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SBR granules used in artificial turf pitches have been subject to criticism for some time now. This is mainly due to the potentially carcinogenic polycyclic aromatic hydrocarbons (PAH) which they contain. Awareness of this problem originally caused a great deal of concern before it was put into perspective by various sources. The following provides a review of the problem.
At the end of 2016, artificial turf with SBR-filler material suddenly became a centre of attention. With a report titled "Gevaarlijk spel" (dangerous game) in the Dutch TV programme "Zembla", the public at large was made aware of the PAH content in artificial turf pitches. As a result, numerous football pitches in the Netherlands were closed due the possible serious consequences for players using this kind of pitch and amateur football came to a standstill in many places. It was not for some time and after tests had been made, that the all-clear was given by the authorities – the PAH is present, but within existing regulations and limits. This resolved the issue for the moment but the problem has not yet been finally clarified.
What are Polycyclic Aromatic Hydrocarbons (PAH)?
PAHs are created by the incomplete burning of organic materials such as oil, coal or wood. They can be released during natural processes (volcano eruptions etc.), industrial processes or private use, e.g. smoking or use of a grill. They are also contained in many plasticisers which are used for the manufacture of products for daily life, including tools, clothing or toys. The problem is that a group of eight PAH variants are scientifically classified as toxic and potentially carcinogenic; two of them also as potentially mutagenic. The most discussed compound is benzo[a]pyrene which has the highest number of negative properties. The SBR granules contain benzo[a]pyrene as well as many others of the PAHs which have an adverse effect on health. SBR stands for styrene butadiene rubber which is manufactured synthetically, mainly for the production of car tires. SBR granulate itself is made from recycled tires. Compared to other filler granulates, SBR is particularly low price and therefore, often used as filler for artificial turf pitches.
What are the existing regulations?
Due to the possible adverse effects of PAHs on health, there are different legal regulations which limit their use. First is the REACH regulation issued by the EU, which defines the registration, evaluation, authorisation and restriction of chemicals in Europe. This regulation lays down an admissible maximum value allowed for use of each individual PAH, which may not be exceeded during the manufacture of materials containing PAHs. It is differentiated, however, between two different classes of products with very different maximum values, "Mixtures" and "Articles". The definition of what a mixture actually is, is very special and usually not explicitly clear. Officially, something is an article when its "specific form, surface or shape" has a greater influence on defining its later function that its chemical composition. If this is the other way around, it is considered to be a mixture. This may sound rather banal, but actually has a very great impact on the admissible maximum values for PAHs. In "mixtures" (REACH Listing 28-30, Appendix XVII), a 100 to 1000 times higher quantity of dangerous PAHs is allowed than in "Articles" (REACH Listing 50/5, Appendix XVII). This also applies to the particularly dangerous benzo[a]pyrene: (Mixture maximum 100 mg/kg, in an Article, maximum 1 mg/kg). While many products in daily use which contain PAHs, such as clothing or toys, are classified as articles – for toys the admissible maximum value was even recently reduced to 0.5 mg/kg – the SBR granules in artificial turf are considered to be mixtures. This means that the admissible amount of benzo[a]pyrene can be up to 200 times higher than in children's toys.
Apart from the REACH regulations, the air and ground have also been tested for PAH content. The German federal soil protection legislation also defines maximum values for benzo[a]pyrene which differ according to the nature of use of the area. In Appendix 2, Para. 1.4, the maximum admissible value for children's playgrounds is 2 mg/kg of dry mass, in residential areas 4 and on sports grounds, 10.
What has happened so far?
Following the reports from the Netherlands, SBR-filled artificial turf pitches throughout Europe were tested for their PAH content. A range of very different results were obtained, but the maximum admissible values (for mixtures) were not exceeded. The European Chemicals Agency (ECHA) also took up the problem on the orders of the European Commission and published its findings at the beginning of 2017. Here, it stated that, "No reason has been found to advise players against sport on artificial turf pitches containing recycled rubber granules as filling material." Nowhere was the concentration of PAHs found to be conspicuous and the degree of concern was, according to the authorities, very low. A final report of the long-term examinations is, however, still not available today. The ECHA, however, is recommending a specific change to the REACH regulations with regard to PAH content in rubber granules, regular measurement of the PAH content in SBR-filled artificial-turf pitches, a more in-depth cooperation between manufacturers and associations as well as improved ventilation of indoor sports facilities with artificial turf surfaces with SBR-granules as filler material. In addition, players should remove granules from themselves, their equipment and clothing after playing on this kind of surface, wash their hands well and never to swallow any granules.
Which questions remain unanswered?
Although the PAH content of SBR-filled artificial turf pitches initially corresponds to the existing rules and regulations, some questions still remain unanswered. Above all the allocation of the granules in the REACH regulations, and the corresponding enormous differences between the maximum values, should be enough to awaken concern. Existing test measurements taken on artificial turf pitches have resulted in findings of quantities of the eight most dangerous PAHs, which are well below the limiting values for mixtures, but if the granulate was classified as an article, the maximum values would have been exceeded by far. Quantities of up to 2.38 mg/kg of the particularly critical benzo[a]pyrene have been measured, for an article, maximum 1 mg/kg are allowed. As the players come into direct bodily contact with the SBR similar to objects in daily use, the classification of the REACH regulations and the striking difference in the maximum values is difficult to understand. The German soil protection legislation should also be reconsidered. Why are the maximum admissible values for benzo[a]pyrene given for sports facilities 5 times higher than for children's playgrounds? Small children also play on artificial turf pitches and come into contact with the surface just as much as on a playground!
What should also be observed?
On the other hand it is naturally very difficult to prove which level of substance will have which possible adverse effects on health. It should also not be forgotten that the PAH-content is not only a problem belonging to artificial turf sports surfaces. Automotive exhaust gases and grilled meats often have just as high levels of PAHs, not to mention cigarette smoke. Another current topic being discussed is a ban on smoking in cars with children as passengers - and it is difficult to see why a ruling should apply in one case, but not in the other. Apart from this, production of SBR granules has so far been a good way to recycle old car tires and not many sensible alternatives are available for this process.
Outlook
Finally it would seem that further tests and investigations are necessary before a reliable evaluation of the situation can be made, and that existing rules and regulations will need to be revised. But it is also true that SBR granules are not the only product suitable for use as filler material for artificial turf pitches. Available alternatives include EPDM, TPE, PE Infill and cork products. These may be somewhat more expensive to purchase, but are completely harmless from a PAH-content point of view. It would of course also be possible to simply ban or no longer allow the use of SBR granules. This would probably be the simplest way to end the matter; but there are different interests involved. In the end, after considering all the pros and cons, every sports-facility owner can decide for themselves which granulate is to be used as filler for an artificial turf pitch.
TT
Photo: TT
