Urine Biomonitoring

Urine Testing · Urine Testing overview

Urine biomonitoring quantifies exposure biomarkers in urine to estimate absorbed dose. UK occupational hygienists use it as the primary tool for solvent, isocyanate and many metal exposures.

Specific urinary biomarkers

Specific biomarkers are uniquely attributable to a single workplace substance. Urinary S-phenylmercapturic acid (S-PMA) for benzene, urinary mandelic acid for styrene, and urinary methylene dianiline (MDA) for MDI are examples. Specific biomarkers allow direct comparison against ACGIH BEIs or HSE BMGVs without background subtraction.

Non-specific biomarkers

Non-specific biomarkers — for example urinary hippuric acid (HA) for toluene — are present at appreciable background levels from dietary or environmental sources. They remain useful for trend monitoring within a cohort but require either a population background reference or a paired pre-/post-shift design.

Sample handling

Most urinary organic biomarkers are stable for 24 hours at 4 °C and several months frozen at -20 °C. Metals are stable for longer in acid-washed containers. Field staff record collection time, last-exposure time and any clinical events that may confound interpretation.