The Chlorine-Breast Cancer Link
Weltman, Eric, Multinational Monitor
The chemical and paper industries face rising calls for the elimination of chlorine-based chemicals, as the evidence linking them to breast cancer and other health problems increases.
Since the 1940s, the incidence of breast cancer has more than doubled in the United States. In the last decade, the breast cancer rate has increased 4 percent annually, making it the most common cancer in women and the leading cause of death among women 40 to 55 years of age. A recent Greenpeace report, Chlorine, Human Health and the Environment: The Breast Cancer Warning, compiles a body of studies linking chlorine-based chemicals with this stunning increase.
Chlorine-based chemicals, or organochlorines, are used primarily in the chemical industry, for making plastics, pesticides and solvents, and in the paper industry for bleaching pulp, with smaller amounts used to disinfect water. Incinerators burning chlorine-containing trash also release organochlorines into the environment.
The Greenpeace report cites studies that show the multiple roles organochlorines play in cancer formation, including suppression of the immune system's defense against cancer, speeding the transformation of chemicals into more carcinogenic forms and causing mutations in genetic material, the first step in the development of cancer.
The World Health Organization's International Agency for Research on Cancer has classified 59 organochlorines as causing cancer in humans or animals, with limited evidence for another 58. The latter include atrazine, one of the most highly used pesticides in the United States, which has been linked to mammary cancers and altered estrogenic activity in rodents and to elevated risk of ovarian cancers in women. In addition, the feedstocks for the common plastic polyvinyl chloride (PVC) have been linked to mammary cancer in rodents. Manufacturing facilities emit an estimated 400 million pounds of vinyl chloride into the air each year.
The Greenpeace report cites studies which have found elevated breast cancer rates in women with elevated exposures to organochlorines, including chemists, chemical workers and women living near hazardous waste sites. A 1993 study by the New York University Women's Health Study found that women with breast cancer had higher blood levels of organochlorines than a control group without breast cancer. Other recent studies have shown similar findings.
Further evidence for the breast cancer-chlorine link comes from Israel, where breast cancer mortality declined sharply in the 1980s. Israeli researchers found that during the period of decline, all known risk factors - such as fat and alcohol consumption - had increased. They concluded that the decline is due to government bans of organochlorine pesticides.
The Greenpeace report also highlights the ability of some organochlorines to disrupt the hormone, or endocrine, system, by mimicking or interfering with reproductive hormones such as estrogen. Scientists have linked endocrine-disruptors to breast cancer, declining sperm count, birth defects and other disorders. This was also the subject of a hearing by the House Subcommittee on Health and the Environment in October, where scientists charged that the Environmental Protection Agency ignores the risks of endocrine-disruptors in its assessments of pesticides and other chemicals.
Dr. Ana Soto, a professor at Tufts University School of Medicine, testified that the widely used pesticide endosulfan has estrogenic properties comparable to DDT and PCBs. Soto's research has also found that the estrogenic effects of toxic chemicals are cumulative, even when exposure to each individual chemical is low. This finding challenges EPA's practice of considering only exposures to individual chemicals in its health risk assessments.
According to Richard Wiles, director of the Environmental Working Group's Agricultural Pollution Prevention Project, more than 220 million pounds of endocrine-disruptors are applied to 68 crops each year. …