Thirdhand Smoke May Bring Lead into Homes

Lead is dangerous to young children, and many parents are aware of how to protect their children from the most common sources of lead exposure in the home. San Diego State University researchers report on an overlooked source of lead exposure: tobacco smoke residue, also known as thirdhand smoke.   

November, 18 2020

By: Katherine Greiner

Lead is dangerous, especially to babies and young children. It is well known that young children who are exposed to lead have learning difficulties and behavior problems, which often contribute to poor school performance. Children are exposed to lead when they breathe in or swallow dust from old lead-based paint or drink water from lead pipes. Lead is also found in some children’s toys and jewelry, and in some imported candies or home remedies. What makes lead a particularly challenging problem is that there is no safe level of exposure, and its effects are irreversible.  

Public health efforts across the country focus on preventing lead exposure by removing sources of lead from children’s environments. New research from a group of researchers at San Diego State University, led by Dr. Georg Matt, highlights an overlooked source of lead: tobacco smoke residue also known as thirdhand smoke.  

Lead is found naturally in soil. As tobacco plants grow in soil that contains lead, the lead comes out of the soil and transfers into the plant material itself. When tobacco is dried and then smoked, lead becomes part of the tobacco smoke inhaled by the smoker and spread throughout the home in secondhand smoke. Dr. Matt explains, “We know that once smoking is over and the secondhand smoke has cleared, the particles in that smoke settle into house dust and on surfaces. The toxic substances in this residue can be found in house dust and on surfaces years later and are incredibly difficult to remove, making it possible to expose people long after the smoker has gone. We wanted to see if lead   remained in house dust as part of the toxic mixture of thirdhand smoke residue.”

In this study, to be published in the Journal of Trace Elements in Medicine and Biology, Dr. Matt and his team tested dust and surfaces in the homes of 60 non-smoking families living in multiunit housing for levels of nicotine, used as an indicator for thirdhand tobacco smoke residue. Dust was collected via vacuum, and surface samples were collected using wipes. The samples were analyzed in the laboratory at the School of Public Health at San Diego State University under the direction of Dr. Eunha Hoh. 

The results show that homes with higher levels of nicotine also had higher levels of lead, and homes with lower levels of nicotine also had lower levels of lead. Because nicotine is specific to tobacco smoke, the findings suggest that the lead found in the dust of apartments where no one smoked had been left behind by a tenant who smoked in the unit before they moved in or was drifting in from the nearby units of people who smoked. Although levels of lead in the dust were below the US Environmental Protection Agency’s proposed hazard level for lead in dust, the study shows another source of lead exposure that should be considered in public health efforts to prevent lead poisoning in children. 

As the use of heavy metals has been banned in many consumer products in North America and Europe, it is important to keep in mind that indoor tobacco use remains a significant sources of lead pollution in home environments. While the best way to prevent new buildup of lead, nicotine, and many other harmful substances is to stop smoking, smoking bans and cessation will not address existing thirdhand smoke contamination. 

Dr. Matt continues, “This is of particular concern for residents of low-income multiunit housing, who are already at higher risk for health concerns associated with heavy metals, and frequently have fewer resources to address the situation if they learn their home is contaminated. It is important that healthy homes programs include smoking bans to prevent thirdhand smoke from building up, but also to include plans for remediation of existing pollution to ensure residents have a safe place to call home.”  

Click here to read the research study.

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