Greenpeace cleverly claims that dioxins may cause cancer. Indeed, almost anything may cause cancer. There is not a shred of credible evidence available that any link exists between dioxins and cancer. There are many sources of dioxin in the environment. A significant portion of all environmental dioxins is natural.
Forest fires provide the most common mechanism.
Of course, you can't litigate against forest fires. The paper pulp industry has become the target of choice. Leading the way is Greenpeace with its stated goal of ultimately eliminating all chlorine uses. The story of the pulp and paper industry might legitimately be called impressive. While Greenpeace continues to fan the fires of dioxin hysteria, industry continues to refine processes to reduce dioxin emissions.