This article says..
Child Mortality
Tobacco users may never smoke indoors, but children can ingest dangerous smoke particles that settle on smokers' clothes and hair. As the U.S. Department of Health and Human Services relates, these particles can be transferred to kids during a hug or kiss, or scooped up from rugs or curtains when babies put their hands in their mouths.
Nicotine, cotinine and other substances in cigarette smoke likely increase risk for sudden infant death syndrome (SIDS) in children who are exposed to smoke. The Centers for Disease Control and Prevention (CDC) report that these chemicals act on the brain to interrupt breathing in infants, which may cause SIDS fatalities.
The article is here
http://www.livestrong.com/article/143848-what-are-dangers-third-hand-smoke-house/
Maybe this isn't enough for you, but it is for me. If the chemicals in cigarettes are linked to SIDS, the kids are exposed to them on others' clothing, carpet etc. It is only a matter of time before the link is fully substantiated.
It's kind of like the people who move their child to a regular seat belt at 4 years old, because that is what the law requires. Common sense and a little research would show that a child that size is not safe in just a seat belt. I don't know why we have to wait for "experts" to tell us something for it to be valid.