120 januari 2011 Tamiflu in the environment Caroline Moermond Charles Bodar Lonneke van Leeuwen Mark Montforts Bianca van de Ven Suzanne Wuijts Monique van der Aa Ans Versteegh

20 januari What is Tamiflu? ●Tamiflu = oseltamivir ●Antiviral drug which slows the spreading of viral cells through the body ●Registered in Europe (EMA) in 2002

20 januari Why a risk assessment? ●Swine flu (‘Mexicaanse griep’) – questions raised about environmental impact of flu-related medication ●In the original risk assessment for authorisation, pandemic use and drinkwater quality were not taken into account ●Advice for the ministry of Environment (VROM) at sept. 1, 2009

20 januari Properties of tamiflu ●Oseltamivir ethylester phosphate transforms in the body  first into pro-drug: oseltamivir ethylester  then into active compound: oseltamivir-acid ●In urine: ethylester:acid 1:4 ●Log Kow = 1.21 for ethylester; log Kow = for acid ●Very soluble, low sorption to organic matter ●Almost no hydrolysis or photolysis ●DT50 in water-sediment system is 86 days ●No degradation in surface water in the dark during 60 days ●  very persistent!

20 januari Environmental risk assessment - general ●For human pharmaceuticals, risk assessment is performed according to EMA guideline ●Two phases: –Phase 1: estimation of exposure ›If trigger value of 0.01 µg/L in surfacewater is met  phase 2 ›If compound is a hormone  always phase 2 –Phase 2: environmental fate and effects analysis ›Base set of fate and effects data ›Risk assessment for surface water, ground water, and STP ›If necessary (sorption) also risk assessment for sediment and soil ●Effect characterisation:

20 januari Estimation of exposure ●Predicted Environmental Concentration (PEC) –EMA guideline gives a basic calculation which can be refined using the prevalence of the disease ●Fraction of market penetration is default 0.01 (1%) ●For oseltamivir: daily dose is 150 mg/day for curative use and 75 mg/day for preventive use  PECsurfacewater using default values: 0,70 µg/L  use by 30% of inhabitants of a region: PECsurfacewater = 20.9 µg/L  1 µg/L if 1.5% of all inhabitants is treated. ●(Almost) no degradation in sewage treatment plant!

20 januari Estimation of exposure – are these values realistic? EMA default exposure scenario0.7 µg/L EMA exposure scenario with 30% use20.9 µg/L Singer et al, µg/L KWR calculations for river Rhine during pandemic use1-10 µg/L UK drinking water inspectorate model calculations (Watts and Crane Associates, 2007) Max 107 µg/L Industry models (Straub, 2009)Max 98 µg/L

20 januari Estimation of exposure – are these values realistic? EMA default exposure scenario0.7 µg/L EMA exposure scenario with 30% use20.9 µg/L Rivers in Japan during ‘normal’ flu season (Söderström et al., 2009) Max 60 ng/L STP effluent in Japan 2008/2009 flu season (Ghosh et al., 2010a) Max. 293 ng/L Rivers in Japan 2008/2009 flu season (Ghosh et al., 2010a) Max. 190 ng/L STP influent in Japan 2009/2010 flu season (Ghosh et al., 2010b) Max. 460 ng/L STP influent Rhine catchment area sept. ’09 (Prasse et al.,. 2010) Max. 53 ng/L River in Germany, sept. ’09 (Prasse et al., 2010)Max. 38 ng/L River Rhine, Germany, sept. ’09 (Prasse et al., 2010)Max. 160 ng/L Measurements agreed very well with modeled concentrations Influence from manufacturing plants?

20 januari Estimation of effects: Single species toxicity tests

20 januari Estimation of effects: criteria for toxic effects ●Chronic ecotoxicity studies required by EMA guideline, because exposure is also chronic ●NOEC = no effect concentration ●LOEC = lowest effect concentration ●LC50 = concentration at which 50% of the test animals has died (L=lethal) ●EC50 = concentration at which 50% of the animals show an effect (behaviour, growth, reproduction, etc.)

20 januari Criteria for toxic effects

20 januari Estimation of effects algae + + crustacea fish Aquaticecosystem?

20 januari Estimation of effects ●Predicted No Effect Concentration (PNEC): PNEC = lowest NOEC / 10 ●Use of assessment/extrapolation factor, covering: –intra- and inter-species variation –short-term to long-term extrapolation –intra- and inter-laboratory variation –lab-to-field extrapolation

20 januari Risk characterisation of surface- and groundwater ●PEC/PNEC < 1: negligible risk ●PEC/PNEC > 1: potential risk ●Oseltamivir in surface water: –Worst-case PEC: 20.9 µg/L –PNEC based on lowest NOECs (≥ 1000 µg/L) = ≥ 100 µg/L  PEC/PNEC = ≤ 0.21 ●Oseltamivir in ground water: –Worst-case PEC: 20.9 µg/L / 4 = 5.2 µg/L –PNEC based on lowest NOECs (≥ 1000 µg/L) = ≥ 100 µg/L  PEC/PNEC = ≤ 0.05  no risk for direct ecotoxicity

20 januari Risk characterisation – sewage treatment plants ●PEC for sewage treatment plants is factor 10 higher than PECsurfacewater (no dilution)  PEC = 209 µg/L ●Respiration-inhibition test (OECD 209) was not performed ●Biodegradation tests showed no effect on micro-organisms at 200 µg/L  PNEC = ≥200 / 10 = ≥ 20 µg/L ●Another study showed an effect at 360 µg/L ●PEC/PNEC = ≤ 10.5  potential risk ●There are indications that tamiflu may have an effect on microbial biofilms ●Combined effect of antibiotics and tamiflu unclear

20 januari Risk characterisation – drinking water ●No guidance in EMA guideline ●No general drinking water standard for pharmaceuticals (Drinkwaterrichtlijnen 98/83/EG and 75/440/EEG) ●Because of the enzymatic mode of action, the compound belongs to the group of pesticides  Pesticide drinking water standards: 0.1 µg/L ●General signal value for alle anthropogenic compounds: 1 µg/L ●Expected concentrations of tamiflu during pandemic use are above these values.

20 januari Risk characterisation – drinking water ●Is this a problem? –Oseltamivir does not sorb to organic carbon  active carbon filtration will not remove oseltamivir –Other types of filtration may remove oseltamivir, but data are scarce –The safety margin between the calculated concentrations and human toxicological effect values is large enough not to expect effects.

20 januari Antiviral resistance formation ●Out of scope of this risk assessment ●But: EC50 for influenza virus is ng/L (Gubareve et al., 2001; Monto et al. 2006). EMA default exposure scenario0.7 µg/L EMA exposure scenario with 30% use20.9 µg/L Rivers in Japan during ‘normal’ flu season (Söderström et al., 2009) Max 60 ng/L STP effluent in Japan 2008/2009 flu season (Ghosh et al., 2010a)Max. 293 ng/L Rivers in Japan 2008/2009 flu season (Ghosh et al., 2010a)Max. 190 ng/L STP influent in Japan 2009/2010 flu season (Ghosh et al., 2010b)Max. 460 ng/L STP influent Rhine catchment area sept. ’09 (Prasse et al.,. 2010)Max. 53 ng/L River in Germany, sept. ’09 (Prasse et al., 2010)Max. 38 ng/L River Rhine, Germany, sept. ’09 (Prasse et al., 2010)Max. 160 ng/L

20 januari Questions?