Dioxin Levels in Ireland well below EU Limits

Date released: Dec 21 2010

The latest EPA report on dioxin levels in the Irish environment shows that the dioxin levels in all of the samples were well below the relevant EU limits.  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. The report is based on dioxin levels measured in cows’ milk in a 2009 survey.

Commenting on the results, Dr. Colman Concannon, Regional Chemist, EPA Office of Environmental Assessment said, 

“The concentrations of dioxins were low by international standards and comparisons.  A total of 37 samples were taken and the average level was less than 10% of the EU limit.  This is the 7th 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.

In 2009, the survey included measurement of dioxin levels in the area of County Carlow near where the feed contamination incident occurred in 2008.  No elevated levels of dioxins were recorded.”

Survey Methodology
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 in June and early July 2009, 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.  Results are expressed in picograms of WHO Toxic Equivalent per gram of fat: 1 pg is 10-12 of a gram. 

The reported ranges for dioxins in milk fat (37 samples) were 0.180 to 0.346 pg WHO-TEQ/g with a mean of 0.233 pg WHO-TEQ/g. (See Figure 1). When PCBs were included, the range is 0.301 to 0.897 pg WHO-TEQ with a mean of 0.385 pg WHO-TEQ/g.  These levels are well below the EU limit in milk and milk products of 3.0 pg WHO-TEQ/g for dioxins only, and 6.0 pg WHO-TEQ/g for dioxins and PCBs combined.  There was no evidence to link the data from the survey to the pork feed contamination incident in late 2008.

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.  However, only Polybrominated Diphenyl Ethers (PBDEs) were detected.  The range for Polybrominated Diphenyl Ethers (PBDEs) (5 samples) was 65 to 332 ng/kg fat with a mean of 143  ng/kg fat, in line with the levels found in the three previous surveys in 2006, 2007 and 2008.  These levels are relatively low by international comparisons.

The report Dioxin Levels in the Irish Environment -Seventh Assessment is available on the EPA website.


Further information: Niamh Hatchell, EPA Media Relations Office 053-9170770 (24 hrs)

Editor’s Notes

What are Dioxins?
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. 

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:

  • Accidental fires
  • Backyard burning of household waste and bonfires
  • Cement kilns (especially where hazardous waste is co-incinerated)
  • Chlorine bleaching of wood pulp
  • Coal fired power plants
  • Copper production
  • Forest fires and other natural fires
  • Incineration of medical waste
  • Incineration of municipal or  hazardous waste
  • Production of steel
  • Residential combustion (especially where wood is used)
  • Sinter plants
  • Traffic

Other Micropollutants
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.