Study finds thirdhand smoke affects weight, blood cells

Feb. 3 (UPI) -- Researchers at the University of California at Berkeley found that thirdhand smoke can lead to lower weight and damage to blood cell development in lab mice.

Thirdhand smoke is the sticky residue left on surfaces like furniture, clothing and walls from tobacco smoke.

The study, conducted by scientists from the U.S. Department of Energy's Lawrence Berkeley National Laboratory, found that newborn mice exposed to thirdhand smoke through smoke-treated cloths for three weeks weighed significantly less than mice in the control group.

Newborn and adult mice exposed to thirdhand smoke also had changes in blood cell counts in the immune system linked to inflammatory and allergic reactions.

"We suspected that the young are most vulnerable because of their immature immune systems, but we didn't have a lot of hard evidence to show that before," Bo Hang, a Berkeley Lab staff and lead author of the study, said in a press release. "In this case, we found that thirdhand smoke appeared to inhibit weight gain in neonatal mice, but not in young adults."

Hang and the team from the Biological Systems and Engineering Division and the Energy Technologies Area at UC Berkeley collaborated with researchers from UC San Francisco and Nanjing Medical University for the study.

Researchers found that the weight effect from thirdhand smoke was temporary and weeks after smoke exposure was stopped, the mice were able to catch up with the mice in the control group.

However, researchers said that human babies and toddlers are at a greater risk because they could come into contact with tobacco residue through crawling and teething at a time when vital immune system development is occurring.

The study shows that while the effects of secondhand smoke are well known but the effects of thirdhand smoke, which may be as harmful if not more, are just being discovered.

The study was published in Scientific Reports.