Thorium is a radioactive element - Edexcel - GCSE Physics - Question 6 - 2017 - Paper 1

The initial activity of a radioactive sample is inversely related to its half-life. Since thorium has a half-life of 1.9 years and radium has a half-life of 3.5 days, radium will show a higher initial activity compared to thorium because it decays much more quickly.

For alpha radiation, I would place an X in option B (is highly ionising) because alpha particles can cause significant ionization in a material due to their charge and mass.

For the toothpaste that contains radioactive thorium, I would place an X in option C (we understand more about the effects of radiation) because advancements in scientific understanding have highlighted the health risks associated with radioactive materials.

Using an isotope of thorium in toothpaste poses significant health risks. Thorium is radioactive and can emit harmful alpha radiation which can cause damage to oral tissues and bones upon contact. Additionally, the decay of thorium into radium and subsequently into radon gas increases the risk of further radiation exposure, which has been linked to cancer and other health issues. Understanding these dangers, strict regulations have been established to prevent the use of such radioactive materials in consumer products.