Leidingwater en kanker?*

Onderzoekers in Barcelona zeggen dat de aanwezigheid van resten van chemische stoffen in leidingwater, en met name van trihalomethanen (THM), een belangrijke risicofactor zijn op blaaskanker bij mannen. Het onderzoek analyseerde gegevens van 2.729 kankerpatiënten en vergeleek die met 5.150 gezonde personen. Mannen die meer dan 3,5 liter water per dag drinken hebben een duidelijk verhoogde kans op blaaskanker in vergelijking met mannen die slechts 2 liter per dag drinken. Dit verschil werd alleen vastgesteld bij leidingwater, niet bij flessenwater. Ook bij vrouwen werd geen verhoogd risico vastgesteld.
Hetzelfde onderzoek stelt ook een verhoogde kans op blaaskanker vast bij mannen die dagelijks meer dan 5 koppen koffie drinken.

Total and specific fluid consumption as determinants of bladder cancer risk.
Villanueva CM, Cantor KP, King WD, Jaakkola JJ, Cordier S, Lynch CF, Porru S, Kogevinas M.
Respiratory and Environmental Health Research Unit, Institut Municipal d'Investigacio Medica (IMIM), Barcelona, Spain.
We pooled the data from 6 case-control studies of bladder cancer with detailed information on fluid intake and water pollutants, particularly trihalomethanes (THM), and evaluated the bladder cancer risk associated with total and specific fluid consumption. The analysis included 2,729 cases and 5,150 controls. Odds ratios (OR) and 95% confidence intervals (CI) for fluid consumption were adjusted for age, gender, study, smoking status, occupation and education. Total fluid intake was associated with an increased risk of bladder cancer in men. The adjusted OR for 1 l/day increase in intake was 1.08, (95% CI 1.03-1.14, p-value for linear trend <0.001), while no trend was observed in women (OR = 1.04, 0.94-1.15; p-value = 0.7). OR was 1.33 (1.12-1.58) for men in the highest category of intake (>3.5 l/day) as compared to those in the lowest (</=2 l/day). An increased risk was associated with intake of tap water. OR for >2 l/day vs. </=0.5 l/day was 1.46 (1.20-1.78), with a higher risk among men (OR = 1.50, 1.21-1.88). No increased risk was observed for the same intake groups of nontap water in men (OR = 0.97, 0.77-1.22) or in women (OR = 0.85, 0.50-1.42). Increased bladder cancer risks were observed for an intake of >5 cups of coffee daily vs. <5 and for THM exposure, but neither exposure confounded or modified the OR for tap water intake. The association of bladder cancer with tap water consumption, but not with nontap water fluids, suggests that carcinogenic chemicals in tap water may explain the increased risk. (c) 2005 Wiley-Liss, Inc. (Februari 2006)