Strontium

formula: Sr; CAS Registry Number: 7440-24-6

Alkaline earth metal with high reactivity that occurs naturally only in compounds with other elements

Strontium (Sr) is a ubiquitous metal. Due to its high chemical reactivity, it occurs naturally only in compounds with other elements. Most common are Sr-sulfate (celestine) and Sr-carbonate (strontianite). The concentration of strontium in ocean water is about 8 mg/L.

Commercial uses of strontium and especially its compounds include those in electronical- and electrical industry (e.g. as component of fluorescence substances, batteries, electrical capacitors, and optical devices), in glass industry, metalworking industry, pyrotechnics and in medicine. In tooth-pastes strontium chloride is used to reduce the temperature sensitivity of teeth.
Furthermore, it is used as tracer in archaeology and geology.

Strontium enters the environment during weathering of rocks and anthropogenic activities. It is found in the atmosphere, in soils and water where it is partly dissolved.

Strontium is taken up by plants. Humans are exposed to strontium via air, water and food.

Most strontium compounds are not toxic. Inside the organism strontium behaves like calcium and is incorporated in bones and teeth. Whereas the stable isotopes of strontium normally pose no health threat, incorporated radioactive 90Sr which is present in radioactive fall-out after nuclear explosions and nuclear accidents may lead to cancer and is thus classified as carcinogenic. The half-life of 90Sr is 28.6 years.

Specimen

Students Student groups with an even number of female and male students at the age of 20 to 29.

Sampling area

Sampling sites (humans) 4 university cities as sampling areas.

Sampling period

1993 - 2018