Regulatory trigger values: Appropriateness, assumptions and gaps in science

EMA ERA Guidance (EMEA, 2006) currently uses a KOC > 10,000 l/kg as a trigger for a Tier B terrestrial data package. The KOC trigger value is based on a Kd of 3,700 l/kg sludge with an organic carbon content of 37% (EMEA, 2006). The questions and answers document (EMA, 2010) requires that a sludge KOC value be determined using a batch equilibrium method and that HPLC method is not suitable for such a Tier B trigger assessment.

The trigger value implies that, when PEC surface water exceeds 0.01 ìg/l and the KOC for the test material exceeds 10,000, there is a potential risk for the terrestrial compartment. It is not clear whether the current trigger is protective of the terrestrial compartment for circumstances of a high volume compound with a KOC value lower than 10,000. There is also a need to update the original terrestrial data set with new data generated since 1997 for both human and veterinary pharmaceuticals, and then reassess the appropriateness of the trigger. It would be helpful to broaden the number of classes of pharmaceutical active ingredients represented in the original data set beyond that of antibacterial, antimicrobial, anticoccidal, parasiticides and performance enhancers (Schmitt et al. 2010).