Phthalates are widely used plasticizers that produce endocrine-disrupting disorders. Quantifying exposure is crucial to perform risk assessments and to develop proper health measures. Herein, a wastewater-based epidemiology approach has been applied to estimate human exposure to six of the mostly used phthalates within the Spanish population. Wastewater samples were collected over four weekdays from seventeen wastewater treatment plants serving thirteen cities and ca. 6 million people (12.8 % of the Spanish population). Phthalate metabolite loads in wastewater were transformed into metabolite concentrations in urine and into daily exposure levels to the parent phthalates. Considering all the sampled sites, population-weighted overall means of the estimated concentrations in urine varied between 0.7 ng/mL and 520 ng/mL. Very high levels, compared to human biomonitoring data, were estimated for monomethyl phthalate, metabolite of dimethyl phthalate. This, together with literature data pointing to other sources of this metabolite in sewage led to its exclusion for exposure assessments. For the remaining metabolites, estimated concentrations were closer to those found in urine. Their 4-days average exposure levels ranged from 2 to 1347 μg/(day∙inh), exceeding in some sites the daily exposure thresholds set for di-i-butyl phthalate and di-n-buthyl phthalate by the European Food Safety Authority.Financial support. This study was supported by MCIU/AEI (projects CTM2016-81935-REDT, CTM2017-84763-C3-1-R, CTM2017-84763-C3-2-R, CTM2017-84763-C3-3-R, and CEX2018-000794-S), Galician Council of Culture, Education and Universities (ED481D 2017/003 and ED431C2017/36), Generalitat Valenciana (projects Prometeo/2018/155 and Prometeo/2019/040) and Universitat Jaume I (project UJI-B2018-55). Several of the above mentioned projects are cofunded by FEDER/ERDF. Sampling, sample and data provision and/or analytical support: Viaqua and Concello de Santiago de Compostela, EMAYA (Palma), Jordi Palatsi from Aqualia (Lleida WWTP), Cristian Mesa and Angela Vidal from Aigues de Barcelona (Barcelona WWTP), Iñigo González (Consorcio de Aguas de Bilbao-Bizkaia), the Public Entity of Wastewater Treatment (EPSAR) of the Generalitat Valenciana and especially Fernando Llavador. Luis Aceiton, Enrique Albors, Angel Jiménez, Maria José Tarrega, Sonia Tristante and all the personal of the WWTPs (Aguas de Valencia, Spain), are acknowledged for their help with the sampling. Sociedad de Fomento Agrícola Castellonense (FACSA, Castellon), and especially WWTP operators Santiago Querol and Sara Gargallo are acknowledged for providing wastewater samples from Castellón, as well as Subdirección General de Gestión del Agua, Ayuntamiento de Madrid, for allowing the collection of samples from Madrid centro.Peer reviewe
