Current ink technology still relies heavily on pigment bases whose environmental impact is potentially harmful. Pigments of concern that are now in wide commercial use are Barium-based Red Lake C; Copper-phthalocyanine blue; and Copper-phthalocyanine green.  The colors shown on this chart have the possibility of exceeding recommended threshold levels of copper and/or barium in their most common formulations.

Additional ink colors that should be avoided include all metallics, (which are 60-70% pigment and contain aluminum and zinc which are acutely toxic to marine life when incinerated particles concentrate in the water), and fluorescents, especially the greens, oranges and opaque yellows used in flexographic inks, which may contain molybdenum orange (which derives about 60% of its weight from lead or chromium).

If you must use a particular color, ask your printer’s ink supplier to create a custom “heavy metal-free” color that matches your color of choice. But your most responsible choice is to use vegetable and soy inks which have significantly lower volatile organic compound (VOC) levels. VOCs are primary contributors to air and water pollution.

Sources:
pidseattle.com
themightyodo.com