Intrauterine and Postnatal Exposure to Tobacco and Secondhand Smoke and Child Cognitive and Behavioral Development

Abstract

Children’s involuntary exposure to tobacco smoke is a common and substantial health problem that has been receiving increasing attention from the pediatric, public health and research communities. According to the 2006 Surgeon General’s Report, there is no safe level of tobacco smoke exposure, yet at least 30% of children in the United States live in households with at least one adult smoker, and nearly 60% have evidence of recent exposure (Machlin, Hill, and Liang 2006). Tobacco smoke exposure has been causally linked to numerous adverse health outcomes and is currently a leading preventable cause of both low birth weight and sudden infant death syndrome, and a major contributor to lower respiratory infections, otitis media, and increased asthma severity (American Academy of Pediatrics, Committee on Environmental Health 1997; Cook and Strachan 1999; DiFranza et al. 2004). Recently, associations between tobacco smoke exposure and other childhood health problems, such as increased rates of dental caries (Aligne et al. 2003; Iida et al. 2007), food insecurity (Cutler et al. in press), and the metabolic syndrome (Weitzman et al. 2005) have been identified. As discussed in this chapter, a growing human and animal literature, which expands upon a more than 25-year-old body of work, also indicates that involuntary exposure to tobacco smoke during the pre- and/or postnatal periods is associated with adverse cognitive and behavioral outcomes in children. Tobacco smoke exposure has been associated with decrements in IQ, problems with learning and memory, difficulty with auditory processing, neonatal hyperactivity, attention-deficit hyperactivity disorder (ADHD), internalizing and externalizing behavioral problems, and conduct disorder. Animal models have provided evidence that tobacco is toxic to the developing brain, and there are plausible biologic pathways that appear to mediate these effects. Exciting new studies have begun to identify specific genes that play a role in the relationship between tobacco smoke exposure and adverse cognitive and behavioral outcomes in children. The term “secondhand smoke” (SHS), also referred to as “environmental tobacco smoke” (ETS), refers to the smoke that is exhaled from a smoker’s lungs, as well as the smoke from the smoldering end of a cigarette.