Dioxins are one type of organochloride, which result from the combination of chlorine and other substances. Pulp and paper mills using chlorine for bleaching produce up to 1,000 of these chlorinated organic compounds. So far, only about 300 of these have been identified, including dioxins, furans, and PCBs. Dioxin is considered to be the most potent chemical toxin known, and studies have shown it to be highly carcinogenic. Toxic emissions from paper mills are concentrated in fish, then are further concentrated when those fish are eaten, whether by a bird or a person.
New studies indicate potential impacts to the reproductive and immune systems.
To give a perspective, the pesticide Endrin, a recognized carcinogen, created quite a stir in Montana when found in waterfowl and upland game birds. It is no longer registered for use due to its persistence. Dioxins can be 10,000 times more toxic than Endrin. Pulp mills discharge around 35 tons of toxic organochlorides each day. Many of these cause cancer or genetic damage, lead to reduced reproductivity in fish, and are persistent and accumulate in the environment.