Millions of non-smokers show nicotine in their blood and don’t know…

Secondhand smoke poses a significant health risk, and millions of Americans are unknowingly exposed to toxic smoke on a regular basis, a new study suggests.

The study, published in the journal Nicotine & Tobacco Research, found 56 million American adults were frequently exposed to toxic secondhand smoke, and that a third of them may be entirely unaware of their exposure.

Secondhand smoke for nonsmokers is classified as “involuntary smoking” or “passive smoking,” according to the American Cancer Society, clarifying that those people breathe in nicotine and toxic chemicals in the same manner as smokers.

Researchers from the University of Florida looked at a nationally representative survey of more than 13,000 adults from 2013 to 2020, mined from the Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey.

“It could be the case that for low-level exposure, maybe you don’t notice it. You’re in a public setting, and maybe you’re not even aware someone is using tobacco around you. Maybe it’s so minor you forgot,” Jennifer LeLaurin, assistant professor of health outcomes and biomedical informatics at UF, said in a media release.

“There’s also the possibility that some of the respondents were aware of some secondhand smoke exposure but chose not to report it due to the stigma,” said LeLaurin, a senior author of the study.

The UF researchers were looking for any traces in participants’ blood of cotinine, which forms after nicotine enters the body, using the chemical as a biomarker for exposure to tobacco from smoke.

They identified the effects of nicotine in the blood of 51% of participants — but of this group, 67.6% claimed they had not been exposed to vapes or cigarettes.

Findings proved that there is a previously unreported and large gap in knowledge about secondhand smoke.

All demographics of participants underreported their smoke exposure, though black people had the highest rates of both exposure and underreporting.

“We think this report will inform targeted interventions for at-risk groups,” Ruixuan (Roxanne) Wang, a doctoral candidate in the College of Public Health and Health Professions at UF, said.

While it’s unclear why the underexposure rates were so high, even small amounts of cotinine can be detected.

However, no amount is considered safe.

“There is no safe level of secondhand smoke exposure, and long-term exposure can increase the risk of many chronic conditions, such as coronary heart disease, respiratory disease and cancers,” Wang, lead author of the study, said.

‘We want people to be aware of their exposure so they can take protective actions,” she added.