Health Highlights: July 13, 2008

A decline in the number of adult smokers to slightly below 20 percent also is a factor, the Associated Press reported.

Some 46 percent of nonsmokers had evidence of measurable blood nicotine levels between 1999 and 2004, compared with 84 percent of nonsmokers sampled in the late 1980s and early 1990s.

Exposure to secondhand smoke can increase a nonsmoker's lung cancer risk by at least 20 percent and the risk of heart disease by at least 25 percent, the wire service said.

Despite the decline, study co-author Cinzia Marano said the numbers were still too high. "There is no safe level of exposure," Marano told the AP.

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