A toxicological chemical assay that measures the concentration of molybdenum (Mo) in a urine sample, typically collected over 24 hours or creatinine-corrected. Urine molybdenum is the most sensitive and reliable biomarker for acute or sub-chronic occupational exposure to molybdenum. Urinary excretion of the element reflects recent absorption and excretion from the body, making it a standard for occupational biomonitoring. It is primarily used to monitor exposed workers in the metallurgical and mining industries.