According to medical records, the global incidence of cancer in the second half of the 20th century than the first half of the increase of nearly 10 times, become a threat to human life of the first killer
The average life span of human beings was about 30 years old at the beginning of the 20th century, 40 years old in the middle of the 20th century, and about 65 years old at present. The average life span of developed countries with high incidence of cancer generally exceeds 70 years old
 This shows that the global ecological imbalance caused by the rapid economic development marked by high technology in the second half of the 20th century is an important cause of cancer