1900:

cancer is the tenth leading cause of death in the U.S., responsible for only three percent of all deaths. By the end of the 20th century, cancer will be the cause of 20 percent of all deaths in the U.S.

Diabetes affects less than one-tenth of one percent of the U.S. population; by the end of the 20th century, almost 20 percent of U.S. citizens will contract types I or II diabetes.

Asthma and related immune system diseases are virtually nonexistent; by the end of the 20th century at least 150 million people worldwide will be afflicted.

Breast cancer in women is very rare in 1900; by 1960, breast cancer will affect one in 20 women; by 2005, one in three women will develop breast cancer.

1906:

the Pure Food and Drug Act is passed by the U.S. Congress, enabling the federal government to remove a food or drug product from circulation if its proves unsafe. But food processors and drug manufacturers are not required to prove their products are safe; the burden is on government to prove the products are unsafe before they can be removed.

1920:

from this date forward to 2000, the U.S. production of synthetic chemicals increases from less than one million pounds a year to more than 140 billion pounds a year.

1921:

General Mills Corporation creates a character named Betty Crocker to convince generations of Americans to use processed foods.

Prior to this date a total of 20 reports of endometriosis in women had been reported worldwide; by the late 1990s, nearly 20 percent of all women of childbearing age are afflicted with endometriosis in the U.S.

1930:

about 3,000 people this year out of a U.S. population of 123 million will die of heart disease; by 1997, at least 727,000 people will die of heart disease out of a U.S. population of 248 million.

1933:

Industrial synthesis of vitamin C: A workable method of synthesizing vitamin C is turned into a commercial success by the pharmaceutical company Roche.

A muckraking book, “100 Million Guinea Pigs: Dangers in Everyday Foods, Drugs, and Cosmetics,” is published and becomes a bestseller. It reveals many cases of harm and death from such products as eyelash liners that blind women, hair removal creams made from rat poison, and cataracts caused by a weight-loss drug.

An American Journal of Medicine paper identifies a new type of diabetes resistant to insulin, called type 2 diabetes, which is becoming a disease epidemic in the U.S.

1936:

a report published by a committee of the U.S. Senate warns the American public: “Do you know that most of us today are suffering from certain dangerous diet deficiencies which cannot be remedied until the depleted soils from which our foods come are brought into proper mineral balance?”

1938:

Pharmaceutical maker Roche, having mastered the industrial synthesis of vitamins A, B1, B2, E and K, becomes the world’s leading supplier of vitamins.

A new federal law, The Food, Drug and Cosmetics Act takes effect. Though the law empowers the U.S. Food and Drug Administration to force manufacturers to prove their products are safe before marketing them, the FDA chooses to focus enforcement efforts on the accuracy of information on product labels.

A powerful new pesticide called DDT is discovered by a Swiss chemist; in this same year British scientists synthesize a synthetic estrogen called DES.

From this date until 1990, average human male sperm counts drop by almost 50 percent; during the same period the incidence of testicular cancer triples.

The first cases of a new childhood disorder called autism are reported by Johns Hopkins University psychiatrist Leo Kanner.