Effect of toilet detergent on morphological change of human spermatozoa

Objective: We encountered a case of a girl killed at her own home and found approximately ten days after death. Five persons were suspected as killer. A condom containing human semen and filled with toilet detergent was found in the toilet chamber pot. The problem was to determine the time when the semen was discarded. Therefore we needed to provide evidence to demonstrate how long the semen had been in the toilet. Design: Validity study was performed in effect of toilet detergent on morphological change of human spermatozoa. Materials and methods: Human semen samples were collected from fifteen healthy volunteers, and the samples were confirmed to be normal by routine semen examination. The semen samples were mixed in two concentrations of a common toilet detergent (0.2 mg/ml and 0.02 mg/ml), or in water as control. AU these preparations were kept at room temperature and were examined periodically under a microscope. The Oppitz's method was used for spermatozoa staining. Results: The major change of spermatozoa was morphological change. Especially, separation of the tail and the head was clearly observed on day 10 under 400 X magnifications. In samples mixed with 0.2 mg/ml solution of toilet detergent, separation of the tail and head was observed in approximately 40% of the spermatozoa on day 10, 80% on day 20 and 98% on day 30. When mixed with 0.02 mg/ml of toilet detergent, the corresponding proportions were approximately 40%, 70% and 95%, respectively. In the water control, only 25% showed separation on day 10, and the percentage on days 20 and 30 was similar to 0.02 mg/ml detergent. Conclusion: The proportion of intact spermatozoa decreased with time when semen specimens were mixed with diluted toilet detergent and kept at room temperature.