Iodine concentration in Polish milk - variations due to season and region

Iodine concentration was studied in Polish consumer milk. The milk originated from 13 provincial cities and 65 dairy cooperatives located in Poland. Milk iodine concentration in the winter season of 2007-2008 was 146.8 mg/L, with a standard deviation for the provinces of 27.9 mg/L and variation coefficient of 19.0% (n = 66 samples). Iodine concentration for provincial cities ranged from 76.3 to 192.0 mg/L. It was highest in the milk samples from the Lubelskie province (191.9 mg/L) and lowest in the milk samples from Podlasie (113.8 mg/L). In the summer season, milk iodine concentration averaged 100.4 mg/L, with a standard deviation of 38.9 ìg/L and variation coefficient of 38.8% (n = 27 samples). Iodine concentration for provincial cities ranged from 63.8 to 173.7 mg/L. Compared to the winter season, milk iodine concentration in the summer season was lower by an average of 25.2%, with a standard deviation of 4.3% (Kielce) to 52.2% (Wrocław).