In order to assess whether the substances in the rubber granulate may have an effect on human health, it is important to know whether any substances may be released under the conditions in which people are exposed to rubber granulate. These could include contact with the skin, swallowing the granulate or inhaling substances that are released while playing sports.

What has been tested?

Rubber granulate samples were taken from 100 synthetic turf fields throughout the Netherlands. This was done to get a good, up-to-date picture of the concentrations of hazardous substances in rubber granulate. To do so, a random sample was drawn from a database of synthetic turf football fields from the KNVB, supplemented with korfball fields, rugby fields and ‘Cruyff Courts’: small football fields or synthetic turf ‘playing fields’ in neighbourhoods. The sample is a random selection of the locations in the Netherlands, the supplier of the material, the age of the rubber granulate and the frequency of use. The fields that are known to use a type of infill material other than rubber granulate from old car tyres were excluded.

Sampling method

Six sites were sampled on each field. These are standard sites that are prescribed by FIFA for testing field quality. Within a circle with a surface area of approx. 400 cm2 (the size of a bucket), rubber granulate was removed using a vacuum cleaner for 2 minutes. This provided approximately a litre of material. The ’gaps’ created by the sampling were subsequently filled with rubber granulate that lay alongside the field. The vacuum cleaner was properly cleaned after each field. The granulate was taken to the laboratory in glass bottles.

Standard analysis

A total of 600 granulate samples (100 fields x 6 samples) were analysed. All samples underwent a standard analysis for 45 hazardous substances that are already known to be potentially present in rubber granulate. These are PAHs (polycyclic aromatic hydrocarbons), heavy metals, volatile organic compounds and phthalates (plasticisers). Earlier studies also examined these substances. See the list of substances standard analysis.

Additional analyses

Three times as many samples were taken from 10 random fields to allow for counterchecks and extra analyses. These tests take more time and are labour-intensive. To ensure that no suspicious substances were overlooked, a ‘General unknown screening’ was performed. That way, substances could be detected that are not normally examined.

Results of field work

The chemical analyses of rubber granulate samples show that rubber granulate has several PAHs, metals, phthalates, benzothiazoles and phenols. Some of the samples also have low concentrations of PCBs. Metals that may be released in water are mainly from zinc, copper and cobalt. Various substances tested, including benzene, were not found in any sample.

There was little variation in the concentrations of substances between fields and between different measuring points per field. Nine of the 100 sampled fields showed that the grains partly came from materials other than rubber granulate from car tyres. Two of these fields contained rubber granulate with more phthalates (plasticisers) than other fields. These concentrations provide no risk to health. The 9 fields are not representative of synthetic turf fields with rubber granulate from car tyres. Therefore, the results from these fields were not included in the summary tables with measurement results.