Characterization of tritium exposures by measuring tritiated metabolites in urine

A high-performance liquid chromatography (HPLC)-based method was developed to look for the presence of characteristic urinary metabolites associated w ith different tritium-exposure situations. Non-volatile metabolites in urin e were isolated by evaporating an aliquot of urine samples, at room tempera ture under nitrogen, from animals percutaneously exposed to tritiated thymi dine, tritiated formaldehyde, tritium-gas-contaminated metal surfaces and t ritiated pump oil. A total of 40 fractions were collected at 1 min interval s with a flow rate of 1 ml min(-1) and their tritium activities were measur ed. The activity profile of tritium showed that the ratios of non-volatile tritiated metabolites in fraction I (0-20 min) to fraction II (20-40 min) w ere noticeably different: among the animals exposed to tritiated thymidine (77.2+/-4.5), tritiated formaldehyde (40.9+/-3.3), tritium-gas-contaminated metal surfaces (16.5+/-2.5), or tritiated pump oil (8.7+/-0.4) 24 h post-e xposure. Our results suggest that, if the nature of a tritium exposure is u nknown, comparison of the ratio of fraction I to fraction II in non-volatil e tritiated metabolites may be useful in characterizing the source and the nature of tritium exposure.