Ingestion of milk is a primary
pathway by which radioactive materials released into the atmosphere
may reach the offsite population. Milk samples are collected
at areas close to the INL boundary and distant to the INL.
Samples are collected from both single-family farms and commercial
dairies. A 2-liter (0.5-gallon) sample is obtained from each
location monthly, except in Idaho Falls where a sample is collected
weekly. Milk from each location is analyzed for
Iodine-131 (131I), and one analysis for
strontium-90
and
tritium at each location is performed during the year.
Milk was the first agricultural product to be monitored,
beginning in at least 1957. The number of samples collected per year has
been relatively constant since about 1962. Because of improvements in
counting technology, the detection limit for 131I has
decreased from about 15,000 pCi/L in early sampling to the current
detection level of about 2 pCi/L.
