Presence and seasonal variation of trihalomethanes (THMs) levels in drinking tap water in Mostaganem Province in northwest Algeria

BACKGROUND: The use of chlorine to disinfect water, produces various disinfection byproducts such as trihalomethanes (THMs). These compounds are formed when free available chlorine reacts with natural organic matter in raw water during water disinfection. Epidemiologic studies have shown an association between long-term exposure to THMs and an increased risk of cancer, all of them are suspected of having carcinogenic effects. AIM: The aim of this study was to determine the presence of THMs in the drinking tap water of Mostaganem Province (Algeria) in order to assess the seasonal variation in trihalomethane levels in tap water and to identify the season of high risk to the consumer. METHODS: This analytical study was conducted in Mostaganem Province, Algeria in March, July, September and December 2015. Primarily, we proceeded to collect 30 samples from different areas of Mostaganem Province which were marked with a higher level of residual chlorine for the year 2015; secondly, we utilised the HS-SPME method for determination of trihalomethanes in drinking tap water over a period of four months. For comparison of trihalomethanes values, we used ANOVA. RESULTS: The results obtained show variability in total THM concentrations from one district to another, with a maximum of 198 μg/l recorded in the Achaacha district during July, but the lowest value 07.84 μg/l is noted at Salamandre city during the same period, noting that these values decrease progressively during the winter period. CONCLUSION: Our drinking tap water samples include a large quantity of THMs with different concentrations, where the dibromochloromethane and the bromoform constitute the major portion of THMs.