Environmental Technology, Wageningen University and Research, P.O. Box 17, 6700AA, Wageningen, the Netherlands.
Environmental Technology, Wageningen University and Research, P.O. Box 17, 6700AA, Wageningen, the Netherlands.
Int J Hyg Environ Health. 2022 Jul;244:114002. doi: 10.1016/j.ijheh.2022.114002. Epub 2022 Jun 24.
Ensuring safe irrigation practices is vital to sustaining food production in water-scarce delta areas. Bangladesh and many other developing countries discharge untreated wastewater into their surrounding surface water bodies, serving as the primary irrigation source. This indirect irrigation of wastewater is believed to pose threats to the farmers, consumers and market vendors and may also affect crop and soil quality. To assess the risk, peri-urban farmers who use surrounding water bodies of Khulna city, Bangladesh, for crop irrigation were selected for the study. The microbial and heavy metal concentrations were measured in water samples collected from various locations over different seasons. For heavy metals As, Co, Ni, Cd, Cr, Cu and Pb, concentrations were below the detection limit, whereas Al, Fe, Mn, Ti and Zn were present but below the FAO recommendation limit for safe irrigation. The mean concentrations of microbial parameters were above the thresholds of WHO guidelines for crop irrigation intended for human consumption. Significant temporal variations in Faecal Coliform, E. coli and Enterococcus concentrations in the water samples were observed. The annual risk of infection for farmers was determined using the screening-level Quantitative Microbial Risk Assessment (QMRA). The results indicated that the annual probability of infection with pathogenic E. coli in different seasons ranges between 5 × 10 to 5 × 10, above the WHO's acceptable threshold for annual risk of infection for safe water reuse in agriculture. During the farmers' survey, around 45% reported health-related issues and more than 26% reported suffering from water-borne diseases after getting in contact with polluted surface water. This illustrates the actuality of the risks in practice. To ensure safe irrigation, the health risks need to be reduced below the acceptable limits. Suggested technical measures include adequate treatment of wastewater before disposal into rivers and access to protective equipment for farmers. This should be complemented by raising awareness through education programs among farmers to reduce accidental ingestion.
确保灌溉安全实践对于维持水资源匮乏的三角洲地区的粮食生产至关重要。孟加拉国和许多其他发展中国家将未经处理的废水排入周围的地表水，作为主要的灌溉水源。这种对废水的间接灌溉被认为对农民、消费者和市场摊贩构成威胁，也可能影响作物和土壤质量。为了评估风险，选择了孟加拉国库尔纳市周边水体进行作物灌溉的城市周边农民进行了研究。在不同季节从不同地点采集水样，测量水样中的微生物和重金属浓度。对于重金属砷、钴、镍、镉、铬、铜和铅，浓度低于检测限，而铝、铁、锰、钛和锌虽然存在，但低于粮农组织推荐的安全灌溉限值。微生物参数的平均浓度高于世卫组织供人类食用的灌溉作物用水指南的阈值。在水样中观察到粪便大肠菌群、大肠杆菌和肠球菌浓度的显著时间变化。使用基于筛选的定量微生物风险评估（QMRA）确定农民的年感染风险。结果表明，不同季节致病性大肠杆菌的年感染概率在 5×10 到 5×10 之间，高于世卫组织对农业安全水再利用的年度感染风险可接受阈值。在农民调查中，约 45%的人报告了与健康有关的问题，超过 26%的人在接触受污染的地表水后报告了水传播疾病。这说明了实际存在的风险。为了确保安全灌溉，需要将健康风险降低到可接受的水平以下。建议的技术措施包括在将废水排入河流之前进行充分处理，以及为农民提供防护设备。这应辅以通过教育计划提高农民的认识，以减少意外摄入。
