Study questions dioxin's link to cancer

Findings from a study of Dow Chemical workers suggest that exposure to dioxin may not increase the risk for certain cancers, as is widely believed.

Compared with deaths in the general U.S. population, researchers found no higher deaths from all cancers, and specifically from lung cancers and non-malignant lung disease, among pesticide plant workers exposed to dioxin over 36 years on average.

Dr. James J. Collins, an epidemiologist at Dow Chemical Company in Midland, Michigan, and colleagues assessed the health effects from long term workplace exposures to the dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin.

This form of dioxin, commonly called TCDD, is listed as a known human carcinogen by the International Agency for Research on Cancer, Collins and colleagues note in a report in the American Journal of Epidemiology.

The 1,615 workers studied had estimated body levels of dioxins "much higher" than estimated levels from environmental exposures in the general population, Collins noted in an email correspondence to Reuters Health.

Yet, outside of a potentially greater risk of a highly malignant soft-tissue sarcoma reported in 4 workers, there were no more cancer deaths among exposed workers than among the general population.

The investigation did reveal slightly more deaths from diabetes, heart disease, leukemia, and a cancer of the lymph nodes called non-Hodgkin lymphoma among TCDD-exposed workers compared with the general population. But Collins' group observed no trend linking these deaths with dioxin exposures.

Despite hundreds of human studies on the potential health effects of dioxins, "there is still no scientific consensus on the potential for health effects related to dioxin," Collins said.

Therefore, "further studies, especially those which measure dioxin body levels, would be prudent," he concluded.

By Joene Hendry
SOURCE: American Journal of Epidemiology, August 15, 2009