Tattoo inks are unregulated in Australia because you can buy ink from anywhere in the world on the internet, China and Eastern Europe (the former Soviet Union) are popular sources of tattoo ink.
The extract below from Wikipedia explains what might actually be in tattoo ink.
Manufacturers are not required to reveal their ingredients or conduct trials, and recipes may be proprietary. Professional inks may be made from iron oxides (rust), metal salts, plastics. Homemade or traditional tattoo inks may be made from pen ink, soot, dirt, blood, or other ingredients.
Heavy metals used for colors include mercury (red); lead (yellow, green, white); cadmium (red, orange, yellow); nickel (black); zinc (yellow, white); chromium (green); cobalt (blue); aluminium (green, violet); titanium (white); copper (blue, green); iron (brown, red, black); and barium (white). Metal oxides used include ferrocyanide and ferricyanide (yellow, red, green, blue). Organic chemicals used include azo-chemicals (orange, brown, yellow, green, violet) and naptha-derived chemicals (red). Carbon (soot or ash) is also used for black. Other elements used as pigments include antimony, arsenic, beryllium, calcium, lithium, selenium, and sulphur.
Tattoo ink manufacturers typically blend the heavy metal pigments and/or use lightening agents (such as lead or titanium) to reduce production costs.
A carrier acts as a solvent for the pigment, to “carry” the pigment from the point of needle trauma to the surrounding dermis. Carriers keep the ink evenly mixed and free from pathogens, and aid application. The most typical solvent is ethyl alcohol or water, but denatured alcohols, methanol, rubbing alcohol, propylene glycol, and glycerine are also used. When an alcohol is used as part of the carrier base in tattoo ink or to disinfect the skin before application of the tattoo, it increases the skin’s permeability, helping to transport more chemicals into the bloodstream.
As is obvious from the Wikipedia extract above it is almost impossible to be sure what is in the coloured inks that your tattoo contains.
So if your tattoo is black, grey or red or a combination of these 3 colours it is easily removed, the more exotic the colour the greater the degree of difficulty.
It is common for a multi coloured tattoo to take between 12 and 20 treatments to be removed effectively. This equates to treatments every 6 weeks taking in total anywhere between 1½ to 2½ years.