JAMB - Chemistry (2002 - No. 19)
The substance least considered as a source of environmental pollution is
Lead compounds
Organophosphorous compounds
Silicate minerals
Uranium
הֶסבֵּר
Lead compounds, Organophosphorous compounds, and Uranium are considered as sources of pollution to the environment while Silicate minerals such as quartz, beryl, feldspar etc causes little impactation on the environment in terms of pollution.