評估農藥的個人與累積暴露和健康風險:以史瓦帝尼的一個農業社區為例

Abstract

"Pesticides are widely used to maintain high crop yields and quality to improve agricultural productivity. As is the case with many other African countries, Eswatini in Southern Africa uses pesticides extensively to support agricultural production, a critical economic activity. Exposure to pesticides poses a significant hazard to pesticide applicators as well as the general population living in close proximity to agricultural farmlands. These agricultural communities may be exposed to pesticide concentrations found in different environmental media such as household indoor air, soil and drinking water. The potential health effects resulting from exposure to agricultural pesticides are very concerning and children are particularly vulnerable. With limited rainfall throughout the year, irrigation water is recycled in Eswatini. This untreated recycled water is potentially contaminated with agricultural pesticides and is not intended for domestic use. However, as clean, uncontaminated water is limited and expensive, residents in rural agricultural communities use recycled water for domestic purposes. Long-term exposure to pesticide residues in the water may result in deleterious health effects. Sugarcane production is an important part of the economy of Eswatini. This study assessed exposure to four commonly used pesticides amongst applicators and residents in an agricultural community in Eswatini: ametryn, atrazine, pendimethalin and 2,4-dichlorophenoxyacetic acid (2,4-D). We collected personal air samples from applicators, as well as samples of household indoor air, from agricultural soil and surface water. Analysis of study samples by liquid chromatography with tandem mass spectrometry (LC-MS/MS) revealed concentration ranges of the four target pesticides in personal air samples during spraying (from not detectable [ND] to 636.11 µg/m3), household indoor air (ND to 3.50 µg/m3), surface water (ND to 0.104 µg/L), and soil (ND to 2.70 µg/g). These results are generally higher than previously published data sourced from developing countries. This study also assessed airborne pesticide levels in applicator and non-applicator households. Notably, the indoor pesticide concentrations in the non-applicator households greatly exceed those in published data, while the ametryn and pendimethalin levels in the applicator households are significantly greater than those in non-applicator households. Daily inhalation exposures to these pesticides resulted in hazard index 95th percentile values greater than 1.0 among children aged 3 years and younger in the applicator households. Thus, the take-home pathway, spray drift, and household-to-field distance are important factors associated with indoor pesticide exposure and health risks, and the take-home pathway is the most important. Our mean concentrations in water samples did not exceed the World Health Organization (WHO) standards for drinking water. Using the CalTOXTM 4.0 beta multimedia exposure model, we conducted a human health and ecological risk assessment on the four pesticides in the study area. We found that ametryn, atrazine and 2,4-D pose the greatest risk, as their total risk exceeded 1.0, especially for children aged 3 years and younger. The ingestion pathway was the greatest contributor to the total risk, which suggests that the consumption of contaminated water by the residents of the study community poses considerable health risks. The ecological risks are <0.1 and suggest that exposures were less than the threshold for fish and aquatic invertebrate species. Of concern is the fact that although all applicators in this study used personal protective equipment (PPE), they nevertheless recorded high inhalation exposure to commonly used pesticides. The findings of this study suggest that pesticide applicators should distance themselves from each other when spraying, to effectively reduce their exposure to pesticides from multiple spraying sources. Further studies are needed to determine the optimal spraying distance between pesticide applicators. It is also recommended that after taking a shower, applicators should change into clean clothes before returning home to their families. This advice is critical for the many families living near agricultural land throughout Africa. Using Eswatini as an example, this case study sought to highlight ongoing concern in regard to potential health and ecological effects from multi-pathway and -route exposures to agricultural pesticide residues in environmental media amongst many African countries."