Ireland must be vigilant to maintain our low environmental dioxin levels.
Dioxins have, in recent years, continued to generate environmental concerns that capture public attention. In order to maintain surveillance of dioxins, furans and other related pollutants, the Environmental Protection Agency (EPA) carries out a number of almost identical surveys based on levels found in cows’ milk.
The latest 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.
This is the tenth such survey undertaken by the EPA since 1995 and the results are in line with the earlier studies. 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.
How was the survey done?
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.
While Zero Waste Ireland welcome’s the results we are concerned that testing in areas downwind of the operating waste incinerators is not done. It is by testing in the vulnerable areas that the real situation is seen. This must become a routine operation in areas where Waste Incinerators are planned or operational. For example only one sample is taken from the Carranstown area of Meath, the site of a large Commercial Waste Incinerator, which has recently received the ok to expand its capacity.
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.
How do we measure 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:
- Incinerators and thermal treatment plants
- 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.
Persistent Organic Pollutants (POPs) & the Stockholm Convention
Dioxins, PCBs and PBDEs (See Chapter 5) are among the substances listed as POPs in the Stockholm Convention. In keeping with its obligations under the Convention, the Environmental Protection Agency is designated as Ireland’s competent authority under the national POPs regulations. It has prepared a National Implementation Plan on POPs which details the measures to be put in place to protect human health and the environment from the POPs that are
listed under the Convention, such as dioxins, PCBs and PBDEs.
The plan ,to whch ZWAI contributed, which was very late in being delivered, sets out further priority actions to support the control of POPs showing how it plans to limit and control POPs.
Sampling Strategy
Two types of sampling stations were chosen:
- Type A background stations covering the entire country (24 samples)
- Type B potential impact stations in areas of perceived potential risk (14 samples)
Type A samples were normally taken from full milk silos (30,000 to 50,000 gallons) in regional dairies. However there were a number of instances where sampling from silos was not possible and the samples were taken instead from road tankers representative of the area to be covered.
Type B samples were taken from road tankers representing the “potential impact” areas.
Test Sample locations.
An appendix to the Report shows the list of locations, however these are not very specific and we would welcome a detailed map of these test locations:
- A1 Mitchelstown Area
- A2 Co. Waterford
- A3 Dublin South.Co./North Wicklow Area
- A4 North Co. Wexford
- A5 Charleville, Co Cork Area
- A6 Ballyragget, Co Kilkenny Area
- A7 Renmore, Co Galway Area
- A8 Moate, Co Westmeath Area
- A9 Tipperary Town/Thurles Areas
- A10 Nenagh, Co. Tipperary Area
- A11 Cavan/Longford/Leitrim
- A12 Drinagh, Co Cork
- A13 Bandon Area
- A14 North Kerry Area
- A15 Co Sligo
- A16 Roscommon/East Galway
- A18 Roscommon/Leitrim
- A19 Co Monaghan
- A20 Co Louth
- A21 North Kildare/West Dublin
- A22 So Kerry (Cahirciveen area)
- A23 South Wexford
- A24 SE Co. Mayo
- A25 Co. Donegal
The potential impact samples B1 – B 18 were taken at:
- B1 Carrigtwohill/Cobh/Great Island
- B2 Aghada/East Cork Harbour
- B3 Askeaton area
- B4 Tarbert, Co. Kerry
- B5 Clarecastle, Co. Clare
- B6 Cooraclare Co. Clare
- B7 Ballydine, So. Tipperary
- B8 Swords/Mulhuddart. Co. Dublin
- B9 Grannagh, Co. Kilkenny
- B13 Kinsale (Dunderow) Co. Cork
- B14 Ringaskiddy area. Co. Cork
- B15 Crossakiel (nr Kells) Co. Meath
- B17 Carranstown, Co. Meath
- B18 Kinnegad, Co Westmeath