From Elite Wiki

A commodity found on the F8 markets screen.

Ores and by-products of quantum-chemical processes. Some systems require traders to have special permit, request info and collect the proper papers in advance.

Traded in TCs & stored in the Cargo Hold for trade.

Cheaper on agricultural worlds, dirt cheap at Rock Hermits and more expensive at industrial worlds.

The Liners ships sometimes have small quantities of waste Radioactives for sale.

New Cargoes OXP

New Cargoes is an OXP which allows trade specifically in such items as Low-energy waste and Quirium Isotopes.

The major legal specific variants of the radioactives commodity are

Gene-splicers: Substances that rewrite genetic code, even in a controlled fashion, are not regularly used. For systems that have overused cloning in the past, though, this can be the only way to reintroduce genetic diversity into the population.
Low-energy waste: Low-level radioactive waste is mostly an annoyance. However, the unpredictable rate of its decay is essential to casinos as a source of unbiased random numbers.
Terraforming nanobots: If you need an inhospitable planet terraforming to be hospitable, these miniature robots will do the trick. Unless you want your ship turning into a tiny planetoid, however, do not open the container inside.
Quirium Isotopes: Larger, more active suns produce a wider range of quirium isotopes. There is therefore a natural surplus of certain isotopes in some systems, and a natural deficit in others. To produce a consistent mix for witchspace engines, some trade is needed.

Illegal variants include Next-generation personality editors (The Communist states have been at the forefront of personality editing, though the technology has become more widespread across all systems. These next-generation editors, transmitted through a viral medium, are viewed with extreme suspicion).