Iodide buildup, organogenesis, tyrosine binding, and thyroid hormone release are all inhibited by an excess of iodine. However, this inhibitory impact (the Wolff-Chaikoff effect) is only present for 10–14 days before being replaced by the so-called escape phenomena. Iodine excess can therefore neither cause nor cure hyperthyroidism or hypothyroidism; rather, it leads to the development of tolerance to iodine intake. The amount of excess iodine that a person can tolerate without suffering any ill effects is called their "iodine threshold". The more sensitive your thyroid gland, the higher this threshold will be. Most people can safely consume up to 150 mg of iodine per day, but some populations (such as those with autoimmune diseases), may require more limited amounts. For example, patients who have had their thyroids removed may need to limit themselves to less than 100 mg of iodine per day because they are at risk of developing cancer-related symptoms if their remaining thyroid tissue becomes overstimulated by iodine. Women who are pregnant or might become pregnant should not exceed 150 mg of iodine per day either from natural sources or through supplementation. Iodine is required for normal brain development during pregnancy and excessive doses may lead to mental retardation. Those who are allergic to iodine should avoid it altogether because even small amounts can be harmful.