Physical Foreign Materials

Physical foreign materials are hard or sharp objects, such as metal, glass, hard plastic, rubber, wood or stone, that get into food and can injure the person who eats it.

  • Food safety
  • Physical hazards & pests

Physical foreign materials are solid objects that are not part of the food and can cause harm. USDA's Food Safety and Inspection Service describes foreign materials as non-animal objects such as metal, plastic, rubber, glass, wood, steel or lead shot. In a food plant they can come from equipment, for example fragments that break off during mechanical cutting or blending or from wire-mesh belts, and from glass containers that break on the line. FDA's preventive controls guidance treats metal and glass as physical hazards that may need process controls, such as separation devices, metal detectors or X-ray inspection.

FDA's Health Hazard Evaluation Board found that hard or sharp objects 7 to 25 mm long can cause trauma or serious injury, and FDA treats ready-to-eat food containing them as adulterated. Smaller pieces can still hurt infants, surgery patients and older adults. FDA guidance lists tooth damage, cuts to the mouth and throat, and intestinal perforation among glass injuries. Detection is not foolproof, either: stainless steel is hard for metal detectors to find, so prevention at the source matters as much as inspection.

Key facts

Size FDA treats as a hazard
7 to 25 mm in ready-to-eat food
Higher-risk groups
Infants, surgery patients, older adults
Hard-to-detect metal
Stainless steel
FDA example check schedule
Before start-up, at least every 4 hours, end of day

In a bakery or commercial kitchen

  • Walk each process step and note where metal, glass, hard plastic or other objects could enter product
  • Use sifters, screens or magnets on flour and other powders, where FDA says separation devices work best
  • Choose metal detection or X-ray for finished goods; X-ray can also find some non-metal objects such as glass
  • Check equipment and work areas for broken or missing parts before start-up, during runs and at day's end
  • Hold and evaluate everything made since the last good check whenever a fragment or broken part turns up

For home and cottage bakers

  • Take extra care with food for infants and older adults, since fragments under 7 mm can still injure them
  • Report hard or sharp objects in store-bought food to FDA, or to USDA for meat, poultry and egg products

Related entries

Sources

Written by VanillaGoods in our own words from these sources. Last reviewed October 17, 2026.

  1. CPG Sec. 555.425 Foods, Adulteration Involving Hard or Sharp Foreign Objects, U.S. Food and Drug Administration
  2. FSIS Directive 7310.5: Presence of Foreign Material in Meat or Poultry Products, USDA Food Safety and Inspection Service
  3. Hazard Analysis and Risk-Based Preventive Controls for Human Food: Draft Guidance for Industry, Chapter 4 (Preventive Controls), U.S. Food and Drug Administration
  4. Fish and Fishery Products Hazards and Controls Guidance, Chapter 21: Glass Inclusion, U.S. Food and Drug Administration
  5. How to Report a Problem with Food, FoodSafety.gov (U.S. Department of Health and Human Services)