uptake of pharmaceuticals in the terrestrial
TRANSCRIPT
Uptake of pharmaceuticals in the terrestrial environment
Laura Carter, Jim Ryan & Alistair Boxall
Pharmaceuticals in the soil environment
Route of entry Detection
Sewage treatment
Pharmaceutical Concentration (mg/kg)
Carbamazepine < 0.006
Ciprofloxacin < 0.401
Diphenydramine < 0.0011
Diazepam < 0.004
Ibuprofen < 0.0002
Naproxen < 0.0007
Norfloxacin < 0.328
Tetracycline < 0.198
Triclosan < 0.019
Trimethoprim < 0.0006
Effluent
Sludge
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Livestock
Current research
Pharmaceutical research to date has included:Extraction of pharmaceuticals from soils
=> Detection of pharmaceuticals
Uptake of human and veterinary medicines into crops
Fate of pharmaceuticals
in soil
Sorption
Leaching
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Why study uptake ?
Uptake into plants and organisms Bioaccumulation through the food chain
Uptake into plants, especially crops Potential human risk via consumption
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Aims and objectives
To explore factors and processes affecting the uptake of pharmaceuticals in the terrestrial environment
Evaluate the relationship between uptake and chemical properties
Study specific aims:
Study the uptake of pharmaceuticals into earthworms
Evaluate existing models for predicting bioconcentration in risk assessment
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Research approach
ModelUptakeSorption
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Earthworm Uptake
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Study compounds
•All pharmaceuticals were 14 C radiolabelled
Log Kow: 2.25pKa: N/AKd: 4.83
Anti‐hypertensiveNeutral
Log Kow: 4.65pKa: 10.1Kd: 608.42
Anti‐depressantBasic
Log Kow: 4.02pKa: 4.1Kd: 28.65
Anti‐inflammatoryAcidic
Carbamazepine Diclofenac Fluoxetine Orlistat
Log Kow: 8.19pKa: N/A
Kd: 1493.98Weight loss aid
Neutral
*Kd values were determined for the test soil by an adaption of Adsorption – Desorption Batch Equilibrium Method OECD 106 (L/kg)** Log Kow values obtained from KOWWIN v. 1.68 database, USEPA EPI suite 4.1 programme*** pKa Various literature sources (Serrano et al., 2011)
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Study soil
Soil Type *† Clay LoamMoisture content * 17.25 %MWHC * 22.3 g / 100gpH † 6.31OC content † 1.89 %C/N † 11.2Organic material † 3.27 %CEC † 10.3 cmol + / kg
Analysis part completed on site at FERA (*)Remaining determinations sent to INRA soil laboratories (†)
Soil properties
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Study set ‐ up
Earthworm ‐ Eisenia fetida
Soil spiked at environmentally relevant concentrations
Four compounds
Controlled conditions
Analysis validated methods earthworm recovery > 86 %
Uptake phase21 Days
8 Sampling points3 Earthworm samples
Depuration phase21 Days
7 Sampling points3 Earthworm samples
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Supplementary studies
Supporting data
Soil levels over time
Pore water levels
Analysis using validated methods soil (recovery > 83 %)
**Various time points throughout uptake study**
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Earthworm modeling
One compartment first‐order toxicokinetic model • Based on work by Ashauer et al., 2010
OpenModel software1
Used measured pore water concentrations
Bioconcentration factors (BCF) can be calculated from modelled uptake and depuration rates
Model was set to run to equilibrium
12Where Cint is the internal concentration (nmol/kg ww), Cpw is the pore water concentration (nmol/L) and kin and kout the uptake (nmol/kg ww d‐1) and elimination rate constant (d‐1). 1 OpenModel v. 1.2, University of Nottingham, 2008.
Carbamazepine
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Pore water
Soil
Earthworm
Model fit
Diclofenac
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Pore water
Soil
Earthworm
Model fit
Modeling results and bioconcentration
Pharmaceutical Steady state?
Dissipation in test system
Kin(uptake rate) (nmol/kg d‐1)
Kout(depuration rate) (d‐1)
BCFpw
Carbamazepine Yes 30 % 0.2408 0.1393 2.21
Diclofenac No 10 % 0.0363 0.0021 21.46
Fluoxetine Near 20 % 1.1079 0.0471 30.8
Orlistat Near 20 % 0.0708 0.0016 51.53
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Risk assessment
Current earthworm BCFpw estimation techniques:
1) BCFwater based on QSAR (Belfroid et al., 1993)
log BCF = 1.06 (±0.16) logKow ‐ 2.36 (±0.20)
2) TGD BCFpw based on QSAR (Jager et al., 1998)
BCFworm = (0.84 + 0.012Kow)/RHOworm
(Where for RHOearthworm is the density of earthworm and by default a value of 1 (kgwwt/L‐1) can be assumed)
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Bioconcentration factor
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Summary
Different patterns of uptake into E. fetida for different compounds
Acidic pharmaceutical – continuous uptake, steady state not reached at 21 days
Basic and neutral – near steady state
Highly hydrophobic ‐ possible cut off for BCF estimation
Current earthworm BCFpw models overestimate uptake by 6 orders of magnitude
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Future research plan
Analyse worm extracts to check for possible metabolite formation
Repeated test design using different soil types
Changing organic matter content
pH range 5 – 7
Already completed for FLX and CBZ
Different terrestrial invertebrates
Lumbricus terrestris
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Acknowledgments
Professor Alistair BoxallUniversity of York
Dr Jim RyanGlaxoSmithKline
EcoChemistry team at Fera
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Soil extraction
Solvent extraction v. ultrasonic extraction
Various solvents and soil solution ratios
Validation: recovery of spiked soilSolvent
Pharmaceutical Solvent Recovery (% ± SD)
Carbamazepine Methanol 100.6 ± 2.12
Diclofenac Ethyl Acetate 82.83 ± 3.29
Fluoxetine Acetonitrile : Water (7:3)
82.94 ± 1.69
Orlistat Acetonitrile 94.38 ± 7.93
Soil
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Earthworm extraction
Earthworm
Injected 14C compound
Homogenised with solvent into suspension
Shaken
Centrifuged
Supernatant removed for analysis
Pharmaceutical Solvent Recovery (%± SD)
Carbamazepine Methanol 100.85 ±4.74
Diclofenac Ethyl Acetate 108.86 ±3.25
Fluoxetine Acetonitrile : Water (7:3)
86.27 ± 7.72
Orilstat Acetonitrile 88.88 ± 8.52
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Bird exposure risk
Pharmaceutical PEC (mg/kg wwt worm‐1)
Daily food consumption (g)a
DD to bird (mg/bird/ day)
Threshold dose for bird (mg/day)b
Number of worms to eat to exceed threshold
Carbamazepine 0.0228 30 6.86 E‐06 1.83 266 225Diclofenac 0.0278 30 8.34 E‐06 0.11 13 699Fluoxetine 0.0339 30 1.02 E‐05 0.09 8 979Orlistat 0.0326 30 9.79 E‐06 0.14 14 007
a Markham et al., 2008 – 30 g wet weight of invertebrates eaten per day for starlingsb Threshold dose for a bird was calculated by extrapolating from a human threshold value, by mass 27
Bird exposure risk
PECoral,predator =Predicted Environmental Conc. in food [mg/kg wwt earthworm‐1]BCFearthworm = bioconcentration factor for earthworms [L/kg wwt earthworm‐1]Cearthworm = concentration in earthworm [mg/kg wwt earthworm ‐1]Cpw = concentration in porewater [mg.L‐1]Csoil = concentration in soil [mg/kg wwt‐1]Wearthworm = weight of earthworm tissue [kg wwt tissue]Wgut = weight of gut contents [kg wwt]
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BCF calculations
At equilibrium dc/dt = 0Kin – Kout *Cworm = 0Kin = Kout * CwormKin/Kout = CwormSo worm concentration at equilibrium when Cpw is set to 1 is equal to Kin/KoutHence you can calculate BCF with the model instead of using Kin/Kout
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The UK Fish Tissue Archive and its application to EU priority substances
Monika Jürgens1, Andrew Johnson1, Alan Lawlor1, Dave Hughes2,Aşkın Birgül2, Athanasios Katsoyiannis2, Kevin Jones2
(1CEH, 2Lancaster University)
Hg‐CH3
The UK National Fish Tissue Archive
In 2007, CEH and the UK Environment Agency began to build an archive of fish tissue samples from a selection of English rivers.