The National Institute for Occupational Safety and Health (NIOSH) conducted a health hazard evaluation at a municipal police department in response to a request submitted by management concerning chemical exposures encountered by criminalists during criminal investigation procedures. At the time of the evaluation, several methods were used by criminalists for processing criminal evidence. Latent fingerprints were identified using one of three methods: (1) fingerprint powder dusting, (2) ninhydrin solution spraying, and (3) super glue fuming. Latent blood was detected by luminol solution spraying. When fingerprint powder is dusted over evidence or on surfaces at a crime scene, the dust adheres to residual oils that fingers leave behind, thereby revealing ridge patterns, or fingerprints. When sprayed on evidence, ninhydrin reacts with residual amino acids that fingers leave behind to form a deep blue or purple fingerprint. In the super glue "fuming" method, ethyl cyanoacrylate, the main ingredient in super glue, is heated inside a chamber containing evidence. The ethyl cyanoacrylate vapors and atmospheric moisture react with fingerprint residues to form awhite polymer. When luminol solution is sprayed onto latent blood, the iron in the hemoglobin catalyzes the reaction between luminol and other components of the solution (including hydrogen peroxide) to produce chemiluminescence, which refers to the emission of light from a chemical reaction. Our evaluation included observing methods used by criminalists and collecting general area and personal breathing zone (PBZ) air samples for the different chemicals they use. We also compared the pressure differentials in the crime lab with adjacent office areas and measured the airflow and capture efficiencies of the local exhaust ventilation (LEV) systems used in the crime lab.
Police-officers; Law-enforcement; Law-enforcement-workers; Forensic-medicine; Laboratory-techniques; Laboratory-workers; Laboratory-testing; Air-sampling; Breathing-zone; Exhaust-ventilation; Exposure-assessment; Occupational-exposure; Emergency-responders; Photochemical-reactions; Chemical-analysis; Amino-acids