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Mapping, emissions and environmental and health assessment of chemical substances in artificial turf

3 Foreign studies

• • 3.1.1 Norwegian studies
  • 3.1.2 Swedish status report
  • 3.1.3 Dutch studies
  • 3.1.4 Swiss study
  • 3.1.5 French study
• 3.2 Overall conclusion of the foreign studies and strategy for this study

Detailed studies of artificial turf pitches have primarily been conducted in Norway (T. Källquist, 2005; C. Dye et al., 2006; T.S.W. Plesser, 2004; T. Sanner, 2006), but ongoing as well as concluded studies with comprehensive monitoring programmes for a number of environmental parameters are also being conducted in Sweden (Swedish Chemicals Agency (Kemikalieinspektionen), 2006), the Netherlands (Verschoor, 2007; M. van Bruggen et al., 2006; U. Hofstra, 2007; R. Moretto, 2007), Switzerland (E. Müller, 2007; H.J. Kolitzus, 2006) and France (R. Moretto, 2007). The Swedish report is primarily based on information from other sources.

3.1.1 Norwegian studies

Four Norwegian reports are available which, in different respects, assess health and environmental risks as a consequence of the laying and use of artificial turf pitches in Norway.

Two of the studies were conducted at the behest of the Norwegian Pollution Control Agency (Statens Forurensningstilsyn (SFT)) (T. Källquist, 2005; C. Dye et al., 2006). One was conducted for the Norwegian football association (T. Sanner, 2006), and the final one was conducted by Byggforsk (T.S.W. Plesser et al., 2004).

SINTEF Building and Infrastructure (Byggforsk) (T.S.W. Plesser et al., 2004) mentioned above has published its final report on potential health and environmental impacts associated with artificial turf pitches for the Norwegian football association in September 2004.

The Byggforsk study included three infill rubber granule types based on recycled rubber (all three presumably from tyres) and an EPDM rubber granule product (presumably not recycled). In addition, two artificial turf fibre types based on PE and PE/PP copolymer were used. One type was split fibre, the other monofibre. Split fibres are produced by slitting PE film. Monofibres are produced by each fibre being extruded separately. This should provide better long-term wear resistance.

The study analysed for total contents of arsenic, lead, cadmium, copper, chromium, mercury, PCB, PAH, phthalates and phenols in the materials. Furthermore, leaching tests and degassing tests were conducted.

The risk assessment was performed in a simplified version, as the total content of environmentally harmful substances in the source materials was compared to the SFT’s normative values for most sensitive area use. In Norway “most sensitive area use” means areas intended for housing, gardens, kindergartens, schools etc.

The contact water from the leaching tests of rubber granules from recycled rubber contained zinc, PAHs, phthalates and phenols. The amount of zinc places the contact water in the SFT class V (very polluted water), but it is lower than the zinc content allowed in the Canadian Environmental Quality Guidelines for drinking water.

The amount of antracene, fluoroanthene, pyrene, phthalates and nonylphenols is higher than that allowed in the Canadian Environmental Quality Guidelines.

According to the authors, it will require a more detailed risk analysis and further tests to determine whether there is a real risk of harm to the environment and health from the substances measured in the contact water.

The rubber granules from the recycled rubber emit a number of alkylated gaseous benzenes. In one of the tests, degassing of trichloromethane was detected, and in another cis-1,2-dichloroethene. The report recommends performing actual measurements on an artificial turf pitch in order to determine whether the emission is problematic.^[1]

With the exception of the of chromium and zinc content, the EPDM granules contained smaller amounts of environmentally dangerous substances than the granules from recycled rubber. EPDM also emitted smaller amounts of volatile substances.

In the actual artificial turf fibres, copper and zinc were detected. In both cases, the leaching of zinc from these types of artificial turf to demineralised water are above the SFT’s threshold values for zinc in drinking water (class V).

In one artificial fibre type, contents of octylphenol and nonylphenol were detected. Furthermore, DEHP was detected in both types of artificial fibre. One sample also contained DMP and DINP.

The Norwegian Institute for Water Research (Norsk Institutt for vannforskning) (T. Källquist, 2005) has assessed the environmental risk on the basis of studies of environmentally harmful substances existing in materials used when laying artificial turf pitches, and their potential as regards leaching via rainwater.

The risk was assessed on the basis of the results in the Byggforsk report described above, and by calculating the PEC/PNEC ratio, where:

PEC is “Predicted Environmental Concentration”, and PNEC is “Predicted No Effect Concentration”, i.e. the highest concentration which will not result in harmful impacts on the environment.

The assessment follows the standard procedures used in risk assessment of chemicals in the EU.

The scenario on which the assessment is based is an artificial turf pitch with an area of 7,200 m², annual precipitation of 800 mm and drainage into a nearby stream. Naturally, the flow rate in the stream will have an impact on the dilution ratio. This was set to be a factor of 10.

The amount of artificial fibre turf and rubber granules for a pitch with the area mentioned was set at 5,760 kg and 129,600 kg, respectively.

It is a supposition for the calculations that the concentrations found in the contact water are equilibrium concentrations, i.e. independent of the water/material volume ratio.

The calculations showed that there is a possibility of environmental impacts for small recipients receiving surface water from artificial turf pitches.

The substances contributing the most are zinc and alkylphenols (in particular octylphenol).

The concentration of leached substances is expected to diminish, but over many years.

The amounts leached into the water are modest, and according to the report, any environmental impacts will therefore only be local.

In order to obtain a better basis for evaluating the environmental impacts of the artificial turf pitches, the authors believe that measurements should be conducted directly on drains from laid artificial turf pitches. The measurements should include toxicity tests.

The Norwegian Institute for Air Research (Norsk Institutt for Luftforskning (NILU)) conducted air pollution measurements in three indoor artificial turf sports halls in 2005 (C. Dye et al., 2006).

The measurements were conducted for artificial turf pitches with newly laid rubber granules (SBR tyres), with rubber granules laid one year previously (SBR tyres) and for an artificial turf pitch with thermoplastic elastomer (TPE) infill.

The measuring programme included analysing flying dust PM₁₀ and PM_2.5 for the proportion of rubber, and the concentration of vulcanisation compounds, anti-ageing agents, phthalates and tar substances (PAHs). Furthermore, measurements were made for volatile organic compounds (VOC) and polycyclic aromatic hydrocarbons (PAHs) in the air phase.

Measurements were made for the total sum of volatile organic compounds (TVOC) in the three sports halls, as well as for a wide range of specific volatile compounds.

The study lists concentrations for benzothiazole, toluene, 4-methyl-2-pentanone, diethyl phthalate (DEP), diisobutyl phthalate (DIBP) and dibutyl phthalate (DBP) as well as TVOC. TVOC was in the interval 136 µg/m³ to 716 µg/m³. The largest concentrations were found for toluene: 15-85 µg/m³ and benzothiazole: 3-16 µg/m³.

The study concludes that TPE provides a lower TVOC than the granules based on SBR from used tyres.

The content of organic materials in the flying dust was considerable in all three sports halls. Typically, these are PAHs, phthalates, semi-volatile organic compounds, benzothiazoles and aromatic amines.

In the report (T. Sanner, 2006) prepared by the Norwegian Institute of Public Health (Nasjonalt folkehelseinstitutt) and the Radium Hospital (Radiumhospitalet), the health risk for football players was assessed.

The assessment used nine exposure scenarios, including inhalation via the respiratory passages, skin exposure and oral intake.

The inhalation scenarios are based on the highest detected VOC level of approx. 716 µg/m³, even though VOC in the other two sports halls monitored was 2.5-3 times lower.

On the basis of the scenarios, the report concludes that, based on the exposures calculated from the use of indoor halls with artificial turf, and where granulated rubber from discarded car tyres is used, there is no reason to assume that these will lead to an increased health risk. However, certain reservations are made regarding the development of asthma/airway allergies, in which area the existing knowledge is limited. This applies in particular to latex allergenes.

It is an open question whether these latex allergenes can occur in dust from artificial turf pitches with infill based on discarded car tyres.

For several of the detected substances in the sports hall air, the toxicological knowledge is limited. However, the concentrations of the substances are very low, and for this reason they are not expected to pose any health risk.

According to the report, the exposure amounts for benzene and PAHs pose no health risks.

According to the authors, it is deemed necessary to replace the current SBR rubber granule infill in the sports halls based on the existing knowledge on health effects, but it is recommended that when adding infill, recycled SBR from tyres should not be used, as there is a possible risk of inducing latex allergy.

3.1.2 Swedish status report

In 2006, the Swedish Chemicals Agency (Kemikalieinspektionen) published a status report “Artificial turf from a chemical perspective” (Konstgræs ur et kemikalieperspektiv) (Kemikalieinspektionen, 2006) concerning health and environmental problems in connection with the use of artificial turf.

The report focuses exclusively on artificial turf football pitches with an infill made from recycled car tyres.

According to the report from June 2006, Sweden has approx. 150 artificial turf football pitches laid on infill made from rubber granules from recycled tyres.

Most pitches are for outdoor use, but indoor pitches also exist.

In the Stockholm area alone, there are apparently plans for 30 new artificial turf pitches.

It is assessed that approx. 90% of the pitches will be based on infill from recycled tyres.

To a large extent, the report is based on the Norwegian studies, the results of which are reviewed.

There are also references to a few individual measurements in artificial turf halls in Sweden.

Measurements and calculations showed a very low content of benzo(a)pyrene, approx. 10,000 times lower than the threshold set by the Swedish working environment authority.

The report reviews European guidelines, including the German provisional standard DIN 18035-7:2002.

The report finally concludes that granules from recycled rubber originating from car tyres should not be used as infill when laying new artificial turf pitches. The reason for this is an environmental objective set by the Swedish parliament, determining that materials containing particularly dangerous substances should not be used.

The other conclusions are very close to the corresponding Norwegian recommendations and with the very same arguments.

3.1.3 Dutch studies

Three comprehensive Dutch studies are available (A.J. Verschoor, 2007; M. van Bruggen et al., 2006; U. Hofstra, 2007):

• RIVM report 601774001, on the leaching of zinc from rubber infill in artificial turf pitches (A.J. Verschoor, 2007)
• RIVM report 609300001, on nitrosamines in rubber granules (M. van Bruggen)
• INTRON report on health and environmental aspects of infill rubber granules from recycled car tyres (in Dutch, but with English summary) (U. Hofstra, 2007).

The report on zinc leaching concludes that the leaching of zinc from SBR infill will show an increasing trend as a consequence of the ageing of the rubber. It is assessed that the zinc impact from infill will be 800 mg/m²/year. In the Dutch Building Materials Decree, an acceptable zinc impact is set at 2,100 mg/m²/100 years. According to the authors, this value is thus exceeded already after approx. three years. It is stated that the zinc impact locally would be approx. 20 times higher than from agriculture (slurry manure and pesticides).

The report concludes that further studies on zinc leaching could reduce the experimental uncertainty which underlies the risk assessment.

It is suggested that studies be made on the ageing of different types of rubber and on the effect of the ageing on the leaching of zinc and other substances which may migrate from rubber.

Furthermore, field measurements are suggested for artificial turf pitches with infill rubber of different ages and qualities. Bioassays of the drainage water are recommended to determine the impact of the mixture of substances emitted from the infill material. Finally, mini field tests (lysimeter) are recommended – e.g. on 1 m³ samples.

An INTRON report (U. Hofstra, 2007) concludes that leaching of zinc from rubber granules from used car tyres is considered to be the most serious source of environmental pollution from outdoor artificial turf pitches. It states that the Dutch threshold values for zinc emissions are expected to be exceeded within a 3-20 years utilisation phase.

A conference presentation (N. Salzmann, 2006) concludes that the amount of airborne nitrosamines (N-nitrosodimethylamine) measured on a pitch^[2] is higher than the health threshold. The assessment is based on a scenario in which the pitch is used for football three times a week for a duration of two hours. According to the paper, the threshold was exceeded after eight years. There were no further details about the experimental parameters and the monitoring.

In another very comprehensive study (P.C.J.M. Janssen, 2006), the concentration of nitrosamines was measured in the air above four artificial turf football pitches in Arnhem at a height of 30-100 cm. It was concluded that nitrosamines could not be detected in the air. Laboratory measurements detected nitrosamines in small concentrations in the actual infill material.

The overall conclusion of this study was that nitrosamines are not a health problem (contrary to the conclusion above).

As regards health risks in the form of skin contact, inhalation or oral intake, it is concluded that there is no significant risk for football players as a consequence of infill in artificial turf pitches based on rubber granules from used car tyres.

3.1.4 Swiss study

In Bern, Switzerland, a project was launched in May 2006 involving at least one year of monitoring of the leaching of selected chemical substances and common parameters (H.J. Kolitzus, 2006).

The study was based on the use of lysimeters, which are used for e.g. studies of the uptake of nutrients by plants. The lysimeters are constructed from reinforced polyester tubes with a diameter of 1 m and a height of 1.5 m. The tubes contain an automatic water collection system. This enables collection of the total amount of rainwater from an artificial turf surface. The collected water is subsequently analysed.

Figure 3.1 Lysimeter test, Bern, Switzerland

Collection takes place in containers connected to the concrete bottoms of the lysimeters.

For the test series, ten different types of surface were selected, which are used in connection with the laying of artificial turf pitches.

EPDM and SBR rubber are included as infill material, as is sand and different types of support layers, e.g. bitumen-based or as recycled SBR rubber granules on top of a free mineral support layer.

A preliminary conclusion has been made on the basis of test results from May-September 2006.

Emissions of aromatic amine complexes and benzothiazoles were detected in the concentration range 10-300 µg/l, but no significant discharge of PAHs to the drainage water was detected, and this was also the case for recycled SBR. The detection limit for the individual PAHs was at approx. 0.02 µg/l.

The preliminary conclusions of the completed study, prepared in German by E. Müller, the professional expert associated with the study, were sent to the Danish Technological Institute by email on 29 August 2007.

In addition, the results were summarised (E. Müller, 2007) in September 2007 at a meeting arranged by the German BASPO (Bundesamt für Sport (Federal Office for Sport) in Magglingen, Switzerland.

Below is the English translation (from Danish) of the most important information and conclusions from the study.

Figure 3.2 Detail from lysimeter tests in Bern, Switzerland

Table 3.1 Studied artificial turf materials in the Swiss lysimeter tests

The study included leaching of the following chemical substances and common parameters:

• Aniline
• Alkylated phenylene diamines
• Benzothiazole
• 16 PAHs
• Zinc
• Ammonium nitrogen
• Nitrate nitrogen
• Nitrite nitrogen
• Sum of dissolved organic nitrogen compounds
• Sum of dissolved organic compounds (DOC)

Additional determination of the zinc content of the different rubber granules was made, as well as thermal analyses and leaching tests in order to characterise the different granules.

It was concluded that with modern analytical measuring equipment, it is possible to detect even the smallest traces of organic substances. The substances are washed from the surface by rainwater after a relatively short period of time. At the end of the one-year period, the concentrations of leached substances were in almost all cases smaller than the detection limit of 0.2 µl per litre. In leaching tests in the laboratory, the leaching profile from the artificial turf pitches was confirmed in the lysimeter tests.

It was also established that the substances leached from rubber granule infills and rubber pads are the same substances which are drained from roads as a result of rubber wear particles from the car tyres, and which are discharged from municipal treatment plants.

During the one-year study period, there was no increase in the leached amount of zinc ions to the aquatic environment. All tests showed the same low content of PAHs on a level with the contents of the O samples. No health or environmentally harmful PAHs could be detected in the water from the tests.

The preliminary conclusion is as follows:

• The rubber granules and elastic pads used for artificial turf pitches are insoluble in water. All granules, newly manufactured as well as granules from crushed car tyres, leave traces of chemical substances which can be detected in the rainwater collected.
• The organic substances present on the surface of the rubber granules will be leached by the rainwater within a short period of time.
• With the knowledge we have today, there is no foundation for any claim about environmental problems concerning the leaching of undesirable chemical substances from artificial turf pitches and elastic layers (infill and pad). However, no long-term studies are available (covering several years).
• The preparation of testing methods and norms should be discouraged as the necessary basis for their development is not available.

3.1.5 French study

A French study is available (R. Moretto, 2007) which was prepared for ADEME, Aliapur and Fieldturf Tarkett i 2007. Aliapur is a French company involved in granulating tyres in France. In 2005, the company’s production of rubber granules from tyres corresponded to a volume of 283,000 tonnes of tyres (85% of tyre refuse in the French market). Fieldturf Tarkett is one of the major international players within third-generation artificial turf. Annually, the company lays 650 major sports pitches, of which 100 were laid in France in 2006. ADEME is the French ministry of the environment, which has supported the fact-finding project. The practical implementation took place in a French research network (EEDEMS).

The study was initiated on the basis of, among other things, the information (the Norwegian reports and the Swedish report) which was presented on the possible health and environmental problems in using recycled tyres as infill for artificial turf pitches.

The reports also formed the basis for implementing some of the studies referred to previously, e.g. those from the Netherlands and Switzerland.

The study included environmental impacts on water as well as an assessment of the health risks associated with gaseous emissions.

As regards materials, the studies included artificial fibres from Fieldturf Tarkett combined with granules from used tyres, virgin EPDM and TPE-based infill.

3.1.5.1 Discharge of substances into water

In the studies involving the discharge of substances into water, infill sand was included as well as the joinings and the polyurethane adhesive used to join the artificial turf pitches.

17.5 kg of sand and 15 kg of elastic infill were used in the experiments.

The experiments were performed as in situ experiments and pilot scenario experiments.

For the in situ experiments, a lysimeter system was applied. The system was based on a stainless steel tray with a surface area of 2 m² and a height of 10 cm at one end and 5 cm at the other. The tray was placed in an artificial turf football pitch. The rainwater percolate was collected in the bottom of the tray and pumped into analysis receptacles.

The monitoring period was 11 months.

For the pilot studies, rectangular aluminium tanks with a length of 2.5 m and a width of 1 m were used. Bottoms and sides were based on waterproof geomembranes. The percolate was collected via drainage pipes at the bottom of the structure.

The test setup was indoors, and rain simulation was carried out by using nozzles which dosed an amount of water corresponding to the average precipitation in a number of European capitals (800 mm of rain annually).

As with the in situ experiments, the monitoring period was 11 months.

The analysis programme in connection with the two types of test setups was extensive. For instance, 42 chemical/physical parameters were monitored:

Total cyanide, phenolic index, total hydrocarbons (THC), 16 PAHs, TOC, Al, As, Ba, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Sb, Se, Sn, Zn, fluorides, nitrates, ammonium, chlorides and sulphates as well as pH and conductivity.

Furthermore, ecotoxicological characterisation of the percolates was carried out through inhibition tests with Daphnia magna in accordance with EN ISO 6341 and with Pseudokirchneriella subcapitata in accordance with EN ISO 28692 (inhibition of algae).

The volume of water dosed in the four pilot studies was 800 l/m²/15 kg of granulate, and the percolate collected was 580 l/m². This is taken to indicate that approx. 27-30% of the water evaporates into the atmosphere.

The conclusion from the two types of experiments is that the concentrations of the substances and common parameters measured are compatible with French and European guidelines, but the authors have not provided detailed specification of the guidelines to which reference is made.

The conclusion from the ecotoxicity tests is that the percolate from third-generation artificial turf pitches, regardless of the type of infill, does not demonstrate a negative impact on the environment.

3.1.5.2 Emission of volatile substances

In the studies looking at the emission of volatile substances, the following materials were tested: artificial turf with green artificial fibres including a band of white fibres, polyurethane adhesive, sand and three different infill granulates. EPDM, SBR from used car tyres and TPE were used as granulates.

As in the studies for discharge into water, 17.5 kg of sand and 15 kg of elastic infill were used in the experiments.

For a sample of 0.15 m², which was actually tested, this corresponded to 2.625 kg of sand and 2.25 kg of granulate.

The test was performed on sample material placed in steel trays measuring 0.78 m x 0.19 m at 23°C and a relative humidity of 50% ± 5%. The test was conducted in accordance with prEn ISO 16000-9: Indoor air – Part 9: Determination of the emission of volatile organic compounds from building products and furnishing – Emission test chamber method.

A specific ventilation speed of q = 1.25 m^3/m²/h was used.

The tests measured for VOC and aldehydes.

The conclusion from the studies were:

• The emission from artificial turf alone is very low (TVOC = 8.3 µg/m³ over a period of 28 days) compared to parquet flooring.
• The emission from artificial turf with granulate from used tyres as infill is low (TVOC = 134 µg/m³ over a period of 28 days).
• The emission from artificial turf with TPE granulate as infill is also low (TVOC = 118 µg/m³ over a period of 28 days).
• The emission from artificial turf with EPDM as infill is higher (TVOC =490 µg/m³ over a period of 28 days).

On the basis of a worst case scenario (for indoor use, the starting point is a hall with an artificial turf surface of 1,800 m² and a volume of 20,000 m³), it was concluded that:

• On the basis of the concentration of VOC and aldehyde emitted to the indoor air, there should be no concerns in connection with outdoor use of artificial turf pitches seen from a health perspective.
• On the same background of measurements, neither should there be any concerns in connection with indoor use, seen from a health perspective. This applies to professional athletes, amateur athletes, children and adults as well as the people installing the pitches.

There exists, however, a risk for the people installing the indoor artificial turf pitches if this takes place in badly ventilated halls over a period of more than five years. In such cases, air replacement of two volumes per hour is recommended.

It should be added that the conclusions regarding the impact as a result of the discharge of substances into water were made on a short-term and medium-term basis.

Furthermore, it was emphasised that there is a comparable impact from the infill material, regardless whether this is based on virgin TPE and EPDM or on granulate from used car tyres.

The conclusion is interesting when compared to the conclusions of the Norwegian, Swedish and Dutch studies. On the basis of the French study, there are thus no grounds for phasing out the use of granulated car tyres (SBR), and in this study, EPDM emits more VOC than SBR. It should be noted, however, that there are many different recipes for EPDM, so a particularly oily type may have been chosen for the comparison.

3.2 Overall conclusion of the foreign studies and strategy for this study

Overall, it can be concluded that more or less all foreign studies conclude that there are no health problems for users of artificial turf pitches, neither indoors or outdoors.

On the other hand, the foreign studies do not reach a common conclusion as regards recommendations/preferences regarding the use of different infill materials for artificial turf pitches and their environmental impact. Here, the results of lysimeter studies carried out in France and Switzerland indicate that, in practice, there should be no problems in using granulated car tyres as infill in the pitches, compared to other infill types. A Dutch study concludes that increased zinc leaching may occur from granulated car tyres as a result of ageing of the rubber. This is the only report making this hypothesis. In Norway, the risk of an environmental impact as a result of leaching of chemical substances from granulated tyres is assessed to be small, with the exception of particularly sensitive areas. The Swedish status report discourages the use of granulated car tyres with reference to restrictions in Swedish law. No lysimeter tests have been carried out in Sweden unlike in France and Switzerland, but the conclusion was largely based on the Norwegian studies.

The foreign studies include a limited number of artificial turf mats and infill types. For instance, coir infill and grey industrial rubber have not been reviewed. This Danish study has therefore emphasised collecting as many different types of artificial turf mats and infills as possible in order to perform a mutual comparison of the materials used on the market as well as the chemistry associated therewith.

In the assessment of the environmental impact on soil and groundwater from the pitches, the Danish Environmental Protection Agency has also been interested in mapping and reviewing the significance of using salt on the artificial turf pitches, as well as the use of any herbicides. This interest is related to the weather in Denmark as well as the fact that all Danish artificial turf pitches, with the exception of two, are outdoors. One Danish municipality has used large quantities of salt, and a hypothesis was therefore made that larger volumes of salt in the form of sodium chloride, as a result of the change in ion strength, could increase the leaching of certain substances to the water and soil. Calcium chloride or magnesium chloride are also used for salting, and it is therefore also possible that divalent positive ions (Ca⁺⁺ and Mg⁺⁺) could have an impact on the leaching of zinc from the artificial turf pitches containing zinc.

The strategy of this project has therefore been to provide comparisons between the artificial turf mats and infill materials available in Denmark, with the main emphasis being on the environmental impact on the soil and water from outdoor artificial turf pitches. At the same time, the focus on the health assessment of the impact on users in connection with contact and inhalation was reduced during the project period as a consequence of the results which were published during the course of the project, and which, more or less without exception, conclude that there are no health problems associated with the use of artificial turf pitches, regardless of the infill type.

Footnotes

^[1] It is not indicated whether the pitch is indoors or outdoors.

^[2] It is not indicated whether the pitch is indoors or outdoors.

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