Dermal exposure to pesticides among sprayers in different agriculture subsectors in Malaysia: observational method using DREAM

Introduction: An assessment of dermal exposure to pesticide mixtures among sprayers was made as a function of crop type, in four agricultural subsectors in Malaysia. Methods: The potential and actual dermal exposures for 160 pesticide sprayers performing pesticide spraying task were estimated by using Dermal Exposure Assessment Method (DREAM). Results: Results showed that there was significant difference between nationality (p<0.001), highest education (p<0.001), monthly income (p=0.002), body mass index (p<0.001) and smoking habit (p<0.001) distributions of sprayers in different agriculture subsectors. Various types of pesticides were used by respondents, where class II (moderately hazardous) and class III (slightly hazardous) pesticides were the most frequently used pesticides. There was a significant difference in both tPDE (χ2 = 118.093, p<0.001) and tADE (χ2 = 84.980, p<0.001) between different agricultural sectors, where the prominent high tPDE was observed among paddy pesticide sprayers (151.39 ± 22.64 DU) while lowest exposure was recorded among oil palm plantation sprayers (47.67 ± 18.47 DU). Conclusion: Based on DREAM exposure categories, majority of the pesticide sprayers (68.9%) working in paddy farming were exposed in low dermal exposure while 26.7% of respondents were exposed to moderate exposure. Pesticide sprayers in other agriculture sectors were exposed to very low to low exposure level. Dermal exposure distributions on body parts were varied between sectors, influenced by several factors such as crop type, height, and spraying methods

Distribution of pesticide emission, deposition and transfer among pesticide sprayers in Malaysian Agriculture Subsectors

Introduction: Extensive use of pesticides appears to be one of the issues that affect the future roles of the agricultural economy, due to occupational disease and poisoning cases associated with pesticide exposure. Emission, deposition and transfer are three main routes involved in transporting pesticide from its sources to the skin surface. This current study was aimed to analyze the distribution of dermal exposure to pesticide on body parts. Methods: A total of 160 pesticide sprayers working in paddy, vegetable, cocoa, and oil palm plantations participated in this study. Dermal Exposure Assessment Method (DREAM) was used to evaluate dermal exposure to pesticide caused by emission, deposition and transfer routes. The Kruskal Wallis Test was used to identify the differences on exposure routes be- tween agriculture sectors. Results: There was significant difference of total exposure through emission, deposition and transfer among sprayers in different farming sectors (p<0.001). Pesticide sprayers in paddy fields have the highest pesticide exposure through deposition (144.31 ± 30.23 DU) and transfer (30.54 ± 1.19 DU), particularly on upper body parts. Meanwhile, vegetable pesticide sprayers were exposed the most on lower body parts, caused by depo- sition of spray droplets from low crop spraying. Emission found to contribute the least of the total exposure among pesticide sprayers in all agriculture sectors, which may indicate less occurrence of major leaks, splashes and spills during pesticide spraying. Conclusion: This study provides insights of exposure assessment, where intervention strategies could be developed with priority given for exposure reductions from relevant exposure routes

Dermal exposure assessment of glyphosate herbicide among pesticide handlers in selected agriculture sectors in Malaysia

Malaysian farmers are still relying on pesticides to govern agriculture activities. Occupational exposure to pesticides can adversely affect farmers’ health, especially those in developing countries where the methods for evaluating dermal exposure are not reasonably well standardized. Therefore, this study aimed to assess dermal exposure and health symptoms among pesticide handlers in selected agriculture sectors in Malaysia (i.e., paddy, vegetable, cocoa and oil palm). This cross-sectional study was conducted in 2016 in four sampling locations, been divided into three sub-studies which are; 1) Dermal exposure assessment using DREAM, 2) Dermal exposure assessment using whole-body dosimetry (WBD) method and 3) Identification of health symptoms. In the first sub-study, socio-demographic characteristics, information on pesticide application and dermal exposure information were assessed. Then, total potential (tPDE) and actual dermal exposure (tADE) among pesticide handlers were determined using DREAM model, and factors affecting the exposure were analysed using logistic regression analysis. In the second sub-study, the concentration of uranine as pesticide surrogate and total PDE were determined using the WBD method. The correlations between the measurements with tPDE from DREAM (Sub-study 1) were then analyzed by estimating the Spearman correlation coefficient. In the third sub-study, health symptoms of skin problems and pesticide poisoning perceived by respondents after pesticide spraying were identified. Then, the association between DREAM data and perceived health symptoms was determined through logistic regression analysis. Based on DREAM, tPDE estimates between different agricultural sectors were significantly different (χ 2 = 118.093, p < 0.001). The prominent highest exposure was recorded among paddy field sprayers (151.39 ± 22.64 DU), and the lowest exposure was among respondents in oil palm plantation (47.67 ± 18.47 DU). The factors significantly related to high tPDE (≥100 Dermal Unit) were pesticide deposition, sprayer’s age, gloves usage and immediate clothes changing after pesticide spraying. The total amount of uranine on Tyvek. sections of respondents in the paddy field was 0.281 mg/kg, followed by respondents in oil palm (0.043 mg/kg), vegetable (0.042 mg/kg) and cocoa farming (0.013 mg/kg). The total potential dermal exposure (PDE) was significantly highest among respondents in paddy field with a mean total PDE of 1.56E-03±1.73E-04 (p < 0.001). A significant positive correlation was found between logged total PDE estimates from DREAM and logged total PDE measured through WBD (rs =0.752, p=0.001). Most of the respondents in the paddy field reported having skin itchiness (53.3%) and itchy wheals (24.4%), while respondents in vegetable farm reported increased salivation (29.4%), diarrhoea (14.7%), urinary frequency (23.5%), cramps (26.5%), muscle weakness (29.4%) and restlessness (17.6%). Total PDE from DREAM was the only variable that significantly contributed to the logistic regression model associated with skin problems and pesticide poisoning symptoms. Our study supports that DREAM able to provide estimates of exposure levels among respondents, gives insight into the distribution and route of dermal exposure, and can be associated with health symptoms. Nevertheless, DREAM estimates on variability in the distribution of dermal exposure on body parts over the measurement data should be further verified for model improvement. (494 words)

Removal of heavy metals and surfactants using activated carbon from wood waste

Activated carbon prepared from wood waste was evaluated as a low cost adsorbent for the removal of heavy metals Copper (II) and Zinc (II), and surfactants (sodium dodecyl sulfate and 3-(N,N- imethylmyristylammonio)propane sulfonate). The effects of pH, initial ion concentration and temperature were studied. Adsorption studies were conducted using initial Copper (II) and Zinc (II) concentration between 5 to 35 mglL, pH range from 2 to 10 and temperature between 30-60 0c. The adsorption capacity for both metals was highest at pH range from 6 to 8. The equilibrium data were satisfactorily fitted to Langmuir and Freundlich isotherms with highest metal uptake of 14.8 and 16.31 mglg were observed for Copper (II) and Zinc (II) respectively at initial pH 6-8 and temperature of 30°C. Adsorption of surfactant was conducted with initial surfactant concentration between 200 to 800 mglL, and pH from 2 to 10. However, the adsorption data of surfactant was unsatisfactorily fitted both Langmuir and Freundlich isotherm models. Both isotherm models represent unfavorable adsorption