Heavy metals
Heavy metals are chemical elements released in industrial waste from factories.
They are especially dangerous when they contaminate water and the ground.
These heavy metals include mercury,lead,antimony,arsenic,tin,cadmium and many others.
Heavy metals in the food chain are very dangerous to humans and animals.
They can cause a number of diseases,many of which are fatal. Lead con cause the destruction of the nervous system and the brain. Too much lead accumulated in the body is fatal.
Mercury can cause certain types of cancer which can kill humans and also minamata a brain disease.
These are usually caught from eating mercury infested fish. Alll heavy metals are dangerous pollution.
Universe and space
Space is the vast area outside the Earth's atmosphere and is the home of our solar system,other stars,planets and other things traveling through space.
Scientists haven't been able to find out exactly how and when the Universe,with its stars and our solar system began.
They believe it may have started some fifteen billion years ago.