Human 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure and thyroid cancer risk

Thyroid cancer incidence has been steadily rising since the 1970s and exposure to environmental pollutants, including persistent organic pollutants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and other dioxins, has emerged as a potential explanation for this increase. This study aimed to summarize available human studies on the association between TCDD exposure and thyroid cancer. A systematic review of the literature was per-formed searching the National Library of Medicine and National Institutes of Health PubMed, Embase, and Scopus databases, through January 2022, using the following keywords: thyroid, 2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD, dioxin, and Agent Orange. Six studies were included in this review. Three studies evaluated the acute exposure to the chemical factory accident in Seveso, Italy, and found a non-significant in-crease in the risk of thyroid cancer. Two studies investigating Agent Orange exposure among United States Vietnam War veterans found a significant risk of thyroid cancer following exposure. No association was found in one study evaluating TCDD exposure through herbicides. The current study highlights the limited information on the potential association between TCDD exposure and thyroid cancer and thus the need for future human studies, especially considering the persistent human exposure to dioxins in the environment.

Automated summary

Thyroid cancer incidence has been steadily increasing since the 1970s, and exposure to environmental pollutants like TCDD and other dioxins may be a potential cause. This study reviewed available human studies on the association between TCDD exposure and thyroid cancer. Six studies were included, with results showing a non-significant increase in thyroid cancer risk from acute TCDD exposure in one case and a significant risk from Agent Orange exposure in two cases. One study evaluating TCDD exposure through herbicides found no association. More human studies are needed to further understand the potential link between TCDD exposure and thyroid cancer.