TESTING STABILITY OF IODINE IN SALT: GENERATING
EVIDENCE TO OPTIMIZE STATUTORY IODIZATION
STANDARDS IN BANGLADESH
Mahfuz A1, Kaushik S2, Uddin MB3 and Mahmud Z4.
1
The Micronutrient Initiative, Bangladesh
2
The Micronutrient Initiative, Asia
3
Bangladesh Agricultural University, Mymensingh, Bangladesh
4
BRAC Institute of Global Health, Bangladesh
ABSTRACT
Objectives: To quantify the exact losses of iodine in
salt (commonly produced and packaged in Bangladesh)
to inform the policy on the optimal level of iodine at
production to ensure adequate iodine at the household
level.
Methods: Salt of different types (vacuum evaporated,
refined, non-refined and mechanical salt) were packed
in 4 types of packaging material (laminated, HDPE, LDPE
and woven plastic bags) and stored in eight climatic zones
in Bangladesh. The initial iodization level of salt was 30
ppm and retrieved at the end of every 3 months and tested.
Results: The average iodine loss (in percent) in all types
of packaging material other than plastic oven bags is 14%.
Iodine loss (and increase in moisture content) lowest in
laminated packaging. There was little variation in iodine
loss across climatic zones.
Policy Implications: Iodization standards at production
level can be fixed at 30 ppm.
FIGURE 3. LOSS OF IODINE AND INCREASE IN MOISTURE
CONTENT BY TYPE OF SALT AND PACKAGING MATERIAL
USED
METHOD
• Four types of salt (vacuum evaporated, mechanical,
traditional upgraded and traditional unrefined) iodized
to a concentration of 30 ± 2 ppm.
• Each type of salt packed in four different types of
packaging material (laminated, high density polythene,
low density polythene and woven plastic bags). Vacuum
evaporated salt also stored in salt shakers.
• Salt samples stored in rural households in 8 agroclimatic zones of Bangladesh.
• Samples were analyzed for iodine and moisture content
at an interval of 0, 3, 6, 9 and 12 months of storage
• Samples were also analyzed for NaCl, Mg as Chloride,
Ca as Sulphate and pH of 5% salt solution in water at 0
month and at the end of 12 months of storage.
Storage Locations
Mymensingh
Sylhet
Bandarban
Potia
Rangpur
Rajshahi
Jessore
Dinajpur
BACKGROUND
• In Bangladesh, salt law stipulates salt produced
should have iodine content of 45-50 ppm at the
production level, 20 ppm at retail level and 15 ppm at
household level.
• Gap of iodine content between the production and
consumer end is to allow for losses of iodine which
take place in transit and storage from the production
of salt to its consumption at the household.
• Iodine is lost in salt due to presence of impurities,
moisture and other environmental conditions.
• In recent years, there has been a significant
improvement in the quality of salt being produced
in the country as well as the packaging material being
used.
• These improvements have a significant bearing on
iodine losses in transit and storage.
• There has also been a significant increase in the
price of potassium iodate in the international
& national markets which significantly increases the
cost of iodization.
POLICY IMPLICATIONS
RESULT
FIGURE 1. IODINE CONTENT AFTER 12 MONTHS OF
STORAGE BY PACKAGING MATERIAL
• Salt iodization standards at production level can be
fixed at 30 ppm as iodine has shown to be stable in
environmental condition in Bangladesh.
• Plastic bags for storage and transport of salt should
be banned as plastic bags does not offer protection
against moisture and accelerates iodine decay below
recommended levels.
INITIAL CONCENTRATION – 32 PPM
ACKNOWLEDGEMENT
OBJECTIVE
We would like to acknowledge the support from
Government of Canada through the Department of
Foreign Affairs, Trade and Development, Industry,
Dept. of Food Technology, Faculty of Agricultural
Engineering, Bangladesh Agricultural University,
Mymensingh for their efforts to achieve desired results.
FIGURE 2. IODINE CONTENT AFTER 12 MONTHS OF
STORAGE BY TYPE OF SALT
35
INITIAL CONCENTRATION – 32 PPM
30
26.1
25
Iodine content (ppm)
• This study was undertaken to quantify the exact
losses of iodine in the different types of salt in
the typical environmental conditions in Bangladesh.
• To inform the policy on the optimal level of salt
iodization which can ensure the recommended
level of iodine intake by the population at the household
level.
• Increase in moisture content is the most important
factor determining iodine loss.
• Packaging material is the most important factor
influencing moisture gain and thereby iodine loss.
• Iodine loss (and increase in moisture content) is
highest in plastic bags followed by LDPE, HDPE. It is
lowest in laminated packaging.
• Variation in iodine loss is less across type of salt. Iodine
loss is less in vacuum evaporated salt.
• Very small changes in iodine loss measured across
climatic zones.
• The average iodine loss (in percent) in all types of
packaging material other than plastic bags is 14% overall
it is 30%.
• No significant correlation is not observed between
presence of impurities and iodine loss.
20.1
20
21.3
21.0
15
10
5
0
Vacuum Evaporated Salt
Mechanical Salt
Correspondence: S Kaushik; [email protected]