Impact after 1 year of compulsory iodisation on the iodine content of table salt at retailer level in South Africa

Abstract

The short-term effectiveness of introducing compulsory iodisation through revised health legislation, evaluated in terms of the iodine content of iodised table salt, was investigated in three of the nine provinces in South Africa. Shortly before the introduction of compulsory iodisation of table salt in December 1995, iodised at a higher level than before, 187 iodised salt samples were purchased at retailers in 48 magisterial districts situated in the three provinces of Western and Eastern Cape and Mpumalanga for analysis of the iodine content using the titration method. In a follow-up 1 year later 287 iodised salt samples were obtained from the same retailers for iodine determination. The mean iodine content of iodised salt increased significantly from 14 to 33ppm. However, large variation in the iodine content of iodised table salt among and within salt brands existed at follow-up, and the mean iodine content was lower than the legal specification of 40 to 60ppm. Only 24% of the samples were found within the range required by the law at follow-up compared to 42% before revising the salt legislation. Despite the introduction of compulsory salt iodisation, the mean retail price of iodised salt remained the same between 1995 and 1996 for a 500g package of salt. Further refinement of the iodisation process is necessary to improve the accuracy of iodisation and decrease the variation in iodine content. This study nevertheless showed that the introduction of compulsory iodisation and elevating the legally specified iodine level of table salt resulted in a significantly elevated mean iodine level of iodised salt within 1 year, without any additional cost to the consumer.