Environmental Risk Assessment of Pharmaceutical Mixtures: - empirical knowledge, gaps and regulatory options Thomas Backhaus University of Gothenburg

[T]here are known knowns; there are things we know that we know. There are known unknowns; that is to say there are things that we now know we don't know. But there are also unknown unknowns – there are things we do not know, we don't know. Donald Rumsfeld, 2002

Background: Different mixture types Type of mixtureComment Products: Compounds that co-occur in a specific product, i.e. the combination of active pharmaceutical ingredients (API) and excipients Not relevant from an environmental perspective Emissions: Pharmaceutical mixtures that are emitted from a common process or emission source, e.g. in an STP stream from a pharmaceutical production facility Immissions / Multi-Pathway Exposure: NOT intentionally produced complex mixtures, occurring in environmental media, in food or in humans as a result of release and emissions from numerous products and processes Co-exposure with chemicals from other use categories

Prospective: In the context of an application for market approval Retrospective: In the context of the Water Framework Directive or the Marine Strategy Framework Directive Background: Environmental Risk Assessment (ERA)

 Mixtures matter. They constitute the typical environmental exposure situation.  Mixtures are more toxic than each individual pharmaceutical at the concentration at which it is present, and they have an impact on biota at exposed sites.  Compliance with individual environmental quality targets does not necessarily safeguard against unwanted mixture effects.  Mixtures are not magic. Modeling approaches, based on Concentration Addition, Independent Action, provide mixture toxicity estimates with a sufficient precision and accuracy for regulation. Known knowns of mixture ecotoxicology

Recent monitoring studies  STP effluents: in average 24 pharmaceuticals (Kostich et al. 2014)  STP sludge: pharmaceuticals (Jelic, 2009)  Drinking water supply: 6-21 pharmaceuticals (Vulliet, 2011)  The typical exposure is towards pharmaceutical mixtures. Known knowns: Mixtures matter

Known knowns: Mixtures are more toxic & individual thresholds do not safeguard Backhaus, Blanck, Sumpter, 2008: “On the ecotoxicology of pharmaceutical mixtures“, Kümmerer (ed) Pharmaceuticals in the environment, Springer

Known knowns: Mixtures are more toxic & individual thresholds do not safeguard Backhaus, Blanck, Sumpter, 2008: “On the ecotoxicology of pharmaceutical mixtures“, Kümmerer (ed) Pharmaceuticals in the environment, Springer

 Direct testing of the mixture of concern  Drawing conclusions from similar mixtures  Component-based approaches Sidestep: Approaches for mixture testing and risk assessment Depending on the specific context, mixture toxicities can be accounted for by

Sidestep: Mixture toxicity concepts E Mix = Effect of the mixture of n compounds E i = Effect of substance i, when applied singly c i = Concentration of component i in the mixture (i = 1...n) ECx i = Concentration of substance i provoking a certain effect x when applied alone ECx (Mix) = Predicted total concentration of the mixture, that provokes x% effect. pi= relative fraction of component i in the mixture Similarly acting substances: Concentration Addition Dissimilarly acting substances: Independent Action

 Only option when the mixture cannot be tested in its entirety  Are applied in conjunction with whole mixture testing for TIE-studies for the identification of causative links.  Introduces an additional extrapolation step (uncertainty) Sidestep: Component based approaches

 CA and IA assume no interaction between the mixture components  CA and IA assume that each component in the mixture affects the endpoint of interest (i.e. all are toxic) Sidestep: Limitations of component based approaches

Known knowns: Mixtures are more toxic & individual thresholds do not safeguard Backhaus, Blanck, Sumpter, 2008: “On the ecotoxicology of pharmaceutical mixtures“, Kümmerer (ed) Pharmaceuticals in the environment, Springer

Known knowns: mixtures are not magic Three independent replicates analyzing the predictive power of CA and IA in an ecological context 5 component mixture of antibiotics ………. CA IA from: Brosche & Backhaus, 2010

 Mixtures matter  Mixtures are more toxic  Individual environmental quality targets do not necessarily safeguard against unwanted mixture effects.  Mixtures are not magic Modeling approaches, based on Concentration Addition, Independent Action, provide mixture toxicity estimates with a sufficient precision and accuracy for regulation. Known knowns of mixture ecotoxicology

 Legal basis is article 8(3) of Directive 2001/83/EC  Details in EMA guideline EMEA/CHMP/SWP/4447/00 corr 1  Based on a classical tiered approach  Tier 0, the “Action Limit” is based solely on an exposure estimation Prospective ERA of Pharmaceuticals

 Mixtures not considered in the final EMA guidelines  Draft from 2005 for human pharmaceuticals states that "Existing information on synergistic effects in the environment should be included in the risk assessment."  The passage that was dropped in the final guideline  Regulatory ERA of pharmaceuticals lags behind Regulatory ERA of pharmaceutial mixtures

Pesticide Regulation EC 1107/2009 Article 4(2) (approval criteria for active substances, residue levels) stipulates that: “The residues of the plant protection products, […], shall meet the following requirements: (a) they shall not have any harmful effects on human health, including that of vulnerable groups, or animal health, taking into account known cumulative and synergistic effects” Mixture Risk Assessment in other Regulations

Biocide Regulation (EU) No 528/2012: Article 19(2) states that that "the evaluation […] shall take into account the following factors: […] cumulative effects, synergistic effects." Mixture Risk Assessment in other Regulations

Known unknowns: limited information on individual pharmaceuticals MEC max / PNEC Bergmann, Compilation of monitoringdata on pharmaceuticals, Report to the German Environment Agency, 2010

 15 Risk Quotients were calculated using an assessment factor > (Bergmann et al, 2010)  Indicates severe data gaps Known unknowns: limited information on individual pharmaceuticals

Known unknowns: what are the drivers of mixture toxicity? Backhaus et al. Water Research, 2014 The contributions of the different pharmaceuticals are different: ecotoxicological profile of an STP effluent from Gothenburg

Known unknowns: when and how often do synergisms and antagonisms occur? Kortenkamp et al., 2009 Anti-androgenic effect of a mixture of -DEHP -Finasteride -Prochloraz -Vinclozolin

Known unknowns

Conclusions – Known knowns  Act on the available scientific knowledge  Modernize regulatory frameworks  Fill in ecotoxicological data gaps  Improve documentation of data

Conclusions – known unknowns  Which pharmaceuticals are “drivers of mixture toxicity”?  Under which conditions?  Improve exposure assessment  Improve understanding of the relevance of synergisms  How important are pharmaceuticals in comparison to other chemical groups?  Marine systems

Conclusions – Unknown unknowns  Improve Read Across and better integrate ERA & HRA  Ecopharmacovigilance  Incidence reporting  Postmarket monitoring

Environmental Risk Assessment of Pharmaceutical Mixtures: - empirical knowledge, gaps and regulatory options Thomas Backhaus University of Gothenburg