Question

which is not a concern related to the proper handling and disposal of batteries and flares?
most batteries contain lead and/or cadmium; cadmium is potentially toxic and may accumulate in fish tissue, and lead is known to have severe and chronic effects upon humans, especially on children.
both flares and batteries contain high levels of a tin compound known as tbt which is highly toxic (in extremely low concentrations to aquatic organisms.
flares contain phosphorus and may degrade after numerous sweatings, so they should be stored in a dry, airtight, but easily accessible container.
because of their toxicity, flares and batteries should be disposed of only in approved containers and locations.

Explanation:

Batteries contain lead and cadmium with known toxicity concerns. Flares with phosphorus need proper storage and both need proper disposal. However, TBT is mainly associated with antifouling paints on ships, not commonly with flares and batteries.

Answer:

Both flares and batteries contain high levels of a tin compound known as TBT which is highly toxic (in extremely low concentrations to aquatic organisms).