RESEARCH ARTICLE DNA repair and metabolic gene polymorphisms affect genetic damage due to diesel engine exhaust exposure Grethel León-Mejía 1 & Milton Quintana-Sosa 1 & Yurina de Moya Hernandez 1 & Ibeth Luna Rodríguez 1 & Cristiano Trindade 1 & Marco Anaya Romero 1 & Jaime Luna-Carrascal 1 & Ludis Oliveros Ortíz 1 & Antonio Acosta-Hoyos 1 & Martha Ruiz-Benitez 1 & Karen Franco Valencia 1 & Paula Rohr 2,3 & Juliana da Silva 3 & João Antônio Pêgas Henriques 4 Received: 2 July 2019 /Accepted: 20 March 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Diesel engine exhaust (DEE) is a complex mixture of toxic gases, halogenated aromatic hydrocarbons, alkyl polycyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, benzene derivatives, metals and diesel exhaust particles (DEPs) generated from the incomplete combustion of diesel fuel. Many of the compounds in this mixture can cause oxidative damage to DNA and are considered carcinogenic for humans. Further, chronic DEE exposure increases risks of cardiovascular and pulmonary diseases. Despite these pervasive health risks, there is limited and inconsistent information regarding genetic factors conferring suscepti- bility or resistance to DEE genotoxicity. The present study evaluated the effects of polymorphisms in two base excision repair (BER) genes (OGG1 Ser326Cys and XRCC1 Arg280His), one homologous recombination (HRR) gene (XRCC3 Thr241Met) and two xenobiotic metabolism genes (GSTM1 and GSTT1) on the genotoxicity profiles among 123 mechanics exposed to workplace DEE. Polymorphisms were determined by PCR-RFLP. In comet assay, individuals with the GSTT1 null genotype demonstrated significantly greater % tail DNA in lymphocytes than those with non-null genotype. In contrast, these null individuals exhibited significantly lower frequencies of binucleated (BN) cells and nuclear buds (NBUDs) in buccal cells than non-null individuals. Heterozygous hOGG1 326 individuals (hOGG1 326 Ser/Cys) exhibited higher buccal cell NBUD frequen- cy than hOGG1 326 Ser/Ser individuals. Individuals carrying the XRCC3 241 Met/Met polymorphism also showed significantly higher buccal cell NBUD frequencies than those carrying the XRCC3 241 Thr/Thr polymorphism. We found a high flow of particulate matter with a diameter of < 2.5 μm (PM 2.5 ) in the workplace. The most abundant metals in DEPs were iron, copper, silicon and manganese as detected by transmission electron microscopy–energy-dispersive X-ray spectroscopy (TEM-EDX). Scanning electron microscopy (SEM-EDS) revealed particles with diameters smaller than PM 2.5 , including nanoparticles forming aggregates and agglomerates. Our results demonstrate the genotoxic effects of DEE and the critical influence of genetic susceptibility conferred by DNA repair and metabolic gene polymorphisms that shed light into the understanding of underlying mechanisms. Keywords Diesel exhaust particles . Polymorphism . DNA repair . DNA oxidative damage . Mechanics Introduction Among the great variety of pollutants emitted in the work environment, diesel engine exhaust (DEE) resulting from in- complete combustion of diesel fuel is considered one of the most hazardous (Reşitoğlu et al. 2015). The International Agency for Research on Cancer (IARC) classifies DEE as a Group 1 carcinogen for humans. At present, there are many mechanics employed worldwide who are responsible for the maintenance of diesel engines; however, they are often un- aware of the potential health effects of continuous exposure to equipment or machinery powered by diesel fuel. Responsible Editor: Philippe Garrigues * Grethel León-Mejía grethelleon@gmail.com; gleon4@unisimonbolivar.edu.co 1 Universidad Simón Bolívar, Facultad de Ciencias Básicas y Biomédicas, Barranquilla, Colombia 2 Laboratório de Genética, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, Campus Carreiros, Av. Itália km 8, Rio Grande, RS 96201-900, Brazil 3 Laboratório de Genética Toxicológica, Universidade Luterana do Brasil (ULBRA), Canoas, RS, Brazil 4 Departamento de Biofísica, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil Environmental Science and Pollution Research https://doi.org/10.1007/s11356-020-08533-6