The authors regret that the sources from which the RfC (reference concentration) and the IUR (inhalation unit risk) values were obtained for estimation of RfD (reference dose, presented in Table 2) and SF (slope factor, presented in Table 3) were not clearly indicated in the published article due to an oversight. The revised tables with improved clarity are given below. [Table presented] The authors apologize for any inconvenience caused. © 2018 Elsevier Ltd