There remains a paucity of data directed at improving the mechanistic understanding of sorption, which is critical for improving the understanding of bioavailability and potential for bioconcentration and bioaccumulation. It would thus be prudent to focus future research needs on the development of improved mechanistic understanding. Boxall et al (2012), for instance, provide 20 priority questions that need to be addressed to elucidate the environmental risks associated with pharmaceuticals. The 20 questions represent seven different categories: 1) prioritisation of substances for assessment; 2) pathways of exposure; 3) bioavailability and uptake; 4) effects characterisation; 5) risk and relative risk; 6) antibiotic resistance; and 7) risk management. The questions identified around pathways of exposure and bioavailability is consistent with areas where research would be needed. Specifically:
• What are the environmental exposure pathways for organisms (including humans) to pharmaceutical and personal care products (PPCPs) in the environment and are any of these missed in current risk assessment approaches?
• How can the uptake of ionisable PPCPs into aquatic and terrestrial organisms and through food chains be predicted?
• What is the bioavailability of non-extractable residues of PPCPs?
While this task force has focused on questions pertaining to bioavailability (exposure), there remains a need for improved hazard assessment of ionisable organic compounds. From the 20 questions identified by Boxall et al (2012) the following were related to hazard assessment, including leading effects and dose-response:
• How can pharmaceutical preclinical and clinical information be used to assess the potential for adverse environmental impacts of pharmaceuticals?
• What can be learned about the evolutionary conservation of PPCP targets across species and life stages in the context of potential adverse outcomes and effects?
• How can ecotoxicological responses, such as histological and molecular-level responses, observed for PPCPs, be translated to traditional ecologically important end-points such as survival, growth and reproduction of a species?
• How can ecotoxicity test methods, which reflect the different modes of actions of active PPCPs, be developed and implemented in customised risk assessment strategies?
• How can effects from long-term exposure to low concentrations of PPCP mixtures on non-target organisms be assessed?
• Can non-animal testing methods be developed that will provide equivalent or better hazard data compared to current in vivo methods?