title: Deterioration of drinking water quality in the distribution system and gastrointestinal morbidity in a Russian city.
abstract: Few studies have been conducted in Russia to assess the relationship between drinking water quality and gastrointestinal (GI) infections. In the city of Cherepovets, effluent water at the treatment plant usually meets the country's hygienic standards. To provide protection against secondary water contamination in the distribution system, concentrations of total residual chlorine in effluent water are maintained#10; at levels from 1 to 2 mg x l(-1). However, residual chlorine concentrations rapidly decline in the distribution system and rechlorination is not practiced. Some areas of the city routinely have very low residual chlorine at taps and little protection against secondary microbiological contamination of water in pipelines. A cross-sectional epidemiological study was conducted in Cherepovets to assess an association between decline in residual chlorine concentrations and risk of GI illness. This study included water quality monitoring and an extensive questionnaire survey of city residents. The results demonstrated a consistent spatial pattern of free chlorine decline in the distribution system. An interquartile range variability in free residual chlorine decline (0.22 mg x l(-1)) was associated with 1.42 (95% confidence interval (CI) = 1.05, 1.91) relative risk of self-reported gastrointestinal illness after control for socioeconomic, hygienic and demographic parameters.
authors.affiliation: Department of Family Medicine and Community Health, Tufts School of Medicine, Boston, Massachusetts 02111, USA. andrey.egorov@tufts.edu
authors.forename: Andrey
authors.initials: A
authors.lastname: Egorov
authors.forename: Timothy
authors.initials: T
authors.lastname: Ford
authors.forename: Andrey
authors.initials: A
authors.lastname: Tereschenko
authors.forename: Nina
authors.initials: N
authors.lastname: Drizhd
authors.forename: Irena
authors.initials: I
authors.lastname: Segedevich
authors.forename: Vladislav
authors.initials: V
authors.lastname: Fourman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D002713:Chlorine / Q000032:analysis*; D004202:Disinfectants; D016021:Epidemiologic Studies; D005260:Female; D005767:Gastrointestinal Diseases / Q000453:epidemiology / Q000209:etiology* / Q000382:microbiology; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D012426:Russia / Q000453:epidemiology; D014505:Urban Population; D018508:Water Purification; D014881:Water Supply
chemical_list: D004202:Disinfectants; D002713:Chlorine