Low-income, rural kids at higher risk for second- or third-hand smoke exposure

Thursday, December 6, 2018

Low-income, rural kids at higher risk for second- or third-hand smoke exposure

Infants and toddlers in low-income, rural areas may be at higher risk for second- and third-hand smoke than previously reported, according to a study supported by the National Institutes of Health. Approximately 15 percent of children in the study tested positive for cotinine, a byproduct formed when the body breaks down nicotine, at levels comparable to those of adult smokers. About 63 percent of children in the study had detectable levels of cotinine, suggesting widespread exposure to smoke. The study appears in Nicotine & Tobacco Research.

鈥淔ew studies have explored the risks of very young children, especially infants, for second- or third-hand exposure to smoking,鈥 said James A. Griffin, Ph.D., deputy chief of the Child Development and Behavior Branch at 51视频鈥檚 Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), which funded the research. 鈥淭he current study suggests that moving frequently, having more adults in the home and spending less time in center-based daycare facilities may increase a child鈥檚 exposure to smoke or smoke residue.鈥 

The researchers analyzed data from the Family Life Project, a long-term study of rural poverty in North Carolina and Pennsylvania. For the study, saliva samples of 1,218 children were tested for cotinine. The samples were collected from children at age 6 months, 15 months, 2 years and 4 years. The presence of cotinine indicates that the child was exposed to second- or third-hand smoke. Second-hand smoke comes from a lit tobacco product, an electronic smoking device or the smoker. Third-hand smoke is an invisible residue from smoke that settles onto floors, furniture and clothing.

The researchers classified the children into three groups based on their cotinine levels. Fifteen percent of the children were in the high exposure group, with cotinine levels comparable to active adult smokers (12ng/mL or higher), 48 percent were in the moderate exposure group (0.46 to 12ng/mL) and 37 percent were in the low exposure group (less than or equal to 0.46ng/mL). These values are higher than those seen in data previously reported in the National Health and Nutrition Examination Survey, which found that only one-third to one-half of children鈥檚 blood samples had detectable cotinine. 

鈥淲e found that infants had higher cotinine levels compared to toddlers,鈥 said Lisa M. Gatzke-Kopp, Ph.D., a professor at Pennsylvania State University and the lead author of the study. 鈥淏ecause infants often put objects into their mouths and crawl on floors, they may be more likely to ingest smoke residue or get it on their skin, compared to older children.鈥

The study team evaluated independent factors that may influence a child鈥檚 probability of being in one of the three exposure groups. They found that lower income, less education, frequent residential moves and fluctuations in the number of adults within the home were associated with high smoke exposure, whereas time spent at a center-based daycare was associated with lower smoke exposure.

Factors influencing cotinine levels included the following:

  • When a caregiver had at least a high school degree, a child was 85 percent less likely to be in the high exposure group, compared to the other two groups.
  • Each residential move increased a child鈥檚 odds of being in the high exposure group, compared to the low exposure group, by 43 percent.
  • Each adult moving into or out of the home increased this risk by 11 percent.
  • A child who spent time in a center-based daycare was 81 percent less likely to be in the high exposure group, compared to the low exposure group.

鈥淥ur results, if supported by future studies, can help educate parents and caregivers, as well as improve prevention programs that seek to reduce children鈥檚 smoke exposure,鈥 said Clancy Blair, Ph.D., M.P.H., a professor at New York University's Steinhardt School of Culture, Education and Human Development and the senior author of the study. 鈥淔or instance, nonsmoking families may not be aware that nicotine can be present in their child鈥檚 environment if their home was previously occupied by a smoker or if smoking is permitted at the workplace.鈥

Funding for the current analysis was provided by NICHD, the National Institute on Drug Abuse, and the Environmental influences on Child Health Outcomes (ECHO) program, all part of 51视频.

About the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD): NICHD conducts and supports research in the United States and throughout the world on fetal, infant and child development; maternal, child and family health; reproductive biology and population issues; and medical rehabilitation. For more information, visit .

About the Environmental influences on Child Health Outcomes (ECHO) program: ECHO is a nationwide research program designed to understand the effects of a broad range of early environmental influences on child health and development. For more information, visit 

About the National Institutes of Health (51视频): 51视频, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. 51视频 is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about 51视频 and its programs, visit www.nih.gov.

51视频鈥urning Discovery Into Health

Gatzke-Kopp LM, Willoughby MT, Warkentien SM, O鈥機onnor T, Granger D, and Blair C. Magnitude and chronicity of environmental smoke exposure across infancy and early childhood in a sample of low-income children. Nicotine & Tobacco Research DOI: 10.1093/ntr/nty228 (2018)

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