Use of urinary trichloroacetic acid as an exposure biomarker of disinfection by-products in cancer studies $, $$ Lucas A. Salas a,b,c , Esther Gracia-Lavedan a,b,c , Fernando Goñi c,d,e , Victor Moreno f,g,h , Cristina M. Villanueva a,b,c,i,n a Centre for Research in Environmental Epidemiology (CREAL), Doctor Aiguader 88, 08003 Barcelona, Spain b Universitat Pompeu Fabra (UPF), Barcelona, Spain c CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain d Basque Laboratory of Health, Gipuzkoa, Spain e BioDonostia Health Research Institute, Spain f Catalan Institute of Oncology (ICO), Spain g Bellvitge Biomedical Research Institute (IDIBELL), Spain h University of Barcelona (UB), Spain i IMIM (Hospital del Mar Medical Research Institute), Spain article info Article history: Received 7 July 2014 Received in revised form 19 September 2014 Accepted 25 September 2014 Keywords: Acetates Biological markers Environmental exposure Trichloroacetic acid Trihalomethanes abstract Urinary trichloroacetic acid (TCAA) has been proposed as a valid exposure biomarker for ingested disinfection by-products (DBP) for reproductive studies. However, it has never been used in epidemio- logic studies on cancer. We investigate the performance of urinary TCAA as a biomarker of DBP exposure in the framework of an epidemiologic study on cancer. We conducted home visits to collect tap water, first morning void urine, and a 48 h fluid intake diary among 120 controls from a case-control study of colorectal cancer in Barcelona, Spain. We measured urine TCAA and creatinine, and 9 haloacetic acids and 4 trihalomethanes (THM) in tap water. Lifetime THM exposure was estimated based on residential history since age 18 plus routine monitoring data. Robust linear regressions were used to estimate mean change in urinary TCAA adjusted by covariates. Among the studied group, mean age was 74 years (range 63–85) and 41 (34%) were females. Mean total tap water consumption was 2.2 l/48 h (standard error, 0.1 l/48 h). Geometric mean urine TCAA excretion rate was 17.3 pmol/min [95%CI: 14.0–21.3], which increased 2% for a 10% increase in TCAA ingestion and decreased with total tap water consumption ( À17%/l), water intake outside home ( À32%), plasmatic volume ( À64%/l), in smokers ( À79%), and in users of non-steroidal anti-inflammatory drugs ( À50%). Urinary TCAA levels were not associated with lifetime THM exposure. In conclusion, our findings support that urine TCAA is not a valid biomarker in case-control studies of adult cancer given that advanced age, comorbidites and medication use are prevalent and are determinants of urine TCAA levels, apart from ingested TCAA levels. In addition, low TCAA concentrations in drinking water limit the validity of urine TCAA as an exposure biomarker. & 2014 Elsevier Inc. All rights reserved. 1. Introduction Water disinfection is central in public health to prevent infections from waterborne pathogens. Nevertheless, disinfection processes produce undesired toxicants known as disinfection by- products (DBP), which constitute a widespread environmental exposure in developed countries. Trihalomethanes (THM) and haloacetic acids (HAA) are the most prevalent DBP classes result- ing from chlorination (Krasner et al., 2006). Disinfection by- products have been linked to an increased risk of bladder cancer (Costet et al., 2011) while evidence of the association with other Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/envres Environmental Research http://dx.doi.org/10.1016/j.envres.2014.09.018 0013-9351/& 2014 Elsevier Inc. All rights reserved. ☆ Ethics committee approval: The study was approved by the Ethics Committee of the Research Center (IMIM-IMAS). ☆☆ Funding resources: This study was funded by the Spanish Health Ministry (Fondo de Investigaciones Sanitarias – FIS, Instituto de Salud Carlos III, Spain number FIS PI11-226). Lucas A. Salas received a Colciencias Ph.D. Scholarship, Colombia (Grant: 529/2011). Parc de Salut Mar Biobank (MARBiobanc) provided biobanking facilities for to the project. MARBiobanc is supported by Instituto de Salud Carlos III FEDER (RD09/0076/00036). n Corresponding author at: Centre for Research in Environmental Epidemiology (CREAL), Doctor Aiguader 88, 08003 Barcelona, Spain. E-mail address: cvillanueva@creal.cat (C.M. Villanueva). Environmental Research 135 (2014) 276–284