Determine the iodine content of salt at the household level and its predictors in Bahirdar Town, Northwest Ethiopia

Introduction iodine deficiency remains a foremost public health problem in developing countries. About 66 million populations were at risk from iodine deficiency, 28 million people suffer from goiter and more than 50,000 prenatal deaths are related to iodine deficiency each year in Ethiopia. Besides, studies from different parts of Ethiopia have shown that a low proportion of households use adequate iodine concentration and varied from one household to another. Despite increased coverage, the quality of available salt is poor. To ensure safe and effective levels of iodine consumption, monitoring the levels of iodine in salt and the iodine status of the population is critical. However, kinds of literature are scant in Ethiopia particularly; no study is conducted in the current study area. Thus, the study aimed to determine the iodine content of salt and associated factors at the household level in Bahir Dar Town, Northwest Ethiopia. Methods a community based cross-sectional study design was carried out in Bahir Dar Town from September to October 2015. A multi-stage sampling technique was used to select 706 study participants. A pre-tested, structured questionnaire and laboratory were used to collect data. A laboratory test, gold standard iodometric titration method was used to measure individual availability of adequately iodized salt. Multivariable logistic regression analysis was fitted to identify factors associated with the content of iodine. Adjusted Odds Ratio (AOR) with corresponding 95% confidence interval was computed to show the strength of association. In multivariable analysis, a p-value of <0.05 was used to declare statistical significance. Results a total, of 690 participants were included in the study. About 70.1% (95%CI: 63.41, 76.76) of the households were used adequate iodized salt (≥15 ppm). The result of the multivariate analysis revealed that respondents with secondary school (AOR=3.05; 95%CI: 1.51,6.18), age 30-44 years (AOR=1.99; 95%CI: 1.08,3.69), good knowledge (AOR=3.34; 95% CI: 2.09,5.32) and being in the highest wealth status (AOR=4.35,95% CI: 2.43,7.8) had higher odds of availability of adequately iodized salt at the household compared to the counterpart. Besides, using covered salt (AOR=6.10, 95% CI: 3.78, 9.87) and storing salt in a dry place (AOR=4.17; 95% CI: 2.21, 7.86) were positively associated with the availability of adequately iodized salt. Conclusion the availability of adequately iodized salt in the household is still low. Further institutionalizing iodized salt regulation and awareness creation will require to improve safe iodine consumption through the community.


Introduction
More than two billion people, 28% in the world and most of them in developing countries (39% in Africa) suffer from inadequate intake of iodine [1,2]. Iodine deficiency causes a wide range of health-related problems that are collectively called iodine deficiency disorders (IDD) characterized by mental impairment, goiter, hypothyroidism, and dwarfism [1][2][3]. Groups at the highest risk to suffer from iodine deficiency are lactating women, pregnant women, and children younger than three years [1,2]. The iodization of salt, a common food that is used by a majority of the population, is a confirmed intervention for the prevention of IDD [4] and in Africa, saved millions of children from its adverse effects, mainly due to the increased household availability of iodized salt [5]. Iodine is an essential trace mineral required in small amounts for the normal physiologic function of humans which is necessary for regulating metabolic rate, growth, and development of body structures, and neuronal function and development [6,7].
About 66 million populations were at risk from iodine deficiency [19], 28 million people suffer from goiter and more than 50,000 prenatal deaths are related to iodine deficiency each year in Ethiopia [20]. Besides, studies from different parts of Ethiopia have shown that a low proportion of households uses adequate iodine concentration i.e. below 30%, and iodine concentration varied from one household to another [14,17,20,21]. Despite increased coverage of iodized salt, the quality of available salt is poor (16). To ensure safe and effective levels of iodine consumption, monitoring the levels of iodine in salt and the iodine status of the population is critical [22,23]. However, a few studies in Ethiopia were conducted to determine the amount of iodine content in the salt at the household level by using qualitative kits, which have low specificity, resulting in high numbers of false positives, and particularly; no study is conducted in the current study area. Thus, the study aimed to determine the iodine content of salt and associated factors at the household level in Bahir Dar Town, Northwest Ethiopia by using the gold standard iodometric titration method.

Methods
Study area and study period: a community based cross-sectional study design was carried out in Bahir Dar Town from September to October 2015. The town is the capital city of the Amhara region state, located 568 km away from Northwest of Addis Ababa, the capital of Ethiopia. A total, of 311,725 populations resides in the town [24]. The town has nine sub-city administrations and there are five iodized salt whole distributors and one producer (repacker) in the town.
Study participants: all households in selected subcities of Bahirdar Town were included in the study.
Sample size and sampling procedure: the sample size was calculated using Epi-info version 7 by considering the following assumptions; 28.9% prevalence of expected households using adequately iodized salt [14], 95% level of confidence, 5% margin of error, 5% non-response rate, and a design effect of 2. Thus, a minimum sample size of 706 was obtained. Regarding the sampling procedure, multi-stage sampling techniques were used to select the study subjects. Firstly, three sub-cities (Tana, Shimbit, and Gishabay sub-city) were randomly selected out of nine sub-cities in the town. Accordingly, a total number of households was proportionally allocated for each sub-city (1 to 3). In the end, households from each sub-city were selected using a systematic sampling method.
Data collection tools and procedures: the pretested, structured, and intervieweradministered questionnaire and laboratory test were used to collect data. The questionnaire was composed of socio-demographic, personal factors (knowledge about iodized salt and IDD), and environmental factors (salt storage place, duration of storage, type of packaging, moisture, heat/sunlight, source of salt). Initially, the English version questionnaire was translated into Amharic, the native language of the study area, and then back-translated to English, to maintain its consistency. The questionnaire was pretested out of the study area. During the pre-test, the acceptability and applicability of procedures and tools were evaluated, six and two were recruited as data collectors and supervisors, respectively. Intensive training was given to data collectors and supervisors for two days. The daily check-up was made on the completed questionnaire during submission.  The household wealth index was computed using composite indicators for urban residents considering the following assets; ownership of the house, selected household assets, and bicycle, motorcycle, and automobile. Principal component analysis (PCA) was performed to determine the households´ wealth index, and then the wealth status of the study participants was categorized into 3: poor, medium, and highest.

Article
Knowledge: respondents who scored 50% and above regarding iodized salt knowledge questions were leveled as good knowledge, whereas below 50% scored leveled as poor knowledge [14].

Measurement of iodine in the salt: in a laboratory
test, the gold standard iodometric titration method was used to measure individual availability of adequate iodized salt [25]. From each household, approximately 50g and homogenized salt samples were collected and transported to the laboratory daily using a moisture-free, clean, and airtight plastic container. The sample was labeled and coded with the following information during collection: date of sampling, source of salt, batch number, production date, and expiry date. The iodometric titration involved the use of reagents: sulphuric acid, potassium iodate, and potassium iodide as principal reagents, standardized sodium thiosulphates (as titrant), and starch solution (as an indicator). A trained analyst using the gold standard iodometric titration method did the laboratory test. Each sample was analyzed in triplicate and the average of these was taken as the iodine concentration of the sample. The conversion of the titration results to iodine concentrations was done using a standardized table as per recommendations of the UNICEF/WHO [26]. Adequately iodized salt at the household level was defined as a salt sample that has ≥15 parts per million (PPM) of iodine, whereas below <15ppm is defined as inadequately iodized salt.
Data management and analysis: data were entered into Epi-info version 3.5.3 and exported to SPSS version 20 for analysis. Descriptive statistics using frequencies and proportions were used to summarize the study variables. A binary logistic regression model was fitted. Both Crude Odds Ratio (COR) and Adjusted Odds Ratio (AOR) with corresponding 95% Confidence Interval (CI) were computed to show the strength of association. In multivariable analysis, variables with P-value<0.05 were considered statistically significant.
Ethical considerations: ethical clearance was obtained from the institutional review boards of the University of Gondar. Permission was obtained from Amhara Regional State Health Bureau, Bahir Dar Town Zone, Health Department, and the selected sub-cities. In addition, the purpose and the importance of the study were explained and verbal informed consent was secured from each household. Respondents were also informed that they could refuse or discontinue participation at any time. Information was recorded anonymously to maintain the confidentiality and privacy of the respondent.

Results
Socio-demographic characteristics of the study participants: a total of 690 household respondents were included in the study with a response rate of 97.73%. The mean (SD) age of the respondent was 34.5 years (SD ± 11.77). Besides, 29.1% and 33.2% of respondents were secondary education and housewife, respectively (Table 1).
Knowledge and practice of respondents regarding iodized salt: the vast majority (95.36%) and 86.1% of the respondents used powdered and packed iodized salt, and were stored in salt and in a dry place away from humidity and heat/fire area, respectively. Besides, more than three-fourths (80.6%) of the respondents had good knowledge about iodized salt and IDD ( Table 2).   (Table 3).

Discussion
The current study revealed that about 70.1% (95%CI: 63.41, 76.76) of the households had adequately iodized salt (≥15 ppm). The findings in South Asia 69% [8] and Vietnam 73.6% [10] have the same result. On the other hand, the present finding was higher than compared to the other findings: in Ethiopia (Gondar Town 28.9% [14], Laelay Maychew District 33% [17] and Assosa Town 26.1% [27]), Somalia 4% and Mauritania 7% [8], Malaysia 6.8% [28], Pakistan (15%) [12] and India 42% [9]. The possible reason for the higher proportion of iodine content in the households in the present study may be that during the past five years, Ethiopia has made a major effort to stimulate and improve efforts under the national salt iodization strategy through regular follow up and monitoring, awareness creation and the rate of salt iodization. In addition, the urban location of the study area could be factors contributing to the higher iodine content observed due to the use of powdered and packed iodized.
In the present study, the proportion of adequately salt in the household was lower as compared to United Nations Children's Fund report from Ruanda (99%), Uganda (99%), Burundi (96%), Burkina Faso (96%) and Kenya (93%) [8]. The possible reason for higher in these countries might be institutionalizing effective iodized salt regulation, updating equipment, and qualitycontrolled iodization technology at the production, following effective transport channels, correct labeling, packaging, and storage may be explanations for high iodine levels, resulting in adequate amounts of iodine in salt at the households.
Multivariate analysis revealed that the odds of availability of adequately iodized salt was higher among households that had medium and highest wealth status compared to households with poor wealth status. This finding was supported by another study report [18]. This may be due to economically better sections of the household are buying better quality salt in the form of powdered and packed salt. Respondents aged 30-44 yearsold 1.99 folds more likely had adequately iodized salt at the household compared with counterparts. This age (30-44 years) might imply the most reproductive age and respondents may have a child and allow households to offer better nutrition for the appropriate child growth and development, which is a tremendous state of affairs that may well contribute to adequate availability of iodized salt.
The present study discovered that secondary school and higher education was associated with increased availability of adequately iodized salt in the household compared to counterparts. Studies conducted in Gondar Town had the same result [14]. This may be because better education may influence good practice; through better awareness about iodized salt.
Respondents having good knowledge about iodized salt and IDD were significantly associated with the availability of adequately iodized salt in the household. The finding was congruent with studies conducted in Gondar [14], Laelay Maychew District [17], and Burie and Wonberma District [20]. The increase in the knowledge levels suggests that, if awareness creation, educational activities, availability, and accessibility of iodized salt are sustained, it is likely that households would become aware of iodized salt and its importance of consuming iodized salt to human health and wellbeing.
Storage of iodized salt in dry places and covering the salt containers were associated with the availability of adequately iodized salt. The findings in Gondar [14], Laelay Michew [17], Kenya [11], and India [9] had the same results. This result verifies that temperature, moisture as well as uncovered storage will affect the viability of the iodine. Because if salt is stored in hummed condition, it attracts moisture and becomes wet, carrying the iodated to the bottom of the container, at hot conditions, salt can release surface moisture, and this may result in iodine loss under its volatility if the container is opened.

Conclusion
The availability of adequately iodized salt in the household is still low. Further institutionalizing iodized salt regulation and awareness creation will need.

What is known about this topic
 Groups at the highest risk to suffer from iodine deficiency are lactating women, pregnant women, and children younger than three years;  The prevalence of goiter is well known;  A few studies in Ethiopia were conducted to determine the amount of iodine content in the salt at the household level.
What this study adds  The availability of adequate iodized salt in the household is still low;  Educated households were having the availability of iodized salt;  Covering and storing in a good place were predictors of the availability of adequately iodized salt.

Competing interests
The authors declare no competing interest.