The study consisted of various components:

• Field work: taking samples around 10 sports pitches.
• Desk study
• Research conducted by the Foundation for Applied Water Research (STOWA). 

Scope and framework of the study

RIVM measured concentrations of a number of substances at 10 synthetic turf pitches with rubber granulate infill in the Netherlands. The ten pitches that were selected had been using rubber granulate infill for some time. The report states the locations of these pitches. Since it is not practically feasible to include all 2000 sports pitches in the Netherlands (or a representative sample) in this exploratory study, the pitches were selected based on a number of worst-case scenarios. One of the key selection criteria was the age of the pitch. Older pitches have had more time for substances to leach out and disperse, which should then be reflected in (elevated) concentrations in the environment. If no environmental risks are detected at these pitches, it is plausible to assume that there will be no problems at the other (comparable) pitches in the Netherlands. If environmental risks are detected, then similar problems could eventually occur at ‘younger’ pitches.

Between 30 January and 14 February 2018, RIVM worked with STOWA to take samples at the synthetic turf pitches and at the control locations (‘real grass’ pitches used for reference). The samples were taken from:

• drainage water 
• surface water (ditch water)
• water bed (‘sludge’)
• soil borders (0 – 10 cm)
• groundwater (shallow)

RIVM took measurements of the soil and groundwater beside the synthetic turf pitches, not under the pitches themselves. However, RIVM did measure the impact of substances that leached out of sublayers (bottom ash, etc.) and dispersed from there via groundwater and/or drainage water. The report shows photos of exactly where the samples were taken.

Information provided by sector associations, research firms, and municipalities about previous studies under and beside synthetic turf pitches was also expressly included. 

Rubber granulate contains hundreds of different substances. We could not measure all those substances in this study. For that reason, we focused on a number of key ‘indicator substances’, such as metals (e.g. heavy metals such as zinc, cobalt, copper and barium), polycyclic aromatic hydrocarbons (PAHs), mineral oils, and benzothiazoles. We know, based in part on the 2016 RIVM study, that these substances can be released from rubber granulate. The report contains a complete overview of all the substances included in the measurements.

Substance measurements and comparison to limits and risk thresholds

We measured substances in the groundwater, ditch water, soil and water bed in the immediate vicinity of the pitches. We also looked at the presence of rubber particles near sports pitches. We compared this information to environmental quality limits and risk thresholds for these substances and for rubber particles. The substances we measured included metals, benzothiazoles and PAHs. Since any contamination would involve environmental exposure not to one substance, but to several substances at once, we also looked at the impact of the substances in combination. 

Analyses

All the measurement results from the RIVM study are available for download.

Desk study

Additional research results were obtained by consulting online resources and by establishing personal contact with municipal authorities. It should be emphasised that this is not a comprehensive overview of all related soil studies conducted in the Netherlands. Moreover, the results of the individual studies were only evaluated in general terms. The other studies covered a total of 41 pitches, all of which used rubber granulate from car tyres as infill.

The STOWA study

At the same time as the RIVM study, STOWA conducted an impact assessment. This study used bioassays to assess the impact of rubber granulate on living organisms in the water and water bed. As a result, the impact of unknown substances that would not have necessarily been detected in the chemical analysis conducted by RIVM was also included through the bioassays. The STOWA study also ensured that mixture toxicity was taken into consideration.

An overview of measurement results is available as download