Intradermal injection of tritiated compounds is a commonly used technique in dermatologic investigation. This study demonstrates a rapid loss of tritiated precursors of nucleic acids following intracutaneous injection in mammals. Thirty minutes following injection, less than 8% of the injected dose remains at the local site. In clinical studies with intradermal injections of such tritiated compounds, the dose and number of injections must be minimized, and the same precautions must be exercised as would be if the compounds were injected systemically.
Arndt KA, Freedberg IM. Recovery of Tritiated Thymidine After Intradermal Injection. Arch Dermatol. 1971;103(3):304-305. doi:10.1001/archderm.1971.04000150074010