Environmental Quality Standards

Published: 16th Sep 2015

by Dr Claire Stone

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It was in 2008 that the European Parliament and Council first published the Environmental Quality Standards Directive.

This publication lays down environmental quality standards (EQS) for priority substances and certain other pollutants as provided for in Article 16 of the Water Framework Directive 2000/60/EC (WFD), with the aim of achieving good surface water chemical status and in accordance with the provisions and objectives of Article 4 of that Directive. As a Europe wide directive, each member state has a plan for both assessing their water bodies and achieving compliance with the annual average and maximum concentrations, as set out in the document.

Originally the directive listed 36 priority substances and other pollutants or groups of pollutants, but in 2013 the directive was revised again with further pollutants added to the list and changes made to the annual average and maximum pollutant concentrations. The directive is due for subsequent review every two years.

More locally, the respective environment agencies in the UK and Ireland are responsible for considering whether a potential pollutant should be determined to be a hazardous substance or a non-hazardous pollutant. To this end the original guidelines issued in 2008 were revised in 2013. This resulted in a number of pollutants being reclassified, as well as the additional pollutants from the European directive being incorporated.

Originally the priority hazardous substance group comprised 16 pollutants. This has now been revised to 25, with three pollutants being changed from priority to priority hazardous and six new pollutants added to the list, including the flame retardant compound PFOS and the pesticides Dicofol and Quinoxyfen. Within this number, 10 of the pollutants have revised EQS levels.

The priority substance group has been revised from its original 21 pollutants to 24, with four of these having revised EQS levels. A further six pollutants were added to the list including a range of herbicides such as Bifenox and Terbutryn. Estradiol, Ethyinylestradiol and Diclofenac have been removed from the list.

The largest list of all is the specific pollutants list, which has expanded from 19 pollutants of interest to 29. This substantial increase sees compounds of various different classes added – from the sanitary product Triclosan through to the VOC Tetrachloroethane and the fungicide Carbendazim. Of the previously existing 19, five have revised EQS levels.

Many of the revisions to the guidelines add pollutants to the lists of designated chemicals that are either not commonly tested for, or where the concentration levels permitted (and thus to be measured) are considerably lower than most current standard laboratory detection levels. As a consequence, changes to the directive are causing considerable challenges to the environmental testing laboratory sector. Of note is that the revisions to the directive apply from 2015 through to 2021 and new pollutants apply from 2018, and in some cases these only apply if analytical techniques exist to support the EQS levels set out in the directive. Each member state is also required to instigate a “watch list” to monitor the occurrence of emerging pollutants, the aim being to report back to REACH and other source control regulators to ensure necessary additional measures are put in place to reduce pollutant release where possible. Within the UK this is called the Chemical Investigation Programme, or CIP.

Each of these groups are detailed and considered in turn, with attention drawn to the respective challenges facing the environmental testing laboratory sector.

Priority hazardous substances

To highlight the differences and challenges in analysing compounds within this EQS group, two polyaromatic hydrocarbon (PAH) compounds can be easily compared and contrasted.

Anthracene (C14H10) is a PAH with a relatively low solubility in water of 44 µg/l. It is a component of coal tar and has been widely used as a wood preservative, in insecticides and as a coating material. It is not a known carcinogen. It has a relatively high EQS level of 0.1 µg/l compared with that of benzo(a)pyrene.

Benzo(a)pyrene is a group 1 carcinogen with mutagenic and highly carcinogenic metabolite. It is also found as a component of coal tar and is released into the environment typically through combustion. It is sparingly soluble in water with a solubility between 0.2 – 6.2 µg/l.

Both of these compounds are commonly tested for, with the most widely used technique being gas chromatography – mass spectroscopy (GC-MS). The compounds are extracted from the water by either liquid /liquid or solid phase extraction and the resulting solvent is injected into the GC-MS. Typical reporting limits are around 0.01 µg/l. For anthracene, this detection limit is perfectly adequate as it’s 10 times lower than the EQS level; however, it’s clearly not suitable for the analysis of benzo(a)pyrene at the EQS level.

The EQS level for benzo(a)pyrene is around 50 times lower than the standard reporting limit, and this calls for more advanced extraction and analysis techniques. As these compounds lend themselves to liquid /liquid or solid phase extraction techniques, the sample can be pre-concentrated by using a larger volume of sample, but this would typically require the handling of samples in excess of 25 litres in size, which is practical neither from the sampling perspective nor during preparation at the laboratory. The resulting solvent could then be concentrated to a smaller volume and analysed by a more sensitive technique such as GC-MS/MS. As much as this sounds relatively straightforward and a combination of the two renders this reporting limit feasible, consideration has to be given to sample concentration steps, as by concentrating the analyte, the concentration of background and interference signals may also increase. Also, instrumental resolution and peak shift may be problematic, notwithstanding the challenge of finding environmental matrices with a sufficiently low pollutant level in order to validate the method and prove the detection and/or reporting limit.

New priority hazardous substances

Newly added priority hazardous pollutants added to the list can also be challenging as they may not previously have been analysed for to any great degree, or the level of interest could be substantially lower than standard methods can achieve, as exemplified by considering Trifluralin and PFOS.

Trifluralin has been moved from the priority substances list to the priority hazardous list. It is a herbicide with a relatively high solubility in water of 0.024 g/l. It also readily undergoes metabolic and chemical changes in the environment and can be analysed as itself or by monitoring complex by-products. It has been banned within the EU due to its high toxicity, affecting fish and other aquatic life.

PFOS is a manmade fluorsurfactant, which has seen use in the product Scotchgard as well as in fire fighting foams. PFOS has earned its place on the priority hazardous substance list as a pollutant that is persistent, bioaccumulative and toxic to mammalian species.

The standard laboratory reporting limits for Trifluralin are around 0.01 µg/l and the standard method is quite straightforward – typically a liquid/liquid extraction using hexane followed by analysis of the compound and any by-products by GC-MS.

The analysis of PFOS at the EQS level is more problematic. Standard methods employing direct injection Liquid Chromatography – Mass Spectroscopy (LC-MS) measure down to around 0.01 µg/l and the EQS level is around 15 times lower than this. The EQS level can be achieved by using a concentrating extraction step, as opposed to direct injection, and then analysis on more sensitive instrumentation such as LC-MS/MS. The more problematic aspect of the analysis, however, is the background level of PFOS. This background can either be found in waters used for validation purposes to justify the reporting limit, or as part of the laboratory background level. It should be noted that even clean waters have quite significant levels of PFOS. Additional consideration should be given to any concentration step that may potentially lead to an increase in both the analyte and interferent signals.

Priority substances

Within this compound group, fluoranthene is another PAH with a revised EQS from 0.1 µg/l to 0.0063 µg/l. It presents similar issues to those discussed previously for benzo(a)pyrene, but to a lesser extent.

Nickel also sees the EQS level changed from 20 µg/l to 4 µg/l (lowest EQS), but neither of these present a significant analytical problem as nickel has been a determinand of environmental interest for many years and established analytical techniques, such as inductively coupled plasma-mass spectroscopy (ICP-MS), are easily able to determine nickel at levels around 10 times lower than the lowest EQS.

Specific pollutants

Existing compounds on the specific pollutants list have largely unchanged EQS values, in fact in some cases such as Toluene, the revised EQS value is now higher than the original, and with Permethrin, a non-existent EQS has been replaced with a value.

Toluene is a compound that has long been tested for as it is a widely used solvent and fuel component, which is soluble in water at around 0.52 g/l. Both the original EQS of 50 µg/l and the revised EQS of 74 µg/l are within the normal range of most methods of analysis – such as Headspace GC-MS or Purge and Trap GC-MS. Typical reporting limits are around 1 µg/l. This implies the testing of Toluene is straightforward.

While this is true in many cases, due to its wide ranging uses it is often found in marker pens that may be used to label environmental samples and can therefore be a source of contamination.

Permethrin is an insecticide and neurotoxin with an activity negatively correlated to temperature, which as such has a more acute effect in cold blooded animals such as insects, fish and frogs. It has a solubility of 5.5 µg/l and relatively long half-life in the environment and as such is recognised as a persistent organic pollutant (POP). Typical reporting limits are in the region of 0.01 µg/l, which means that permethrin is another analyte that presents the laboratory with some work to do when aiming to achieve reporting at the EQS level of 0.0002 µg/l. The analysis of permethrin lends itself to different options for extraction – either large volume liquid/liquid extraction or solid phase extraction, followed by analysis using specialist instrumentation: chemical ionisation with electron impact GC-MS/MS. At such low levels with complex extraction, the presence of background levels in the laboratory may present a significant effect on the analysis.

Analytical innovation

The original EQS (2008) supporting documentation 3 does give some guidance on standard analytical methods that may be employed for the analysis of pollutants; however, even at this time it was acknowledged that standard methods may not meet the required levels and since 2013 most of the EQS levels have been revised to lower values. EQS levels are largely derived from ecological and human toxicology data 4 and as such are not necessarily representative of what existing laboratory techniques are able to deliver, hence the setting of an EQS is a key driver in the innovation cycle for new and improved techniques.

Within the remit of the directive, new pollutants are often identified, thereby a new EQS is set and the cycle continues. With the European Water Framework directive being revised every two years and each member state setting a programme of chemical investigation, this legislation is constantly evolving and it can only be hoped that analytical techniques and capabilities are able to keep up with the rate of change.

Published: 16th Sep 2015 in AWE International

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