Abstract
The main objective of the study was to assess the effect of physico-chemical and
environmental factors such as, packaging materials, type of salt, moisture content of
salt and impurities of salt on stability of iodine in iodized salt. The study was
designed to quantify the total losses of iodine in the different types of iodized salt in
different packaging materials with varied environmental condition. The study result
indicated the optimal level of iodization at production level. The study involved
storage of different types of iodized salts packed in different packaging materials in
8 districts - representing seven climatic zones in Bangladesh. Salt of different types
(vacuum evaporated, mechanical, traditional upgraded and traditional non-refined
salt) were packed in 4 types of packaging material (laminated foil, high density poly
ethylene (HDPE), low density poly ethylene (LDPE) and woven plastic bags). The
salt samples had an initial iodization level of 32 ppm and samples were retrieved at
the end of every 3 months and tested for iodine, moisture content and other
parameters. The study concluded on average of 14 per cent iodine loss in iodized salt
over a period of onene year. This loss is much lower than previously anticipated and
the iodine content is above the minimum mandated levels of 15 ppm of iodine at
household level. However, in plastic bag which is still being used to transport and
store salt in Bangladesh, the loss is as high as 82%. The salient features of findings of
the studies are, increase in moisture content is an important factor determining
iodine loss; packaging material is an important factor influencing moisture gain and
thereby iodine loss; very small changes in iodine loss observed across climatic zones.
Iodine content across all combinations of packaging material and salt types is above
24 ppm after 12 months except in plastic bag. The average iodine loss (in percent) in
all types of packaging material excluding plastic bags is 14% and including plastic
bags is 82% and overall it is 30%. The findings strongly suggest a lowering of salt
iodization standards at the production level and can be fixed at 30 ppm as iodine has
shown to be stable in environmental condition in Bangladesh