Question

Strontium-90 and radon-222 both pose serious health risks. \({ }^{90} \mathrm{Sr}\) decays by \(\beta\) -particle production and has a relatively long half-life (28.9 years). Radon-222 decays by \(\alpha\) -particle production and has a relatively short half-life (3.82 days). Explain why each decay process poses health risks.

Short answer

Strontium-90 decays by \(\beta\)-particle production and has a long half-life of 28.9 years, leading to prolonged environmental contamination. It can accumulate in bones and teeth due to its similarity to calcium, causing cell damage and increasing the risk of cancer. Radon-222, on the other hand, decays by \(\alpha\)-particle production and has a short half-life of 3.82 days. As a noble gas, Radon-222 can be inhaled and accumulate in the lungs, where its fast decay and high-energy alpha particles can damage lung tissue, increasing the risk of lung cancer.

Step-by-step solution

Strontium-90 decay process

Strontium-90 (\({ }^{90}\mathrm{Sr}\)) is a radioactive isotope that decays by \(\beta\)-particle production. In this decay process, a neutron within its nucleus is transformed into a proton, causing the emission of an energetic electron called a beta particle.

Strontium-90 half-life

The half-life of Strontium-90 is relatively long, at 28.9 years. This means it takes 28.9 years for half of the Strontium-90 present to decay, which contributes to its increased ability to cause long-term contamination and damage.

Strontium-90 health risks

Given its long half-life, Strontium-90 can remain in the environment for an extended period, potentially contaminating water, soil, and food sources. Moreover, Strontium-90 has properties similar to calcium and can be taken up by the body and incorporated into bones and teeth, as it deposits there. This exposure to beta radiation can damage cells, potentially causing cancer or other disorders.

Radon-222 decay process

Radon-222 (\({ }^{222}\mathrm{Rn}\)) is another radioactive isotope that poses significant health risks. It decays by \(\alpha\)-particle production, which is a process involving the emission of two protons and two neutrons (as an alpha particle) from its nucleus.

Radon-222 half-life

The half-life of Radon-222 is relatively short, at only 3.82 days. This means that it takes 3.82 days for half of the Radon-222 present to decay, and it decays relatively quickly compared to other radioactive elements.

Radon-222 health risks

Radon-222 is a noble gas and chemically inert, so it can be inhaled and accumulate in the lungs. The fast decay and high energy of the emitted alpha particles can cause significant damage to lung tissue. Regular exposure to high levels of Radon-222 over an extended period can lead to lung cancer. Since it is a gas, it can easily infiltrate buildings through cracks, water, or soil, leading to a risk of indoor radon exposure.

Key concepts

Beta Decay

In beta decay, a neutron in an atom's nucleus transforms into a proton. This process releases an electron, known as a beta particle. This transformation alters the atomic structure, changing one element into another with a different atomic number.
Understanding beta decay is important because:

• It changes the element into a new one, affecting its chemical and physical properties.
• Beta particles are moderately penetrating, able to pass through paper but stopped by materials like aluminum.
• Exposure to beta particles can lead to damage in living cells, increasing cancer risk.

Alpha Decay

Alpha decay involves the release of an alpha particle, consisting of two protons and two neutrons, from the nucleus of an atom. This process results in a new element with an atomic number reduced by two and a mass number reduced by four.
Key aspects of alpha decay include:

• Alpha particles are large and heavy compared to other forms of radiation.
• They have low penetration power, often stopped by just a sheet of paper or human skin.
• However, if ingested or inhaled, alpha particles can cause serious internal damage.

Half-life

The half-life of a radioactive substance is the time it takes for half of its atoms to decay. This measurement helps determine how long a radioactive material remains active or hazardous.
Important points about half-life:

• A long half-life means prolonged environmental presence, as seen with Strontium-90 (28.9 years).
• A short half-life leads to rapid decay, like Radon-222's 3.82 days, posing immediate but transient health risks.
• Half-life helps in calculating the decay rate of radioisotopes, aiding in safety measures.

Radiation Health Risks

Radiation from decay processes can have different health impacts depending on the type and amount of exposure. Both beta and alpha decays pose distinct health risks:
Some health risks include:

• Beta radiation can penetrate skin but is less harmful internally compared to alpha radiation.
• Alpha radiation, though less penetrating, is highly dangerous when substances are inhaled or ingested, targeting internal organs.
• Long-term exposure to radioactive materials can lead to cancer, genetic mutations, and other health disorders.
• Radon exposure is significant indoors, requiring regular ventilation to mitigate health risks.

Understanding these risks helps in taking preventive measures to protect health and the environment.