Determinants of environmental tobacco smoke in a population of Puerto Rican children.

This study was designed to determine among various personal, socioeconomic, and environmental factors those which had the greatest influence on exposure to environmental tobacco smoke (ETS) in a population of children residing in a tropical environment and to compare these results with those obtained in the literature of tobacco exposed children in temperate climates. Urine specimens were collected from 606 healthy Puerto Rican children (2-12 years) living in an industrial area and analyzed for cotinine, a quantitative biomarker for exposure to ETS. Parents completed a questionnaire covering smoking habits and socioeconomic information. Seventy per cent of the children were reported to be exposed to ETS, 50% resulting from exposure to smoke from either or both parents. Major determinants to ETS exposure were found to be presence of smoker, number of smokers, identity of smoker, number of cigarettes smoked in the household and child age with the youngest children suffering twice the exposure of older children. Non-determinants were exposure to smoke other than from the parent, sex of the child, season of the year and several socioeconomic factors including civil and employment status of the mother, mother's age and educational background and whether food stamps were being received. Results of a multiple regression analysis showed that our predictors accounted for 40% of cotinine appearing in the urine. Reasons for this relatively low value may be due in part to precision of our analytic method and lower levels of ambient smoke in our population vs. others that reported higher R(2) values. Predictions from questionnaire information for high ETS exposure were not always the same as those indicated by urinary cotinine emphasizing that the bioindicator, which indicates the actual inhalation of ETS, is a better predictor of exposure than responses from a questionnaire.