The Effect of Mold on Diapers and RSID™ Semen and RSID™ Saliva

Background

At the request of a forensic laboratory, experiments were performed to determine the effects of mold on diapers when using RSID™-Semen or RSID™-Saliva for body fluid detection. We examined 22 used diapers (urine soaked only, no feces) that were collected and stored at room temperature to promote the growth of mold. After 8 months of storage, 11 of 22 diapers grew visible mold, including black and brown mold as well as areas of pink spots and green streaks. Two samples from each diaper containing mold, as well as substrate controls, were extracted and tested with RSID-Saliva and RSID-Semen.

Testing with RSID™ Semen and RSID™ Saliva

One half (½) of each moldy diaper sample was extracted in 400 µL of Universal buffer for 1 hour; extract was collected using a spineze basket. Two volumes of the extract, 20 µL and 100 µL, were tested on RSID™-Saliva (lot 102512A1) and RSID™-Semen (lot 091312S1).

Results

All RSID™-Saliva and RSID™-Semen tests were negative using the 20 µL samples. Data from the 100 µL are shown below.

RSID™-Semen:

Of the 11 diapers tested that contained visible spots of mold, 3 extracts developed shadow bands with RSID-Semen (samples L3- A, L6-S1, and L8-B, highlighted in yellow), 2 samples were weakly positive (samples L7-S1 and L8-A, highlighted in orange), and one sample (sample L4-S1) was a strong positive (highlighted in red). Samples collected on 1/15/13 and 4/13/13 were labeled as S1 or S2 and samples collected on 4/1/13 were labeled as A or B. We interpret shadow bands as negative, and therefore 3 of the 11 diapers containing mold were positive with RSID-Semen.

RSID™-Saliva:

Two samples tested weakly positive (L6-S1 and L7-S1, highlighted in orange) and similar to the RSID-Semen result, L4 S1 was a strong positive (highlighted in red) and therefor 3 of the 11 diapers were positive with RSID-Saliva.

Summary

Of the 11 diapers that grew mold, 4 diapers showed positive results on either RSID-Semen or RSID-Saliva. Please see the table below.

Conclusions

We have observed that the presence of mold on diapers can result in a false positive when using the 100 µL extract volume on RSID™-Saliva or RSID™-Semen. Due to this observation, we cannot recommend the use of RSID™-Saliva or RSID™-Semen if diaper samples contain mold.