Plant uptakePlant uptake andand human health riskshuman health risks from dietary exposurefrom dietary exposure Ondřej Mikeš Organic nonOrganic non--ionised chemicalsionised chemicals 1. Pathways between soil/plant/air 2. Building model 3. Different crops 4. Chemicals 5. Dietary exposure Research Centre for Toxic Compounds in the Environment, Masaryk UniversityResearch Centre for Toxic Compounds in the Environment, Masaryk UniversityResearch Centre for Toxic Compounds in the Environment, Masaryk University Particle deposition Phloem transportAir/shoot exchange Direct contact with soil Sorption and desorption Evaporation Transpiration stream Xylem translocation Trapp (with permission) • Roots = take up water and solutes • Stems = transport water and solutes • Xylem = dead water pipe • Phloem = living sugar pipe • Leaves = transpire water and take up gas • Fruits = sink for phloem and xylem Research Centre for Toxic Compounds in the Environment, Masaryk University 1. Pathways between soil/plant/air 2. Building model 3. Different crops 4. Chemicals 5. Dietary exposure Research Centre for Toxic Compounds in the Environment, Masaryk University Soil pore waterSoil pore water What is in the solution? Bioavailable CW /CSoil = KWS = ρwet /(Kd x ρdry + PW) Kd=KOCxOC – sorption to soil (organic matter) LogKOC=0.81 logKOW+0.1 (EU,1996) (Abdul, Piwoni, Karickhoff, Molecular connectivity…) CW-in mg/L, CSoil-bulk mg/kg, OC-kg/kg, ρ-kg/L, Pw-pore water fraction in bulk soil KWS Research Centre for Toxic Compounds in the Environment, Masaryk University RootsRoots • Can‘t see them • Livers of the Earth • Monocotyledon –all cereals • Dicotyledon- all root vegetables • Root hairs • Bioavailability Research Centre for Toxic Compounds in the Environment, Masaryk University Diffusion and advectionDiffusion and advection • High surface – equilibrium assumption Change of concentration in roots =Change of concentration in roots = + uptake with water+ uptake with water –– transport to shootstransport to shoots –– dilution by growth or metabolism (rate k)dilution by growth or metabolism (rate k) dCdCRR/dt/dt = + C= + CWWQ/MQ/MRR –– CCXyXyQQ/M/MRR –– kCkCRR wherewhere kk -- growth + metabolism rate [dgrowth + metabolism rate [d--11]] CCXyXy-- concentration in xylem = Cconcentration in xylem = CRR/K/KRWRW CCWW -- concentration in soil pore waterconcentration in soil pore water QQ -- transpiration stream (L/d)transpiration stream (L/d) MM -- Mass of the roots (kg)Mass of the roots (kg) KKRWRW=W=WRR+L+LRR aa KKOWOW bb Research Centre for Toxic Compounds in the Environment, Masaryk University Translocation upwardsTranslocation upwards •• TSCF =TSCF = ””Transpiration stream concentration factorTranspiration stream concentration factor”” •• CCXyXy/C/CW,W, TSCFTSCF≤≤11 •• CCXyXy-- outfluxoutflux from roots = influx to stem or leavesfrom roots = influx to stem or leaves Research Centre for Toxic Compounds in the Environment, Masaryk University LeavesLeaves •• Uptake from roots with transpirationUptake from roots with transpiration waterwater •• Uptake from air (conductanceUptake from air (conductance –– m/sm/s)) •• Loss to airLoss to air •• DegradationDegradation •• Particle depositionParticle deposition •• Soil attachedSoil attached •• Phloem transportPhloem transport KKLWLW=W=WLL+L+LLL aa KKOWOW bb -- leaf/waterleaf/water KKLALA=K=KLWLW/K/KAWAW -- leaf hang in the airleaf hang in the air + CR(Q/MLxKRW) + CA(ALxg/ML) - CL(ALxgx1000Lm-3/KLAxML) - CL(kL) dCL/dt= Leaves are plant material, like roots. But they do not hang in soil nor in water. Leaves hang in air. Research Centre for Toxic Compounds in the Environment, Masaryk University 1. Pathways between soil/plant/air 2. Building model 3. Different crops 4. Chemicals 5. Dietary exposure Research Centre for Toxic Compounds in the Environment, Masaryk University Different crops – phloem, influx to fruits, particles, turtuousity BUT similar model structure http://homepage.env.dtu.dk/stt/ For more information ask me or mail directly to Stefan Trapp stt@env.dtu.dk Research Centre for Toxic Compounds in the Environment, Masaryk University Trapp (with permission) 1. Pathways between soil/plant/air 2. Building model 3. Different crops 4. Chemicals and model 5. Dietary exposure Research Centre for Toxic Compounds in the Environment, Masaryk University Standard Plant uptake modelStandard Plant uptake model Yellow-chemicals entry, blue-concentration, light brown-soil entry, light blue- root entry, dark greenleaves, orange- fruits, grey- calculation (don't touch), white-data entry and results Research Centre for Toxic Compounds in the Environment, Masaryk University Exercise 1Exercise 1 Create 2 graphs for Croot, leaf, corn(steady-state) when: Cair=1.10-6 mg/m3 ,Csoil=1mg/kg,OC=0,02 1st – Kaw=1.10-4, log Kow=-1,2,4,7 2nd– log Kow=2, Kaw= 10-9,10-7,10-5,10-2,101 logKow -1 2 4 7 Croot Cleaf Ccorn Kaw 1,00E-09 1,00E-07 1,00E-05 1,00E-02 1,00E+00 Croot Cleaf Ccorn Research Centre for Toxic Compounds in the Environment, Masaryk University ResultsResults Research Centre for Toxic Compounds in the Environment, Masaryk UniversityResearch Centre for Toxic Compounds in the Environment, Masaryk UniversityResearch Centre for Toxic Compounds in the Environment, Masaryk University 1,00E-03 1,00E-02 1,00E-01 1,00E+00 1,00E+01 1,00E+02 -1 2 4 7 logKow logCplant(mg/kg) Croot Cleaf Ccorn ResultsResults 1,00E-06 1,00E-05 1,00E-04 1,00E-03 1,00E-02 1,00E-01 1,00E+00 1,00E+01 1,00E+02 -9 -7 -5 -2 1 logKaw logCplant(mg/kg) Croot Cleaf Ccorn Research Centre for Toxic Compounds in the Environment, Masaryk University -2 0 2 4 6 8 1 -3 -7 1.00E-02 1.00E-01 1.00E+00 1.00E+01 1.00E+02 leaves/soil log Kow log Kaw Csoil=1 mg/kg Cair = 0 mg/m3 OC= 2% Output from the model SOIL to LEAVESOutput from the model SOIL to LEAVES Low to moderateLow to moderate KowKow Low to moderate KawLow to moderate Kaw Drin´s, HCH´s, low molecular PAH´s hydrophobicity volatility Research Centre for Toxic Compounds in the Environment, Masaryk University Csoil=0 mg/kg Cair = 1E-6 mg/m3 OC= 2% Output from the model AIR to LEAVESOutput from the model AIR to LEAVES HighHigh to moderateto moderate KowKow Low to moderate KawLow to moderate Kaw -2 0 2 4 6 8 1 -3 -7 1.00E-10 1.00E-09 1.00E-08 1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 leaves/air log Kow log Kaw High molecular PAH´s Toxaphene, Chlordane, BDE-99, DDX, Mirex, Highly chlorinated PCB´s hydrophobicity volatility Research Centre for Toxic Compounds in the Environment, Masaryk University 1. Pathways between soil/plant/air 2. Building model 3. Different crops 4. Chemicals 5. Dietary exposure Research Centre for Toxic Compounds in the Environment, Masaryk University Health riskHealth risk “Dosis facit venumum“ Effect = Exposure x toxicityEffect = Exposure x toxicity Exposure – measured or modelled Toxicity – usually measured NOEL/UF Oral exposure Dermal exposure usually US-EPA guidelines Inhalation exposure Dietary exposure measured food concentration needed Research Centre for Toxic Compounds in the Environment, Masaryk University Data collectionData collection Needed: log KOW, KAW, metabolism const., CSOIL,CAIR,CWATER, OC (Env. Journals) Phys-chem • Databases: Mackay, Rippen,Verschueren… • QSAR models : EPISuite,ACD/iLab,MOLPRO... http://www.epa.gov/oppt/exposure/pubs/episuitedl.htm Research Centre for Toxic Compounds in the Environment, Masaryk University Exercise 2Exercise 2 Dietary risk for beta-HCH and BDE-99 : 1st- phys-chem from EPI-Suite programme 2nd- environmental concentrations (lit.-given) 3rd- toxicology profiles US-EPA databases 4th- consumption data (national Czech survey) 5th- plant and risk calculation CAS-60348-60-9 CAS-319-85-7 Research Centre for Toxic Compounds in the Environment, Masaryk University log KOW KAW Ref. CSOIL(WW) (mg/kg) CAIR (mg/m 3 ) SF (mg/kg-day) -1 RfD (mg/kg- day) -1 Ref. BDE-99 6,84 4,82.10 -5 EPISUITE 2,63.10 -6 Hassanin 2004 2,20.10 -8 , AMAP 2003 - 1,0.10 -4 IRIS- US_EPA β-HCH 4,14 2,10.10 -4 EPISUITE 3,41.10 -5 Mikes 2009 1,90.10 -6 , Mikes 2009 1,8 - IRIS- US_EPA Input DataInput Data Women-adult (95%-percentile) units INroot 1,4 g/kg bw/day INleaf 1,94 g/kg bw/day INcorn 5 g/kg bw/day Weight 67,7 kg http://www.epa.gov/reg3hscd/risk/human/rbhttp://www.epa.gov/reg3hscd/risk/human/rb--concentration_table/Generic_Tables/index.htmconcentration_table/Generic_Tables/index.htm http://http://czvp.szu.cz/spotrebapotravin.htmczvp.szu.cz/spotrebapotravin.htm Corg=0,014 (average Czech soil) (1,4%) Research Centre for Toxic Compounds in the Environment, Masaryk University Risk calculationRisk calculation BDE-99 (non-carc): Risk=CDI/RfD CDI=____ RfD= 1E-4 Risk=____ β-HCH (carc): Risk= 1- exp (-CDI * SF) CDI=____ SF= 1,8 Risk=____ BDE-99 (mg/kg) beta-HCH (mg/kg) Food (kg/kg bw day) BDE-99 consumption (mg/kg bw day) β-HCH consumption (mg/kg bw day) Croot Cleaf Ccorn SUMA 7E-7 7E-3 No risk, but! 1E-5 1,8E-5 Risky, but! BDE-99 (mg/kg) beta-HCH (mg/kg) Food (kg/kg bw day) BDE-99 consumption (mg/kg bw day) β-HCH consumption (mg/kg bw day) Croot 6,27E-09 9,97E-06 0,0014 8,78441E-12 1,39624E-08 Cleaf 2,37E-04 1,76E-03 0,00194 4,59799E-07 3,40977E-06 Ccorn 4,76E-05 1,35E-03 0,005 2,38041E-07 6,74114E-06 SUMA 6,97849E-07 1,01649E-05 Research Centre for Toxic Compounds in the Environment, Masaryk University Czech dietary uptakeCzech dietary uptake 0 50 100 150 200 250 300 350 400 450 W aterM ilk products B eer C ereals(bread,corn,rice) Fruits (+tom atoes,beans) Lem onade (+juice,syrup) M eat Potatoes (+fries,crisps) Leafy vegetables W ine R ootvegetables Average consumption in g/day in Czech republic, Ruprich et al., 2006 30% of consumption are plants Fruit model Potato model Leafy model Root model Potential fruit model + water concentration Research Centre for Toxic Compounds in the Environment, Masaryk University Some limitationsSome limitations 1. Non-ionic – ionic diffusion follows NernstPlanck equation 2. Metabolism (Michaelis-Menten kinetics usually more soluble compounds) 3. Growth is considered exponential 4. TSCF calculations 5. Easier approach? Travis and Arms (1988) log BV (dry wt) = 1.588 – 0.578 log KOW 6. On-spot measuring, exposure studies, worst case scenario 7. Always be careful with interpretation risk analysis results Can we eat this fruit or is it too polluted, Eva? Don’t worry – it’s below legal standard, Adam. Trapp (with permission) Research Centre for Toxic Compounds in the Environment, Masaryk University Other dietary/crop models?Other dietary/crop models? •• PatersonPaterson andand MackayMackay(1994),(1994), ChiouChiou(2001)(2001) FantkeFantke(2011),(2011), •• Ionic chemicalsIonic chemicals ((MAMI,MAMI,Trapp, 2009)Trapp, 2009) •• Heavy metalsHeavy metals ((CSOIL,CLEA,FIAM,CSOIL,CLEA,FIAM,Hough, 2001)Hough, 2001) •• Breast milkBreast milk (US(US--EPA,2008EPA,2008,, Trapp, 2009)Trapp, 2009) Research Centre for Toxic Compounds in the Environment, Masaryk University Knowledge to goKnowledge to go • Semi-volatile chemicals • Low Kow (root uptake) High Kow (shoot uptake) • Model is not predicting exact concentration – guide to insight and design experiments • Modelling is easy • Not only air is important • Czech drinks a lots of beer Research Centre for Toxic Compounds in the Environment, Masaryk University Question timeQuestion time