RISK PRIORITIZATION AND HUMAN EXPOSURE MODELLING FOR CECS: PESTICIDES CONTAMINATION ORIGINATING FROM RIVER BASIN (CASE STUDY: UPPER CITARUM RIVER BASIN, WEST JAVA)

• Main Author: Retno Utami, Rosetyati
• Format: Dissertations
• Language: Indonesia
• Subjects: Teknik saniter dan perkotaan; teknik perlindungan lingkungan
• Online Access: https://digilib.itb.ac.id/gdl/view/62398
• Institution: Institut Teknologi Bandung

As the water source for Jakarta and West Java, the Citarum River is in a critical condition. The river was stated as one from 10 Most Polluted Places in The World based on an article in The Daily Star in 2013. Among the different forms of pollution, Contaminants of Emerging Concern (CECs) are one of particular concern. CECs can have a harmful impact on both aquatic ecosystems and human health. This study aims to implement a series of risk assessment methods in the UCRB. A series of risk assessment methods developed in this study consist of runoff modelling to predict CECs concentratin in the river water, model validation using passive sampling method, risk prioritization, exposure uptake and hazard quotient estimation, and effect prediction using mathematical model. The method was applied to a group of CECs, i.e. pesticide, which is highly used in UCRB due to its massively farming practices. This study started with estimating the use of pesticides in the agricultural area of UCRB with a survey of 174 farmers in eight districts along the basin by using the random walk and quota sampling method. The survey results showed that 31 different pesticides were used for 21 types of crops. Profenofos and Mancozeb were the two most used pesticides, among all. Overall, the pesticide used estimation in the study area is relatively high, with an annual average of 24.6 kg/ha/year. The data from pesticide used questionnaire survey were inputted into a runoff model to predict pesticide concentration (PECs) in the river water. The model result were validated with Measured Environmental Concentrations (MECs) in the Citarum River by passive sampling technique. The ecological and health risk prioritization methods were applied to both PECs and MECs. Risk ranking of pesticides based on PECs generally showed good agreement with ranking based on MECs by passive sampling. The individual pesticide intake through the consumption of river water was predicted to cause negligible human health risks (i.e. CDI/HRV < 1), but substantial aquatic risks (i.e. PEC/PNEC > 1) were predicted for Profenofos (5.2E+01), Propineb (3.6E+01), Chlorpyrifos (2.6E+01), Carbofuran (1.7E+01), Imidacloprid (9.4E+00), Methomyl (7.6E+00) and Chlorantraniliprole (3.6E+00). From the risk prioritization results, Chlorpyrifos was selected for the next step in this study which is human exposure modelling. In this study, input of the pesticide exposure model can be obtained from a water usage pattern by the communities in UCRB. A questionnaire survey of water usage behaviour was done by face to face interview to 217 respondents from Kampong Ciwalengke where its resident still use Citarum River water as their daily water source. The survey results showed that average total volume of water usage was 114.6 L/person/day. These survey results were used as input of Chlorpyrifos external human exposure model using NORMTOX Model and Monte Carlo Simulation. The NORMTOX probabilistic model output showed that total uptake (from oral and dermal exposure) of Chlorpyrifos from age group of 18-65 years was 2.46E-05 mg/kg/day, and 2.58E-05 mg/kg/day for age group of 65-75 years. While, the model output showed hazard quotient (????????) value for age groups of 18-65 years was 0.0142 dan 0.0202 for age groups of 65-75 years. Chlorpyrifos ???????? values for both groups were predicted to cause negligible human health risks because its values were < 1. However, it should be kept in mind that we did not include other exposure routes and potential interaction between pesticides. The next step for Chlorpyrifos exposure modelling is internal exposure simulation of PBPK/PD Model using RStudio and PopGen software. Chlorpyrifos exposure was modelled for human with average age of 45 years (based on water usage questionnaire survey result) by predicting response of Chlorpyrifos (CPF) and Chlorpyrifos-oxon (CPF-oxon) concentration in blood and brain as its biomarker in human body. The model also simulated the response of ChE enzym inhibition in red blood cell (RBC), blood plasma and brain. Model simulation with Chlorpyrifos exposure range of 0.1 – 100 mg/kg, showed that the higher dose of Chlorpyrifos exposure, the level of CPF and CPF-oxon in blood and brain would be elevated. The simulation also resulted that the higher dose of Chlorpyrifos exposure, enzym activity in RBC, plasma, and human brain will be decreased. Chlorpyrifos exposure was also simulated by age function, where the Chlorpyrifos uptake value of 0.03 µg/kg from NORMTOX Model and 1 mg/kg as comparison control value were inputted into the PBPK/PD simulation. Chlorpyrifos uptake value from NORMTOX Model resulted imperceptible response to human body during a lifetime, while the comparison value showed a response that differ significantly. This result generally showed good agreement with Chlorpyrifos health risk estimation in risk prioritization (RIhum) and hazard quotient (????????) prediction in NORMTOX Model.