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Serum dioxin concentrations and breast cancer risk in the Seveso Women's Health Study
Marcella Warner1, Brenda Eskenazi, Paolo Mocarelli
1School of Public Health, University of California at Berkeley, Berkeley, California 94720, USA. mwarner@uclinik4.berkeley.edu
Abstract:
2,3,7,8-Tetrachlorodibenzo-(italic)p(/italic)-dioxin (TCDD or dioxin), a widespread environmental contaminant, has been shown to disrupt multiple endocrine pathways. The International Agency for Research on Cancer classified TCDD as a known human carcinogen, primarily based on occupational studies of increased mortality from all cancers combined. Using data from the Seveso Women's Health Study (SWHS), we examined the association between individual serum TCDD levels and breast cancer risk in women residing around Seveso, Italy, in 1976, at the time of an industrial explosion that resulted in the highest known population exposure to TCDD. The SWHS cohort comprises 981 women who were infants to 40 years old in 1976, resided in the most contaminated areas at the time of the explosion, and had archived sera that was collected soon after the explosion. For each woman, serum TCDD exposure was measured by high-resolution mass spectrometry. Cancer cases were identified during interview and confirmed by medical record. At interview, 15 women (1.5%) had been diagnosed with breast cancer and serum TCDD levels for cases ranged from 13 to 1,960 ppt. Cox proportional hazards modeling showed that the hazard ratio for breast cancer associated with a 10-fold increase in serum TCDD levels (log(subscript)10(/subscript) TCDD) was significantly increased to 2.1 (95% confidence interval, 1.0-4.6). Covariate-adjusted results were not different. Individual serum TCDD is significantly related with breast cancer incidence among women in the SWHS cohort. Continued follow-up of the cohort will help shed light on the possible role of TCDD in the pathogenesis of breast cancer.
Insights
Exposure to dioxin (2,3,7,8-Tetrachlorodibenzo-p-dioxin) significantly increases breast cancer risk. This study found a 2.1-fold increased hazard for breast cancer with higher dioxin levels in women exposed after the Seveso explosion.
Area of Science:
- Environmental Health
- Toxicology
- Epidemiology
Background:
- 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), a persistent environmental contaminant, is known to disrupt endocrine pathways and is classified as a human carcinogen.
- Occupational studies have linked TCDD exposure to increased all-cancer mortality, but specific associations with breast cancer risk require further investigation.
- The Seveso disaster in 1976 caused unprecedented population exposure to TCDD, providing a unique cohort for studying long-term health effects.
Purpose of the Study:
- To investigate the association between individual serum levels of TCDD and the risk of developing breast cancer.
- To analyze data from the Seveso Women's Health Study (SWHS) cohort, which experienced high TCDD exposure in 1976.
Main Methods:
- Utilized the SWHS cohort of 981 women with archived sera collected shortly after the 1976 Seveso industrial explosion.
- Measured individual serum TCDD levels using high-resolution mass spectrometry.
- Employed Cox proportional hazards modeling to assess the relationship between TCDD exposure and breast cancer incidence, adjusting for covariates.
Main Results:
- Fifteen women (1.5%) in the cohort were diagnosed with breast cancer.
- A 10-fold increase in serum TCDD levels was associated with a significantly increased hazard ratio of 2.1 for breast cancer (95% CI, 1.0-4.6).
- Covariate adjustments did not alter the observed association between serum TCDD levels and breast cancer risk.
Conclusions:
- Individual serum TCDD levels are significantly associated with an increased incidence of breast cancer in the Seveso Women's Health Study cohort.
- These findings highlight the potential role of TCDD in breast cancer pathogenesis.
- Continued follow-up of the SWHS cohort is warranted to further elucidate the long-term impact of TCDD exposure on breast cancer development.
