Many different chemicals are widely used in INTENSIVE FARMING to speed up the growth of plants and animals, and to kill bugs and stop diseases. One of the main problems is that although these chemicals work in the short term, they do not just disappear and stay in the food that we eat. Our food is thus contaminated with chemicals. Soil used to grow the plants will also be contaminated and have chemicals living in it for a very long time. Animals which eat the grass which has had chemicals sprayed on to it will absorb them into their blood and therefore their flesh and brain. They too become contaminated.