Etiological Study of Thyroid Disorders in the Foot Hill Settlements of Pir Panjal Range

A comprehensive methodology has been adopted to carry out the present study. Figure 3 shows the general data base and methodological scheme divided into many related steps in order to accomplish the objectives of the present work.

The study area was delineated from Survey of India (SOI) toposheets of 1:50,000 scale of 1971 with numbers as 43 O/2, 43 O/3, 43 O/6 and 43 O/7 with the help of Arc View 3.2a software. The base contour was taken as 1,800th m AMSL and top one as 3,000^th m AMSL [15]. These two contours were connected on the lateral sides by taking the watershed limits through digitization.

By digitizing 2,400^th m contour, the area under study was divided into two altitudinal zones, namely, Lower Foot Hills (LFHs) and Upper Foot Hills (UFHs) varying in altitude from 1,800^th-2,400^th m and 2,400th-3,000^th m respectively. The LFHs are characterized by good permanent human occupancy while as the UFHs experience mostly seasonal human inhabitations. By digitizing 2,100^th m contour, the LFHs were further sub-divided into two sub-zones namely, LFHs-1 and LFHs-2 varying in elevation from 1,800th-2,100^th m and 2,100^th-2,400^th m (Figure 4a) for comparative analysis.

Stratified random sampling technique was used for the selection of sample sites (sample villages, soil and water sample sites) and sample households as shown in tables 2 and 3 and figures 4b, 5a and 5b.

The soil samples were collected in clean unused polythene bags and were labeled properly. A clean spade was used to take the soil samples. In order to reduce variability, a composite sample was obtained from each sample site. A composite sample comprised of five sub-samples taken from each sample site in 10 m × 10 m grid format. Four sub-samples were taken from four corners of the square and one from the center. Soil samples were taken from depths of 0-20, 0-40 and 0-60 cm in relation to different major land uses i.e., agricultural, horticultural and forest respectively [16,17]. Water samples were collected in clean unused plastic bottles from the selected sample sites and were labeled properly and reached to the lab within 24 h. Both types of samples were analyzed in Research Centre for Residue and Quality Analysis Lab, SKUAST, Shalimar. The socio-economic survey was done through the structured schedules to give the socio-economic picture of the area and to assess the dependence of people on local food items, income status, methods of cooking, households using iodized salt and boiled drinking water and percentage of households purchasing food from the market. The data regarding the prevalence of IDDs was collected from the prescriptions given by the registered practitioners.

The soil samples were air-dried, crushed with a wooden roller, passed through a 10 mesh (<2 mm) sieve, and then ground in an agate mortar. The recovered<63 µm particles were separated for chemical analysis. The samples were analyzed under Atomic Absorption Spectrophotometer (AAS-4141, Electronic Corporation Limited, India). A total concentration of I was determined after 4-acid digestion (HF, HClO₄, HNO₃ and HCl) by AAS. The samples were analyzed for iodine, pH and organic matter (OM).

The study showed that the soils and drinking water sources of the foot hills of Pir Panjal range in Anantnag district are deficient in iodine content in all the altitudinal zones (Tables 4 and 5) and have iodine content less than the world averages.

From table 6, it is obvious that the soils are iodine deficient at all the elevation levels in the study area. The organic matter and pH influence the concentration of I in the soils. In soil type-61, iodine content first increases with altitude because of increase in OM in the soil and then slightly decreases with altitude due to increasing slope and coarser texture of soil. OM binds up iodine ions in the soil but the increasing slope and coarser texture cause iodine ions flow and translocate easily during rainfalls. In soil type-106, iodine content first decreases with altitude because of increase in the acidity of the soil and then increases with altitude. The acidic pH in soil catalyzes the loss of iodine ions in soil through leaching.

Likewise, table 4 shows the concentration of iodine in drinking water sources in the area. Iodine content in drinking water sources first increases with altitude and then decreases. It shows affinity to the surrounding soils and their physico-chemical character.

The study revealed that about 17.6% people suffer from different IDDs in all the age-sex groups (Table 6). These people have greater (66.89%) dependence on locally cultivated food items because of their disadvantaged economic condition. More than 62.4% households comprising low and medium income status households fall below poverty line as per international standards of income-based poverty lines (Rs. 2371.5 month^-1 person^-1). They also have inadequate income as per the local economic scenario is concerned. It is evident from the table 5 that in the sample village of UFH region, about 30.2% people suffer from IDDs as compared to 24.0% of LFH region. This variation can be attributed to the greater dependence of people on locally cultivated iodine deficit food items, and less use of iodized salt in UFHs than the people in LFHs (Table 7). In the sample village in UFHs, about 92.9% households fall in low and medium income groups (Table 8) which forces them to rely on whatever food items they cultivate locally. About 92.85% households have >50% dependence on local iodine deficit foods and 42.8% people used iodized salt in UFHs as compared to the LFHs in which about 81.76% households in the sample villages have >50% reliance on local foods and 75.4% people use iodized salt (Table 7).

The prevalence of IDDs in LFHs shows a decline from LFHs-1 to LFHs-2. About 17.4% people suffer from IDDs in LFHs-1 as compared to 16.4% in LFHs-2 (Table 6). This variation seems to be outcome of the differential lifestyles especially the food cooking methods. In LFHs-1, about 96.7% households surveyed are accustomed to inappropriate cooking methods such as long period boiling, braising, blanching and frying as compared to LFHs-2 in which the value is 83.4% (Table 7).

The prevalence of IDDs in the sample villages in the sub-zones decreases with altitude with respect to changing iodine, pH and OM content in the respective soil types and socio-economic conditions with the exception of SS5-ANG. In the LFHs-1, SS1-ANG (soil type-61) records 21.4% and SS2-ANG (soil type-106) records 16.9% of patients and in LFHs-2, SS3-ANG (soil type-61) records 16.4% and SS4-ANG (soil type-106) records 16.5% of patients and in UFH sub-zone, SS5-ANG (soil type-61) experiences 22.2% of patients to its total surveyed population. The increase in the percentage of patients suffering from IDDs in SS5-ANG is due to high (4.90%) OM in soil (Table 4). Though the concentration of iodine at SS5-ANG is relatively greater than some of the other sites, it has the disadvantage of having high OM. The OM decreases the bioavailability of iodine for the plants/crops resulting in iodine deficient foods. It may also be attributed to the greater dependence of the people on local foods (Table 7). Difference in the percentage prevalence of IDDs with respect to age and sex groups can be attributed to the relative differences in the life styles.

A diagrammatic model (Figure 6) has been developed related to the present study that shows cyclic movement of the iodine in the different phases of environment, the pathways how iodine reaches to the human body, its losses at different stages of movement at the dual hands of nature and humankind and the consequent results i.e., IDDs. The diagram also highlights the role of natural pools of iodine transfer and the life style of the people of the area under study in contributing the causation of the different IDDs. The lithospheric and atmospheric pools of iodine cycle are iodine deficient while as the hydrospheric pool is efficient in iodine content but not sufficient to save human beings from IDDs. So, the food derived from the soil is deficient in iodine. An individual human being derives only about 0.5 µg d^-1 of iodine from inhalation [18]. The marine food is rich in iodine but unfortunately people make less use of marine foods perhaps because of their low income status and high price of the food. The problem of iodine deficiency and loss from the whatsoever food and water is used is further coupled by the unsuitable and unhealthy cooking methods and other lifestyles.