TCDD and cancer: A critical review of epidemiologic studies

Abstract

The authors reviewed the epidemiologic studies on exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and cancer risk, published since the last full-scale review made by the International Agency for Research on Cancer Monographs program in 1997. The update of a cohort of US herbicide producers generated negative results overall; the internal analysis provided evidence of an increased “all-cancer” risk in the highest exposure category, with a statistically significant exposure-response association in some of the many analyses performed.The update of a similar Dutch cohort did not confirm the previously observed association with TCDD exposure. The updated surveillance of the Seveso population provided evidence of increased all-cancer mortality 15-20 years after exposure among those living in the most contaminated area but might also reflect random variation, as overall excesses in the most recent follow-up were not observed. Corresponding data on cancer incidence offer little support to the mortality results. Updated results from cohort studies of Vietnam veterans potentially exposed to TCDD did not consistently suggest an increased risk of cancer. Results of additional, smaller studies of other occupational groups potentially exposed to TCDD, and of community-based case-control studies, did not provide consistent evidence of an increased cancer risk. In conclusion, recent epidemiological evidence falls far short of conclusively demonstrating a causal link between TCDD exposure and cancer risk in humans. The emphasis on results for overall cancer risk—rather than risk for specific neoplasms—is notjustified on epidemiologic grounds and is nota reason for ignoring the weaknesses of the available evidence.

Chronic Exposure to Chlorophenol Related Compounds in the Pesticide Production Workplace and Lung Cancer: A Meta-Analysis

“…Since, aryl hydrocarbon receptor activation mediates the tumorgenicity of dioxin compounds, MicroRNAs expression by TCDD regulate lung cancer promotion of these compounds (Singh et al, 2012). Overall, IARC multinational study and NIOSH Dioxin Registry report a wide range of lung cancer in workplace site (Boffetta et al, 2011). Our findings are comparable with the result of past studies.…”

“…Last evaluation focused on lung cancer in TCDD exposure (Boffetta et al, 2011). CPsR pesticide has significant contaminated levels of dioxins.…”

A critical review of the epidemiology of Agent Orange or 2,3,7,8-tetrachlorodibenzo-p-dioxin and lymphoid malignancies

“…As in previous reviews of the epidemiology of Agent Orange or TCDD exposure and cancer [100,101], to improve the specificity of the included evidence, studies (other than those of Vietnam veterans) were excluded if they did not estimate associations with exposure to Agent Orange or TCDD in particular. Thus, we excluded studies of workers exposed to herbicides not contaminated by TCDD, agents contaminated by polychlorinated dibenzo-p-dioxins other than TCDD, or groups of pesticides or herbicides not uniformly contaminated by TCDD.…”

Polycyclic Aromatic Hydrocarbons (PAHs) Mediate Transcriptional Activation of the ATP Binding Cassette Transporter ABCB6 Gene via the Aryl Hydrocarbon Receptor (AhR)

“…In addition to their ability to precipitate porphyria, PAHs are carcinogenic in many animal species (26,29,52,53). Following their conversion to dihydrodiol epoxides and epoxide hydrolase by CYP1A1, these compounds interact with DNA and form PAH-DNA adducts (54,55).…”