É mais provável que um display LCD moderno de tablets seja retroiluminado usando LEDs, portanto não há mercúrio.
LCD televisions and monitors typically use cold cathode fluorescent lamps (CCFLs) to illuminate the screen. Most CCFLs contain mercury, and therefore questions arise as to the best way to handle LCD equipment at the end of its life.
The latest generation of LCD equipment has seen LCD manufacturers replacing
CCFLs with mercury-free light emitting diode (LED) backlights. The move to
LED backlighting is gathering pace, with companies such as Sharp Electronics of Japan aiming to have all their high definition LCD televisions LED backlit by 2012.
Source: http://www.alr.ie/Download/Mercury_in_waste_LCD_backlights_summary_research_report.63ad9220.11115.pdf
Eu ficaria bastante preocupado com a lesão das linhas afiadas do vidro quebrado. No entanto, uma folha pode evitar tocá-los diretamente.