Fifty years after the first U.S. surgeon general's report declared smoking a hazard to human health, the tally of smoking-related effects keeps rising, with liver and colorectal cancers, diabetes, rheumatoid arthritis and even erectile dysfunction joining the list, according to a report released on Friday.

The report, the first in more than a decade, found that smoking has killed more than 20 million Americans prematurely in the last half century, and warns that, if current trends continue, another 5.6 million children are at risk of dying prematurely.

Although adult smoking rates have fallen to the current 18 per cent from 43 per cent of Americans in 1965, each day, more than 3,200 youths under the age 18 try their first cigarette, the report found.

"Enough is enough," acting Surgeon General Dr Boris Lushniak said in a telephone interview. "We need to eliminate the use of cigarettes and create a tobacco-free generation."

Lushniak is calling on businesses, state and local governments, and society as a whole, to end smoking within a generation through hard-hitting media campaigns, smoke-free air policies, tobacco taxes, unhindered access to cessation treatment and more spending by state and local governments on tobacco control.

"It's not just the federal lead on this anymore," he said. "To get this done, we have to go to industry. We have to go to healthcare providers and remind them that this problem is not yet solved."

The report, dubbed The Health Consequences of Smoking, 50 Years of Progress, details the growing science showing the diseases and health conditions caused by smoking since Dr. Luther Terry issued the landmark report on Jan. 11, 1964, that first confirmed smoking tobacco caused lung cancer.

Earlier, on June 17, 1963, Canada's Minister of National Health and Welfare, Judy LaMarsh, rose in the House of Commons to make a declaration : "There is scientific evidence that cigarette smoking is a contributory cause of lung cancer and that it may also be associated with chronic bronchitis and coronary heart disease." 

But it was the Surgeon General's report that captured the world's attention. 

In that first U.S. report, only lung cancer was associated with smoking.

"We're up to 13 right now — 13 different cancers associated with smoking in 2014," Lushniak said.

The new report adds liver and colorectal cancer to that list, but it also details several other conditions caused by smoking, including diabetes, rheumatoid arthritis and impaired immune function, and cleft palate in infants.

And in a startling statistic, the report found that exposure to secondhand smoke increases the risk of stroke by 20 to 30 per cent.

"It really is astonishing that even 50 years in, we are finding new ways that tobacco maims and kills people," Dr Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention, said in a telephone interview.

He said the report found that smoking costs the nation $130 billion US in direct medical expenses each year.

Frieden reiterated that tobacco control efforts have saved as many as 8 million lives in the past 50 years, but stressed that much more needs to be done to eliminate smoking, which remains the leading cause of preventable death in the United States.

E-cigarette questions

The report briefly touched on the increasingly controversial topic of electronic or e-cigarettes — devices designed to deliver nicotine through vapor instead of tobacco smoke. It noted that major tobacco companies, including Altria Group Inc , best known for its Marlboro brand; Reynolds American Inc , maker of Camel cigarettes; and Lorillard Inc, maker of Newport cigarettes, have invested in the products.

Previous studies have suggested that people can use the devices as smoking cessation tools, but some public health advocates worry that e-cigarettes might introduce more people to nicotine, the addicting chemical found in tobacco. Electronic devices that feature fruit and candy flavors are even more worrying, critics say, because they could introduce children to smoking.

And there are still questions about the safety of the vapours released by the devices.

Lushniak said there is not enough information about the long-term effects of the products, or whether their use might delay people from quitting or lead former smokers to relapse. Health groups and state attorneys general have been pressuring the FDA to impose regulations on the devices.

Altria said in a statement that it supports the FDA's authority to regulate e-cigarettes as an extension of its power to regulate tobacco.

"Our tobacco companies continue to focus on developing lower-risk products that appeal to adult tobacco consumers and see this as an important business opportunity under FDA regulation," the company added.