The potato grows underground and is subject to root grub and potato beetle attacks. Systemic chemicals like organochlorines are applied to the soil so that they can penetrate the potato and harm their pests. During storage, potatoes are also subject to attacks from weevils which can make undesirable and ungainly looking holes. Thirty years ago, dangerous bromides like aluminium phosphide were used. These are now prohibited by law except to registered government agencies. Fumigants are now used in their place. These come in the form of tablets which when dissolved in water release a toxic gas.