“A growing body of literature has demonstrated the harmful
physical health effects of secondhand smoke exposure,” according
to the authors. “Given the highly prevalent exposure to
secondhand smoke—in the United States, an estimated 60 percent
of American non-smokers had biological evidence of exposure to
secondhand smoke—even a low level of risk may have a major
public health impact.” Mark Hamer, Ph.D., of University College
London, and colleagues studied 5,560 non-smoking adults (average
age 49.8) and 2,595 smokers (average age 44.8) who did not have
a history of mental illness and participated in the Scottish
Health Survey in 1998 or 2003. Participants were assessed with a
questionnaire about psychological distress, and admissions to
psychiatric hospitals were tracked over six years of follow-up.
Exposure to secondhand smoke among non-smokers was assessed
using saliva levels of cotinine—the main product formed when
nicotine is broken down by the body—“a reliable and valid
circulating biochemical marker of n