EPA survey shows dioxin levels in the Irish Environment remain well below EU limits

Date released: Jan 09 2014, 11:00 AM

The latest Environmental Protection Agency (EPA) report on dioxin levels in the Irish environment shows that dioxin levels in all of the samples taken in a 2012 survey were well below the relevant EU limits. The report is based on dioxin levels measured in cows’ milk in a 2012 survey. 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 survey confirms the continuing low levels of dioxins and dioxin-like substances in the Irish environment.  A total of 38 samples were taken and, at an average of 10 per cent of the EU limit, concentrations of dioxins were low by international standards and comparisons.  This is the tenth such survey undertaken by the EPA since 1995 and the results are in line with the earlier studies.”

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 between June and early August 2012, 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.

Main findings:

  • There was a slight decrease in average dioxin levels in 2012.  The levels found in the survey are well below the EU limit in milk and milk products. 
  • Dioxin-like polychlorinated biphenyls (PCB) levels were also found to be lower in 2012 samples than those in 2011, by 25 per cent on average. 
  • These differences - in average dioxin levels and dioxin-like PCB levels - are not significant either in environmental or analytical terms and can partly be explained by a downward revision of the International World Health Organization (WHO) toxicity factors for some of the dioxin compounds.  
  • The results of this survey are in line with the dioxin results from the latest report from the Cork County Council animal health surveillance programme (published in December 2013) which has been operating in the Cork Harbour Region   since 1991.  
  •  The data are also consistent with an FSAI breast milk study (2010) which confirmed low levels of exposure of the Irish    population to dioxins and other micropollutants. 
  • 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.  Only Polybrominated diphenyl ethers (PBDEs) were found in any appreciable quantities in the survey and are consistent with international norms.
  • Non-Dioxin PCBs were also measured for the first time. The levels found were not of concern.

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

Notes to Editor

Measuring dioxins:
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. 

2012 Dioxin Levels:
Average dioxin levels in 2012 slightly decreased from 0.261 pg WHO-TEQ/g in 2011 to 0.196 pg WHO-TEQ/g. The levels are well below the EU limit in milk and milk products. The revised EU limits are 2.5 pg WHO-TEQ/g for dioxins only, and 5.5 pg WHO-TEQ/g for dioxins and polychlorinated biphenyls (PCBs) combined. 

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:

  • Residential combustion 
  • Open burning of waste (backyard burning, bonfires) 
  • Wood preservation (~15%) 
  • Iron and steel industry 
  • Power production, non-ferrous metals, chemical industry 
  • 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.