The review by Delange (6) has been based mostly on the compilation of publications in peer reviewed journals and occasionally on information kindly provided as personal communications by prominent personalities in the field of IDD in the different European countries. This paper also provided updated information on the regulations governing the use of iodized salt and market shares of iodized household salt. For this part, the information has been largely collected by Mr. Bernard Moinier, Secretary of the European Salt Producers Association, ESPA, and by Professor Hans Bürgi. This review paper provided essentially clinical data collected during the past 10 years on the prevalence of goiter and on urinary iodine concentrations. Thus, it evaluated the present status of iodine nutrition. It concluded that a country could be considered as iodine sufficient if, based on a national survey, the prevalence of goiter in the country was below 5 % and the median urinary iodine was within the normal range, i.e. between 100 and 200 µg/L (9). This report was unable to state that iodine deficiency had been eliminated in a given country as the criteria proposed by WHO, UNICEF and ICCIDD for reaching this conclusion are more exhaustive, including a proportion of households using adequately iodized salt above 90 %, a frequency of urine samples with an iodine concentration of 100 µg/L iodine lower than 50% and the fulfilment of at least 8 of 10 programmatic indicators dealing essentially with the administrative and political aspects of the organization of the programs at country level (9).

Epidemiology

Western and Central Europe include 32 countries, plus Andora, San Marino and Lichtenstein for which no data are available. National surveys on the status of iodine nutrition have been conducted during the past 10 years in 17 of these 32 countries. The outcome of these surveys in terms of prevalence of goiter and urinary iodine concentrations are detailed in the recent review of the region (6). They cannot be reported in details here. The global outcome of this European review in terms of status of iodine nutrition is summarized in the Table :

Doctor Gerasimov recently produced an extensive report with comprehensive bibliography on the IDD status, control program and salt iodization in 15 countries of Eastern Europe and Central Asia, including 12 countries of the Commonwealth of the Independent States (CIS) and the three Baltic States (8).
In the past 5 years, significant information has been collected on the extent of iodine deficiency in the region. National and sub-national IDD surveys were conducted in Armenia, Azerbaijan, Belarus and Uzbekistan. The quite impressive outcome of this survey is that, with the exception of Armenia where iodine deficiency appears as currently under control with a median urinary iodine above 100 µg/L, but with persisting goiter prevalence up to 30 %, iodine deficiency persists in all other countries, varying from mild to severe ; generally mild in the Baltic countries, especially Estonia and Lithuania up to mostly severe in Tajikistan where a survey performed in 1999 reported a prevalence of goiter varying from 33 to 90 %. Russia never had a national IDD survey on its enormous territory but several regional assessments conducted from 1998 to 2001 concluded that iodine deficiency persists in most of the administrative regions. An IDD survey performed in Ukraine in 2000 indicated that significant iodine deficiency was present not only in the Northern area close to the Tchernobyl nuclear station but also nationwide.
The iodized salt production was extremely limited in almost all countries in the region until 1997. Since then, significant efforts by the salt industry, with international support, have made iodized salt now available in all countries, and production is scaling up. For example, Russia increased its iodized salt production from 10,000 ton in 1997 to 120,000 ton in 2001. Most countries in the region adopted harmonized levels of salt iodization at 40 ±15 ppm and shifted from potassium iodide to the more stable potassium iodate.

This review underlines major improvement of iodine nutrition in Europe, as compared to the situation described in details in 1993 for Western and Central Europe and in 1997 for Eastern Europe, Central Asia and the Baltic States.
In Western and Central Europe, the 1993 report (4) indicated that only 5 countries had reached iodine sufficiency, namely Switzerland, Austria, Norway, Finland and Sweden. The present figure is 14 countries plus 5 additional countries which have almost reached the goal. In 1999, WHO, UNICEF and ICCIDD reported that 18 countries in Western and Central Europe were still affected by iodine deficiency (12). But data from the literature indicate that three additional countries were also affected, namely Denmark, France and Ireland (6), which makes a total of 21 affected countries in this part of the continent. This figure has now been decreased to 12 countries plus Albania for which no firm data are available but where iodine deficiency is very likely.
In Eastern Europe, the countries have made substantial progress in evaluation of IDD status and in expanded production, supply and use of iodized salt.
However, the goal of sustainable elimination of IDD has not yet been reached, especially in Eastern Europe where only Armenia, and to a lesser extend Turkmenistan, are close to virtual elimination of iodine deficiency (8). In 1999, Europe was the less efficient region in the world in terms of access to iodized salt at the household level in iodine deficient countries (12). In spite of the progress achieved since, further efforts have to be developed in order to ensure the recommended daily intake of iodine for all ages in all inhabitants of Europe, i.e. 90 µg/day from 0 to 59 months, 120 µg/day between 6 and 12 years, 100 µg/day in adolescents and adults and 200 µg/day in pregnant and lactating women (9). This has to be achieved principally through implementation of efficient programs of salt iodization without undue concern to the possible side effects of the increase of iodine intake (13,14).
The main impact of iodine deficiency is on pregnant and lactating women and young infants due to role of maternal, fetal and neonatal hypothyroxinemia in the development of brain damage resulting in irreversible mental retardation (15-17). As a reply to the famous editorial by Peter Laurberg in 1994 (18): « Iodine intake. What are we aiming at ? », the reply is clearly that the correction aims not only at increased access to properly iodized salt and normalization of urinary iodine but mostly at the correction of the thyroid function during the critical period of brain development and, consequently, at the prevention of brain damage (19). Iodine deficiency remains the leading cause of potentially preventable mental retardation in childhood (14).
The iodine nutrition of Western and Central Europe differs in several ways from that in other parts of the world (7). Most Western European countries have iodized salt available but in about half its use is only voluntary. As in the United States and Canada, most dietary salt comes from processed food, so the amount of salt added at table and cooking at home is a relatively minor component of salt intake. Therefore, table salt is a less important source of iodine nutrition than in developing countries and the iodization of salt for the baker and for the food industry are particularly important. National responsibility for iodine nutrition and its prophylaxis is much weaker in most Western European countries than in Eastern Europe and in developing countries. The laws and practices relating to iodized salt vary widely among the countries of Western and Central Europe and additional efforts to educate the government, the citizens and even the health professionals have to be markedly increased.

In conclusion, more than half of the people in Western and Central Europe and a large majority of the people in Eastern Europe and Central Asia still live in conditions of iodine deficiency. In Western Europe, in contrast to developing countries, governmental programs to deal with iodine nutrition are weak or non existent. Consequently, much of the responsibility for optimal iodine nutrition must be shouldered by others, especially thyroidologists, academic institutions and the salt industry. In Eastern Europe where national programs are much stronger, additional efforts are needed especially in the field of quality control in monitoring the programs. In Europe as a whole, as long as USI (the Universal salt Iodisation efforts launched in 1992) is not systematically implemented, special attention has to be devoted to the protection of the two main target groups to the effects of iodine deficiency, i.e. pregnant and nursing women, neonates and young infants. If iodine deficient, these age groups should be supplemented with physiological quantities of iodine for example by including iodine to the multivitamins prepared for them or by using iodized oil. Moreover, the iodine content of formula milk should be increased in Europe to the presently recommended level of 10 µg/dl milk for fullterms and 20 µg/dl for preterms (4).
The elimination of iodine deficiency is within reach and would constitute an unprecedented public health success in the field of non communicable diseases. Additional efforts have to be developed in Europe in order to reach the goal and, in this part of the world, thyroidologists and their scientific societies should play a leading role in this direction.

REFERENCES