Electric Shocks
The dangerous bit of an electric shock is the current measured in amps. Current(Amps) = Voltage(Volts)/Resistance(Ohms) so an increase in voltage with the same resistance increases the current making an electric shock more dangerous. As little as 100mA can be fatal. But which is more dangerous AC or DC? It depends on number of factors but generally AC is more dangerous for a number a reasons. Firstly the voltage of a 240V AC mains supply is just an average voltage and the maximum voltage of an AC current could be as much as 1.4 times higher or 336V. This is different from a DC power supply, which gives 240V. Secondly AC power alternates this is what causes the higher voltage at certain times but is not what makes the alternating of the current more dangerous. If the alternating current of an AC current passes through your heart it can cause fibrillation, which causes the heart muscles to start moving independently of each. This affects the blood flow through your heart and can cause brain damage and eventually cardiac arrest. This does not happen with DC because it does not alternate it is a direct current and causes the heart to freeze, which is not good for your heart but has a greater chance of recovery over a fibrillating. This is because with a fibrillating heart you need to reestablish a rhythm. AC current also requires less current than DC current to cause damage because it alternates causing the affected muscles to contract and relax depending on the frequency. Whereas a DC current causes one continuous contraction this means at the same voltage DC requires more current than AC to kill you. This affects the let-go threshold which is at what current your muscle contract not allowing you let go. For AC it is between 3-22mA and for DC it is between 15-88mA. DC current is still very dangerous and deep tissue burns are more common from DC current than from AC current. Overall AC current is more dangerous because of the affects it has on the heart but DC current can still kill you.
http://www.brighthubengineering.com/power-plants/89792-ac-and-dc-shock-comparison/
http://www.brighthubengineering.com/power-plants/89792-ac-and-dc-shock-comparison/