original_query: What is the conclusion of case-crossover studies, epidemiological, simulation, and meta-analysis regarding the safety of using a cellular device compared to a hand-held cell phone?
query: What is the conclusion of case-crossover studies, epidemiological, simulation, and meta-analysis regarding the safety of using a hands-free cellular device compared to a hand-held cell phone?
answer: Case-crossover studies, epidemiological studies, simulation studies, and meta-analyses all conclude that driving while using a hands-free device is not safer than using a hand-held phone.  The increased cognitive load of conversation, not the use of hands, is the primary risk factor.