ABSTRACT
Background: We aimed to study the relationship between the use of pesticides and the health risks faced by Chinese water chestnut farmers in this country. Methods: This cross-sectional survey was conducted among 425 farmers in Sriprachan district, Suphanburi Province, Thailand in 2021. Samples were recruited using the cluster sampling method, and data collection took place through questionnaires. The questionnaire consisted of 3 parts, 76 items, namely personal information of farmers (12 items checklist), the use of pesticides by chemical risk assessment was a 5-point rating scale (40 items), and health risk assessment exposure to pesticides was a 5-point rating scale (24 items). The content validity index for scale (S-CVI) was 0.963 and the reliability with Cronbach's alpha coefficient was 0.904. Data were analyzed using descriptive statistics, chi-square, relative risk, and 95% CI. Results: The overall pesticide use among farmers was at a moderate level (Mean=3.26, SD=0.60). Farmers' signs and symptoms of exposure were compared to their use of pesticides. The pesticide use increased health risks by 15.57 (95% CI: 12.33 to 18.14). Hazard identification was 10.79 higher (95% CI: 8.19 to 13.40). Dose-response assessment was -16.23 higher (95% CI: -17.63 to -14.82). Exposure assessment was 11.49 higher (95% CI: 9.87 to 13.10) and the risk characteristic was -7.46 (95% CI: -8.49 to -6.44). It was statistically significant at <.001. Conclusion: Careless and incorrect use of pesticides by Chinese water chestnut farmers can lead to health risks from exposure to toxic substances.
ABSTRACT
The decolorization of Reactive Blue 19 (RB 19) wastewater by an ozonation membrane contactor and Fenton oxidation was studied. The aims of the study were to investigate the affecting parameters and to compare the performance of RB 19 decolorization by two different processes. The results showed that Fe2+ and H2O2 concentrations for Fenton oxidation and ozone concentration with different membranes for the membrane contacting process played the most important roles in RB 19 decolorization. The optimum conditions for RB 19 decolorization by Fenton oxidation were initial pH 3.0, 1.5 mM H2O2 and 0.25 mM Fe2+; in contrast, the optimum conditions for the membrane contactor were initial pH 11 and 40 mg L-1 ozone concentration. Under these conditions, the decolorization of RB 19 by the membrane contactor was almost completed and was higher than by Fenton and photo-Fenton oxidations for 90 min. The decolorizations of RB 19 by Fenton and photo-Fenton oxidations were constant after 30 min, but the decolorization of RB 19 by ozonation with a membrane contactor gradually increased via ozone consumption until 90 min operation, which was higher than that of Fenton oxidations. The use of a PVDF-PAM membrane in the membrane contactor resulted in higher decolorization efficiency than a PVDF membrane. The results demonstrated a COD removal efficiency of 63% by an ozonation membrane contacting process using PVDF-PAM, which was lower than that of Fenton oxidation (73%), but resulted in higher BOD5/COD and NO3 - and SO4 2- releases. Under these conditions, the ozonation membrane contacting process showed the lowest electric energy consumption.
