High levels of dioxin-like PCBs found in organic-farmed eggs caused by coating materials of asbestos-cement fiber plates: A case study

Our plain-English summary of High levels of dioxin-like PCBs found in organic-farmed eggs caused by coating materials of asbestos-cement fiber plates: A case study, by J. Winkler (Environment International, 2015).

The study

• Author: J. Winkler
• Journal: Environment International
• Published: 2015;80:72-8
• Cited by: 16 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

During a regional monitoring project of organic-farmed, free-range and cage-free eggs, high levels of dioxin-like compounds were detected in organic-farmed eggs, using the dioxin responsive chemical-activated luciferase gene expression (DR-CALUX®) bioassay. Further evaluations performed with GC-HRMS (gas chromatography in combination with high resolution mass spectrometry) revealed elevated amounts of non-dioxin-like (non-dl) polychlorinated biphenyls (PCBs) dominated by most lipophilic congeners like PCB 138, 153 and 180 and of dioxin-like (dl) PCBs, with a congener pattern in the descending order of PCB 118, 156, 167, 105, 189, 157, 105, 126 and PCB 77. Contaminations with polychlorinated dibenzo-p-dioxins (PCDDs) appeared of minor priority, with only hepta- and octa-substituted dioxins above their limits of quantification (LOQs). The pattern of polychlorinated dibenzofurans (PCDFs) was dominated by low amounts of tetra- and penta-chlorinated congeners. To identify the source of contamination, several samples of organic-farmed eggs, soil, laying hens, feedstuff, corrugated asbestos-cement cover plates (ACPs), stable dust and debris collected in the gutter of the stable, were analyzed. Comparing PCB congener-pattern of individual samples, the source was traced back to the coating of ACPs, which covered roof and sidewalls of the stable. Because coating materials probably have been used for roofing and cladding in many countries worldwide, there is a high probability that the presented case report is not a local incident but rather describes a new source of PCB contamination, yet widely unknown or underestimated.

Copyright © 2015 Elsevier Ltd. All rights reserved.

In plain English

This case study looked into why eggs from one organic farm in Hesse, Germany, showed high levels of dioxin-like compounds during a 2012/13 monitoring project of about 40 egg samples. The author tested eggs, hens, feed, soil from four backyards and a reference area, pieces of 46-year-old corrugated asbestos-cement roof and wall plates, gutter debris, and stable dust. Feed contained only trace amounts and was excluded as the source. Soil and eggs were most contaminated in the backyard bordering the asbestos-cement cladding. Eggs from three yards had 6.1 to 11.8 pg toxic equivalents per g of fat, counting dioxins, furans and dioxin-like PCBs together. Eggs from backyard 4, described as farthest from the stable, had 2.9 pg per g of fat on the same measure, which the author called well below the current EU limit. Material scraped from the plate surface had about 8 times the dioxin-like PCB toxic equivalents per gram of whole plates. Gutter debris was far higher still. PCB patterns were similar across the plates, soil, hens and eggs. The author concluded that the plates' coating was the main source of the PCBs. The study measured PCB chemicals, not asbestos fibers or human disease.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: case study tracing the source of chemical (PCB and dioxin) contamination at one organic farm, using a bioassay screen and confirmatory chemical analysis (GC-HRMS)
• Who was studied: About 40 egg samples (organic-farmed, free-range and cage-free) collected in 2012/13 in the state of Hesse, Germany. Follow-up at one organic farm covered eggs from 4 backyards, a pooled sample of 10 hens, 10 soil samples, feedstuff, asbestos-cement plate pieces, gutter debris and stable dust.
• Exposure: Dioxin-like and non-dioxin-like PCBs, and dioxins and furans, from the coating of 46-year-old corrugated asbestos-cement cover plates on the stable's roof and sidewalls. Asbestos fiber types were not studied.
• Main results:
  • Feedstuff (shell limestone, complete feed, triticale) contained only trace amounts and was excluded as a source.
  • Soil and eggs from backyard 1, which directly bordered the asbestos-cement sidewalls, had the highest PCB and dioxin/furan contamination.
  • The highest soil level was 70.2 pg dioxin-like PCB toxic equivalents per g dry matter, in soil directly beneath the asbestos-cement cladding of backyard 1.
  • Soil from backyards 1, 2 and 3 (total TEQ 9.3 to 46.4 ng/kg dry matter) went with egg contamination of 6.1 to 11.8 pg TEQ/g lipid. Backyard 4 soil (6 ng/kg dry matter) went with eggs at 2.9 pg TEQ/g lipid, which the author called well below the current EU limit. These totals combine dioxins/furans and dioxin-like PCBs.
  • Whole asbestos-cement plates contained 2.9 pg dioxin-like PCB toxic equivalents (TEQ) per g dry matter. Material scraped from the plate surface contained 23.5 pg dl-PCB-TEQ/g dry matter, which the author described as about 8 times the whole-plate value. This comparison is in toxic equivalents, not in the mass of PCBs.
  • Fine-grained debris from the roof gutter contained 28,410 pg dioxin-like PCB TEQ/g dry matter.
  • Dust from inside the stable, taken near the roof plates, contained 64.5 pg dioxin-like PCB TEQ/g dry matter.
  • Dioxin-like PCB patterns were similar across samples, usually in the descending order PCB 118, PCB 156 and PCB 167.
  • Non-dioxin-like PCBs in all egg samples were below the EU limit of 40 ng/g lipid.
• The authors' conclusion: The author concluded that the coating of the corrugated asbestos-cement plates on the stable's roof and side walls was the main source of the dioxin-like PCB contamination, with similar PCB patterns found in the plates, soil, hens and eggs.
• Limitations the authors state:
  • It remained unclear whether rainwater leaching alone or other weathering such as abrasion moved the compounds from the plates into the soil.
  • Other factors could make it harder to trace contamination by comparing congener patterns, including feeding habits, physiological state, flock size and egg-laying rhythm.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement.

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