[Odors and health: a descriptive epidemiological study around a wastewater treatment plant]

Following community concern regarding potential health effects associated with odors of a wastewater treatment plant, a descriptive epidemiological study was conducted to assess the complaints and the health status of the community and to identify potentially more susceptible groups.

Questionnaires were administered by telephone to nearly 3.000 subjects, randomly selected in the 8 nearby towns, using a geographical Information System. Residents of three areas were compared, according to the distance from the site: 0-1.5 km (high exposed group), 1.5-3 km (moderate exposed group) and 3-4.5 km (low exposed group). Questions measured demographic characteristics, concerns, perceived environmental risk and health effects (symptoms in the past 1 month and in the past 1 year). Multivariate logistic models study the relationships of complaints and health effects, with area and susceptibility factors.

Two thousand eight hundred and sixty seven eligible adults participated in an interview. Taking in account confounding factors, population of high and moderate exposed groups reported more odor complaints than the low exposed group, with adjusted odds ratio (OR) of 4.73 (CI95%: 3.63-6.14) and 2.06 (CI95%: 1.59-2.66) respectively. But these 2 groups did not report more frequent health effects compared to the low exposed group. Several health effects were significantly more frequent in persons with self-reported chemical intolerance and in persons considering malodor in terms of health threat. In this last sub-group of population, rhinitis were significantly more frequent in the high exposed group compared to low exposed group, whereas respiratory infections and asthma attacks showed the same non significant patterns.

If 24,2% of the total sample complaints from odors of the site, this study did not show a higher frequency of health effects in people living near the site (high exposed group). But 2 susceptible groups (with a higher frequency of symptoms potentially related to odors) were identified: persons with self-reported chemical intolerance, among those, many allergic and asthmatic subjects, and persons considering malodor in terms of health threat.