Objectives: Exposure to chlorination by-products during pregnancy has been associated with reproductive outcomes but the evidence remains inconclusive. Levels of trihalomethanes, the most prevalent chlorination by-products, are high in some areas of Spain. Within the framework of a follow-up study in pregnant women, we describe: 1) the personal habits of water use and consumption, and 2) trihalomethane levels in the drinking water of the study areas.
Methods: We performed a follow-up cohort study in pregnant women in Valencia (n = 800), Sabadell (n = 800), the Basque Country (n = 600), Asturias (n = 500), and Granada (n = 700). Interviews were conducted in the third trimester of pregnancy to obtain individual information on the sources and amounts of drinking water, and on the frequency of showering, bathing, and swimming pool attendance. Water samples were collected to analyze trihalomethane levels.
Results: The main source of drinking water was bottled water, both inside and outside the home (82% and 94% of the women, respectively). Drinking water for cooking was mainly municipal (91%). Women preferred to take showers (98.2%) and did so, on average, 6.8 times/week for 11.7 minutes. A total of 58.5% of the women went to swimming pools during pregnancy, on average 9.4 times/month to outdoor swimming pools in the summer and 3.1 times/month the rest of the year for 32.6 and 21.7 minutes, respectively. Average trihalomethane levels ranged from 4 microg/l in the province of Granada to 117 microg/l in Sabadell.
Conclusion: These preliminary results suggest that the main routes of trihalomethane exposure during pregnancy are dermal absorption and inhalation. Ingestion is a minor exposure route.