I can assure him that even those who would be allergic to iodine would not be affected by the minute quantities which, however, would still be effective in preventing goitre.
That is done because for reasons that no one knows for certain there has hitherto been a high incidence of goitre.
What do we do about people who suffer from a toxic goitre?
No; his whole object in life was to find out why these people were getting goitre, and how to prevent it.
It has been found that the addition of iodine into the water supply reduces goitre.
The same argument applies in regard to pulling iodine into salt to counteract goitre.
Iodine has been added to food in the most obvious centres of goitre, with the most beneficial results.
From about 1900 the local salt was increasingly refined, and goitre started to increase to a high level until iodisation was begun in 1924.