Tadpoles present in iodine deficient water cannot become adults. Why?

Iodine is an essential element of thyroid hormone. The thyroid hormone with its essential iodine constituent is responsible for the control of metabolism and also for metamorphosis. If Iodine is not present in the diet ,the thyroid may produce an inefficient amount of hormone which will adversely affect the metamorphosis . So the tadpoles will not be able to become adult frogs.