POLICE doctors may be missing important evidence of sexual assaults and child abuse. Semen fluoresces under the right wavelength of ultraviolet light, but the lamps used in the US produce the wrong wavelength, say researchers.
For decades, doctors have relied on a device called a Wood's lamp to detect traces of semen on skin and clothes. But Karen Santucci of Yale University School of Medicine in New Haven, Connecticut, has discovered that semen doesn't fluoresce under commercially available Wood's lamps, which typically emit ultraviolet at wavelengths between 320 and 400 nanometres.
Santucci originally set out to discover whether medical products, such as lubricants or ointments might give false positives. She tested the ability of 41 doctors to distinguish between various medical products and semen dabbed onto pieces of cloth. Although 25 said they had detected semen using a Wood's lamp in the past, none of them could tell the difference. ...
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