How can limits for cleaning purposes be established?

Although the EMA guideline (EMA/CHMP/CVMP/SWP/169430/2012) may be used to justify cleaning limits (To recommend an approach to review and evaluate pharmacological and toxicological data of individual active substances and thus enable determination of threshold levels as referred to in the GMP guideline. These levels can be used as a risk identification tool and can also be used to justify carry over limits used in cleaning validation.), it is not intended to be used to set cleaning limits at the level of the calculated HBEL. For existing products, manufacturer’s historically used cleaning limits should be retained and can be considered alert limits provided that when taking cleaning process capability into account, they provide sufficient assurance that excursions above the HBEL will be prevented. A similar process should be adopted when establishing cleaning alert levels for products introduced into a facility for the first-time. Results above the alert cleaning limit should trigger an investigation and, where appropriate, corrective action to bring the cleaning process performance within the alert cleaning limits. Repeated excursions above the alert cleaning limit will not be considered acceptable where these indicate that the cleaning method is not in control. Recognised appropriate statistical methods may be used to determine whether the cleaning process is in control or not.