In the section Physiological effects of electricity it is stated that DC is "more likely to "freeze" a victim in a shock scenario" but the Ohm's Law (again) section has a chart which seems to contradict this statement by showing that it is hard to let go of a wire with only 16ma of AC at 60HZ vs. 76ma DC. If you look at high frequency 10khz the threshold is about equal between AC and DC, but 60Hz is what people would most likely be exposed to.
Merck states that 60HZ AC is "3 to 5 times more dangerous than DC of the same voltage and amperage. Low-frequency AC produces extended muscle contraction (tetany), which may freeze the hand to the current's source, prolonging exposure. DC is most likely to cause a single convulsive contraction, which often forces the victim away from the current's source."
<http://www.merck.com/mmpe/sec21/ch316/ch316b.html>
Merck states that 60HZ AC is "3 to 5 times more dangerous than DC of the same voltage and amperage. Low-frequency AC produces extended muscle contraction (tetany), which may freeze the hand to the current's source, prolonging exposure. DC is most likely to cause a single convulsive contraction, which often forces the victim away from the current's source."
<http://www.merck.com/mmpe/sec21/ch316/ch316b.html>