Every day, people come into contact with thousands of chemicals. These chemicals are said to be harmless to human health. In fact，the chemicals are considered so safe that we wash with them. We put them on our bodies and even our faces. Other chemical products are used throughout our homes.

By the time you walk out of your front door, you have already been exposed to thousands of chemicals.

On its own, each chemical seems harmless. But in combination with other chemicals, they may become deadly. That is the finding of a two-year study by a high-profile task force of scientists. The task force was told to investigate the cancer-causing possibility of chemical mixtures.

Linda Gulliver was one of 174 scientists on the task force. Their job was to study the cancer-causing potential of 85 chemicals. All 85 are said to be common in the environment.

Ms. Gulliver explains that chemicals have the potential or y to form dangerous mixtures. Even simple minerals can become dangerous when mixed with chemicals found in plastics or beauty products.

Working in groups, the scientists explored how different chemical mixtures could lead to cancer. Ms. Gulliver’s team looked at the ability of different combinations to support the in- crease of malignant (惡性的) human cells.

She says the current way to identify whether chemicals cause cancer is to test them one at a time. This method leads, she adds, to a long list of supposedly “safe” chemicals. She and her team say that approach needs to change.

“We definitely need certain research… to find out what mixtures of chemicals would be more harmful than others; what groups of chemicals, when together, would produce more harmful effects. And at the moment, that is not known.”

An estimated one in five cancers has been linked to chemical exposure. It may turn out that the cancer-causing villain (惡棍) is not a single chemical at all.

1.What effect may one single chemical have on us according to the text?

A. It may let us suffer from cancer.

B. It may not cause danger to us.

C. It may destroy our body.

D. It may let our body make a change.

2.What can we learn about Ms. Gulliver’s research?

A. She has found reasons for five kinds of cancers.

B. She has found that only one chemical can cause cancer.

C. She has found 85 cancer-causing chemicals.

D. She is not sure what mixtures of chemicals are more harmful.

3.According to the text? we can infer that the study .

A. is just wasting time and money

B. is in need of great efforts

C. will cause panic in public

D. will be resisted by the public

4.What is the best title for the text?

A. Mixtures of Safe Chemicals May Cause Cancer

B. Being Exposed to One Chemical Is Dangerous

C. How Mixtures of Safe Chemicals Come into Being?

D. What Is the Real Cause for Cancer?

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