Another important risk factor for HL is the Epstein–Barr virus (EBV) [3], which causes infectious mononucleosis in adolescents or young adulthood 35–50 % of the time [22]. Studies have shown that approximately 25–50 % of HL cases are EBV-positive [3]. EBV positivity among HL cases tends to be higher among children under 10 years old and in the older age group, but less frequent in young adults [3, 23], where we observed greater risks. Furthermore, EBV positivity is mostly associated with the mixed cellularity subtype [24–27]. The differences in EBV positivity found by age and histologic type may help provide another explanation for the differences in the risk of HL found among older versus younger age groups. Since we lacked information on EBV positivity among individuals, it was not possible to evaluate interaction between EBV, immune system function, pesticides and HL in our study