A paper titled “How many crashes are caused by driver interaction with passengers? A meta-analysis approach” authored by Athanasios Theofilatos, Apostolos Ziakopoulos, Eleonora Papadimitriou, and George Yannis is now published in Journal of Safety Research. Conversation and other interactions with passengers while driving induce a level of distraction to the person driving. This paper conducts a qualitative literature review on the effect of passenger interaction on road safety and then extends it by using meta-analysis techniques.  The findings of the random-effects meta-analyses that were carried out showed that driver interaction with passengers causes a non-negligible proportion of road crashes, namely 3,5% of crashes regardless of the age of the passengers and 3.8% when child and teen passengers are excluded. doi