Children's exposure to ETS: race and ethnicity matter.

Parental smoking at home has long been known to increase children's exposure to environmental tobacco smoke (ETS). It is also recognized that adults' smoking rates vary by ethnicity, race, and immigrant status. But little is known about how these factors combine whether race and ethnicity are risk factors for childhood exposure to ETS. Now Ken Sexton and colleagues at the University of Minnesota report that elementary school--age children in two economically disadvantaged neighborhoods show consistent differences in ETS exposure by ethnicity and race [EHP 112:392-397].

The children were participants in the School Health Initiative: Environment, Learning, and Disease study of multiple environmental exposures, and lived in urban neighborhoods in Minneapolis. The children's primary caregivers were asked questions about their smoking behavior and their children's health. In the winter of 2000 and again in the spring, the children gave urine samples at school. During the 48 hours before the collection of urine samples, the children, aided by caregivers, interviewers/translators, and field technicians, kept time-activity logs recording the amount of time they spent in the presence of active smokers.

The results showed a clear pattern of differential ETS exposure, with African-American children receiving the highest average exposure. Significantly, nearly half of the African-American children lived in homes where the caregiver smoked, and more than 40% of those children were exposed to ETS. Exposure was moderately low for Hispanic children (8.5% lived in homes where their caregivers smoked) and lowest for Somali immigrant children, none of whom lived with caregivers who smoked. Less than 20% of children in the "other" category (white/Southeast Asian/Native American) lived in homes where their caregivers smoked.

In shedding new light on ETS exposure among children of low-income families, the research underscores mounting evidence that socioeconomic status, ethnicity, and race can be risk factors for children's exposure to many pollutants. This study, the authors write, demonstrates the importance of considering smoking prevalence by ethnicity and race when conducting child ETS exposure studies.

Another important finding may lessen the cost and difficulty of future studies. The researchers found that relatively inexpensive metrics can be effective in screening children for ETS exposure. The research is the first to compare four metrics: inexpensive baseline questionnaires, time-activity logs, and two relatively expensive biomarker measurements, urinary total cotinine and urinary metabolites of the tobacco-specific lung carcinogen NNK. All four metrics suggested that a substantial number of the children were routinely exposed to ETS, and three--questionnaires, logs, and urinary cotinine--showed consistent differences by race and ethnicity. Moreover, the questionnaires and logs indicated that reducing adults' smoking at home would help reduce children's ETS exposure. -Laura Alderson