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Noguera, Viteri, Daza & Mora |
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Noguera, Viteri, Daza & Mora |
EVALUATION OF THE CURRENT STATUS OF
ENDEMIC GOITER AND PROGRAMS
FOR ITS CONTROL IN LATIN AMERICA
Introduction and Background
Despite the significant progress achieved in the last decades in the control of endemic goiter (1), this nutritional deficiency still persists as a serious public health problem in some countries of the Americas. Nevertheless, in those countries that hav e been successful in reducing their overall prevalence to levels ower than what is considered a public health problem, there are still high-prevalence foci and, in some cases, the problem threatens to recur if follow-up and control measures in the program s are not adequately carried out (2).
The most important cause of endemic goiter is low iodine content in foods and, as a result, insufficient dietary intake of this essential micronutrient. Various goitrogenic factors have been identified, both environmental and dietary, that can cause goit er under certain conditions (3-7). For practical purposes, however, the basic etiological factor is a deficiency of iodine in the diet, which is observed most frequently in communities that depend on the local production of foods in iodine-poor land, esp ecially in mountainous areas and regions originating from crystalline and igneous rock formations (8).
The iodine-deficient geographical area in the Region is concentrated mainly in the western, mountain ranges that extend from the mountains of Mexico through the Andes as far as Chile. Although a complete and updated evaluation of the problem is not avail able for several of the countries, it is well known that goiter-endemic areas of the Andean Region are the most affected and are thus the ones that require priority action.
Endemic goiter is more than merely an esthetic problem, since it is associated epidemiologically with endemic cretinism, deaf-mutism, and mental retardation, as well as with increases in perinatal death rates, low birthweight, and retardation in child dev elopment (9, 10). Even in mild instances of iodine deficiency there can be clinical hypothyroidism and moderate forms of myxedema, along with significantly reduced mental development. Children born to iodine-deficient mothers can have variable degrees o f mental retardation, ranging from the mild forms that are difficult to recognize up to marked cretinism. The latter has been found very frequently in the goitrogenic areas of the Andean Region, especially in Bolivia, Ecuador, and Peru (11). The prevale nce and incidence of pathological alterations of the thyroid gland of a neoplastic nature, and of autonomous hyperfunctioning nodes, are also greater in persons with long-standing endemic goiter (12,l3). Thus, both the consequences for health and the soc ial and economic repercussions of endemic goiter are obvious, and it can constitute a serious obstacle to development in the affected communities. Consequently, programs for the control of endemic goiter are amply justified (14).
The prevention of endemic goiter depends mainly on increasing iodine intake in the population that lives in the goitrous areas. When the amount of iodine reaches the estimated minimum requirement (l00 to 150 mcg per day in adults), there is a concomitant reduction in the prevalence of goiter. The two approaches known for increasing the intake of iodine are adding it to foods, especially table salt, and administering iodized compounds (l, 11, 15). In areas where the consumption of goitrogen-containing f oods is an important factor, additional measures for reducing their consumption also may be necessary (4, 6).
The most effective and economical method of preventing endemic goiter is through the fortification of salt with iodine (iodization or iodination), using either sodium or potassium iodide or iodate. The iodization of salt is effective, simple, and does no t produce adverse chemical reactions. The objective of the procedure is to add a small, predetermined proportion of the compound in such a way that it is uniformly and permanently mixed with the salt and thus provides an amount not less than 150 mcg or m ore than 1,000 mcg/person/day. Based on periodic evaluations of the processes and impact of the programs, necessary adjustments should be made to optimize the effectiveness of the iodination. Addition of iodine to drinking water (15) also can be effecti ve under certain conditions.
In order to establish effective programs of salt iodization, there is need not only for legislation and appropriate regulations, but also for the provision of adequate financing and for the administrative, technical, and operational support required for t he production and marketing of iodized salt, for mass education, and for the creation of efficient control systems at various levels of the process. Equipment is available, as are low-cost, proven techniques of iodization. Appropriate technologies for c ertain specific situations must be developed, however, such as in the case of exploitation and marketing of rock salt or blocks taken directly from salt mines. ln some countries of the Andean Region, the organization of programs for salt iodization has be en complicated by problems of a geographical, economic, social, or administrative nature (2).
All the countries of the Hemisphere with endemic goiter at the level of the general population have passed legislation and are carry-ing out programs of salt iodization, but in most cases they suffer from serious deficiencies in their execution. In some countries, coverage at the national level is not sufficiently broad and the goiter problem persists; in others, the established systems are not adequate for ensuring control and supervision of the iodization process; in most of them, there has been no eva luation of the impact of the programs. The most frequent problems stem from inadequate distribution of iodized salt in areas where transportation is deficient from lack of technical support and supervision of the iodization process, frequently complicate d by a multiplicity of sites where salt is produced; from a diversity of types of salt on the market, including types of salt that legally are not iodized; from internal infiltration and external contraband of noniodized salt; and from lack of awareness o f the problem on the part of authorities, the general population, and the technicians in health and development.
In areas where, for any of the foregoing reasons, consumption of iodized salt is not feasible or possibly is going to take several years to be implemented, the administration of iodized oil can provide both an immediate and a long-term source of iodine. Experience in large-scale iodized oil programs in the Western Hemisphere is still limited, but what there is, is very positive (1, 11, 16, 17). Injected iodized oil can offer adequate protection for three to four years (a single dose of 475 mg of iodine f or adults) without any significant complications; recent studies suggest that the oral administration of iodized oil, which is easier to give on a mass scale, can provide adequate levels of iodine for 18 to 24 months without any unfavorable reactions (18) . There is need for more experience in the oral use of iodized oil, for which the outlook seems to be promising.
The use of other measure of proven effectiveness should not be ruled out in certain populations, including the weekly consumption by each person of a drop of Lugol's solution diluted in water or the addition of iodine to the home drinking-water supply thr ough systems currently under study (l, 15).
We are convinced that the knowledge, the technology, and the experience developed over long years in programs for the prevention and control of iodine deficiency and, as a result, of goiter and endemic cretinism, make it possible to state that the Western Hemisphere can effectively control the problem in the short or medium term if there is a political decision to implement measures of proven effectiveness.
Justification
Current information on the status of endemic goiter and cretinism and on salt iodization programs in the Region of the Americas is neither complete nor fully up-to-date. This information is needed to ascertain the current status of endemic diseases and t heir trend, and to determine the effectiveness and limitations of control programs.
The notable success obtained in the control of iodine deficiency and endemic goiter in some of the countries has apparently led to certain negligence in the control of the programs, which could result in an increase in prevalence, again to a level of publ ic health significance. On the other hand, it is necessary to understand in detail the process of salt production, marketing, distribution, and consumption in the countries in order to identify the specific factors that limit the effectiveness of salt io dization programs. This information will permit PAHO/WHO and its specialized centers to identify objectively the type, degree, and scope of technical cooperation that the countries of the Region require to control and eradicate goiter as part of the larg er goal of health for all.
Objectives
(1) To obtain information on the evolution and current state of endemic goiter, as well as on control programs in Latin America.
(2) To request information from the countries for a critical analysis that will guide the reformulation, development. control, and evaluation of endemic goiter control programs.
(3) To maintain complete and up-to-date information to serve as a baseline for a system of regional surveillance of this problem.
(4) To identify areas of research that promote the eradication of iodine deficiency, endemic goiter, and cretinism in the Western Hemisphere.
(5) To obtain relevant infuriation for objectively orienting technical cooperation policies and actions by PAHO/WHO, including INCAP and CFNI, in regard to the control of endemic goiter in the Western Hemisphere.
Materials and Methods
Review of the Literature
A review was undertaken of the literature available on the iodine nutritional status, including such aspects as urinary excretion of iodine, thyroid function, and endemic cretinism. ln addition, a literature review of the legal provisions and technical st andards of the salt iodization programs was made. This information has been organized by country in Annex 1.
Form CHSICNUl83.3. Evaluation of the Current Status of Endemic Goiter and Programs for Its Control.
A form for the collection of data on endemic goiter and programs for its control was designed and tested in Nicaragua. lt. was then sent to the following countries in Latin America: Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Cuba, Ecuador, E I Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Uruguay, and Venezuela.
The following information was requested on the form: evaluation of the status of endemic goiter and/or cretinism; existing legislation and regulations; production of salt; consumption of salt per capita/day; procedures for the iodization of salt; costs of iodization; current status of control and problems encountered; utilization of iodized oil; programs for health promotion and education in regard to endemic goiter, cretinism, and/or use of iodized salt; and observations and recommendations on technical cooperation and financial assistance to the national programs (see Annex 2).
Visits to the Latin American Countries
A consultant of the Pan American Sanitary Bureau (PASB), Dr. Arnulfo Noguera, traveled to Bolivia, Brazil, Colombia, Costa Rica, Ecuador, EI Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, and Venezuela to assist in collecting th e information requested in the above form. This included visits to the field when such were considered necessary.
Evaluation of the Information Collected
On the basis of the data collected on Form CHS/CNU/83.3, a plan of analysis was developed, which generated 16 summary tables (shown in Annex 3). This information served as a basis for obtaining the results described in the next section of this paper, whi ch in turn made it possible to arrive at the conclusions and recommendations contained in subsequent sections.
Results
Laws and Regulations on Salt Iodization in the Countries (see Table I)
Argentina.A law and regulations were passed in 1967 making iodization compulsory for salt for human and animal consumption throughout the country.
Bolivia.ln 1968, a law and regulations were passed that make iodization compulsory for salt for human and animal consumption throughout the country.
Brazil.Legislation on the iodization of salt was passed in 1953, with regulations enacted in 1953 and 1977, to ensure the iodization of salt for human consumption throughout the national territory.
Chile.This is the only entry in the Hemisphere where compulsory iodization of salt has been repealed. This took place in 1982.
Colombia.In 1947, a law on salt iodization was decreed, with regulations enacted in 1955; the coverage is national and includes only salt for human consumption.
Costa Rica.In 1941, a law was passed on the iodization of salt, with regulations in 1970, that covers salt for human consumption and is national in scope.
Cuba.There are no laws for the compulsory iodization of salt.
Ecuador.The law on salt iodization was passed in 1968 and regulated in 1969; it is national in scope and does not include salt for animal consumption.
El Salvador. ln 1961, a law was passed that makes the iodization of salt for human consumption compulsory throughout the national territory; it was regulated in 1967.
Guatemala.The law on salt iodization, which was passed in 1954 and regulated in 1955, is national in scope, and covers all salt for human and animal consumption.
Honduras.In 1960, the iodization of salt was declared compulsory for human and animal consumption throughout the national territory; it was regulated in 1961.
Mexico.Salt iodization, decreed in 1963 and regulated in 1963-1974, is national in its coverage and includes only salt for human consumption.
Nicaragua.Salt iodization was made compulsory in 1969 and regulated in 1977; the provisions call for the iodization of salt that is distributed in the country for human and animal consumption.
Panama.The law on salt iodization was promulgated in 1965 and regulated in 1969; it is national in coverage but does not include salt for animal or industrial consumption.
Paraguay.The law on the iodization of salt was promulgated in 1958 and regulated in 1966 and 1980; it is national in coverage and includes salt for human and animal consumption.
Peru.The law on salt iodization was decreed in 1969 and its regulations approved in 1971; it is compulsory nationwide and affects ail salt for human and animal consumption.
Uruguay.A law on the iodization of salt was decreed in 1961 and regulated in 1963 and 1974. lt. only includes salt for human consumption and is compulsory only in the endemic areas.
Venezuela.The law on salt iodization was passed in 1%6 and regulated in 1968; it is national in coverage and makes iodization compulsory for all salt for human and animal consumption.
Prevalence of Endemic Goiter and Measures for Its Control (see Tables 2, 3, 4, and 5)
Argentina.In 1967, a survey of goiter conducted in 4,431 schoolchildren indicated an overall prevalence of 49.8%, with a range from 12.5% to 61.9%.
A study done in 47,679 adults showed a prevalence of 15.6%, with a range between 4.3% and 53.6%. Salt iodization was initiated in 1970. Potassium iodate or iodide is used, at a fortification level of 30 ppm. There is no subsequent information that indic ates the impact at the level of the general population.
Bolivia.In La Paz, 4,200 schoolchildren were examined in 1976, indicating a goiter prevalence of 68%; another evaluation of 680 schoolchildren in the department of Pando showed a prevalence of 77%. ln 1977, salt iodization was initiated at a fortif ication level of 30 to 40 ppm using potassium iodate. A national survey carried out in 1981 on 38,500 schoolchildren revealed an overall prevalence of 60.8%: 61.64% in La Paz and 43% in Pando.
After four years of salt iodization, the prevalence of goiter continues to be high.
Brazil.In 1966, a total of 45,924 schoolchildren from 45 municipalities were examined, revealing a goiter prevalence of 27.2%. In 1967, a survey was carried out among 48,443 schoolchildren from 41 municipalities indicating a prevalence of 21.9%. ln 1975, a survey conducted at the national level of 266,373 schoolchildren indicated a prevalence of 14.7%; in this last evaluation the criterion of palpable goiter was not considered.
In 1957, salt iodization was initiated at a level of 10 ppm. Currently, the fortification level is 15 to 30 ppm; potassium iodate is used.
Chile.A study of the general population in three communities in the Andean Region of this entry yielded a goiter prevalence of 24.8%.
Colombia.In 1945, there were 183,243 schoolchildren examined throughout the entry, disclosing an overall goiter prevalence of 53%. The prevalence observed in 8,062 schoolchildren from eight municipalities of high endemicity was 83%.
In 1950, an experimental project was initiated for the iodization of salt in the eight high-endemicity municipalities. This intervention was evaluated in 1952 by means of a goiter prevalence survey done on 6,511 schoolchildren, in whom a prevalence of 33 .9% was found.
In 1962, the program of salt iodization reached the point of national coverage, the fortification levels being from 70 to 100 ppm with potassium iodide. In 1965, a survey conducted in 12,166 schoolchildren in the eight municipalities studied in 1952, ind icated a goiter prevalence of 1.8%, a figure that demonstrated the effectiveness of the intervention. No data are available at the national level to document whether this success is applicable throughout the country.
Costa Rica.In 1966, a total of 4,06,5 persons were examined throughout the country, showing an overall goiter prevalence of 18% and an average urinary excretion of less than 25 mcg/day. ln 1972, a program of salt iodization was undertaken at a prop ortion of 30 to 50 ppm using potassium iodate. This program was evaluated in 1979 by surveying S,061 schoolchildren, who showed a prevalence of 3.5% and an average urinary excretion of 557 mcg/g of creatinine. Thus, Costa Rica is one of the countries of Latin America that has endemic goiter under control.
Cuba.In 1974, a study of 2,664 persons from six to 20 years of age in the region of Baracoa showed a goiter prevalence of 30%. The result of the analyses of ioduria indicated an excretion range from 15 to 46 mcg of iodine per gram of creatinine.
ln Havana, 6,149 persons of all the ages were examined in 1976, revealing a prevalence of 3.4% and an average urinary excretion of 90 mcg/g of creatinine.
There is no knowledge of specific measures in the endemic areas.
Ecuador.In 1969, a national survey of 28,639 schoolchildren found a prevalence of 23.7%. ln 1973, a salt iodization program was initiated using potassium iodide at a fortification level of 50 ppm. In 1978, a new evaluation of 36,962 schoolchildren in the same localities as in 1969 showed a prevalence of 12%, only half the figure observed nine years earlier.
ln 1979, ioduria was determined in 2,276 schoolchildren living at different altitudes above sea level; the averages ranged between 42 and 101 mcg/g of creatinine. ln populations living at an altitude between 2,400 and 3,100 meters, the average ioduria was less than 50 mcg/g of creatinine.
EI Salvador.In 1966, a study of 3,231 persons throughout the country yielded a goiter prevalence of 48% and an average urinary excretion of iodine of less than 25 mcg per day. ln 1972, a program of salt iodization was started using potassium iodate , the fortification level being established at 60 to 100 ppm. There are no subsequent data that evaluate the program from the point of view of goiter control and ioduria.
Guatemala.Guatemala was one of the first countries in Latin America and the first in Central America to reduce the prevalence of endemic goiter to levels that make it no longer a public health problem. An evaluation done in 1954, at the national l evel, revealed an overall goiter prevalence of 38%. Salt iodization was initiated in 1959 using potassium iodate, with a fortification level of 60 to 100 ppm. In 1965, a total of 4,113 persons were examined throughout the country, indicating an overall goiter prevalence of 5.2%, a figure that showed the effectiveness of the program. In 1979, a national survey of 2,995 schoolchildren found a prevalence of 10.5%. Ioduria declined during the period between the last surveys, from an average excretion of 40 0 mcg/day per person in 1965 to 70 mcg/g creatinine in 1979. The results obtained in the last evaluation indicated a decline at the level of the population in terms of endemic goiter control and ioduria.
Honduras.In 1966, a survey was carried out among 3,654 persons at the national level]. lt. showed a goiter prevalence of 17% and an average ioduria of less than 25 mcg/day per person. ln 1971, a national program was implemented calling for salt iod ization at a level of 60 to 100 ppm using potassium iodate. To date, the expected impact has not been evaluated at the level of the population.
Mexico.A representative sample from the entire population in eight Mexican states showed a goiter prevalence ranging from 5% to 46% in 1950. Salt iodization was initiated in 1963, but is not currently being practiced.
Nicaragua.In 1966, a total of 3,302 persons were examined throughout the country. The survey found a goiter prevalence of 32% and an average ioduria per person of less than 25 mcg/day. A new national survey of 13,814 persons in 1977 indicated a p revalence of 33%; the average urinary excretion of iodine in 1,488 samples analyzed was 51 mcg/g of creatinine.
lt is clear that, over this l I -year period, the overall prevalence of goiter did not vary. In tl978, a program for the control of endemic goiter and salt iodization was initiated at the national level, with iodization established at a level of 30 to 50 ppm with potassium iodate.
In 1981, a new evaluation carried out in 6,252 persons throughout the country revealed an overall prevalence of 20%, while the average urinary excretion determined for 751 samples was 99 mcg/g of creatinine. The most significant reduction in prevalence w as seen in the group of schoolchildren (from 14% in 1977 to 3% in 1981)1 which suggests a reduction in goiter incidence, since most new cases occur in this age group.
Panama.In 1967, a nationwide survey of 3,071 persons showed a goiter prevalence of 16.5% and an average urinary excretion of iodine of less than 25 mcg/day. A program of salt iodization at a level of 30 to 50 ppm using potassium iodate was impleme nted in 1970.
ln 1975, an overall prevalence of 6% was found among the 4,084 persons examined throughout the country. This low figure attests to the effectiveness of the program and indicates that goiter is no longer a public health problem.
Paraguay.In 1976, a national survey of 4,078 persons showed an overall goiter prevalence of 18. l %. ln 1980, 343 persons from the maternal and child group were examined, revealing a prevalence of 23.6%. In 1982, 420 schoolchildren from six communi ties were examined; the range of prevalence varied from 16% to 40%.
ln 1965, ioduria was measured in 262 persons throughout the country; the values found were between 16 and 38 mcg/g of creatinine. A program of salt iodization was initiated in 1966 at levels of 60 to 80 ppm, using potassium iodate.
Peru.In 1968, a national goiter survey was carried out in 181,118 schoolchildren, indicating a prevalence of 22%.
In 1972, salt iodization was implemented, using potassium iodate, and the fortification level was established at from 30 to 40 ppm.
An evaluation carried out on 9,293 persons in the country in 1976 showed an overall prevalence of 15%, with prevalence on the coast at less than 5%; in the mountains and the jungle it ranged between 13% and 38%, and 1l% and 20%, respectively. Several stu dies indicate that the distribution of iodized salt in the mountains and the jungle is very limited.
Uruguay.In 1973, in a study at the departmental level, 2,515 schoolchildren were found to have a goiter prevalence of 9%. In 1980, surveys of 1,254 schoolchildren at the departmental level showed a prevalence of 2%.
In 1963, a program of salt iodization was implemented in those departments where endemic goiter represented a problem. Potassium iodate is used, and the level of iodization is 30 ppm. The information available indicates that Uruguay has succeeded in con trol, ling goiter in its endemic areas.
Venezuela.In 1966, a survey at the national level of 470,207 schoolchildren yielded a goiter prevalence of 13%.
ln 1968, salt iodization was initiated with potassium iodate, with levels set between 20 and 30 ppm.
In 1981, a national goiter survey was carried out among schoolchildren and adolescents; a prevalence of 21.37% was observed. (The method used for the evaluation of goiter on this occasion was different from that used in 1966.)
Salt Iodization: Methods, Systems of Iodization, and Utilization of Installed Capacity, and Control Measures in the Past Year (see Tables S, 6, and 7)
Argentina.The level of iodization set by law is 30 ppm. lt. uses a dry-mix method, with potassium iodate and calcium carbonate in a proportion of one to nine. Quantitative control is exercised in iodization plants and in markets. The control valu es for the past year are not available.
Bolivia.Both the dry-mix and the drip methods of salt iodization are used. For the first, potassium iodate is used with calcium carbonate in a proportion of one to nine. Potassium iodate in solution is used for the drip method.
Responsibility for control is vested with the Ministry of Health through the Division of Nutrition. The law provides for the creation of a permanent committee on salt made up of delegates from the Ministries of Health, Agriculture, Economy, Mines and Pet roleum, and Interior; the General Bureau of Industries; and a representative of the salt producers. This committee has advisory and intersectoral coordination functions. At the moment it is not functioning.
Analyses done on sample sales lots indicated that they did not contain iodine.
Brazil.The drip method is employed, using potassium iodate at a level of 15 to 30 ppm.
The Ministry of Health and the National Institute of Food and Nutrition are responsible for the control of salt iodization in the country.
The Brazilian Government donates both the plants for iodization and the potassium iodate necessary. An analysis of 252 samples taken from different iodization plants in the State of Rio de Janeiro during July 1983 showed values ranging between 19 and 30 PPM.
The Ministry of Health appointed a technical group, coordinated by the National Institute of Food and Nutrition, to establish the Program Unit to Combat Endemic Goiter (GT/UPBE), made up of the National Institute of Food and Nutrition (INAN/S), the Superi ntendency for Public Health Campaigns (SUCAM/S), and the National Department of Health Surveillance (SNVS/S). This group has an advisory function and is also responsible for supervision and coordination.
Chile.The necessary information is not available.
Colombia.The aspersion method is employed, using one part of potassium iodide to nine parts of calcium stearate as stabilizer. The salt industries perform quality control analysis every hour.
During July 1983, 81 salt samples were collected at retail outlets, of which 25% contained less than 20 ppm; 43% from 20 to 60 ppm; 26% between 60 and 100 ppm; and 6% more than 100 ppm. The level established is from 70 to 100 ppm.
Responsibility for the control of iodization rests with the Colombian Institute of Family Welfare.
Reprinted from "Towards the Eradication of Endemic Goiter, Cretinism, and Iodine Deficiency" with permission from Pan American Health Organization. This publication is available in full from the Pan American Health Organization, $10.- plus $6.- shipping and handling. To request a publications catalog, write to: Pan American Health Organization, Publications Program, 525 Twenty-third St., NW, Washington, DC 20037. Fax: 202/338-0869.
