White paper, produced from tree-coloured fibres, undergoes a bleaching process. In the past chlorine bleaching was the preferred method because it produced the whitest pulp; however it produces organochloride compounds, an extremely toxic carcinogen. Many paper mills have converted their chlorine bleaching to more environmentally-preferable bleaching methods in order to reduce their dioxin emissions.

Bleaching methods
There are three methods of environmentally preferably bleaching processes:

• Elemental Chlorine Free (ECF) which substitutes more benign compounds such as chlorine dioxide for elemental chlorine gas. Dioxins and other persistent carcinogens still remain in ECF effluent, albeit at significantly lower levels than from chlorine gas based processes.
• Process Chlorine Free (PCF) which substitutes benign agents such as ozone, hydrogen peroxide, and oxygen, though the pulp may contain recycled or recovered materials that were originally bleached with chlorine.
• Totally Chlorine Free (TCF) which substitutes more benign agents such as ozone, hydrogen peroxide and oxygen.

If you require white paper, avoid paper that is bleached with elemental chlorine. Look for a certification stating the bleaching process is either ECF, PCF or TCF. For a paper to claim to be TCF it cannot have utilised any post-consumer recycled paper. If it claims to have recycled content this can only be pre-consumer fibre that the mill would have recycled anyway.