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 2011. 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 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 2011. 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 most recent dioxin report published by the EPA shows continually low levels of dioxins and dioxin-like substances in the Irish environment, in line with earlier EPA studies. The concentrations of dioxins were low by international standards and comparisons. This is the ninth such survey and on this occasion a total of 38 samples were taken with the average dioxin level less than 10% of the EU limit.”
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 2011, 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. Only Polybrominated diphenyl ethers (PBDEs) were detected and were at low levels by European comparison.
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.
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 0.169 to 0.520 pg WHO-TEQ/g with a mean of 0.261 pg WHO-TEQ/g. 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 0.299 to 0.826 pg WHO-TEQ/g and the mean value was 0.184 pg WHO-TEQ/g.
Dioxins, PCBs and certain PBDEs as Persistent Organic Pollutants
Dioxins, PCBs (polychlorinated biphenyls) and certain PBDEs (Polybrominated diphenyl ethers) are listed under the Stockholm Convention on Persistent Organic Pollutants (POPs) which is a global treaty that aims to protect human health and the environment from POPs. In line with Ireland’s obligations under the Convention, the EPA has recently prepared a National Implementation Plan on POPs in consultation with a number of public authorities, national stakeholders and the public. The National Implementation Plan on POPs includes an assessment of POPs in Ireland, including dioxins, PCBs and certain PBDEs, and details the measures put in place to protect human health and the environment from POPs. The Plan also outlines a number of activities which will be carried out to support the control of POPs including, for example, continued raising of public awareness regarding harmful emissions associated with backyard burning.
Successful implementation of measures outlined in the Plan requires proactive engagement of a number of key stakeholders including the public. The National Implementation Plan on POPs is available at www.pops.ie.
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
- Industrial combustion processes
- 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 treated wood is used)
- Sinter plants
- Traffic
The principal sources in Ireland, given the absence of many of the above industrial sources, are believed to be from domestic sources such as backyard burning of waste, residential fires, bonfires and accidental fires.
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 S-PBDEs (N=5) in the survey results was 60 to 134 ng/kg fat with a mean of 95 ng/kg fat. These levels are in line with international comparisons.
Source: Envirocentre.ie – Dioxin Levels in Ireland Well Below EU Limits
