Foreign Body Contamination Control: The Complete Guide

Foreign body contamination (FBC) is a physical‐hazard risk category that spans metal, glass, hard plastics, rubber, bone, stones, and more. Under BRCGS Food Safety Issue 9, FBC controls are concentrated in Clause 4.9 (control of foreign materials) and Clause 4.10 (detection and removal equipment). In the US, FSMA’s Preventive Controls for Human Food (21 CFR 117) requires a documented hazard analysis and risk-based preventive controls for physical hazards, with training and records to prove effectiveness. Together, these frameworks expect a risk-based programme/program backed by validated equipment checks, verified at defined frequencies, and trended over time.

What counts as a “foreign body” (and why regulators care)

Regulators classify hard or sharp extraneous materials (e.g., metal, glass, hard plastic) as potential injury hazards and grounds for product adulteration/recall. Risk rises with fragment hardness, shape, and size. FDA’s long-standing compliance policy explains the public-health basis for controlling these hazards.

Typical sources in plants

  • Processing & maintenance: swarf, fasteners, blade fragments, gasket/seal wear, cable ties.

  • Raw materials & packaging: stones, bone, glass, clips/staples, can/seamer debris.

  • Portable items & PPE: pens, markers, earplugs, plasters/bandages, hairnets, knives. BRCGS Issue 9 raised expectations for controlling portable items and “other” material types via risk-based procedures.

Standards snapshot: BRCGS Issue 9 vs FSMA PCHF

BRCGS Issue 9 (Food Safety)

  • 4.9: Control of foreign materials, including portable items (pens, etc.) and 4.9.6.3 “other foreign materials” requiring risk-based procedures.

  • 4.10: Foreign-body detection and removal equipment (sieves/filters, magnets, metal detectors, X-ray, container inspection) with defined checks and records.

FSMA PCHF (21 CFR 117)

  • Requires a hazard analysis and risk-based preventive controls for physical hazards, supported by monitoring, corrective actions, verification/validation, and records. FDA guidance explains how physical hazards are identified and controlled.

Takeaway: Your FBC programme should map BRCGS 4.9/4.10 requirements to FSMA preventive controls language (where applicable) so one set of procedures satisfies both auditor and regulator.

Build a risk-based FBC programme/program (step-by-step)

Step 1 - Hazard analysis and zoning

  • Map unit operations and the intended use to identify reasonably foreseeable physical hazards (intake → prep → cook → pack → dispatch).

  • Rate severity/likelihood; specify CCPs (critical control points) or preventive controls as appropriate. Use conservative assumptions for ready-to-eat and high-risk consumers.

Step 2 - Control of portable items & small tools (BRCGS 4.9)

  • Establish a portable items register covering pens, markers, cable ties, scrapers, knives/blades, and engineering consumables.

  • Standardise on food-industry designs that are robust and detectable where detection is in use; issue, number/identify, and control changeovers/returns.

Step 3 - Glass & brittle plastics, lighting, and infrastructure (BRCGS 4.9)

  • Maintain a glass & brittle plastic register, defined inspection frequencies, and a breakage response SOP (isolation, cleanup, release).

  • Use shatter-resistant fittings, guards, and covers in open product areas.

Step 4 - Detection & removal equipment (BRCGS 4.10)

Design a layered system. Typical order: sieving/filtration → magnets → metal detection and/or X-ray → container inspection/vision.

  • Sieves & filters: Select mesh by ingredient particle size; define inspection/pressure-drop checks; record integrity failures and investigate.

  • Magnets: Specify type (grate, plate, pipeline, bullet), gauss/pull test method, location, and cleaning schedule; document verification and trend results. 

  • Metal detectors: Use unless a documented risk assessment shows no added protection; justify any absence. Define test frequencies and reject validations.

  • X-ray inspection: Use for products/packaging where metal detection is limited (e.g., foil packs, dense products); define start-up and routine checks, sensitivity limits, and image-reject verification.

  • Vision/optical systems: Apply for non-metal hazards (e.g., stones, plastic) and for pack presentation/closure checks; validate under real illumination/product effect conditions. (Context within 4.10 "foreign-body detection".)

Step 5 - Validation vs verification (make it audit-proof)

  • Validation: Prove the set-up can achieve the intended removal/detection (worst-case product, pack format, line speed).

  • Verification: Document start-up and end-of-run checks for MD/X-ray (and at defined intervals/changeovers), plus sieve/magnet inspections. Use certified test pieces and record outcomes.

Step 6 - Supplier & intake controls (FSMA + BRCGS)

  • Write purchase specs (e.g., mandatory magnet strength at supplier, pre-sieve mesh size, clip/staple policy).

  • Implement incoming screening (sieves/magnets) and COA/COC review; escalate with supplier corrective actions when trends worsen.

Step 7 - People, training, and behaviours

Train operators on recognition of foreign materials, correct response to detector rejects, and do-not-use items (e.g., snap-off blades in high-care). Keep sign-out logs for knives/blades and maintenance tools. (Aligns to BRCGS Site Standards R4/Issue 9 expectations.)

Step 8 - Records, trending, and continuous improvement

Trend rejects per million, false reject rate, magnet findings, sieve failures, and customer complaints. Trigger CAPA for spikes; feed lessons back into the hazard analysis. FDA guidance emphasises this lifecycle approach under preventive controls.

Choosing the right technology

Scenario Recommended control(s) Why
Dry milled flours/spices Grate magnets → fine mesh sieve → metal detector Magnets capture ferrous/SS wear; sieve catches oversize; MD verifies pack.
Foil-wrapped or high-salt products X-ray (plus upstream magnets/sieves) Product effect limits MD; XR sees dense hazards incl. glass/metal.
Viscous liquids/slurries Pipeline magnets/filters → MD/X-ray Inline removal then detection before pack.
RTE salads/produce Vision/optical sorters + sieving where relevant Finds stones/plastic where MD is blind.

How auditors will test you (and how to pass)

  • Show the logic: A hazard analysis that justifies each control (why this mesh? why XR not MD? why magnet grade/position?). FSMA framing helps US sites.

  • Prove it works: Validation study + labelled test piece sizes, materials, and test positions; worst-case product effect considered.

  • Show it keeps working: Start-up/hourly/changeover/end checks for MD/XR, sieve/magnet inspection logs, reject bin controls, and CAPA evidence for failures.

  • Control “everything else”: Evidence you meet 4.9.6.3 for other foreign materials (e.g., cable ties, clips, wood, elastomer fragments) with risk-based controls and registers.

Programme/program documents you’ll need (grab-and-go list)

  1. Foreign Body Control Policy (scope, responsibilities, KPIs)

  2. Portable Items Register + issue/return logs (pens, PPE ancillaries, knives)

  3. Glass & Brittle Plastics Register + breakage SOP

  4. Sieve/Filter SOP (spec, inspection, response)

  5. Magnet SOP (spec, pull-test/gauss method, cleaning, trending)

  6. Metal Detector SOP (sensitivity, product effect studies, test frequencies) + X-ray SOP (image parameters, sensitivity checks)

  7. Test Pieces Control (certificates, storage, annual recertification) 

  8. Supplier/Intake Controls (specs, COA/COC, incoming screening)

  9. Training Matrix (roles vs competencies)

  10. Trending & CAPA (rejects, sieve/magnet findings, complaint analysis)

Special topic: Detectable polymers, seals & gaskets

Elastomer and polymer fragments are a frequent root cause. Where feasible, switch critical parts to detectable grades (PTFE, UHMW-PE, PU, EPDM) so MD/X-ray can find them. Combine with life-time tracking, inspection intervals, and controlled changeovers to reduce breakage risk.

KPIs that demonstrate control

  • Metal/X-ray first pass yield (FPY) and rejects per million (RPM)

  • Magnet findings per tonne/batch and proportion ferrous vs stainless

  • Sieve integrity failures per period and time-to-resolution

  • Complaint rate for foreign materials (by type/source) and recidivism
    Trend monthly and review in food safety team meetings; use results to adjust frequencies/specs (FSMA verification mindset).

Common non-conformities (and quick fixes)

  • Portable items only partially controlled (e.g., pens but not markers, scrapers, cable ties). Fix: expand register; standardise on detectable, one-piece designs; number and issue.

  • Sieve/magnet checks poorly defined (ad-hoc cleaning, no pull-test criteria). Fix: formal SOP, acceptance criteria, and trending.

  • MD/X-ray checks missing at changeovers or end-of-run. Fix: bake these into the line clearance checklist; record failures + corrective actions.

  • “Other materials” not addressed. Fix: risk-based procedures under 4.9.6.3 for wood, elastomers, clips, etc.

Audit-ready checklist (print and use)

  • Documented hazard analysis names each physical hazard and control.

  • Current portable items and glass/brittle plastics registers.

  • Sieve, filter, and magnet specs, locations, and inspection records

  • MD/X-ray validation study + routine verification logs (start-up, changeover, end).

  • Certified test pieces on hand with certificates and calibration dates.

  • Supplier controls (specs, COA/COC, intake checks) and complaint trending with CAPA.

FAQ

What is the difference between validation and verification for metal detection/X-ray?
Validation proves the system can achieve the target detection performance under worst-case conditions; verification are the routine checks at start-up/changeover/end that show it continues to work. BRCGS Issue 9 and its auditor tools expect documented evidence of both.

Do I need metal detection if I have robust upstream magnets and sieves?
BRCGS 4.10.3 expects metal detection unless a risk assessment shows no improved protection; if MD is not used, you must justify and document. In many cases, X-ray is chosen instead (e.g., foil packs).

How does FSMA PCHF view foreign body controls?
FSMA requires a hazard analysis and risk-based preventive controls for physical hazards, with monitoring, corrective actions, verification, and records within your Food Safety Plan.

What test piece sizes should we use?
Sizes and materials should reflect your risk assessment, product, and equipment capability; define them in validation and verify at routine frequencies. Use certified test standards and record results.

When is X-ray preferred to metal detection?
When MD is limited by product effect (e.g., high salt/moisture) or packaging (e.g., foil), X-ray offers broader detection, including some glass, stones, and dense plastics. Validate sensitivity on your products.