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  2. My purpose for participation of the training program To understand the general ideas of ecological risk assessment for pesticide To construct the basic know-how for conducting relevant researches on ecological risk assessment of pesticide

  3. What I have achieved so far • General framework Human Risk assessment for environmental chemicals • General framework of ecological Risk assessment for pesticide • About SIMULATION MODEL PCBF-1 • Relevant instrumental techniques

  4. Research/ testing Risk Assessment Clinical studies Epidemiology Toxicology studies Hazard identification Dose-response Assessment Risk characterization Data on levels of chemicals in the environment and on rates of human contact with and exposure to Human Exposure Assessment Frameworks for Risk assessment for environmental chemicals

  5. Research and testing • Clinical studies and epidemiology • Toxicology studies • Exposure studies

  6. Clinical studies and epidemiology • If any, all the clinical and epidemiological evidences concerning the adverse effects of given chemical on human body will be reviewed as to support the hazard identification.

  7. Toxicology studies • Provide information for hazard identification if epidemiological and clinical evidence is absence ( for example, new chemical) or not enough • .Provide information for dose-response assessment • Contents of the studies are subject to the specific chemicals, chemical management regulations and toxicology studies guidelines, etc.,

  8. Exposure studies • Data on levels of chemicals in the environment and on rates of human contact with and exposure to are reviewed

  9. Hazard identification • With the information from clinical and epidemiology or toxicology studies, the following questions can be answered: • What chemicals? • What toxic effects? • What mechanisms of toxic action? • Relevance to humans?

  10. Dose-response assessment • How does risk of toxic effect change with dose? • During the phase, a Dose-response curve and NOAEL will be obtained to show the incidence or severity of specific adverse health effects.

  11. Human exposure assessment • With information from exposure studies the following question are to be answered: • What population? • What dose? • What route of exposure? • Over what period of time?

  12. Risk assessment • With information from hazard identification, dose-response assessment as well as the human exposure assessment, the following questions are to be answered during this phrase: • Is there a risk to health? • What is it’s magnitude? • How well is it known?

  13. Frameworks for Ecological Risk assessment for pesticides Hazard studies Core data requirement for AIs Further studies requirements on AIs Additional study requirement for EUPs Higher tier and field study Risk characterization Risk assessment and management Exposure studies pesticide use pattern pesticide fate Route of entry Water body of concern Mathematical models for generating exposures Subject I ‘m interested

  14. About PCPF-1 General information • Components of the model • Basic parameters

  15. General information • PCPF-1 model is a simulation model for predicting pesticide concentrations in paddy water and surface soil through simulating the fate and transport of pesticide in paddy water and 1cm deep oxidative paddy surface soil layer, or the pesticide source layer (PSL)

  16. Components of the models • Water balance equation in paddy field • Mass balance equation in paddy field water compartment • Mass balance equation in surface soil(1cm)

  17. dh [ ] = * + - - - W A A RAIN IRR DRAIN PERC ET dt Water Balance Equation in Paddy Field A: Area of Paddy Field(L2) dh / dt: Temporal change of paddy water depth(LT-1) RAIN: Precipitation(LT-1) IRR: Irrigation(LT-1) DRAIN: Outflow(LT-1) PERC: Percolation(LT-1) ET: Evapotranspiration(LT-1)

  18. ) d(C h = W W A dt C - + - W A h k (C C ) Ah ρ k (C ) - - W dissol slb W Source b Source des S Source ρ W + - - A IRR C A DRAIN C A PERC C - W IRR W W æ ö dE + - - ç ÷ UVB - C Ah k k C - W PHOTO BIOCHEM W W è dt ø Mass Balance Equation in Paddy Water Compartment hW: Depth of paddy water (L) CW: Pesticide concentration in paddy water (ML-3) kdissol: Dissolution rate constant of pesticide (T-1) Cslb: Water solubility of pesticide (ML-3) hSource: Depth of surface soil(L) bSource:Balk density of surface soil (ML-3) kdes: Desorption rate constant (T-1) CS-Source: Pesticide concentration in surface soil (MM-1) CW-IRR: Pesticide concentration in irrigation water (ML-3) kHYD: Hydrolysis rate constant of pesticide (T-1) kPHOTO: Photolysis rate constant of pesticide (L1M-2T2) dEUVB-C/dt: Temporal change of cumulative UV-B radiation (L1M-2T) kBIOCHEM-W: Biol.+ Chemical degradation rate constant of pesticide (T-1)

  19. æ ö Ah θ dC ç ÷ + = - - Source Sat Source S Source Ah ρ ç ÷ - Source b Source k dt è ø d 1 + - + - (Ah θ Ah ρ k )k (C C ) A PERC (C C ) - - - Source Sat Source Source b Source d dissol slb W W S Source k d C 1 - - - W Ah θ k C Ah ρ k (C ) - - - - - Source Sat Source BIOCHEM S S Source Source b source des S Source k ρ d W Mass Balance Equation in Surface Soil(0-1cm)Compartment hSource: Depth of surface soil (L) Sat-Source:Saturated volumetric water content (L3L-3) kd: Adsorption coefficient (LM-3) dCS-Source /dt:TemporalChange of pesticide concentration in surface soil (MM-1T-1) CS-Source: Pesticide concentration in surface soil (MM-1) kBIOCHEM-S: Degradation rate of pesticide in surface soil(T-1)

  20. Input parameters for paddy water Unit 1 Maximum simulation period day 2 Time interval day 2 3 Application rate g/m 2 4 Paddy field area m 5 Water solubility of the pesticide mg/L 6 The dissolution rate constant 1/day 7 The 1st phase desorption rate constant* 1/day 8 The 2nd phase desorption rate constant* 1/day 9 Mass transfer coeff. of pesticide volatilization m/day 2 10 The 1st order photolysis rate constant m /kJ 11 The biochemical degradation rate constant 1/day 12 Pesticide concentration in irrigation water mg/L 13 Phase intercept concentration for desorption mg/L Input parameters for surface soil Unit 14 Depth cm 3 15 Particle density g/cm 3 16 Bulk density g/cm 3 3 17 Saturated volumetric water content cm /cm 18 Adsorption coefficient (Kd)* L/kg 19 The 1st phase degradation rate constant* 1/day 20 The 2nd phase degradation rate constant* 1/day Input parameters and data files for PCPF-1 simulation <Parameters> <Data files> • Daily water balance data • (precipitation, irrigation, • percolation and evapo- • transpiration) • Daily UV-B radiation data • (below rice canopy) *: Sensitive parameters

  21. Relevant instrumental techniques • Through about 14 days practice in Horiba, Shimazu, and Hitachi company we have studied the basic theories and analytical operation for the following lab instruments:

  22. Atomic absorption spectrophotometer • High performance liquid chromatography • Gas chromatography • LC/MS • Water quality analyzer • Spectrophotometer

  23. Interesting and Beneficial subjects list • Introduction and Agrochemicals (Hideo Ohkawa) • Behavior of Pesticide in Paddy Field, Prediction and Control of the Fate Using Simulation Model (Kazuhiro Takagi) • Ecological Risk Assessment of Environmental Chemicals (Masaru Nokata) • Safety Evaluation of Chemical Substances (Shigeki Miyachi) • Lab practices in HPTCAFF

  24. Subjects expect to be followed up • The relatively detailed study on the simulation models (PCPF-1) • Further strengthening for what we have studies over analytical instrument particularity HPLC, GC and GC-MS • Pretreatment techniques for soil samples

  25. Theme for action plan • An Initial Studies on Application of a Simulation Model(PCBF-1)for Predicting Pesticide Concentration in Paddy Water and Surface Soil in Paddy Field in Guizhou Province

  26. Thank you!

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