<unk>  may refer to the chemical<unk>  of a<unk>  sample, but can also refer to microscopic<unk>  or comparison. Chemical<unk>  may be considered for retrospective purposes when blood and urine are no longer expected to contain a particular contaminant, typically three months or less. Its most widely accepted use is in the fields of forensic toxicology and, increasingly, environmental toxicology. Several alternative medicine fields also use various<unk>  for environmental toxicology, but these uses are controversial, evolving, and not standardized. Microscopic<unk>  has traditionally been used in forensics as well.<unk>  examine a number of different characteristics of<unk> s under a microscope, usually comparing<unk>  taken from a crime scene and<unk>  taken from a suspect. It is still acknowledged as a useful technique for confirming that<unk> s do not match. But DNA testing of evidence has overturned many convictions that relied on<unk> . Since 2012, the Department of Justice has conducted a study of cases in which<unk>  testimony was given by its agents, and found that a high proportion of testimony could not be supported by the state of science of<unk> .
Hair analysis
Pencil-beam scanning
Anthropometric cosmetology
Rape statistics
Kick chart
Ultraviolet index
Foodomics
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