That is an easy one to answer: baby boomers, gen-x, and anyone over ~33 years old as of now... they didn't have cell phones or tablets growing up. But I think

That is an easy one to answer: baby boomers, gen-x, and anyone over ~33 years old as of now... they didn't have cell phones or tablets growing up. But I think what you are getting at is you want data supporting the emergence of a correlation in this new, younger cohort. I'd argue that a close proxy is the introduction of the PC workstation in the 70's and 80's and the "ergonomics" industry that resulted. Seems pretty easy to assume the same dynamics are at play again. "The result of this study showed that prolonged use of smartphones could negatively affect both, posture and respiratory function." [0] There is negative financial incentive for the device producers (Apple, Samsung, Microsoft, etc) if it is discovered that their products are harmful to consumer health. [1] As for data confirming emergence of harm caused by smartphone/tablet, it is a easy google search to see professionals at top research universities and hospitals provide anecdotal evidence that there is a correlation. [2][3] From personal experience, a talk with a professional in Physical Therapy or Occupation Therapy will yield their first hand experience with the identification of cell phone/tablet (and laptop) use as the source of the physical stressor, and the subsequent mitigation (through behavioral (use it less) and environmental (use ergonomically) change) as its cure. [0] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4756000/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4756000/ [1] http://www.crn.com/news/mobility/300089826/apple-ceo-tim-cook-said-ipad-sales-are-surging-in-education-mac-sales-are-up-7-percent.htm http://www.crn.com/news/mobility/300089826/apple-ceo-tim-coo... [2] https://health.usnews.com/health-news/family-health/pain/articles/2009/10/17/video-games-can-play-havoc-with-kids-joints https://health.usnews.com/health-news/family-health/pain/art... [3] https://www.google.com/search?client=safari&rls=en&q=is+smartphone+bad+for+kids+posture&ie=UTF-8&oe=UTF-8 https://www.google.com/search?client=safari&rls=en&q=is+smar... *edited for more linkz