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Date released: Dec 16 2011
The most recent Environmental Protection Agency (EPA) report on dioxin levels in the Irish environment shows that the dioxin levels in all of the samples tested were well below the relevant EU limits. The report is based on dioxin levels measured in cows’ milk in a survey carried out in 2010. The report also shows that dioxin levels measured in this survey compare favourably with those taken from similar surveys in the EU and other countries.
Commenting on the results, Dr. Colman Concannon, Dublin Regional Chemist, EPA Office of Environmental Assessment said,
“The concentrations of dioxins were low by international standards and comparisons. A total of 38 samples were taken and the average level was less than 10% of the EU limit. This is the eighth such survey undertaken by the EPA since 1995 and the results are in line with the earlier studies. The survey confirms the continuing low levels of dioxins and dioxin-like substances in the Irish environment.”
The principal mechanism for the entry of dioxins into the environment in Ireland is by low-level emissions from multiple combustion sources to the atmosphere, with subsequent deposition onto vegetation such as grass. Any dioxins on grass ingested by cows tend to concentrate in the milk fat. Hence, sampling for dioxin levels in the milk of grazing cows is the approach adopted. The survey was carried out between June and early August 2010, during the peak outdoor grazing season, by taking a series of milk samples mainly from representative regional dairies. Additional samples were also taken from localities that might be seen as areas of potential risk of raised dioxin levels.
The WHO Toxic Equivalent is the current internationally recognised system for comparing dioxin toxicities of different samples. Samples were tested for dioxins only and for dioxins and PCBs combined and the levels found were well below the EU limit in milk and milk products.
In view of the increased international awareness of the presence in the environment of brominated flame retardants (BFRs) and brominated dioxins (PBDD/PBDF), a broad range of these substances was also tested in the survey. One sample showed elevated levels of Polybrominated diphenyl ethers (PBDEs) though this level was not high by European comparison. The elevated levels originated from one farm in Cork. The EPA notified the anomaly to the Department of Agriculture, Food and the Marine and the Food Safety Authority of Ireland for further investigation.
The report Dioxin Levels in the Irish Environment - Eighth Assessment is available on the EPA website.
Further information: Annette Cahalane/Emily Williamson EPA Media Relations Office 053-9170770 (24 hours)
Dioxins form a group of some 210 closely related, complex organic compounds, the vast majority of which are considered to have little environmental significance at the levels normally encountered. However, 17 of these substances have been shown to possess a very high toxicity, particularly in animal tests. The toxic responses include dermal effects, immunotoxicity and carcinogenicity, as well as reproductive and developmental toxicity. Dioxins arise mainly as unintentional by-products of incomplete combustion and from certain chemical processes. Similar effects are caused by some of the dioxin-like polychlorinated biphenyls (PCBs) and in order to conform to current practice, testing for these compounds was also included in this programme.
Results for dioxins in the survey
The EU limit for dioxins only in milk and milk products is 3.0 pg WHO-TEQ/g. The reported ranges for dioxins in milk fat in the survey (38 samples) were 0.158 to 0.356 pg WHO-TEQ/g with a mean of 0.202 pg WHO-TEQ/g. (See Figure 1). See Glossary in report for an explanation of terms.
The EU limit for dioxins and PCBs combined in milk and milk products is 6.0 pg WHO-TEQ/g for dioxins. In the survey results when PCBs were included, the reported range for dioxins and PCBs combined were 0.098 to 0.537 pg WHO-TEQ/g and the mean value was 0.196 pg WHO-TEQ/g.
Sources of Dioxins
Although PCDDs and PCDFs are not produced intentionally except for research and analysis purposes their formation is often a by-product of many activities. Some significant sources internationally are:
Other Micropollutants: BFRs, PBDDs and PBDFs
An emerging category of pollutants, brominated flame retardants (BFRs) and brominated dioxins (PBDD/PBDF) were measured as part of the main survey. Brominated dioxins (PBDDs and PBDFs) are also formed unintentionally, mainly through incineration of wastes or accidental fires that include consumer products containing brominated flame retardants (BFRs). Many of the BFRs have been banned for future use because of their toxicity and environmental persistence but they continue to be found in many consumer products such as furniture, fabrics and electronic products.
Results for BFRs, PBDDs and PBDFs in the survey
There are no maximum limits set for brominated flame retardants (BFRs) and brominated dioxins (PBDD/PBDF). The range for Σ−PBDEs (N=5) in the survey results was 69 to 646 ng/kg fat with a mean of 202 ng/kg fat. These levels are in line with international comparisons.
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