Common hazardous ingredients
Acids, bases, heavy metals, various toxic salts.
Reactive; corrosive; flammable.
Use chemical splash goggles.
Keep lids of chemicals tightly closed when not in use and store out of reach of small children and away from sources of flames.
Best: If the set contains dried out picric acid, avoid transporting it. Contact the explosives disposal team of your local police or fire department.
Second best: Take to a hazardous waste facility or collection event.
Choose the least hazardous experimental sets.