Screening for secondhand smoke in schoolchildren in Japan.

Background: There is no systematic screening for secondhand smoke exposure in children.

Methods: In 2002, we began a secondhand smoke screening (SSS) program for grade 4 elementary schoolchildren with the cooperation of public administration. The SSS program consisted of urinary cotinine measurement in children and a questionnaire survey of their parents.

Results: More than 1200 schoolchildren were enrolled in this program annually. The level of urinary cotinine in 30% of the children was >5 ng/mL, whereas in half of them it was undetectable. The major risk factor affecting cotinine level was mother's smoking. Average cotinine was significantly high in children who had a history of "short stature", "decayed tooth and/or periodontal disease," and "frequent stridor". In addition, the highest level of cotinine was detected in children whose father and/or mother smoked in the living room and the lowest level of cotinine was detected in children whose father and/or mother smoked on the veranda or outside the door. These levels, however, were two-fivefold higher than in children whose parents did not smoke. On follow-up questionnaire survey 4 years after initial SSS, significant elevated motivation for smoking cessation was noted.

Conclusions: The SSS program is a very simple mass screen that can be done using only a urine test and is very effective for motivating parents to stop smoking with regard to cost benefit.