Table 5.

Characteristics of studies of water quality integrity.^a

Study	Design	Exposure	Comparison exposure	Outcome assessment	Effect estimate (95% CI)
Semenza et al. 1998	Cross-sectionalb	Nondetectable chlorine in household water sample from piped supply	Detectable chlorine in household water sample from piped supply	Self-report	IDR = 1.60 (0.70, 3.70)
Egorov et al. 2002	Cross-sectional	Interquartile range (0.22 mg/L) decrease in chlorine	NA	Self-report	IDR = 1.42 (1.05, 1.91)
Mohanty et al. 2002	Ecological	Unit increase in percentage of distribution system samples with nondetectable chlorine in service zone	NA	Self-report	Regression coefficient 0.46 (p = 0.64)
Abbreviations: IDR, incidence density ratio; NA, not applicable. aResults not pooled. bCross-sectional analysis within exposed group of cluster-randomized trial.