Dioxin Proven to Cause Cancer and Heart Disease

The work of Dr. Flesch-Janys is significant in finding a dose-relationship between dioxin and cancer and heart disease mortality for workers of a pesticide manufacturing plant located in Hamburg, Germany that had produced phenoxy herbicides including 2,4-D, chlorophenols, and other herbicides and insecticides known to be contaminated with dioxins and furans for a period of thirty-two years.

The major strength of this study is the availability of a quantitative exposure measurement, which allowed a direct estimate of dose-response relations for the 1189 studied workers. Actual dioxin exposure was based on measurements of blood dioxin levels in 190 workers.

The study is comprehensive and includes all plant workers who were employed for longer than three months from 1952 until the plant was shut down in 1984. The workers then were followed medically through the end of 1992.

A control group was utilized which consisted of 2528 workers at a gas supply company located nearby who were not exposed to dioxins in their employment. This control group and the availability of actual blood dioxin levels results in this study being the most conclusive and reliable of any recent research on dioxin.

The study found an increase in all deaths, cancer deaths, and deaths due to heart disease, when compared to the control group. The increased deaths due to heart disease is new information.

Following the explosion of a pentachlorophenol-pesticide plant operated by Hoffman-LaRoche in Seveso, Italy in 1976, increased deaths due to heart attacks were acknowledged,but speculatively attributed to post-explosion stress. This study supports the conclusion that those deaths were most probably due to dioxin exposure.

More significant is the finding that disease-related deaths increased with increased dioxin exposure.

Employees with the highest dioxin exposures were three times more likely to die from cancer, and nearly three times as likely to die from ischemic heart disease [narrowing of arteries leading to heart attack], compared to the control group, thereby confirming a dose-response relationship.

Smoking was ruled out as a confounding factor in this study because both the studied workers and the control group had the same proportion of smokers. But exposure of the plant workers to other cancer-causing chemicals could not be ruled out.

The finding of cancer deaths in dioxin-exposed workers is not a new finding.

Three previous studies have reported that cancer increases death among dioxin-exposed workers. A. Zober, et al, "Thirty-Four Year Mortality Follow-up of BASF Employees Exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin After the 1953 Accident," 62 International Archives of Occupational and Environmental Health 139-157 (1990); Marilyn Fingerhut, W.E. Halperin, et al, "Cancer Mortality in Workers Exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin," 199 New England Journal of Medicine 212-218 (1991); A. Manz, J. Berger, et al, "Cancer Mortality Among Workers in a Chemical Plant Contaminated with Dioxin," 338 The Lancet 959-964 (1991).

This new study is unique because it is based on actual blood dioxin levels, as opposed to previous studies which estimated dioxin exposures. With hard blood dioxin data available for this cohort, a dose-response relationship could be investigated and was clearly demonstrated. For this reason this study will be given much greater weight than previous research.