Dioxins are environmental pollutants belonging to the so-called “dirty dozen,” a group of pollutants that persist in the environment and bioaccumulate in the fatty tissues of animals. Indeed, the World Health Organization (WHO) posits that the half-life of dioxins in the human body is 7 to 11 years and that animals at the top of the food chain, including humans, are at the greatest risk for exposure and persistent contamination.1 The WHO also lists fetuses and newborns as particularly sensitive to the effects of dioxin exposure.
In this study, Bianco et al. (2013) present a preliminary case study on the levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in the breast milk of women living in a highly industrialized area near Taranto, Southern Italy.2 This location has been assessed as one of high risk of environmental crisis and identified as an area of interest for environmental remediation. The researchers believe that the information in this report may provide a foundation for future studies and, ultimately, for the implementation of environmental remediation protocols.
The researchers collected breast milk samples from fifteen primiparous women and gathered supplementary information regarding their social statistics (smoking, dietary habits, living conditions, etc.). They subjected these samples to gas chromatography–high-resolution mass spectrometry (GC-HRMS) using a DFS high-resolution MS machine coupled with a TRACE GC Ultra gas chromatograph (Thermo Scientific) for the detection of seventeen 2,3,7,8-PCDD/F congeners with known toxicity. For positive identification, the compounds met the following four criteria: MS detection of two ions of the specific congeners; retention time of the peak within a well-defined limit; isotope ratio of the two monitored ions within 15% of the theoretical isotopic ratio; signal-to-noise ratio of greater than or equal to 3. The legal limit for human consumption of dioxin is 3 pg/g fat.
Bianco et al. positively identified the following congeners in the breast milk samples: 2,3,7,8-tetrachlorodibenzo-p-dioxin; 2,3,4,7,8-pentachlorodibenzofuran; 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin; and octachlorodibenzodioxin. The most abundant congener was 2,3,4,7,8-PeCDF, with a concentration of 6 pg/g. The scientists detected the most toxic congener—2,3,7,8-TCDD—in three of the samples (samples 1, 6 and 7). The toxic equivalents for four of the samples (samples 1, 6, 7 and 13) were well above the legal limit (13.0 ± 0.3, 15.0 ± 0.9, 8.0 ± 0, 4.3 ± 0.9 pg/g fat). The researchers report that these toxic-equivalency levels are comparable to, or even higher than, those documented in similar case studies.
The team compared the estimated daily intake (EDI) and estimated weekly intake (EWI) for the infants fed with samples 1, 6, 7 and 13 to the tolerable daily intake (TDI) set forth by the WHO and the tolerable weekly intake (TWI) established by the European Union Scientific Committee on Food. They found that the EDI values were 5 to 20 times higher than the TDI recommendations. Similarly, the EWI values were 10 to 40 times higher than the parameters for the TWI. Because the infant digestive tract absorbs 95% of ingested quantities, these values represent dangerous levels of exposure during a crucial period of organ growth and development.
Bianco et al. call for further surveillance of regional PCCD/F levels, as well as investigations into the causal link between dioxin exposure and adverse child development. In addition to reiterating their goal of environmental remediation for the area, the authors posit that infants in industrialized areas may benefit from routine breast milk monitoring, with dioxin-free goat milk and donor breast milk possible sources for supplementation.
1. World Health Organization. (2010, May) “Dioxins and their effects on human health,” Fact sheet #225, available at http://www.who.int/mediacentre/factsheets/fs225/en.
2. Bianco, G., et al. (2013) “Dibenzo-p-dioxins and dibenzofurans in human breast milk collected in the area of Taranto (Southern Italy): First case study,” Analytical and Bioanalytical Chemistry, 405 (pp. 2405–10), doi: 10.1007/s00216-013-6706-7.
Post Author: Melissa J. Mayer. Melissa is a freelance writer who specializes in science journalism. She possesses passion for and experience in the fields of proteomics, cellular/molecular biology, microbiology, biochemistry, and immunology. Melissa is also bilingual (Spanish) and holds a teaching certificate with a biology endorsement.