The pulp and paper industry is the world's second largest consumer of chlorine and the greatest source of toxic organochlorine discharges directly into the waterways. Although dozens of mills across the world are now producing high-quality, bright paper using totally chlorine-free (TCF) technology, most of the world's producers have yet to switch. Recognising the damage being caused by elemental chlorine (chlorine gas), new investors in pulp mills either choose TCF or elemental chlorine-free (ECF) technologies. Paper manufacturers often claim to be chlorine-free when in fact they have only moved halfway by using chlorine dioxide.

Over 300 organochlorines have been identified in the discharge of bleached pulp mills, including dioxins, furans, chlorinated phenols, acids, benzenes, and many others. These identified compounds account for less than 10 per cent of all organochlorines in the effluent: the majority remain mystery chemicals that have not been specifically identified.

Many organochlorines resist natural breakdown processes, so they build up over time in the environment. Organochlorines from pulp mills have been found in the water, sediment, and food chain as far as 1400 kilometres from their source, claims Greenpeace. Pulp mills also release organochlorines into the air, particularly chloroform, a cause of cancer in animals. Finally, organochlorines are found in paper products themselves. Environmental Canada, an environmental research organisation in Canada, has estimated that 2 per cent of the organoclorines formed in the bleaching process remain in the pulp. Green activists say there is extensive evidence that effluent from chlorine-bleaching pulp mills harms fish and aquatic systems.