CASE-CONTROL RESEARCH STUDY - Article Example of Interest: The subjects recruited for the case study were exposed to trihalomethane, a by-product produced during the chlorination of water, which is done for the purpose of disinfection. Patients who were histologically confirmed to have primary bladder cancer were recruited as the case population for the study and they were identified with the help of urologic services. The other inclusion criteria’s for the recruitment of the case population were: age group between 20 and 80 years and they must reside within the geographical area surrounding the hospital. The study was a multi-center case-control study conducted in Spain and the subjects were recruited from 18 participating hospitals located at five different geographic regions in and around Spain. The cases were recruited through regular reviews of the discharge and pathology records in hospitals at by the research staffs who were involved in the study. The number of cases who participated in the study was 338 out of the 1,457 eligible cases who were interviewed.
