The objective of the study was to assess the optimal level of iodine in edible salt at production level in Pakistan, by quantifying the losses of iodine in transit and storage from production to household purchase. Future analyses will evaluate stability in the household once opened.
400 salt samples from a range of 6 salt types (Washed and Dried Lake Salt, Refined Lake Salt, Good Quality Rock Salt (Punjab), Poor Quality Rock Salt (KPK), Refined Rock Salt and Sea Salt) were drawn from and stored in 4 climatic zones (Marine Tropical Coastland, Sub Tropical Continental Lowlands, Sub-Tropical Continental Highlands and Sub Tropical Continental Plateau). with 4 packing types (High Density Polyethylene, low Density Polyethylene, laminated Polyethylene bags and Polypropylene). All salt types were iodized at 30±2 mg of iodine per kg.
Retention of iodine over 12 months storage was >90% for majority of samles except one. The Polypropylene 40 kg bulk packing showed the lowest iodine losses and one type of rock salt from Khyber Pakhtunkhwa contained contaminants that caused iodine to deposit onto the inner walls of the impermeable packing, with 77% reduction in iodine in the salt at 12 months.
Most current packing and storage methods allow more iodine retention at one year than expected. Household storage periods and losses must also be confirmed, but the current recommendation of 30ppm iodine at production level might not be necessary in Pakistan to allow 15ppm at point of consumption