Zerofen 22% Granules (Horse Wormer) Contra-indications, warnings, etc Do not use in animals with known hypersensitivity to the active ingredient. Withdrawal Period Horses may only be slaughtered for human consumption from 35 days after the last treatment. Operator warnings Direct contact with the skin should be kept to a minimum. Avoid inhalation of dust. Wash hands after use. Environmental warnings Unused product and containers should be disposed of in accordance with any guidance from an appropriate waste regulation authority. General precautions Keep out of the reach of children. For animal treatment only.