Toxicity of Mancozeb

Mancozeb is a broad-spectrum contact fungicide which is labeled for use on many fruit, vegetable, nut, and field crops in Minnesota. It provides protection against a wide spectrum of fungal diseases, including potato blight, leaf spot, scab, and rust. It is also used as seed treatment for potatoes, corn, sorghum, tomatoes, and cereal grains. In 2017, approximately 1.1 million pounds of mancozeb were sold in Minnesota.

Mode of Action

Mancozeb is classified by the Fungicide Resistance Action Committee (FRAC)2 as a mode-of-action group M, multi-site, fungicide. It interferes with enzymes containing sulphydryl groups, disrupting several biochemical processes within the fungal cell cytoplasm and mitochondria.

Mechanism of Toxicity

Mancozeb has been classified as a contact fungicide with preventive activity. It inhibits enzyme activity in fungi by forming a complex with metal-containing enzymes including those that are involved in the production of ATP.

Mancozeb has effects on various organ systems. Its primary mechanism of toxicity is via skin contact, leading to contact dermatitis and dermal sensitization. Mancozeb has also been shown to have teratogenic and reproductive effects. Mancozeb exposure also alters the reproductive and endocrine structures, leading to decreased fertility. Animals orally exposed to mancozeb showed thyroid hyperplasia, probably via its ability to inhibit the synthesis of thyroxin. Additionally, mancozeb exposure produces neurotoxicity via yet an unknown mechanism.

Similar to maneb, mancozeb also has chelating properties, allowing it to possibly interfere with a number of enzyme systems that contain metals, such as zinc, copper, and iron (e.g., dopamine β-hydroxylase).