Justify residue acceptance limits
Carryover limits require toxicological justification and consideration of equipment trains.
CV-REQ-000002
EU GMP Annex 15: Qualification and Validation§ 10.6
TOPIC EXPLORER
MACO
Translating an exposure assessment into a justified carryover limit.
2 connected references
Distinguish HBELs from cleaning alert limits
An HBEL is not automatically the operational cleaning limit.
CV-REQ-000022
HBEL and cross-contamination: questions and answers§ Q6
Practical guidance
The State of Cleaning Validation 2026: Five Developments Reshaping the Field
Two years of regulatory revision, enforcement, new standards, tighter analytics and a first serious statistics stack have moved cleaning validation out of the appendix and into the centre of GMP. Five developments define where the field stands in September 2026 — and each one changes something a programme owner has to decide.
Visual Clean Is Important — but When Is It Enough?
Visual inspection was present in every one of the cleaning findings FDA issued between 2024 and 2026 — never as the accused technique, always as the whole of the evidence. The distinction between a qualified visual method and a visual-only release decision is the difference between a control and an assumption.
A MACO Is Only as Good as the Assumptions Behind It
A maximum allowable carry-over value is a PDE multiplied by a set of process assumptions — batch size, dose, surface area, recovery and the cleaning step itself. Read as a body of evidence, the 2025–2026 enforcement record is rarely about toxicity assessment, and almost always about those assumptions.
PIC/S Publishes PI 006-4: A New Qualification and Validation Recommendation Takes Effect in October
PIC/S has published PI 006-4, the revised Recommendations on Qualification and Validation, superseding the 2007 PI 006-3 and entering into force on 1 October 2026. Cleaning validation now occupies a full chapter, with HBEL-driven scope, explicit limits on visual inspection and a clear position against continued test-until-clean practice.
FDA Challenges a Visual-Only Cleaning Validation Strategy
A 2026 FDA warning letter to Dabur India rejects a shared-equipment cleaning programme that relied exclusively on visual inspection. The objection is narrower than it appears — and it turns on missing quantitative limits, not on visual inspection itself.
What FDA Has Been Citing in Cleaning Validation: The Recurring Themes of 2025–2026
Twelve FDA warning letters issued between 3 December 2024 and 24 July 2026 cite cleaning and cross-contamination control. Read together rather than case by case, they stop looking like twelve incidents and start looking like one audit checklist: worst-case selection, hold times, recovery, MACO justification, visual-only strategies, sampling locations, change control and lifecycle management — in that order of frequency.
ADCs Are Creating a New Cleaning Validation Problem
Antibody-drug conjugates combine a biologic, a chemical linker and a cytotoxic payload on shared equipment. A STERIS webinar frames the problem; independent guidance shows why one product-specific assay no longer answers the question.
Peptide APIs Put Cleaning Limits Under the Microscope: FDA Cites Missing MACO for Semaglutide and Tirzepatide
FDA's 1 May 2026 warning letter to Harbin Jixianglong Biotech found a cleaning procedure that required a toxicity-based carryover limit, and a validation study that established none — with no justification for swab locations and no swab results.
AI Enters Continued Cleaning Process Verification — but the Statistics Come First
A January 2026 AAPS PharmSciTech paper proposes normalising every residue result to a percentage of its own specification limit, so that cleaning data from different products can finally be pooled, analysed non-parametrically and monitored as a Stage 3 capability index. The statistical argument is the substance; the AI framing is thinner than the title suggests.
ASTM Updates Its HBEL Guide: What E3219-25 Means for Cleaning Validation
ASTM has re-issued E3219 as E3219-25, the current reference for deriving health-based exposure limits. HBELs are a decade-old regulatory expectation, not a 2025 novelty — but the revision sharpens how limits are derived, documented and defended.
INTERPHEX 2025: Process Monitoring Reaches the Cleaning Suite
INTERPHEX 2025 in New York put cleaning validation on the process-monitoring agenda: a dedicated panel on analytics, contamination control and sustainability, plus cleanroom and environmental-monitoring sessions. Industry-press report from Javits Center, 1-3 April 2025.
When MACO Is Not Enough: What the Granules India Warning Letter Really Teaches
The FDA rejected a retrospective MACO argument in a February 2025 warning letter — not because the arithmetic was wrong, but because the cleaning it assumed had not been performed. What cleaning-validation teams can take from it.
What Happens to Biologics During Cleaning? New Data on Cleaning-Induced Protein Degradants
A bench-scale study puts the 650 ug/dose parenteral PDE for cleaning-induced protein degradants to the test with human-cell immunogenicity assays on HLE BiTE and mAb degradants, spiked into the same and a cross product.