The Legacy of Copper-Based Fungicide Use in Vineyard Soils: Accumulation, Ecotoxicity, Human Health Risks, and Sustainable Remediation

The long-term use of copper (Cu)-based fungicides in viticulture has led to substantial Cu accumulation in vineyard soils, raising concerns about soil health, ecological integrity, plant physiology, and potential human exposure. Since their introduction in the late 19th century, Cu-based fungicides have remained essential for controlling fungal diseases, particularly in organic production systems where viable alternatives are limited. In contrast to organic systems, conventional viticulture can rely on modern synthetic fungicides (such as fluxapyroxad, pyraclostrobin, tebuconazole, and fludioxonil), which provide less harmful alternatives to copper because they are applied at much lower rates and do not accumulate in soils, making them generally more environmentally benign than copper based fungicides. As a result, copper concentrations in vineyard soils frequently exceed European regulatory thresholds, often surpassing 200 mg/kg soil and occasionally exceeding 1000 mg/kg soil. Copper accumulation is influenced by soil physicochemical properties, climate, terrain, and vineyard management practices, while its bioavailability dictates its ecological and toxicological impacts. Elevated copper levels adversely affect soil biota, reducing microbial diversity, impairing enzymatic activity, and disrupting nutrient cycling and key soil functions that underpin fertility and ecosystem stability. Although mature grapevines demonstrate relatively high copper tolerance through deep rooting and physiological detoxification mechanisms, young vines and crops planted following vineyard conversion are more susceptible to copper toxicity. In humans, copper is an essential micronutrient with a U-shaped dose-response curve and toxicity is uncommon at typical dietary exposure levels. Nonetheless, copper residues in grapes and wine can occasionally exceed the maximum limits established by the International Organisation of Vine and Wine (OIV), underscoring the need for continued monitoring. Mitigating copper contamination requires preventive approaches, such as reducing copper inputs, employing forecasting tools, adopting precision viticulture technologies, and cultivating resistant varieties, alongside sustainable remediation strategies. Among these, phytoremediation, particularly phytoextraction, offers a promising, non-invasive, and cost-effective method for managing low to moderately copper contaminated vineyard soils.