch. The swatches were observed for up to 30 minutes.
Following the same procedure for the rugs, the newspaper samples were stained with various urine samples. They were allowed to dry and then were stained and observed.
With the rug samples, the initial application of the ninhydrin, yielded no immediate change. However, as time allowed, the change in color from a pink hue to a more defined purple, in some cases, became very apparent. The older the participant, the more significant and faster the color change occurred. The color reaction of the 5 year-old female required a longer period of time in relation to the adult subject samples. The color intensity was much darker with male subjects. As time passed, the male cat sample began to match that of the human male subject. In comparison of the samples, it was determined that both male specimens were significantly darker in color compared to the female specimens. There was no further color change in the human male's specimen, but it was found that the cat urine sample appeared to revert back to a no reaction result.
In comparing the rug swatches to the newspapers, there was a significant color change with the newspapers over a shorter period of time. This may be due to the difference in surface, or not enough absorbency of the urine in the rug (i.e., chemical treatment of the rugs swatches, etc.). Another possible reason for the intense color in the newspaper samples could be due to the kind of paper and exposure to the ink. The color difference with respect to the 5 and 20 year-old female subject could have been due to the issue of age of the 5 year-old female, whereas the under development of certain chemical changes (i.e., hormones) in the body. For the 20 year-old female, color change is possibly due to the fact that the subject was taking birth control pills at the time of the experiment. The subject may have possibly been experiencing premenstrual syndrome. Unfortunately, we did not have more subjects with the same conditions to compare samples with in all situations.
The later observation of the cat urine sample sprayed with ninhydrin on newspaper showed to revert back to a no reaction result. Differences in animal to human pH balance could also play a major role in the color change reaction of the sample. The cat's urine is slightly more basic than the human sample (i.e., cat pH=6.6, human pH=5.8).
To conclude, any body fluid at a crime scene could be used as a forensic tool, and that includes urine. Although difficult to draw conclusive results, gender and age determination could be used as a screening method. Since urine sometimes contains white blood cells(2), a DNA fingerprint could be obtained. With the advances in technology today, we feel that if the present study were to be re-conducted, it would produce a more significant and consistent results.
REFERENCES
1. http://antoine.frostburg.edu/chem/senese/101/organic/faq/amino-acid-test.shtml
2. http://en.wikipedia.org/wiki/Urine
Dennis Walsh is an Associate Professor of Forensics at MassBay Community College. He received a Masters degree from UMass-Lowell. He is affiliated with several Biotechnology companies and has taught for 18 years at the college level. His current research is in the classical forensics area of hair and chemical analysis in humans.
