There are increasing concerns about the hazard posed to drinking water resources by persistent, mobile, and toxic (PMT) substances in the environment. For example, the extensive use of metaldehyde-based molluscicide to control slug populations in agricultural fields has frequently led to pollution of surface waters and contamination of drinking water at levels exceeding the statutory limit. Regulatory environmental fate assessments and studies in the literature did not predict that metaldehyde would be persistent in the environment, contrary to observations from monitoring schemes. To understand the reasons for this disparity, this study conducted a suite of degradation experiments, covering different soil types and environmentally realistic conditions in Northern Europe, and generated a distribution of DT₅₀ values for metaldehyde to examine whether degradation rates are underestimated by current risk assessments. The results were found to vary, showing DT₅₀ values ranging from 3.0 to 4150 days, which indicated that metaldehyde had the potential to become persistent. Lack of prior metaldehyde exposure, high moisture content, low temperature, and locally high metaldehyde concentration under pellets were identified as high-risk conditions for low pesticide biodegradation in UK soils.

人们越来越担心环境中的持久性、流动性和有毒 (PMT) 物质对饮用水资源造成的危害。例如，在农田中大量使用以甲醛为基础的杀软体动物剂控制蛞蝓种群，经常导致地表水污染和饮用水污染超过法定限值。与监测计划的观察结果相反，监管环境归宿评估和文献研究并未预测甲醛会在环境中持久存在。为了解造成这种差异的原因，本研究进行了一系列降解实验，涵盖北欧不同的土壤类型和环境现实条件，并生成了 DT ₅₀的分布值，以检查当前的风险评估是否低估了降解率。发现结果各不相同，显示 DT ₅₀值从 3.0 天到 4150 天不等，这表明乙醛有可能变得持久。先前未接触过甲醛、水分含量高、温度低和颗粒下局部高浓度的甲醛被确定为英国土壤中农药生物降解率低的高风险条件。