For example, we can quit smoking, avoid getting too much sun, and eat a healthy diet. Scientists learn about the causes of cancer from specific observations. They also look for patterns of cancer in large groups of people. Research studies and trials study the toxic effects of substances on animals, tissues or cells. They determine what the risks and effects are by testing how strong and how reliable the scientific proof is.
People often worry that common things in their environment can increase their risk of cancer.
Here is what research studies have found out about some of these concerns. It is hard to know how much air pollution affects cancer. This is partly because air pollution is hard to define and measure. It is also difficult to measure how being exposed to low levels of pollution affects large populations. Actually, more polluting substances come from smoking than from air pollution.