When heated, myclobutanil decomposes to produce corrosive and/or toxic fumes, including carbon monoxide, carbon dioxide, hydrogen chloride, hydrogen cyanide, and nitrogen oxides.

[2][3] Myclobutanil is banned in Canada, Colorado, Washington, Oregon, and Oklahoma for the production of medical and recreational cannabis.

In 2014, a Canadian news investigation by The Globe and Mail reported the discovery of myclobutanil in medical cannabis produced by at least one government licensed grower.

[4] In September 2019, NBC News commissioned CannaSafe to test THC cartridges for heavy metals, pesticides, and residual solvents like Vitamin E; pesticides, including myclobutanil, was found in products from unlicensed dealers.

[5] In Michigan, the current state action limit for myclobutanil is 200 ppb in cannabis products.