Successful efforts toward elimination iodine deficiency disorders in India.

Iodine deficiency (ID) is the world's single most important preventable cause of brain damage and mental retardation. Iodine deficiency disorders (IDDs) is a public health problem in 130 countries, affecting 13% of the world population. The simplest solution to prevent the IDD is to consume iodized common salt every day. In India, significant progress has been achieved toward elimination of IDD, in the last 30 years. Satisfactory levels of urinary iodine excretion and iodine content of salt have been documented by the research surveys conducted by research scientists. The results indicate that we are progressing toward elimination of IDD. IDD is due to a nutritional deficiency, which is prima-rily that of iodine, in soil and water. IDD is known to re-appear if the IDD Control Program is not sustained. To ensure that the population continues to have intake of adequate amount of iodine, there is a need of i) periodic surveys to assess the magnitude of the IDD with respect to impact of iodized salt (IS) intervention; ii) strengthening the health and nutrition education activities to create demand for IS and iii) development of a monitoring information system (MIS) for ensuring that the adequately IS is available to the beneficiaries.

Introduction

Iodine deficiency (ID) is the single most important preventable cause of brain damage.(1) Iodine deficiency disorders (IDDs) refer to all of the consequences of ID in a population, which can be prevented by ensuring that the population has an adequate intake of iodine. Iodine is one of the essential elements. Its daily per capita requirement is 150 µg. Iodine is required for the synthesis of the thyroid hormones, thyroxine (T4 ) and triiodothyronine (T3). Iodine is present in the superficial layers of the soil and absorbed by crops grown on it. Glaciations, heavy snow and heavy rain leach away iodine from the soil. This problem is further accelerated by deforestation and soil erosion. Consumption of crops and plants grown on iodine-deficient soils leads to ID in populations solely dependent on this vegetation for their iodine requirements. When iodine intake falls below the recommended levels, the thyroid may no longer be able to synthesize sufficient amounts of thyroid hormones. The resulting low level of thyroid hormones in the blood (hypothy-roidism) is the principal factor responsible for damage to the developing brain of fetus.(2)

ID causes its impact right from the development of fetus to people of all age groups. It results in abortion, stillbirth, mental retardation, deaf-mutism, squint, dwarfism, goiter of all ages, neuromotor defects, etc. ID directly affects human resource development, which in turn greatly affects the human productivity and country′s development at large. People living in areas affected by severe ID may have an intelligence quotient (IQ) of up to 13.5 points below that of those from comparable communities in areas where there is no ID.(3)

Magnitude of IDD

IDD constitutes a major nutrition deficiency disorder in India. The survey conducted by the central and state health directorates, Indian Council of Medical Research and medical colleges have demonstrated that not even a single state is free from the problem of IDD. Out of 582 districts in the country, district level surveys conducted in 324 districts have revealed that IDD is a major public health problem in 263 districts, i.e. a total goiter prevalence rate of 10% and more in the population.(4) Realizing the magnitude of the problem, the Government of India launched a 100% centrally assisted National Goitre Control Programme (NGCP) in 1962. In 1992, the NGCP was renamed as NIDDCP. The program has the following objectives:(4)

initial surveys to assess the magnitude of the IDDs;

supply of iodized salt (IS) in place of common salt; and

resurveys to assess the impact of IS after every 5 years.

The Government of India under the Prevention of Food Adulteration Act (PFA) has defined that IS should have a minimum of 30 ppm iodine at the production level and a minimum of 15 ppm at the retail trader level. India has adopted a policy of Universal Salt Iodization (USI) in 1983 to ensure that all edible salt for human and animal con-sumption is iodized. The major activities undertaken under the program include i) production and distribution of IS; ii) establishment of goiter cell in all states and UTs; iii) information education and communication activities to increase the consumption of IS; iv) to achieve effective inter-sectoral coordination amongst various government sectors participating in implementation of NIDDCP; v) laboratory support for assessing iodine content of salt and urinary iodine excretion (UIE) levels estimation; vi) training of health functionaries in IDD at different levels; and vii) establishment of monitoring and reporting system for NIDDCP.(4)

Progress achieved toward elimination of IDD in India

According to World Health Organization (WHO), to assess progress toward elimination of IDD, the following two activities should be undertaken: i) measurement of UIE levels and ii) analysis of the iodine content of salt. The data available on these two aspects from India reflect the success story.

Status of UIE in India

In a community with optimal iodine nutriture, the median UIE levels should be in the range of 100-200 µg/l.(5) The status of UIR levels in different regions of country has been extensively assessed by district level surveys in the recent years [Table 1]. More than 86% of districts had median UIE levels of 100 mcg/l, indicating success of NIDDCP.

Table 1

Urinary iodine excretion levels in selected districts of India

Status of iodine content of salt in India

The level of salt iodization should provide a physiological intake of 100-150 µg/day, which should bring the median UIE level within a range of 100-200 µg/l. To achieve this, 30 ± 10 ppm iodine needs to be added to salt at the manufacturing level.(5) The status of salt iodization in different districts of the country has been extensively assessed in the recent years. Table 2 depicts the same. More than 58% of districts had an iodine content of salt of 15 ppm and more at beneficiary level, indicating success of Universal Salt Iodization Program activity in the country.

Table 2

Iodine content of salt samples collected at beneficiary level in selected districts of India

A countrywide evaluation conducted under NFHS-3, in 2005-2006 measured the iodine content of cooking salt [Table 3]. Overall, 49% of the households used salt that was iodized at the recommended level of 15 ppm or more. About 22% salt was inadequately iodized i.e. less than 15 ppm. It was found that the use of IS varied dramatically from one state to another. The use of IS was high (90% and more) in the northeastern region where salt is transported by railways. However, all the states in the southern region had low levels of use of adequately IS, ranging from only 21% in Tamil Nadu to 43% in Karnataka.(6)

Table 3

Percent distribution of households with salt tested for iodine content, by level of iodine in salt (parts per million), according to state, India, 2005-06:NFHS-3

The salt department, under its monitoring information system, receives reports from State Health Authorities. During 2005, the reports received from 12 states revealed that 73.7% of IS tested by State Health Laboratories under State Health Department were adequately iodized (15 ppm and more iodine).(7)

Contribution of salt department in the success of NIDDCP

The production of IS in country was about 0.2 million tons in 1983. This had increased to about 5.3.million tons in 2009. There are 807 salt iodization units including 42 refineries, which have a total installed capacity of production of 116 lakh tons. This capacity established is more than double the requirement of salt for human consumption in the country. The Salt Department has facilitated the establishment of 18 potassium iodate manufacturing units to help salt producers to iodize the salt. The sustained joint efforts of NIDDCP and Salt Department have ensured that IS is distributed through Public Distribution System for below the poverty line (BPL) population in the 15 states of the country [Table 4].(7)

Table 4

States undertaking distribution of iodized salt through public distribution system

Areas requiring strengthening to achieve the elimination of IDD

A high priority is needed to be given to the NIDDCP by the state governments to prevent irregular distribution of IS.

Adequate enforcement of PFA by the state/UT governments is required to ensure that the quality of IS is available to the beneficiary.

Adequate coordination is required between salt traders and food inspectors in the states (the implementers of PFA) for smooth procurement, distribution and sale of IS.

There are three states which have not implemented the ban notification in all the districts on sale of non-IS. This is helping the sale of non-IS. There is need of implementing complete ban in the entire state.

There is a need of undertaking regular periodic surveys for monitoring of UIE levels and assessing the iodine contents of salt. This would help in identifying the areas with poor iodine content of salt and initiating the remedial measures.

In southern states that have high level of literacy but there is resistance for the consumption of IS, qualitative research is required for identification of points of resistance toward consumption of IS.

IS versus iodized oil in the prevention of IDD

The inexpensive technology, a time-honored and time-tested one, for the control of IDD is the iodization of common salt. Programs for IDD control must rest squarely and socially on this technology. Periodic parenteral administration of iodated oil (not presently manufactured in India) at times is suggested as an alternative approach, especially in areas inaccessible to common salt. It is difficult to imagine any area in India, which is now inaccessible to common salt but readily accessible to disposable syringes and to an army of “injectors”. There has been a steep rise in the HIV seropositivity rate and hepatitis "B" carriers in India during the last few years. The consequences of resorting to a technology that is dependent on repeated injections could increase the risk of transmission of HIV and hepatitis B and is not recommended.

Conclusion

The sustainability of activities of NIDDCP is vital for achieving elimination of IDD. The subjects with large goiter are no more seen. The hidden consequences like neonatal hypothyroidism in specific areas may possibly continue. There is a need of undertaking IDD surveys to assess the current incidence of neonatal hypothyroidism. There is a need to give more emphasis on impact of ID on loss of IQ points in school children and their poor scholastic performance.

IDD is a nutritional deficiency that prima-rily results from deficiency of iodine in soil and water. IDD can therefore re-emerge at any time after its elimination, if program success is not sus-tained. There is evidence that ID is returning to some countries where it had been eliminated in the past. Hence, we need continued efforts for all time to come in the future.