Complex sentence: In the early 20th century a series of "medical" products which contained radioactivity were marketed to the general public, these are included in this discussion of nuclear/radioactive crime because the sale and production of these products is now covered by criminal law.
Split into simpler sentences: In the early 20th century a series of "medical" products which contained radioactive elements were marketed to the general public. These are included in this discussion of nuclear/radioactive crime because the sale and production of these products is now covered by criminal law.