ETIOLOGY OF IODINE DEFICIENCY DISORDERS IN SELECTED VILLAGES OF DISTRICT CHAMOLI IN GARHWAL HIMALAYA

Introduction:Iodine deficiency is an ecological phenomenon which occurs naturally. This arises from the distant past through glaciations, compounded by the leaching effects of snow, water and heavy rainfall, which remove iodine from the soil resulting in Environmental Iodine Deficiency (EID). The mountainous regions of the Indian Subcontinent, China, Europe, Andean region in South America and lesser ranges of Africa are all iodine deficient. But in addition the soil of flooded river valleys is also deprived of iodine as in the Ganga Valley in India, Irawady Valley in Burma & Songkala valley in Northern China. The deficiency in the soil leads to iodine deficiency in all forms of plant life and cereal grown in the soil. Hence populations living in systems of subsistence agriculture are considered at risk of iodine deficiency.

local markets. The local suppliers obtained goods from Mandis (big wholesale markets) situated in the lower terai region (sub-Himalayan region) namely Najeemabad and Sahranpur.  It is significant that the least affected villages ( Salla, Awani, Ratoli & Nargoli) happen to belong to category of villages (A) which consumed protein rich pulses soyabean, urad, gahat throughout the year as against those that consume these only over to six months. Peas & bean are also cultivated here (not in the category B villages).  The size of family in the surveyed villages ranged from 2 to 11 members. And there was normal distribution of families in the villages according to size. The daily consumption of staple food increases with the increment in family size (as expected).
Socio-economic status:-Results are summarized in table 8  In this study the inhabitants of surveyed area were categorized into labour/ farmer and service class. The majority of inhabitants (60 -100 % population of a villages) were labour / farmer in majority of villages (about 73 % villages) and in three villages (out of 11) i.e Salla, Ratoli & Awani 90 -95% inhabitant were from service class. The literacy rate was very high (about 95 %) in all the villages.  Inhabitants were found highly aware toward personal and environmental hygiene.  Inhabitants were also well aware towards routine health checkup and national health program but health care facility are lacking in entire region.

Pedigree analysis of the families:
 Results indicated occurrence of strabismus in 68 families out of 184.  Results of pedigree analysis indicated that the different traits including strabismus, hearing defects etc are running in different generations of families.  Out of 184 families Strabismus was found running in three generations in 10 families and two generations in 12 families.  Speech defects were found in two generations in 2 families and in three generations in a single family  Hearing defects were found in two generations in a single family.  These results are in the process of being subjected to detailed genetic analysis. Which will constitute a deeper investigation.
Discussion:- In the face of iodine deficiency as observed by the current analysis. It is remarkable that without any iodine prophylaxis the incidence of visible goitre was zero in district Chamoli. Either iodine deficiency actually does not produce drastic effects or some amount of iodine is reaching the diet (other than iodised salt). The latter possibility appears more likely. Till about 40 years ago villagers in Garhwal were totally dependent on the indigenous agricultural products and they continue to practice the age-old annual system bartering the local produce Amaranthus for cheaper open uniodised crystal gara salt which is stored for the entire year. In recent years people, to fulfill their need,s buy grains from general suppliers and from government grain supply agencies also which derive from larger stockists or from government godowns in the plains. The supplies to the godowns may come from fertile areas of the country e. g plains of U P, Punjab etc. which are not so called iodine deficient. This may be one possibility of iodine reaching the diet.
Obviously the present study raises questions on the success of iodization program of Govt in these areas. During the survey, it was found that Govt representatives rarely or never visited these villages to ensure availability of iodized salt. This may be due to remoteness, rough terrain & lack of transport facilities to reach these villages.
Socioeconomic status of this area has become better since last 4-5 decades. Low incidence of thyroid hormone disorders in the present intensive study comparing with previous results and other endemics may be related to bettering socio-economic status. There are reports from other endemics also indicating that prevalence of goitre increases with decrease in low socio-economic status (Knudsen N 2003). Prevalence of goitre and cretinism was found to decrease with increasing socio-economic status (Stott et. al 1931, Najjar and Woodruff 1963, Correa 1980, Jiangun and Xin 1987. In our study it is significant that three villages Slla, Ratoli, Awani, villages i.e group A with almost negligible IDD also happened to be socially more aware, economically better with 79% families in service class. However this issue requires greater sample size to be resolved.

Feeding Habits in different villages in Garhwal Himalaya:-
Daily requirement of iodine is met through food, fruits, salt and water. Drinking water is limited source of dietary iodine. The iodine content in food and water depends on the content of the soil either the soil is iodine deficient or iodine sufficient (Hercus et. al 1925, CIEB 1958, Kelly and Snedden 1960. These Substances in diet also have been known to interfere with iodine trapping mechanism resulting in suppressed thyroid function. Many plants which are included in the main staple diet of the area have been documented to have goitrogenic effect.
In Garhwal Himalaya the main indigenous grains, pulses, vegetables used by the inhabitants of this area are given in Table 4  Studies also showed the consumption of vegetables, millet, cereals rich in goitrogens. However their contribution to development of IDD in this area needs to be further examined separately before drawing unequivocal conclusion.

Is there a genetic basis of IDD?
The spectrum of iodine deficiency disorders includes goitre, cretinism, mental retardation, spastic diplegia, deaf/mutism and strabismus. Deficient thyroid synthesis due to inadequate iodine supplementation to the body is the major known cause for the goitre and associated IDDs. The results of our study (discussed in earlier section), however, indicated incidence of different IDDs in the absence of visible goitre. Results of the hormonal profiles are also in harmony with the observed low incidence of goitre. Considering the above finding we explored the possibility of factors other than iodine deficiency & goitre being involved in the genesis of associated neuromotor developmental & neuromotor disorders e.g. Cretinism, spastic diplegia, deaf mute, strabismus, hearing defects, speech defects,. Families with two or more generation of these disoders were data mined from the results. Results indicated strabismus running over three generation in 10 families and in two generations in 12 families. Speech and hearing defects were also found running in different generations (speech defects over two generation in two generations of one family). Surveys on social marital pattern indicated narrowmarriage system (marriages in geographically not very distant villages). The studies strongly indicated that these thyroid hormone disorders in this area of Garhwal Himalaya may have a genetic origin also. Pedigree analyses using special software are in progress and shall constitute a deeper study.
Present results explain the incidence of IDD in the absence of goitre as observed in Farswan 2007 & support the presumption that iodine deficiency disorders need not necessarily be due to iodine deficiency.