Overview
The Global Environment Monitoring System — Food Contamination Monitoring and Assessment Programme (GEMS/Food) is the WHO’s global repository of individual-measurement contaminant occurrence data: one record per sample, per analyte, per food, with the food (Codex food code), region, year, detection limit (LOD/LOQ), sampling representativeness, food origin, and analytical basis. It is the authoritative, agency-curated occurrence dataset that national exposure assessments and the JECFA evaluations draw on, which is why it is graded A-tier here.
This source is not a paper and is not ingested through the PDF/Cochrane pipeline. It enters the wiki as structured occurrence data through tools/evidence/ingest-gems.mjs, which streams the raw CSVs (held in raw/, never committed — Cd alone is ~190 MB), normalises units to ppb (µg/kg), separates censored (below-detection) from detected measurements, keeps wet (“as is”) and dry bases apart, and emits per-(analyte × food × basis) distribution aggregates to the structured evidence register. Every value derived from GEMS carries source_id: who-gems-food-database for provenance, so any cell can be re-derived from, or contested against, the GEMS records.
Coverage in this export
The June 2026 export covers Pb, Cd, tHg, iAs/tAs, Al, Cr, Ni, and Sn across the full Codex food taxonomy, with dedicated infant-and-children subsets for the priority analytes. Record counts run to hundreds of thousands per analyte (Lead ~588k rows; Cadmium larger).
How GEMS feeds contamination profiles
GEMS distributions are pooled, per the synthesis methodology, into the contamination_profile blocks on ingredient and product pages: the detected-value percentiles supply typical_ppb and p95_ppb, the record count supplies sample weight, and the censoring fraction and per-region/per-year spread supply the geographic and temporal variance the defensibility argument relies on. The GEMS food taxonomy maps to wiki ingredient/product slugs through the food crosswalk before any value lands on a page.
Update history
This page has no substantive edit history yet. Future revisions will be recorded here once the change lands in git.