The iodine content of fresh milk samples in Natal and the effect of iodophor teat dips on milk iodine content

Abstract

The iodine content of fresh milk samples from bulk milk transport vehicles (tankers) and from bulk tanks on individual farms was determined. Approximately 75 percent of all the samples fell within the normal range of 25 to 300 micrograms iodine/l of milk. The mean iodine concentration in the tanker samples was 257 micrograms/l and in the farm tank samples 294 micrograms/l, while the medians of the iodine concentrations in the surveys were 214 and 218 micrograms/l respectively. A total of 1.75 percent of the tanker samples and 5.5 percent of the individual farm samples contained more than 1000 micrograms/iodine/l, a level which is considered to be undesirable for human consumption. Iodine containing teat dips (2000 mg available iodine/l) increased the iodine concentration of the milk of cows treated with these teat dips by between 11 and 60 micrograms/l.