It's a common claim in school yards (and from parents?) that you should not draw on your skin with a pen, or you will suffer "ink poisoning".
Here's an example for notability: a Facebook page called People have warned me about ink poisoning... but I draw on my hands anyway
Wikipedia makes the following unreferenced claim,
There is a misconception that ink is non-toxic even if swallowed. Once ingested, ink can be hazardous to one's health. Certain inks, such as those used in digital printers, and even those found in a common pen can be harmful. Though ink does not easily cause death, inappropriate contact can cause effects such as severe headaches, skin irritation, or nervous system damage.
I've heard people say it leads to cancer; supposedly because the skin absorbs the ink chemicals.
However, I have never seen a warning on any pen or its packaging, which I would expect if it was toxic.
Conversely, many links returned from a Google search suggest that it's not toxic.
Can drawing on yourself with a normal ball-point pen lead to harm?