Faculty of Chemical Engineering, Muenster University of Applied Science, Stegerwaldstrasse 39, 48565, Steinfurt, Germany.
Department für Hepatobiliäre Chirurgie und Viszerale Transplantation, Universität Leipzig, Liebigstrasse 20, 04103, Leipzig, Germany.
Arch Toxicol. 2020 Jul;94(7):2319-2329. doi: 10.1007/s00204-020-02762-x. Epub 2020 May 5.
Lead (Pb) exposure of consumers and the environment has been reduced over the past decades. Despite all measures taken, immission of Pb onto agricultural soils still occurs, with fertilizer application, lead shot from hunting activities, and Pb from air deposition representing major sources. Little is known about the intermediate and long-term consequences of these emissions. To gain more insight, we established a mathematical model that considers input from fertilizer, ammunition, deposition from air, uptake of Pb by crops, and wash-out to simulate the resulting Pb concentrations in soil over extended periods. In a further step, human oral exposure by crop-based food was simulated and blood concentrations were derived to estimate the margin of exposure to Pb-induced toxic effects. Simulating current farming scenarios, a new equilibrium concentration of Pb in soil would be established after several centuries. Developmental neurotoxicity represents the most critical toxicological effect of Pb for humans. According to our model, a Pb concentration of ~ 5 mg/kg in agricultural soil leads to an intake of approximately 10 µg Pb per person per day by the consumption of agricultural products, the dose corresponding to the tolerable daily intake (TDI). Therefore, 5 mg Pb/kg represents a critical concentration in soil that should not be exceeded. Starting with a soil concentration of 0.1 mg/kg, the current control level for crop fields, our simulation predicts periods of ~ 50 and ~ 175 years for two Pb immission scenarios for mass of Pb per area and year [scenario 1: ~ 400 g Pb/(ha × a); scenario 2: ~ 175 g Pb/(ha × a)], until the critical concentration of ~ 5 mg/kg Pb in soil would be reached. The two scenarios, which differ in their Pb input via fertilizer, represent relatively high but not unrealistic Pb immissions. From these scenarios, we calculated that the annual deposition of Pb onto soil should remain below ~ 100 g/(ha × a) in order not to exceed the critical soil level of 5 mg/kg. We propose as efficient measures to reduce Pb input into agricultural soil to lower the Pb content of compost and to use alternatives to Pb ammunition for hunting.
在过去几十年中，消费者和环境中的铅 (Pb) 暴露水平已经降低。尽管已经采取了所有措施，但农业土壤中的 Pb 仍在不断输入，肥料的施用、狩猎活动中的铅弹以及空气沉降中的 Pb 是主要来源。人们对这些排放物的中长期后果知之甚少。为了更深入地了解这一点，我们建立了一个数学模型，该模型考虑了肥料、弹药、空气沉降、作物对 Pb 的吸收以及冲刷等因素，以模拟长时间内土壤中 Pb 的浓度。在进一步的步骤中，我们模拟了基于农作物的食物对人类的口腔暴露，并得出了血液中的 Pb 浓度，以评估 Pb 诱导的毒性效应的暴露边界。模拟当前的农业情景，几百年后土壤中的 Pb 浓度将达到新的平衡。发育神经毒性是 Pb 对人类最关键的毒性作用。根据我们的模型，农业土壤中 Pb 的浓度约为 5mg/kg 时，人们通过食用农产品摄入的 Pb 量约为每人每天 10µg，这一剂量与可耐受每日摄入量 (TDI) 相当。因此，5mg/kg 的 Pb 浓度代表土壤中不应超过的临界浓度。以土壤浓度为 0.1mg/kg 为起点，这是农田目前的控制水平，我们的模拟预测了在两种 Pb 输入情景下，土壤中 Pb 浓度达到 5mg/kg 所需的时间：情景 1：每年每单位面积 Pb 输入量约为 400g；情景 2：每年每单位面积 Pb 输入量约为 175g。这两种情景的 Pb 输入量通过肥料有所不同，代表了相对较高但并非不现实的 Pb 输入量。根据这两种情景，我们计算得出，为了不超过 5mg/kg 的临界土壤水平，每年土壤中 Pb 的沉积量应保持在 100g/ha 以下。我们建议采取有效的措施，减少农业土壤中 Pb 的输入，降低堆肥中的 Pb 含量，并在狩猎中使用替代 Pb 弹药。
