Activity Concentrations in Milk: 1966-2007 4
Activity concentrations
Activity concentrations in milk |
| 1966 | 1975 | 1987 | 2005 | 2006 | 2007 |
|---|
Caesium 137 (Bq/litre) | 1.90 | 0.30 | 11.00 | 0.051 | 0.051 | 0.050 |
|---|
Strontium 90 (Bq/gram of calcium) | 0.60 | 0.13 | 0.06 | <0.074 | <0.067 | <0.057 |
|---|
Exposure to high levels of ionising radiation from radioactive substances can lead to radiation sickness and is associated with genetic damage that can cause cancer.
To monitor exposure to radionuclides through the diet, activity concentrations in cows' milk are valuable indicators. Between 1966 and 1980, there were gradual falls in the concentrations of caesium-137 ( 137Cs) and strontium-90 ( 90Sr). This reflects a decline in atmospheric radioactive fall-out, following the ban on above-ground nuclear weapons testing under the 1963 Partial Test Ban Treaty between the UK, USA and former USSR.
Activity levels of 137Cs in milk peaked following the Chernobyl reactor incident in 1986, with 1987 levels 220 times greater than in 1985. 5 Concentrations then fell rapidly in 1988, and are now below pre-Chernobyl levels.
Community Food Intervention Levels ( EC/686/95) set post-accident activity levels for food at which intervention should occur. In milk, these are 1000 Bq/kg (1030 Bq/l) for 137Cs and 125 Bq/kg (1.01 Bq/g of calcium) for 90Sr. Peak concentrations in milk are now well below the EC intervention levels, which were derived to ensure public protection.
Source: Scottish Environment Protection Agency