Burning and persistent organic pollutants
Burning large amounts of fossil fuel in factories, vehicles, thermal power stations and homes, and burning waste such as polythene and plastic, adds gases such as dioxins, carbon monoxide (CO), carbon dioxide (CO2) and sulphur dioxide (SO2) to the environment.
Persistent organic pollutants (POPs)
A group of challenging organic chemicals entering the environment from many sources has been identified as persistent organic pollutants. They:
- remain in the environment for a very long time without breaking down;
- build up in living bodies along food chains;
- spread over very wide areas;
- are highly poisonous.
Twelve of the persistent organic pollutants that could be a great threat to the Earth have been named the dirty dozen.
For extra knowledge — the dirty dozen
| Industrial chemicals | By-products of industry and burning | Pesticides |
|---|---|---|
| Hexachlorobenzene | Dioxin | Aldrin, chlordane, DDT |
| Polychlorinated biphenyls (PCBs) | Furan | Dieldrin, endrin, heptachlor |
| Mirex, toxaphene |
Many more compounds also count as persistent organic pollutants. Their effects include deformities at birth, cancer, lowered intelligence, and weakening of the immune and reproductive systems.
Why burning plastic is so bad
Plastics such as PVC contain chlorine, as you saw in chapter 14. Burned at the low temperature of a garden fire, their chains break into fragments that join into dioxins and furans — two members of the dirty dozen. Once formed they settle on grass and water, are eaten by animals, and pass up food chains into meat, milk and fish. This is why plastic should never be burned in the open, even though burning seems to make the rubbish disappear.
Persistent, poisonous, widespread
POPs such as dioxins, DDT and PCBs last long, spread widely, build up in food chains and cause cancer and birth defects.