As the variety of food sources dramatically increased in Europe and North America and the populations became less completely dependent on locally grown food, the prevalence of endemic goitre diminished. This is supported by a 1979 WHO publication which concluded that "changes in the origin of food supplies may account for the otherwise unexplained disappearance of endemic goitre from a number of localities during the past 50 years".The early 20th century saw the discovery of the relationships of neurological impairment with hypothyroidism due to iodine deficiency. Both have been largely eliminated in the developed world. Terminology
The term cretin was originally used to describe a person affected by this condition, but, as with words such as spastic and lunatic, it underwent pejoration and is now considered derogatory and inappropriate. Cretin became a medical term in the 18th century, from an Occitan and an Alpine French expression, prevalent in a region where persons with such a condition were especially common (see below); it saw wide medical use in the 19th and early 20th centuries, and was a "tick box" category on Victorian-era census forms in the UK. The term spread more widely in popular English as a markedly derogatory term for a person who behaves stupidly. Because of its pejorative connotations in popular speech, current usage among health care professionals has abandoned the noun "cretin" referring to a person. The noun cretinism, referring to the condition, still occurs in medical literature and textbooks but its use is waning.The etymology of cretin is uncertain. Several hypotheses exist.
The most common derivation provided in English dictionaries is from the Alpine French dialect pronunciation of the word Chrétien ("(a) Christian"), which was a greeting there. According to the Oxford English Dictionary, the translation of the French term into "human creature" implies that the label "Christian" is a reminder of the humanity of the affected, in contrast to brute beasts. Other sources suggest that Christian describes the persons "Christ-like" inability to sin, stemming, in such cases, from an incapacity to distinguish right from wrong.Other speculative etymologies have been offered:

From creta, Latin for chalk, because of the pallor of those affected. From cretira, Grison-Romanche creature, from Latin creatus. From cretine, French for alluvium (soil deposited by flowing water), an allusion to the conditions suspected origin in inadequate soil. See also
Moron (psychology)

References
External links
 Media related to Congenital iodine deficiency syndrome at Wikimedia Commons