Strontium compounds that are water-insoluble can become water-soluble, as a result of chemical reactions. The water-soluble compounds are a greater threat to human health than the water-insoluble ones. Therefore, water-soluble forms of strontium have the opportunity to pollute drinking water. Fortunately the concentrations in drinking water are usually quite low.

People can be exposed to small levels of (radioactive) strontium by breathing air or dust, eating food, drinking water, or by contact with soil that contains strontium. We are most likely to come in contact with strontium by eating or drinking.
Strontium concentrations in food contribute to the strontium concentrations in the human body. Foodstuffs that contain significantly high concentrations of strontium are grains, leafy vegetables and dairy products.

For most people, strontium uptake will be moderate. The only strontium compound that is considered a danger to human health, even in small quantities, is strontium chromate. The toxic chromium that it contains mainly causes this. Strontium chromate is known to cause lung cancer, but the risks of exposure have been greatly reduced by safety procedures in companies, so that it is no longer an important health risk.

The uptake of high strontium concentrations is generally not known to be a great danger to human health. In one described case someone experienced an allergic reaction to strontium, but there have been no similar cases described since. For children exceeded strontium uptake may be a health risk, as it can cause problems with bone development.

Strontium salts are not known to cause skin rashes or other skin problems of any kind.
When strontium uptake is extremely high, it can cause disruption of bone development. But this effect can only occur when strontium uptake is in the g/kg bodyweight range. Strontium levels in food and drinking water are never high enough to be able to cause these effects.