Tyrosine is a pharmacologically active or chemically reactive compound used in pharmaceutical manufacturing as an active ingredient, synthetic intermediate, or process reagent, requiring toxicological characterisation to establish protective occupational exposure limits. Available data from in vitro and in vivo studies are evaluated in a weight-of-evidence assessment to identify the critical study, the most sensitive adverse effect endpoint, and the applicable NOAEL or LOAEL that serves as the point of departure for PDE calculation. Data gaps are addressed through read-across from structurally related compounds, (Q)SAR predictions, or application of TTC defaults where scientifically justified.
Genotoxicity data for Tyrosine are assessed under the ICH M7 framework for carcinogenic impurity qualification. A positive Ames test result without a clear non-genotoxic mechanism triggers linear extrapolation from carcinogenicity data, with the acceptable intake derived from the TD50 or the default value of 1.5 µg/day for lifetime exposure product