The biological mimicry of strontium-90
At its core, strontium's chemical similarity to calcium is the central mechanism behind its harmful effects. In the human body, calcium is essential for building and maintaining strong bones and teeth. Strontium, which is in the same group of elements on the periodic table, is a metabolic impostor. When radioactive strontium-90 enters the body, it is treated much like calcium by the body's natural processes.
This is particularly relevant for healthy aging and senior care, as bone density changes with age. As a result, any internal radiation that accumulates in the skeletal structure can have more pronounced and devastating effects. The body's bone turnover process, which slows down in older adults, means that strontium-90 can be retained in the skeleton for decades, causing prolonged internal radiation exposure.
Accumulation and prolonged exposure
Once ingested or inhaled, a significant portion of strontium-90 is deposited in the mineral matrix of bones and teeth, with the rest distributed among soft tissues and blood. The half-life of strontium-90 is approximately 29 years, which means it remains a radioactive threat for a very long time once integrated into the skeletal structure.
The mechanism of bone deposition
- Children and young people: In developing skeletons, strontium-90 can be permanently incorporated into the hard bone mineral, where it stays for many years. This is why children are considered more vulnerable, as their bone growth is more rapid, leading to higher absorption rates.
- Adults and seniors: In adults, strontium-90 primarily attaches to the surface of bones. Over time, it can be released back into the bloodstream during normal bone remodeling processes, but its residence time in the skeleton is still very long, estimated at an average biological half-life of 18 years.
The cascade of radioactive damage
Strontium-90 decays by emitting high-energy beta particles. This radiation damages the surrounding bone tissue and, most critically, the soft bone marrow, which is responsible for producing blood cells. The effects of this prolonged, localized irradiation include:
- DNA damage: The beta particles can cause mutations in the genetic material (DNA) of cells, leading to uncontrolled growth and cancer.
- Cellular death: High radiation doses can directly kill cells, particularly the rapidly dividing cells in the bone marrow, leading to anemia and other blood disorders.
Health effects and risks
The primary health risks associated with internal exposure to high levels of strontium-90 are cancer and blood disorders. While low-level environmental exposure is less of a concern, high-level exposure from nuclear accidents or industrial contamination poses a serious threat.
Cancers and blood disorders
- Bone cancer (osteosarcoma): The constant irradiation of bone tissue from absorbed strontium-90 can induce the formation of malignant bone tumors.
- Leukemia: Damage to the hematopoietic stem cells in the bone marrow can lead to leukemia, a cancer of the blood-forming tissues.
- Immune suppression and anemia: The destruction of bone marrow can result in a suppressed immune system and anemia (low red blood cell count), causing excessive tiredness and impaired blood clotting.
Comparison of calcium vs. strontium-90 in the body
| Feature | Calcium (Stable) | Strontium-90 (Radioactive) |
|---|---|---|
| Function | Essential for bone and teeth structure, muscle function, and nerve signaling. | No beneficial biological function; acts as a harmful calcium mimic. |
| Absorption | Actively regulated by the body; more efficient absorption in the intestines. | Absorbed via mechanisms similar to calcium, but less efficiently; uptake is higher in growing skeletons. |
| Deposition | Integrates precisely into the bone mineral lattice to form strong, healthy bone. | Integrates into bones and teeth, but its atomic properties differ slightly from calcium, potentially affecting bone structure. |
| Radiation | Not radioactive. | Emits high-energy beta particles that damage nearby cells and tissues. |
| Health Effects | Supports strong bones and overall health. | Increased risk of bone cancers, leukemia, and other radiation-induced diseases. |
| Half-life | Stable. | 29.1 years, causing long-term internal exposure. |
What to do if exposure is suspected
While accidental exposure is rare for most people, those working in nuclear facilities or living near areas with contamination may be at risk. In the event of potential exposure, prompt medical attention is crucial. Immediate steps include decontamination by removing clothing and thoroughly washing the skin.
Medical countermeasures for internal contamination, such as using stable calcium or aluminum hydroxide, may be administered by healthcare professionals to block or reduce the absorption of radioactive strontium. These treatments work by either competing with strontium for absorption in the gut or occupying bone-binding sites to minimize radioactive strontium uptake.
Conclusion: the long-term impact on the body
In conclusion, strontium-90's danger lies in its ability to be mistaken for calcium by the human body, leading to its incorporation into the skeleton. This effectively turns the body's largest mineral reserve into a source of continuous internal radiation. Over time, the beta radiation emitted can cause significant damage to the bone tissue and, more critically, the bone marrow, raising the risk of developing cancers like osteosarcoma and leukemia. While treatments exist to mitigate the effects after exposure, preventing exposure is the best course of action. For more information on general radiation safety and managing internal contamination, refer to the Radiation Emergency Medical Management website.
