Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Several authors stated that genotoxicity induced by environmental pollutants may involve the interaction of them with DNA, either directly or indirectly via the induction of oxidative stress (Gichner et al. 2008; Patnaik et al. 2011).
Category: