Determination of Sr in milk and milk powder in Tehran and estimation of annual effective dose.

Thirty-eight different milk and milk powder samples from Tehran-Iran were collected and analyzed for Sr activity using a method in which the daughter product of Sr decay (Y) was extracted by tributyl phosphate from ashed milk. Y was then back extracted with water, and oxalate was precipitated . Following the sample analyzing, beta counting was performed with an ultralow-level liquid scintillation spectrometer. The quality control and assurance of the method were obtained by standard samples prepared with an IAEA-certified reference material. The mean determined Sr activity concentration in the analyzed milk and milk powder (0.225 ± 0.042 and 0.216 ± 0.024 Bq kg, respectively) showed that the radioactivity concentration in our samples was too low to induce biological hazards. These data can provide useful information of the background level of contamination, which in turn can be used in the following environmental monitoring programs. [ABSTRACT FROM AUTHOR]