The NHANES 2015–2016 aromatic diamine urinary biomonitoring data: A critical review and suggestions for improved data collection.

This article critically reviews the 2015–2016 National Health and Nutrition Examination Survey (NHANES) data on urinary aromatic diamines, biomarkers obtained after acid hydrolysis of urine samples, which are used to assess exposure to aromatic diisocyanates (DII), aromatic diamines, and polyurethanes (PU). It highlights that these urinary diamines are not unique to a single exposure source, complicating interpretation, as they may originate from occupational or home use of diisocyanates, direct exposure to diamines (notably from hair dye products), or degradation of PU medical implants. The review evaluates expected urinary diamine levels from various sources, identifies limitations in the NHANES analytical methods and detection limits, and underscores the need for improved data collection strategies, including better source mapping, separation of confounding isomers, and documentation of product use or medical device presence to enhance exposure assessment and potential health risk correlations.