Bottom-up surveillance: why digital community adulteration reporting belongs in the European drug early warning architecture

Drug checking services cover only a minority of people who use drugs. This perspective argues that digital community-based adulteration reporting platforms, crowdsourced, anonymous, real-time systems collecting user- and professional-generated reports of suspected adulteration, constitute a complementary surveillance layer that should be formally integrated with the EUDA Early Warning System and national equivalents. Four complementarities between chemical-analysis services and community reporting are identified (epistemic, temporal, coverage, infrastructural), four implementation principles are proposed, and three objections are examined. Three concrete policy steps are outlined: a reference data model under EUDA coordination, formal recognition of community reporting as preliminary evidence within the EWS, and pilot integration workflows in member states with mature drug checking architectures.